GB2581071A - Hybrid energy storage devices including support filaments - Google Patents

Abstract

An electrode comprises a conductive substrate 105, and a material comprising (i) a plurality of carbon nanofibres 110 acting as support fibres; (ii) a binder 1140; (iii) a faradaic material that interacts with charge carriers on a surface of the material, which comprises an intercalation material 1610; and (iv) a plurality of nanoparticles 1430. The intercalation material may be Si and may be coated on the carbon nanofibres, and the nanoparticles may be concentrated on the surface of the intercalation material (figure 18). The carbon nanofibres may be detached from the substrate and connected thereto via the binder (as shown), or may be directly connected to the substrate, preferably in an array of vertically aligned fibres (Fig 14). The highly conductive and mechanically stable CNF core supporting a coaxially coated amorphous Si shell is claimed to have a higher theoretical specific capacity by forming a fully lithiated alloy. Addition of the nanoparticles provide surface effect dominant sites in close proximity to the intercalation medium, resulting in a hybrid device that includes advantages of both batteries and capacitors.

Description

Hybrid Energy E.nerly Storage Devices Including Support /ii, -n CROSS-R 1 ER;NCF 10 RELATED APPLI T1ONS 10011 This application is: a continuation-m-pa t of U.S. n:*n-provisional patent application 77/ 409 filed February 1013; a continuation-in-part of U.S. non-provisional patent application Ser. No. 13/725,969 tiled December 21, 2012; and claims benefit and priority to U.S. provisional patent applications: 61/667,876 tiled Jul. 3, 2012, 61/677,317 filed Jul. 30, 2012, tiled March 29, 2013, and 61/752437 filed Jan 14, 2013, This application is also related to U.S. nompro isional patent app Lie ations 131779,47? 13%779,c1. 13/779,571 all filed on March 26, 2013.

[002] The disclosures of all the above provisional and non-provisional: patent applications are hereby incorporated herein by reference.

BACK ICU D

[003 Field Or e Invention

100,11he invention is in the field of energy storage devices, including but not limited to batteries, capacitors and Fuel cells.

[0061 Rechargeable lithium ion batteries are key F lectrical energy slot ege devices for power supply in portable electron:power tools, and fun vehicles. Improving the specific energy capacity, cli g speed, and cling lifetime is en broader applications.

10071 in current commercial Li-ion o her carbonaceous materials are used as the a ie awe a theoretical ca calmed L C,, compound. in contrast, silicon has a much hie* ecific capacity of 4.2 /g by forming fully lithiated alloy LiaaSi, he 1. rue volume expansion of titillated Si by up to -300-400% causes great structuralthat in the past in itably lead to fractures and mechanical failure, which significantly limited the hFatime of prior art Si anodes.

SUMMARY

- . some embodiments, a power storage device includes a hybrid core-shell N (nano-wirer architecture i high-perfonnance anode by incorporating an arra vertically aligned carbon nanofibers CV ACNI's) coa y coated with a. CT of amorphous silicon. The ity aligned (NE's include multiwalled carbon nanotuhes (MWCNTs), which are optionally grown on a Cu substrate using a DC-biased plasma chemical vapor deposition (PECVD) process. The carbon nanofibers (CNFs) grown by this method can have a unique interior morphology distinguishing them from the hollow structure of common MWCNTs and conventional solid carbon nanofibers, One of the distinguishing characteristics is that these CNFs optionally consist of a series of bamboo-like nodes across the mostly hollow central channel. This microstructure can he attributed to a stack of conical graphitic cups discussed further elsewhere herein. In larger length scale, these PECVD-grown CNFs are typically uniformly aligned normal Iratesumac separated from each other. They 'nay be without any entanglem nt or minimal entanglement, and thus form ahush-Likereferred to as a VACINE array, diameter of individual CNFs can be selected to provide desired. me'chantcal strength so that the VA NF array is robust and can set-till its integrity ti epOS nn electrochemical tests.

[009 at o s embodiments of the invention include s of support i ther than VACNFs. These support filaments can include, P3r example, nanowires; carbon sheets or other structures described herein. Other embodiments ot include any support filaments and use a binder instead.

10010! Various embodiments ofthe intention include an energy storage system comprising a conductive substrate; a plurainv a# verttcally aligned carbon nanofibers grown on the suns rate, the carbon nanofibers inch. nu a plurality multi-walled carbon nanotubest and an electrolyte including one or more charge earners.

100111 Various embodiments of the invention include an energy storage system compnsmg a conductive substrate; a plurality of vertically aligned carbon nanofibers grown on the substrate; and a layer of intercalation erial disposed on the plurality tinned carbon nanofibers and configured to have a lithium ion storage capacity ofbetween approximately 1,500 and 4.000 rnAh per gram of intercalation material.

100121 Various embodiments of the invention include an energy storage system conductive ubstrate; a plurality of vertically aligned hot nanofibers grown on the substrate; and a layer of intercalation material disposed on the plurality of vertically aligned carbon nanofibers and configured such that an ion storage capacity of the intercalation material is appn nattily the same at charging tes of IC and 3C.

100131 Various embodiments of the invention include a method of producing n erten storage 1ec, the method comprising providi on -tubers on the subs carbon nonofibers havinga - one structi plying intercalaLion material to the carbon nanofibers, the intercalation material being intercalation c, i - the invention include an comprising: 100141 Various an electrolyte includingmore charge carriers conductive substrate; a plurality of td filaments attached to:pion material disposed on each of the support filaments and configured to reversibly adsorb members of the charge carriers within a bulk of the tt;c intercalationmaterial; and a binder disposed on the intercalation material and including a plum nan ti -1-s each of the nanopanicies bei to provide urface effect dominant sites confilgured to adsorb members of the charge carriers via laradaic interactions on surfaces of the nanopartieles.

l0015! Various embodiments of the invention include an energy storaue system comprising: art electrolyte tiding one or more charge carriers; a conductive substrate; a plurality of support filaments attached to the substrate; intercalation material disposed on each of the support filaments and configured to reversibly adsorb members of he charge -a s within a bulk of the intercalation material; and a binder disposed on the intercalation trial and including a plurality of surface effect dominant sites configured to catalyze intercalation of the charge carriers into the intercalation material.

f00161 Various embodiments of the invention include an energy storage system com an electrolyte including one or more charge carriers; conductive substrate; intercalation material configured to reversibly adsorb members of the charge carriers within a bulk of the intercalation material; and a binder disposed on the intercalation material and including a plurality of nanoparticles, each of the nanoparticles being configured to provide surface effect dominant sites o donate electrons to members of the charge carriers interactions on.surface of the nanoparticles.

(00171 Various embodiments of the inl ention include energy storage system comprising: a cathode; and an anode separated from the cathode by an elc etrolyt. including one or more charge earners, the anode compnintercalation materialo d to iniercal 0e carriers and ate electrons to ti arriers at a first cacti( moparticies including surface ef dominant sit eketrons to the charge carriers absolute difference e the Last reaction potential and t,e se potential being less a 2.4V.

s ime of the i meant le a system comprising means for establishing a 'potential grat ode ofa charge storage device, the a an electrolyte, a plurality of surface effect dominant sites, an ntercalation material and a substrate; means for receiving a charge of the electrolyte at one of the surface eff nt sites; means for receiving electron at the charge carrier from erne o effect dominant sites;, and means for receiving a charge carrier at the intercalation material. 11)0191 Various embodiments of the invention include a method of producing an energy storage device, the method comprising: providing a conductive substrate; growing support filaments on the substrate; applying intercalation material to the support nark:fibers, the intercalation material being configured for intercalation of charge carriers; and applying a plurality of surface effect dominant sites in close proximity to the intercalation material. 100201 Various embodiments of the invention include a method of producing an anode, the method comprising: providing a conductive substrate; mixing binding material, surface effect dominant sites and intercalation material, the surface effect dominant sites i configured to accept electrons from charge carriers at a first reaction potential and the on material being configure pt hi carriers or electrons from the charge carriers at a second reaction and applying the material, surface poten inant sites and intercalation material the b [0021] Various e cull n include a method of product ei n storage device the method co,.., g: prot iding a conductive substrate; providing support filaments; applying di., 1 to the support filaments, the intercalation m aerial being configured for intercalation of (immix arriers, and adding surface effect dominant sites to the support filaments.

[00221 device, the method cot P, chase sto charge cirri I the ini cntion inelude a method of charging a charge scot g establishing a potential between a cathode and an anode the harge storage devises; including an electrolyte; reee !hie at a surface effect d of e anode: transferring electron of the anode to the first charge ca if a second charge carrier of the electrolyte at an 1 lation material of the anode; and transferring an electron om the intercalation material to the second charge ca [00231 Various embodiments of the invention include a method of charging a charge storage device, the method cc p tablishing a potential gradient at an anode of the charge storage -vice, the anode including an electrolyte. a plurality of nanoparticles having surface dominantmaterial and to substrate receiving a first charge carrier of the electrolyte at one of the surface eff set dominant sites; transferring an electron to the first charge carrier from the orle of the surface effect dominant sites; receiving a second charge carrier at the intercalation material of the anode; and transferring an electron from the intercalation finial to the second charge carrier.

100241 Various embodiments of the invention Include an isrgy storage system comprising conductive substrate; a carbon nanofiber, or other support filament, connected to the conductive substrate, the carbon nanofiber including a plurality of exposed nanoscale edges along the ength of the carbon nanofiber; and an inter on material configured to form a shell over at least part of the carbon nano fiber.

100251 Various embodiment-of the inventioninclude an enc gy storage system such as a battery sir electrode,compr conductive substrate; a carbon nanotiber, or other support he conductive substrate, nanofiber includi re th f the carbonnanofiber; a id an art int configured to form a shell over ast par. el.

[00261 k arotts embodiments of the in enhon include an enemy storage system comprising conductive mbstratet a carbon nanolthe support n3rnent, connected to the conductiv sub material configured to form a shell over at least of the carb on r,tiio ibexc intercalation material posed iit a feather-like structure along a length of the carbon artofiber.

100271 Various embodiments of the invention include an energy storage system comprising a conductive substrate; a carbon nanofiber connected to the conductive substrate; and an intercalation t configured to form a shell over at least part of the carbon nanofiber, the ntercalation mater being configured such that expansion of the intercalation material is non-delaminating of the intercalation material from the carbon nanofiber.

100281 Various embodiments of the aveniion include29. A method of producing an energy storage device, the method comprising providing a conductive substrate; adding carbon nanofibers to the conductive substrate, the arbor! ft -gibers each includin a plurality of exposed nanoscale edges along the length of the carbon nanofiber; and applying intercalation material to the carbon nanofibers, the termilation material being configured for intercalation of charge carriers.

[00291 Various embodiments f the invention:elude a method of producing storage device:, the method comprising providing a conductive substrate; adding carbon nanofibers to the conductive substrate; carbon nanofibers each including a pi urality of cup-like structureslength of the carbon nanofiber; and applyin [ to the carbon nanofibers, the intercalation martial being configured or intercalation of charge. carriers, [00301 Various embodiments of the e invention include a method of producing an energy St0 ethod co noising providingconductive subseat adding nanofibers ducti s applying inter the carbon nanofibers, the intercalation 1, being configured of charge car and the intercalation material being disposed in a ream, carbon nanotibet.

BRIEF DESCRIPTION OF TUE

IA and 1F3 illustrate a CNF array comprising a plurality of CNF tzrown on a substrate, according to various embodiments of the ins ention.

[00321 FIGs. 2A-2C illustrate a plurality of vertically aligned CNFs ra stales, according to carious embodiments of the invention.

100331 FIGs. 3A-3C illustrate details of a CNF, according to various embodiments of the invention.

100341 FIG. 4 illustrates a schematic of the stacked-cone structure of a C NF, according to various embodiments of the invention.

[00351 FIGS. 5A-5C illustrate an electrochemical characterization of -3 according to various embodiments of the invention.

100361 FIGS. 6A-6C illustrates scanning electron microscopy images of 3long CNFs, according to various embodiments of theinvention_ 100371 FICis, 7A-7C illustrate results obtaine s including a Si layer as Li-ion battery anodes, according to various embodiments oT the inventio 100381 FIG. 8 illusunt capacityof a CNF array char rate, accord ions eu; according to to embodiments of 100391 FIG. 9 illustratesRam rn s spectra of C the invention.

[00401 FIGs. li;A-I OC shows the variation ofLi insertio C I efficiency over 15 charge-discharge cycles, ace and the eruhod the inventio [0041] FiGs. I.11C show scanning electron microscopy images of freshly prepared GNI' arrays, according to various embodiments of the invention, [00421 FIG. 1]D shows a cross-section of a nanofiberlsilicon complex including more than one CNF.

00431 FIG. 12 illustrates a carbon nano-fiber array including fibers of 10 um in length, according to various embodiments of the invention.

[00441 FIG. 13 illustrates methods of producing C.NF arrays and/or CNFs, according to various embodiments of the invention.

100451 FIG. 14A illustrates a CNF including a power enhancement material, according to various embodiments of the invention.

100461 FIG. 14B illustrates detail of the power enhancement material illustrated in FIG, 14A, according to various embodiments of the invention.

[0047i FIG. 14C illustrates alternative detail of the power enhancement material illustrated in FIG. WA, according to various embodiments of the invention.

100481 FIG. 15 illustrates an electrode surface including a power enhancement material and non-aligned CNTls coated by intercalation material, according to various embodiments of the invention.

10049i FIG. 16 illustrates an electrode surface including power enhancement material, nonaligned Chifs and free intercalation material, according to various embodiments of the invention.

100501 FIG. 17 illustrates an electrode surface including intercalation material and power enhancement material, without CrsiFs, according to various embodiments of the invention. 100511 FIG. S illustrates an electrode surface including surface effect dominant sites disposed in close proximity to CNIiis. according to various embodiments of the invention, 100521 FtGs. 19 and 2 *t a resin on lauding surface effect enult disposed in close proximity of the invert:loft corninci to 100531 FIG 21 illustrates methods a s i n n electrode surface.ccordilru-to various embodiments of the invention.

100541 FIG, illustrates methods of operating a charge storage device, according to various embodiments of the Invention.

DETAIL 12'C PTION 100551 FIGS. IA and lB illustrate a CLINT Array 100 comprising a plurality of (NV 110 grown on aconductive Substrate 105, according to various embodiments of theinvention_ In FIG lA the CNF Array 100 is shown in the Lextracted (discharged) state and in FIG. CNF Array 100 is shown in the Li inserted (charged) state. The CNF 110 in these and other embodiments discussed herein are optionally vertically aligned. The CNF 110 arc grown on a Substrate 105 of Cu using a DC-biased plasma chemical vapor deposition (PECYD) process.

As discussed above, the CNFs 110 grown by this method can have a unique n ology that includes a stack of conical graphitic structures similar to stacked cups or cones or a spiral.

This creates a very fine structure that facilitates lithium rcalation. -referred to here as the "stacked-cone" structure elsewhere herein. In larger length scale, these CNIls 110 are typically uniformly aligned normal to the s hstrate surface and are separated from each other. The diameter of India idual CNIN can be selected to provide desired mechanical mech.nical strength so that the CM' y 100 is robust and can retain its l.tegnt through Si deposition and wet electrochemical cycles. A seed layer optionally em rowinge 105. In use the CNF. Am 100 is placed in contact with an Elects oly* which can be a solid, or liquid, or a combination solid and liquid, and s including one or more charge carriers, such lithium ion the 11N.I's 110 are configured such that some of Electrolyte 125 is disposed between 's I l0 ndior can tis ri * via gaps between CNFs 110.

100561 The diameter of indit dual CNFs 10 llustrated in EEGs. IA and 18 are nominally between 100 and 200 tun, although diameters between 75 and 300 'am, or ether ranges are possible. CNFs 110 are optionally tapered along their length. The CNFs 110 produced using the techniques discussed herein have excellent electrical conductivity = --7 105 Sim) along the axis and do form firm Ohmic Ohmi contacts ith Substrate 105. The open space between the CNFs 110 enables a Silicon Layer i i 5 to he deposited onto each CNFs to form a gradually thinned coaxial shell ith a mass at a Tip 120 of the CNF 110. This design enables the whole Silicon Layer 115 to be electrically connected through the CNF 110 and to remain fully active during charge-discharge cycling. The expansion that occurs on alloying of lithium -115 can be easily accommodated in the radial direction, e.g. perpendicular to the long dimension of the CNFs 1 11. The charge and discharge capacity and cycling stabil ty of P' -Si-coated CNFs 110 and Si-coated CNFs 110 can he compared. The addition of Silicon Layer 115 provided a remarkable Li insertion (charge) capacity up to 3938 mAhlgsi at the C/2 rate and anal retained 1944 mAh/tisi after 110:dykes. This charge/discharge rate and the corresponding capacity significantly higher than previous architectures using Si nanowires or hybrid Si-C nanostruetures. FIGs. IA and 113 are perspective views.

100571 Invarious embodiments,from 0.01 up to 0,5, 5 3 0, 4,0, 10, 20, 75 pm (or more) nominal Si thickness can he deposited onto 3 pm long CNFs 110 form CE1F Arrays IOU such as the ted in. FIG.s IA and 1B. Lk A in various embodiments, from 0.01 up 0 5, 1.0. 1.5, 1, i0.20, 25 um Si thickness can be deposited onto 10 W11 long (NEs 110 to form CNF Arrays 1 noire ernoc the nominal thickness of Si is between 0.01 and the mean dis3ance betwcot f00581 Using CNF Arrays 100, Li ion storage with up to -4,000 nas capacity at C12 rate is achieved. This capacity is significantlyhigher than those obtained with Si nanow'ires alone or ether Si-nanostruetured carbon hybrids at the the same power rate. The improved performance is bated to the Tully activated Si:shell due to effective charge collection by CNFs 110 and short U path length in this hybrid architecture. Good cycling stability has been demonstrated in over 1.10 cycles. In various embodiments the storage a storage of CNF Arrays 100 is approximately 750, 1500, 2000, 2500, 3000, 3500 or 4000 inAh per gram of Si, or within any range between these values, As used herein, the term "nominal thickness" (of the amount of Sithat would produce a flat layer of Si, of the said thickness, on Substrate 105. For xample, a nominal thickness of Si of 1.0 Tun. is an amount of Si that would result in a 1.0]tin thick layer of Si if depositcd directly on Substrate 105. Nominal thickness is reported because it can easily be measured by weight using ethods know in the art. A nominal thickness of tun will result in a smaller thickness of Si Layer 115 on CT fisi 110 because the Si is distributed over the greater area of the CNFs 110 surfaces.

[00591 FiGs. illustrate GNI' Array 10th having an average fiber length of approximatelt, 3 p.m, according to various embodiments of the invention. FIGs. 2A-2C are scan ng electron microscopy (SEM) images. FIG. 2A shows a plurality of vertically aligned CNFs 110 without Silicon Layer 115. 2B shows a plurality o trtically aligned CNFs includi on Layer 115, FIG. a plurality of enieally aligned eltifs 110 in the extracted (discharged) state at experiencing 100 lithiitihh cha rge-discha, The CNIrsi 110 are tinily attached to a Cu Substrate 105 with essential ly unifor alignmentmini:cr distribution on the surface of the substrate nples used in this study eta i im average areal density of 1.1 lx1;puntedt om top-view SEM images), correspon an average nearest-Bergh bor d iStanceof -330 am. The average :1.2 length of the CiNlis 110 in Figure 2 is -3.0 um with >90% of CNIF's in the range of 2.5 to 3.5 gm in length. The diameter spreads from -80 am to 240 am whit an average of -147 am. An inverse teardrop shaped Ni catalyst at Tip 120 presents at the tip of each C.NF 110 capping the hollow channel at the center of the CNF, which promoted the tip growth of CiNli 110 during the PECVD process. The size of the Ni catalyst nanoparticies defined the char eter of each CISTF's 110. Longer ONlis 110, up to 10 um, were also employed in some studies to be discussed in later sections.

100601 In various embodiments the average nearest neighbor distance can vary between 200-450nm, 275-385 min, 300-360nm, or the like. Further, the average length of the CINEis 110 can be between approximately 2-20, 20-40, 40-60, 60-80, 80-100, 100-120, 120-250 (pm), or more. Standard carbon nanotibers long as a millimeter long are known in the art. In various em.bodiments, the average diameter can vary between approximately 50-125, 100- 200, 125-175 r or other ranges.

[0061] An amorphous Si Layer 115 was deposited onto the GNP Array 100 by magnetron sputtering. The open structure of brush-like CNF Arrays 100 made it possible for Si to reach deep down into the array and produce confornial structures between the CNF's 110. As a result, it formed_ a thick Si coating at the CNF tip followed by a gradually thinned coaxial Si shell around the lower portion of the CNF, presenting an interesting tapered care-shell structure similar to a cotton swab. The amount of Si. deposition is characterized by the nominal thickness of Si films a flat surface using a quartz crystal robalance (QCM) during sputtering. The Li' insertion/extraction capacities were normalized to the total Si mass derived from the nominal thickness. At 0.50 um nominal thickness, the Si-coated CNFs 110 were well-separated from each other, forming an open core-shell array structure (shown in FIG. 213). This structure allowed electrolyte to freely accessing the entire surface of the Si Layer 115. In the embodiment illustrated the average tip diameter was -457 ma in comparison.he '7 rut average diameter of the GNP's. 110 prior o applieatiott of the Si The aver ge radial Si thickness at the Tip 120 was eztimated to be -155 mm Pei titan the 0,50 inn nominal Si thickness since most along the full e th Other radial Si thicknesses in the ranee of 10-1000, 20-500, 50-25-0, 100-200 different ranges are found In alternative embodiments. As herein, the stacked-cone of CNFs 110 provides additional tine structure to the Si Layer 115 The stacked-cone structure is optionally the result of a spiral gro pattern that produces the stacked-cone structure cture when viewed in cross-section.

100621 The trans ssion electron microscopy (TEM) images in FiCis. 3A -3C further illustrate the structural details of Si-coated CNFs 110. A Si Layer 115 of -4390 rim Si was produced directly above the Tip 120 of a -210 um diameter CNF 110. The largest portion of the cotton-swab-shaped Si Layer 115 was -430 nm in diameter which appeared near the very end or the Tip 120. The coaxial Si Layer 115 around the CNF 110 showed a feather-like texture with modulated contrast, clearly different from the uniform Si deposits ahoy (see FIG. 3A). This s likely a result of the stacked-cone microstmeture of the PECVD-grown CNFs 110, It is known from the literature that ch CNFs 110 include unevenly stacked cuplike graphitic shuctures along the CNF 110 center axis. The use of such variations n the diameter of CNFs 110 was previously disclosed in commonly owned U.S. Patent Application Ser. No. 12/1)04,113 filed Oct 13, 2010.

100631 The stacked-cone structure along the length of each CNF consists of one t five, five re han ten up-hke ic laver.. that can be clearly-seen in FIG. 3B as indicated by the dashed la f each cone the side edges of some of the layers posed. At these lithium may he able to penetrate between the graphitic scale, the cup -h ut 3 comprise cones of hem and/or graphitic sheets with which lithium can interact. The cup edges are nanoscale edges and can have the properties of graphene edges while between the graph layers may be found properties graphene sheets. he cup edges provide seems in the vertically aligned carbon nano-fibers through which lit._ium ions can generates stacks of exposed graphitic edges along tits length of the CNF sidewall, e.g. the cup edges, These nanoscale edges are similar to the edges typically thund on grapheme/graphitic sheets and ribbons. These exposed cup edges result in varied silicon nucleation rates and thus a modulated silicon shell texture is produced. These exposed edges also form a good interface between the VACNF core and the Si shell to facilitate fast electron transfer in this hybrid structure. The two different structures of the Si shell can be controlled by varying the growth process of the VACNTs. Areas of the VACNF that include the cup structure results in the feather like Si shell, while areas of the VACNIF that do not include the cup stricture have a Si structure similar to that observed at the tip of the VACiAlF. The li/ACNF is optionally configured to have one or nitre areas without the cup stacking structure along the length of the VACNTs as well as at the tip. In alternative embodiments, the carbon nano-fibers still include the cup stacking structure having exposed,graphitic grapheme or graphite edges but are not vertically aligned andlor even directly attached to the substrate. While the use of a "cup-stacking" graphitic microstructure is discussed elsewhere herein, other methods of producing exposed nanoscale edges of graphite s heels elude unzipping carbon nanotuhes using an acid. Exposed nanoscale edges produce xpe o also provide rms of controlling andier securing id may be included in some embodiments. For example, the edges dimensi ins on the nanoscale (less than one micrometer). ons.

it at t o de, for example, w nanoscale ribbons can be used to influence the growth of a Si shell am 1004,41 As d here, the term lotaber" tide tubes an boons in whicha thickness and width are nanoscale but a length may or ma he nanoscale. The term nano-fiber is meant to xcl t1L traphene sheets lell a kness ngth and w are both nanoscale. In sic, .ms cmbori the Support 100651 The resolution nd contrast of Flt is cc 0 beam needs to penetrate through hundreds of nanometer thick CNF or Si-CNF hybrid, but the structural characteristics are consistent with the high-resolution TENT studies using smaller literature. This unique structure generated clusters of broken graphitic edges along the CNE side, all which cause i alied nucleation rates daring Si deposition and thus modulate the density of the Si Layer 115 on the CNF 110 sidewali. The modulated density results in the ultra-high suriiice area Si structures indicated by a (100 affi square) Box 310 in FIG 3A. The feather like Si structures of Si Layer 15 provide an excellent Li ion interface that results in very high Li capacity and also fast electron transfer to CNF 110. In FIG. 3.4 the dark area at Fip 120 is Nickel catalyst:for growth of the CNFs. Other catalysts can also be used. [00661 FIGS. 313 and 3C are images recorded before (3B) and after (3C) lithium intercalation/extraction cycles. The sample in 3C was in the delithiated (discharged) state when it was taken o±it of an elcefrocibernical cell. The dashed lines in FIG. 3B are visual ce of the stacked-cone graphic layers inside the CNFs 110. The long dashed lines F10. 3C represent the sidewali surface of the CNF 110.

/0067j As discussed elsewhere herein, the stacked-conestructure of CNTs 110 is drastically different from commonly used carbon nanotuhes (C 1's) Mite The stacked-cone structure results in n d Li* insertion, even in relative to standard carbon nanotuuhes or nail( For example, the stacked-cone a cure of CNI's 110 allows!.i interval tion into the graphitic layers through tare sidewall of CNFs 110 (rather than merely at the ends). The Li+ transport path across the wail of each of CNFs 110 is very short (with D -290 run in some 1 6 ong path from. the open ends in commonly used seamless carbon (CNTs). FIG. 4 schematic of the stacked-cone structure of CNFs 110, in this embodiment the average values of the patan2eters 2 Cy F radius -74 rim, wall thickness tw 50 sun, graphitic cone angle 0 = l0'1, and the graphitic.one length D= twirsine -290 am.

100681 FIGs. 5A-5C illustrate an electrochemical characterization of -3 um long CNFs 3 I0.

This characterization illustrates the phenomenon described in n to FIG 4, FIG. 5A shows cyclic voltammogra s (CV) from 1.5 V to 0.001 V versus a Li/Lk reference electrode at 0.1. 0.5 and 1.0 niVls scan rates. A lithium disk was used as the counter electrode. Data were taken from the second cycle d normalized to the exposed geometric rface area. FIG. 58 shows the ealvanostatic charge-discharge profiles at C/0.5, CI and C/2 power rates, corresponding to current densities of 647, 323 and 162 mA/g (normalized to estimated carbon mass) 71.0, 35.5 and 17.8 rtAlcm2 (normalized to the geometric surface area), respectively. FIG. 5C shows intercalation and extraction capacities (to ictL vertical axis) and Coulombic efficiency vertical axis) versus the cycle number at C/1 charge-discharge rate. (The disc = 1 hour, C/2 discharge rate = 120 min. 7C = Ci0.5 -s 30 etc.) 100691 A freshly assembled typically showed the open circuit potential (0CP) of the uncoated CNIFs 110 anode was --2.50 to 3.00 V vs. Li/Li reference electrode. The CVs measured between 0.001 V and 1.50 V show that Liintercalationas the electrapotential is below 120 V. The first cycle from. COCF of a necessary layer, i.e, the solid electrolyte decompositionof solvent, stilts, and impurities Sub: eclueti CVs sho ed stnailer but cants. The cathodic current associated! realation rose slowly as the electrode potential swept a 001 V involved the t-a (SF1), by the led a is ge cathodiccu sharp cathodic peak appeared at 0.18 V. As the electrode potential was reversed to positive after reaching the low limit at 0.001 V, lithium extraction was observed in the whole range up to 1.50 V, indicated by the continuous anodic current and a broad peak at 1.06 V. 100701 The CV features of (INF arrays 100 were somewhat different from those of staged intercalation into graphite and slow LI diffusion into the hollow channel of CNTs.

insertion into CNTs 110 is likely through intercalation between graphitic layers from the sidewall due to its unique smite-Wm. The TEM image in FIG. 3C indicates that the graphitic stacks in the stacked-cones inside the CNT.110 are somewhat disrupted during Li intercalation --extraction cycles, likely due to the large volume change that occurs on Li' intercalation. Some debris and nanopartieles are observed as white objects inside CNFs 110 as well as at the exterior surface. These show penetration into the interior of the CNI-is through the sidowall.

[0071; The galvano,static charge-discharge profiles in FIG. 513 showed that the Li+ storage capacity decreased as the power rate was increased from C/2 to C/0.5 (C/0.5 is also referred to as "2C1). To make it easier to compare the rates (particularly for those higher than C/11, we use the fractional notation C/0.5 herein instead of "2C" that is more popularly used in the literature. The Li intercalation and extraction capacities were normalized to the estimated mass of the ClsiFs 110 (1.1 x 104 glom) that was calculated based on a hollow vertically aligned CNT structure with the following average parameters: length (3.0 um), density (1.1 x I 09 CNIiis per ca), outer diameter ((47 am), and hollow inner diameter (49 um, -1 /3 of the outer diameter). The density of the solid graphitic wall of the CrifFs 110 was assumed to be the same as graphite (2.2 glom). At the normal C/2 rate, the intercalation capacity was 430 mA h and the extraction capacity is 390 szeLA gi', both of which are slightly higher than the theoretical value of 372 mA h g" for graphite, which may be attributed to Slid thrmation and the irreversible Li/ insertion into the hollow compartments inside the CiNfs 110. The ere found to be more than 90% of the intereala rates and both the intercalation and extraction capacities dee eI increased from C/2 to CR and by -201'4 from Cri to C/0.5, comparable to graphite anodes.

[00721 Upon charge rge cycling, the intercalation capacity as found to slightly from Olt mA h g71 to 370 mA. h after 20 cycles at the C/1 rate, while the extraction ca:maintained between 375 and 355 inA h The overall coulombic efficiency (i.e. the aoo of extraction capacity to intercalation capacity) was 94%, except in the first two cycles due to SET to:: the CNT 110 surface The SFI film is known to form readily on carbonaceous anodes during th which allows lithium ton diffusion but is electrically insulating, leading to a crease in series csistance. The TEM image (FIG.

image (FIG. 6A) show that a non-uniform thin film was deposited on the CNF 110 surface during charge-discharge cycles in some embodiments, the SEI serves s sheath to increase the mechanical strength of the CNFs 110, enting than from front collapsing into microbunciles by the cohesive capillary force of a solvent as observed in the study with other polymer coatings.

100731 FIGS. 6A--óC iliustrates scanning electron microscopy images of 3 inn Long CNFs 110, accord; g o various embodiments of the invention. FIG, 6A shows CNFs 110 in dellthiated (discharged) state after intercalation 'extraction cycles. FIG. 68 shows GNPs 110 including Si Layer after 00 cycles in the delithimcd slate. FIG. 6C show ncluding Si 1.5 alter 100 cycles in the lithiated state. These images are 45 degree perspective Le - [00741 FIGs. 7A-7C illustrate results obtained using CNFs 110 including a Si Layer 115 as it battery anodes. These results were obtained using a nominal thickness of 0.50 inn.

Ha 7A shows cyclic voltamn ograms between 1.5 V and 0.05 V versus Li/Li' at 0.10, 0.50 and 1.0 ilf.* scan rates. The measurements were made after the san?pla going through 150 charge-discharge cycles and the data of second ie at eachr FIG. 7B shows gal anostati charge-discharge Miles at 00,5: CO and C/2 power rates with the sample at 120, cycles.All profiles were tak econd cycle at each rate. FIG. 7C shows inse,non and extraction capacities (to the left vet 1 a ' -1 and coiilo2n'ic efficiency (to the right ideal axis) of two Off Arrays 100 (used as electrodes) versus the charge-discharge cycle number, The first CNF Array 100 was first conditione ith tsne cycle at he C/10 rate, one cycle at the C/5 rate, and two cycles at the C/2 rate. it was then tested at the C.72 insertion rate and C/5 extraction rate for therest of the 96 e The filled and open es represent ion and extract)", capacities, respectively. The second electrode was first conditioned with two cycles each at C/10, C/5, C/2, C/1, C/0.5 and C/0.2 rates, It was subsequently tested at the Cll rate for the next 88 cycles. The columbie efficiencies of both electrodes are represented by filled (1st electrode) and open (2nd electrode) diamonds, which mostly overlap at 99%.

[0075] The CV s in FIG. 7A present very similar features to those of Siano-wirt.

Compared to uncoated CNF Affray 110, both the cathodic wave for st and the anodic wave for Li' extraction shift to lower values (below -0.5 and 0.7 V, respectively). The peak current density increases by 10 to 30 times after application of Si Layer 115 and is directly proportional to the scan rata. Cleary, alloy-finming Li' insertion into Si is much faster than intercalation into uncoated CNFs, which was limited by the low diffusion of Li betweengrip tic layers. The cathodic '-as not observe on pure Si uanowires. The three anodic peaks representing the transfitrin -Li-Si alloy tt,m p. s a fires despite shifting. to lower to 200 trig'.

100761 T1 c galyanos ttic charge discharge profiles of a CNF Array in<_luding Si Laver 115, shown in PG. 78included two remarkable features: on (charge) and extraction (dis charge) e =pacify 3000 mA h (gsi) d at the 02 rate even after cycles; and (2) the Li' capacityIS 02, and C/0.5 power rates. In other words, the capacity of CNF Array 100 to operate as an electrode did not decline when charging rates were Increased trout L'/2 5. Over these charging rates the capacity was net lent of charging rate, in embodiments. The total it storage capacity of CNT Arrays 100 including Si Layer 115 was about 10 times greater than CST Arrays 100 that lacked Si Layer 115. This occurred even though the low potential limit for the charging cycle was increased from 0.001 V to 0.050 V. Asa r amount of Li-intercalation into the CNF core appears to have been negligible. The s ccif capacity was calculated by dividing only the mass of Sihat was calculated from the measured nominal thin ess and a bulk density of 2_33 g can 3. This method was chosen as an appropriate metric to compare the specific capacity of the Si Layer 115 to the theoretical value of bulk Si. For the 3.0 pm long CNFs 110 deposited with a Si Layer 115 o0.456 pm nominal thickness, the real mass density of Si Layer 115 was -1.06 x 10 g cir2, comparable to that of CNFs 110 ((-1.1 x 10-4 g -).1 The corresponding coulornbic efficiency in FIG. 7B is greater than 99% at all three power rates, much higher than that of the C? Fs 110 widiom Si Layer [15.

10077) FIG. 8 illustrates how the capacity of CNF 100 v anes a ith charging rate, according to various embodiments of the invention. Data is shown for several numbers of cycles. FIG. 8 shot erase specific discharge capacity for a group of cycles with identical currcut rate, versus, rate (C-rate) required to achie, hill capacity in set hours (Oh e.g., full Capacity /hours). Vertical Lines are used on 04 t C, 3C and 8C. The CNF Array was first conditioned with tt o cycles each at 08, 04, C/2, 01, C/0.8, 00.4, and 00.16 rates symmetrically, and subsequently tested at a 01 symmetric he a. dt 88 cycles.

This was repeated from cycle 101 to cycle 200. Starting at cycle 201,1 01 cycled for aye eye: t eaoh 04, 03, C/2, 01 5, 00.66, 00.50, Ca.1.11, C/0.20 and 00.15 rates symmetrically symmeticaliy and subsequently tested at a Cr I symmetric rate lot the next 45 cycl I 'as repeated -ycle 301 to ' . 400 and from cycle 401 t cycle 500. The change in capacity is small (<16%) while C-rate is van d. The electrode alter 100 cycles showed increased capacity la the Cl-rate is cha 3C. to 8C Thus. '_aster charge rates resulted in improved capacity. High capacity (%2,700 milt was obtained at high and lower rates (4. and SC). Capacity at rates above increase as C-rate increased. The drop in sp-cific capacity with the number of cycles is due to known, correctable, factors.

[00781 Both the CVs and charge-discharge measurements indicated that the Li' insertion Si Layer 115 was fast and highly reversible, which are features desired for high-performance battery anodes. This «gas further demonstrated (See FIG. 7C) with two long cycling tests on two identical samples at different -sting conditions: ( 1) slow asymmetric tests with the C1/2 rate for insertionand the C/5 rate for extraction; and (2) the fast synu et ic test at the C/1 rat for both insertion and extraction. Both sets of data showed >93% eoulombic efficiencyetliciency over the long cycling except for the initial conditioning cycles (4 cycles in the and 12 cycles in the latter at vaned low rates), In the slow;symmetric tests, the insertion capacity only dropped by 3,3% from 3643 mA h g-i at the 5th cycle to 3341 inA h g at the 100th cycle. Even at the 01 charge-discharge rate, the insertion capacity only drops % from. 309<i rrAgH at the I ycle to "757 mA h at 100th cycle. he tt e in the Li;capacity between these two sets of data was mostly table initial conditioning parameters and small sample-to-sample ra ations. This was indicated by the similar values of insertion -extraction 11}liras: CY"L s-s in at -010 and C,25 rates. The taster rates (00.5 for 9th and 10th ycles and (7/0 2 for sample r42) were found to be harmful and caused an irreversible drop in the capacity. Elowevelectrode became stabilized aft < longer cycling. As shown in FIG. 7B, the charge-discharee profiles are almost identical at C/2, C l and C/0.5 rates, e measured with sample #1 after going through 120 cycles. This is over charging o 100791 The specific capacity in the range of 3000 to 3650 mA h g consistent with the highest values of amorphous Si anodes summarized in It is remarkable that the entire Si shell in the CM; Array 110 was active for remained nearly 90% of the capacity over 120 cycles, which to our knowledge has not been achieved before except with fiat ultrathin (<50 am) Si films. The specific capacity disclosed itrein is sin-idle nilI n those reported using other nanostructured Si materials at over luding -2500 mA It at the C/2 rate and -2200 mA h g at the C/1 rate with Si NWs, and --800 mA h gr at the with randomly oriented carbon nanofiber-st co shell N Ws. Clearly, the coaxial core-shell NW structure on well-separated Chills 110, such as included in various embodiments of the invention, rovides an enhanced charge-discharge rate, early full Li' storage capacity of Si, and a long cycle life, relative to the prior art.

[00801 As shown in FIG. 7C, an anomalously high insertion capacity (-4500 trA h g ') was always observed in the initial cycles, which was 20-30% higher than the latter cycles. In contrast, he extraction values were relatively stable over all cycles. The extra insertion Capacity scan be attributed 'e co ahination ofte reactions: formation of a thin SET (surface electrolyte emphatic) layer (of tens of nanometers (2) reacts) with Sift presented on the Si surface (S.O, T 2. Li Si - Lis,0); and (3 on of iO the Marti ystalline Si coating with a liter theoretical capacity t--4200 mA into amt plums Siwith lowe (<3800 mA h <4'1). The TEEM image (FIG. 3C) and sE11.1 image th 6B) showed that a non-uniform SEI can be deposited on the surface e charge--discharge cycles. This elastic SU film can help secure Si Layer 1 on the CNF 110 surfaces as Clod' Array 110 goes through the large expansion-contraction cycles that occur during he charge-discharge cycles. The iramalic differ-c between the SEM images in FIGS. 6B and 6C indicates the large expansion of Si Layer 115 in the lithiated (charged) state relative to the non-1 dated state. :though some of the expansion may be due to oxidation of Li by air as the electrochemical cell was dissembled for imaging.) Note that the p luction of SEI d initial charge discharge cycles differences seen in Si Layer 115 between FIGs. 3A and 313. In Fla 313 the Si has acted to produce SE1 that tills the gaps between the feather-like structures. The interaction 'an include mixing, chemical reactions, charge coupling, encapsulation, and/or the like. The Si Laye uniformre i1G. 313. However, the Si La_ I. 15 now comprises interleaved layers of Si (the feather-like structures} and SEL Each of these interleaved layers can be on the order of lOs of manometers, The SEI layer can he an ion permeable material that is a product of interaction between di olyte and Si Layer (or other electrode material).

100811 The crystalline and amorphous structure of the Sishell baled by Raman spectroscopy. As shown in EIG, 9, the pristine CNF Army 100 including Si Layer 115 showed multiple broad bands overlapped in the Ige of 350 to 550 c corresponding to amorphous Si, and a much high sharp band at 480 coresponding to nanocrystalline Si.

After eharee he sharp peak disappeared while the broad hand call l are CNF s 110 did not show any a s The crystalline Si peak d.wnshifted by --40 em-' from that meal ured with a single-eryst i Si(l 00) wafer and by other micro-crystalline Stn Terials. This shift was disorders. The original Si Layer I I S likely consisted of nano_ embedded in an arnz rphous nassociated t' likely due to the much smaller st id large leather-like TEN" image in FIG. 3A. After initial cycles, the Si nomystals were ce amorphous Si, consistent with the '1 FM images ho cycling test (see FIGs. 3B and 3C). However, the Si Layer 115 apparently did not slide atop gth of the CNF, contrast to the lamae rongitudinal expansion(by up to 100%) in pure Si NWs. T1 u that, in some embodiments,expansion of the silicon is primarily radial rather than longitudinal with r espect to the carbon nano-fiber. in some embodiments, expansion occurs between the feather-like structures of the Si. For example, the expansion of one feather may be in the direction of the nearest eighbor feathers above and below, thus filling the gap between the feathers. in either c, the expansion occurs in a manner such that delamination of the silicon is dramatically reduced relative to nor art. Si Layer 115 was, thus, securely attached tc CNFs 110 for over 120 cycles. The volume change of the Si shell during Li insertion was dominated by radial expansion, while the CNT-Si interface rematned int 100821 Various embodiments of the. in. ention include CNFs 110 having different lengths and silicon shell thickness. One factor that can be controlled when CNFs 110 are ge s Like open space between each CNF 110, e.g., the mean distance between CNFs110 within CNF Array 100. This space allows Si Layer 115 to expand radially when charging and, thus in sonic embodiments provides stability. Because an optimum electrode structure depends on both the length of CNFs 110 and the thickness of Si Layer 1 1 t is sometimes desirable to use longer CNFs d thicker Si Layers 115 in order to obtain higher total Li storage cam. Lon:ter CNFs10 do correlate with greater storag pacity. FIGs 10A-10C shows the variation of Li' i sertion-extraction canacitiec.efficiency over 15 charge-discharge cycles with three 10 um long CM' 110 samples deposited with Si Layer 115 at a nominal thickness of 0.50, 1.5 a 14.0 tun, respectively. After conditioning at the rate for the t cycle and the C/5 rate for the second uric rates (C12 For insertion and C.t5 for extraction) ere used in subsequent leg si mi1 xi to the measurements 7j of sample Y1 in FIG, 7G. This protocol provided nearly 100% coulombic efficiency and minimum degradation over the cycles. The nominal thickness was measured in situ with a quartz crystal microbalanee during sputtering.

100831 The specific capacities as high as 3597 mA g" and 3416 inA h were obtained with 0"50 and 1.5 pm thick Si Layer 115, respectively, very similar to that with 0.50 pin thick Si Layer 115 on 3.0 pm long C'NF's 110 (see FIG. IC). The capacity remained nearly constant over 15 cycles. However, the electrode with 4.0 pm nominal Si thickness showed a significantly lower specific capacity at only 2221 mA h M'. This indicates that, with expansion, the Si Layers 115 from adjacent CNFs 110 began to contact into each other, limiting them from further expansion and limiting diffusion of Li between CiNfis 110. As a result, only a fraction of the silicon coating was active in lithium insertion. The cycle stability was correspondingly worse than the samples with thinner Si Layers 115.

[00841 The same amount of Si (500 min nominal thickness) CNF Arrays lit) comprising pm tong CNFs 1.10 gave nearly the same amount of Li-storage capacity (3597 mA h see Fig, 6a) as that of 3 pm long CINF's 110 (3643 mA h g-1, see MG. 7C), even though the carbon mass is more than 3 times higher. This is very strong evidence that the contribution of CNFs 110 is negligible calculating-1X' storage. It is likely that very little Li' ions were intercalated into CNFs 110 in the Si-coated sample, this contributes to the stability of the structure during multiple eharge--diseharge cycles, 100851 The variation of the specific Li' storage capacity in the three samples correlated well with their structures revealed by the SEM images illustrated in FIGs. 11A-11C. FIGs. 11A I IC show scanning electron microscopy images of freshly prepared GNE Arrays 100 (on -10 urn long GNPs 110). The Si Layer 115 was generated using a nominal Si thickness of (a) 0.50 um, (h) 1.5 um, and c) 4.0 um, which were measured in-situ using a quartz crystal microbalance during deposition. All images are 45" perspective views. At 0.50 pm nominal Si thickness, the average tip diameter as found to he -388 rim on the 0 pm long CNFs, much smaller than the -4517 nm average diameter on the 3.0 p.m long CNFs 110. The Si Layer thinner nut more uniformly spread along the 10 p.m long CNFs 110.

100861 I growing i.) a;r. C iti1=s * 10 took 120 t gar., about six times its long as growing the 3 urn CNTs 110. Some nickel catalysts were slowly etched by NH) during the long.PECVD process, resulti continuous reduction in the Ni nanoparticle size and leading to tapered Tip 120 (as shown in FIG. 12). The CNF 110 length variation also increased with long CNFs 110. These s collectively reduced the shadow effects of the Tip 120. Asa result, even at 1.5 p.m nominal Si thickness, the CNFs 110 coated with Si Layer 115 are well separated from each other. The SEE. image of 1.5 pm Si on 10 pm UNE Arrays 100 (FIG. 11B) is very similar to that of 0.50 um. Si on 3.0 um CNF Arrays 110 (FIG. 2B). But as the nominal Si thickness was increased to 4.0 pm, the Si Layers 1 [5 clearly merged w ea -h other and titled up most of the space between the s 110 (see FIG. IOC). This reduced the five space needed to accommodate tite volumetric expansion ofthe Si Layer 1151. As a result, the specific Li storage capacity significantly dropped.

1008171 FiCs. 11A and 11B each include roughly the same number of GNPs 110, however, FIG. 1.18 ha 1 * fewer visible Tips 120. This is because Si Layer 115 can form a nant. on complex that includes a single CNF 110 (a cross-section of which is st FIG. Or, Si Layer 115 can form a nanott 'silicon complex that includes two, tl or more CN 0 under a single cover of silicon. This occurs when two or more CNFs110 Come g ayer 115 deposition process. A nanofiberls structure that includes a continuous Sithat envelops one or more CNT 110. A cross-section of a nanofiber/silicon complex that eludes two CNF 110 is illustrated in FIG. -II D. in various embodiments at 1%, 5% or 10% of nanof.bcrisihcon complexes include more than one CNF 110. 4.1

[00881 in various embodiments, instances of CNII Arrays 100 having 0.50 and 1.5 pm nominal Si thicknesses have comparable mass-specific capacities of 3208 343 and 3212 234 niA h respectively. The samples with a 4.0 pm nominal Si thickness eive much lower capacity at 2072 -it 298 mA grl. The thinner Si coatings are fully activaied and provide the maximum Li insertion capacity that amorphous Si could afford, On the other hand, the area-specific capacity increases proportionally with the Si thickness from 0.373 +OO4Soutbozm 2 at 0.50 pm Si to 1.12 0.08 mA h cmi2 at. 1.5 pin Si thickness, but drops off from the linear curve to give 1.93 0.28 mA h cm2 at 4.0 pm nominal Si thickness. Al the 4.0 micrometer nominal silicon thickness, only a fraction of the extra silicon in the thick Si coating is actively involved in Li storage. The thickness of 4.0 pin is greater than the mean distance between CNFs 110. The electrochemical results are consistent with the structure shown in SFA1 image in FIG. 11C, which shows that space between CNFs 110 is essentially tilled.

10089/ In various embodiments of the invention, the structure of (TNT An-ay 100 includes an Si Layer of approximately 200 to 300 rim radial thickness on CiNfs 110 having a length of approximately 30-40, 40-75, 75-125 microns (or more or combinations thereof) and diameters on the order of -50 rim In some embodiments, these CNF Array 100 are grown on conductive foils having a thickness within the ranges of -10 microns, -10-20 microns, -10-50 microns, or more. In various embodiments, Si (equivalent to 1.5 um nominal thickness on flat surface) is deposited onto 10 pm long CNFs 100 to form CNF Arrays 10D. This is accomplished while maintain the open vertical core-shell nanowire structuna with individual CNFs 110 well separated nom each other such that Li ions can penetrate the (INF Arrays 100 between the eNlis 110. This unique hybrid architecture allowed the Si Layers 115 to freely expandkontract in the radial direction during Li+ insertion and extraction. High-performance Li storage with a mass-spec:fie capacity of 3000 to 3650 inA g-1 was obtained even at. the Cil rate. The capacity matched the maximum value that would be expected from a similar MB Si, indicating that the Si Layer 115 was hilly active. This 3D n.anostractured chitectare enables cal connection with bulk quantities of Si material_ le maintaining a short Li+ insertion-;xtraction path. As a result, high capacity near the theoretical lin discharge cycle.

change in pacify as the rate was increased 20 times from C/10 to C/0.5 (or The high capacity at improved charging and power rates and the et ordinary cycle stability make this novel structure a choice amide material for high-performance Li-ion batteries, The same core-shell concept may be applied to cathode materials by replacing the Si shell with LiCo02, 1 iNiO2, LiMn204, LiFePO4, Li20, i.isT or the like.

100901 PIG 13 illustrates methods of producing the CM' Arrays 100 and/or CNFs 110 disclosed Provide Substrate Step 1310 a Substrate 105 is provided. Substrate is optionally suitable for growth of CNFs 110. Substrate 105 may include a variety of materials, for example Cu, Substrate 105 is optionally a conductive foil having a thickness described elsewhere herein. ht an ptional Provide Nucleation Sites Step 1320 nucleation cites for the growth of CM-is 110 are provided on Substrate 105. A variety of nucleation materials, such as Ni particles, are kno in the art. The nucleation cites re optionally rn tided at a density' so as to produce mean distances between CNFs 110, such as those taught elsewhere herein. Provide Nucleation Sites Step 1320 is optional in etubodiments in which nucleation is not required for growth of CNFs 110, or simi lar stiuctures, or in which CNFs 110 are attached to Substrate 105 using a binder after being grown elsewhere. [00911 in a Grow CNT's Step 1330 CNFs 110 are grown on Substrate 105 or, in some bodimeuLs separate from Substrate 105. The CNFs 110 a many grown to produce the stacker -cone structure taught elsewhere herein, to produce structures having exposed dges along their le igth, or to produce similarly vtriable structure 'The CNTs 110 can be grown to any of the lengths taught elsewhere herein, Growth is option accomplished using PECVD processes such as those taught or cited in ''A high-performance lithium-ion battery anode based on the core-shell huterostructure of silicon-coated vertically aligned carbon nonofibers" Monks-iv/ski et al. Mater. Chem. A, 2013, I, 1055.

[00921 In an Apply Si Layer Step 1340 an intercalation material such as Si Layer 115 is applied to the grown Cistfis 110. In sonic embodiments, Apply Si Layer Step 1340 occurs before CsilEs 110 am attached to Substrate 105. The applied material may have any of the nominal thicknesses taught elsewhere herein so as to produce a Si Layer 115 thickness of tens or hundreds of nanometers. In some embodiments, Apply Si Layer Step 1340 includes erowing intercalation material in structures that are dependent on exposed edges alona the lengths of CNEs 110. For example, when CilsTs 110 include the cup-like structure discussed herein, Apply Si Layer Step [340 includes growing the feather-like structures illustrated in the figures, e.g. FIG 3A..

100931 In an optional Apply PENT Step [345 a power enhancement matenal (PENT) is added to the GNI' Array100 or CPSEis 110. In some embodiments, Apply PENT Step 1345 occurs before CN Es 110 are attached to Substrate 105. The PENT typically includes a binder and surface effect dominant sites, as discussed in further detail elsewhere herein. In an optional Condition Step 1350 the GNI An-ay 100 produced using Steps 1310-1340 is conditioned using one or more lithium intercalation cycles.

[00941 FIG. 14A illustrates a CM; 110 including a Power Enhancement Material 1320, according to various embodiments of the invention. The Power Enhancement Material 1320 is applied as a layer over the intercalation material, e.g. over Silicon. Layer 115. FIG. 14B illustrates detail of the Power Enhancement Material 1320 illustrated in FIG. 148, according to various embodiments of the invention, Power Enhancement Material 1320 includes Surface Effect Dominant Sites 1430 and an optional Binder 1440. Silicon Layer 115 is but one example of intercalation material. Where Silicon Layer 115 is used as an example herein, it should be understood that p of intercalationintercala Lion material can be sub combined with silicon Such alternative or additional intercalation materials include Bi, C, Se, Sb. Sn and 7n. The CNF 110 illustrated in HO. 14 rs typically one of a large number of CM' 110 within a -ray 100.

100951 In some embodiments, Surface Effect Dominant Sites 1430 include surthecs of a mmoparticle configured to adsorb charge carriers in a faradaic interaction, to undergo redox actions with charge carriers. They are referred to as "surface effect dominant because typically, for these nanoparucles, the faradaic interaction between the charge ca and the minopandele surfaces dominate bulk farad-is interactions. Thus, the charge carriers are much more likely to react at the surface relative to the bulk of the nanoparticles. For example, a lithium ion would more likely adsorb onto the surface of the nanoparticle rather than being absorbed into the bulk of the nanopartiele. These nanoparticle are sometimes referred to as surface r lox particles. The faradaic interaction results in a pseudo capacitor that can store a significant amount of loosely bo rid charge and thus provide a significant power density. in pse pacitancc an electron is exchanged te,g., donated). in this case between the charge carrier to the nanoparticle. While some potentials would result in some intercalation of charge carrier into the nanoparticle, this does not constitute the bulk of the interaction at Surface Effect Dominant Sites 1430 and can degrade some t s of nanoparticies. A faradaic in is an interaction in which a chars e is transferred (e.g., donated) as a result of an electrochemical interaction.

/00961 The nano zrtic les that include Surface Effect Dominant Sites 1430 can be comprised of tran des, as 'DO?, ',/a205, MnO, Mr102, NiO, tantalum oxide.

-ubidium oxide, tin oxide, cobalt oxid * opper txidc, iron oxit, the like. They may also be comprised of metal nitrides, carbon, activated carbon, graphene graphite. titanate (a:Esc), 2), olys n, germanium, metal hydrides, it osphates, 1>oiy aniline. mesophose carbon, an * It is appree that mixtures of theInc an or 0 materiais having it;dale. -map tt included in the Surface Effect Dominant Sites 1430. in vanous embodiments, these n: _ panicles can be less than 1, 2, 3, 5, 13. 21 or 34 nanometers n di ter. The lower of the na particle size is a function oldie size of the moi.

materials. A nanoparttole includes at least a few molecules. A smaller size prov greater surface to bulk ratio of possible adsorptionsites. However, a particle comprising only a couple of molecules has reduced stability. The na ides are optionally multi-layered.

For example, they can comprise a TiO2 layer (or any of the other nanopartieie materials discussed herein) on a transition metal, Co, Ni, ^pin Ta, Ru, Rb, Ti, Su, FeD, or Fe core or a grapthme/graphite layer on a core of some other material. In some embodiments, different core materials affect the reaction potentials of the surface material. The amount of Surf t Dominant Sites 1430 is optionally selected depending on desired power and energy lensities For ex, wle, a greater pow(' densitymay be achieved by have a larger number of Surface Effect Dominant Sites 1430 per quantity of intercalation material,or a o eater amount of energy density may be achieved by having a larger amount of intercalation material per number of Surface Effect Dominant Sites 1430. It is an advantage of some embodiments of the invention that oth historically high energy anti power density be achieved simultaneously.

[00971 By adsorbingchar e carrierson the rface of the ianoparticle the charge carriers can density such as previously only achieved i4 ith capacitors. This is because the release of the charge is not dependent on diffusion of cl age carriers thong intercalation material. Further, by placing the Surface S=treet Dominant Sites 1430 in close proximity to the intercal iR mater ame ca a. Onl file' intercalation material to the Surface Effect Dominant Sites 14 irectly to the electrolyte). This results in energy densities that are equal to or greater than conventional batteries. Both the energy densities of batteries and the power denshies of capacitors are achieved in the same device. Note that during discharge charge carriers within the intercalation material can migrate to the Suithee Effect Dominate Sites 1430 and thus recharge these sites.

[00981 In some embodiments, Surface Effect Dominant Sites 1430 are disposed on larger particles, For example, the partiete size may be greater than 1, 10, 25, 100 or 250 microns, (but generally less than 1 millimeter). Activated carbon, graphite and gmphene are materials that can be included in particles of these sizes. For example, activated carbon can be included in Power Enhancement Material 1320 while having a pore size of Surface Effect Dominant Sites 1430 similar to the nanoparticle diameters taught above. For the purposes of this disclosure, a nanopartiele is a particle with an average diameter of less than.' inn. 100991 Optional Binder i 440 is configured to keep the Surtace Effect Dominant Sites [430 in proximity to the intercalation material. In some embodiments, the distribution of Surface Effect Dominant Sites 1430 is uniform throuahout Binder 1440. For example, nanopartieles including the Surface Effect Dominant Sites 1430 may be mixed with Binder 1440 before:Binder1440 is applied to the intercalation material to produce a relatively uniform distribution. Alternatively, the nanoparticies may be applied to the surface of the intercalation material prior to application of Binder 1440. This can result in a greater concentration of Suidace Effect Dominant Sites 1430 (within Binder 1440) proximate to the intercalation material as compared to areas of Binder 1440 that are distal to the intercalation material. Binder 1440 is optional in embodiments in which Surface Effect Dominant Sites 1430 or the associated nanoparticies are directly attached to the intercalation material, e.g., attached to Silicon Layer 115.

1001001 Binder 1440 is permeable porous) to charge carriers of the electrolyte. Examples of suitable materials for Binder 1440 include polyvinyl-idene fluoride WV-DE), styrene binadiene rubber, poly fittaylie acid) (PAM, carbo-xymethyl-cellulose (CIVIC), andlor the like. Other binders may be used that meet the permeability requirements. Binder 1440 optionally includes materials that inorease its conductivity. For example, Binder 1440 may include conductive polymer, graphite, graphene, metal nanoparticles, carbon nano-tubes, carbon nano fibers, metal nano-wires, Superh' ;conductive carbon black), and/or the like. The materials are preferably at concentrations high enoueh to make Binder 1440 conductive, e.g., a percolation threshold.

10111011 The addition of Surthee Effect Dominant Sites 1430 in close proximity to the intercalation material (e.g., Silicon Layer 115) does not necessarily require the use of vertically aligned CNF 110, or any support filaments. For example, FIG. 15 illustrates an electrode surface including Power Enhancement Material 1320 and non-aligned CNITs 110 coated by intercalation material, according to various embodiments of the invention. In these embodiments, the CNFs []0 are not directly attached to Substrate 110, but are held in close proximity to Substrate 1 EC) by Binder 1440, In some embodiments, CNTs 110 including the cup like stnicture illustrated in for example, FIG. 3B, arc used in the non-attached confieurations, such as illustrated in FIG. 15, In these embodiments, the cuplike structure still helps to prevent delamination of the silicon from the underlying CNF 110, While CNF 110 are used herein as an example of support filaments, it should be understood that other types of support filaments discussed herein can be used to supplemem or replace the carbon nanolibers of CM' 110 in any of the examples.

1901021 The embodiments illustrated by FIG. 15 can be produced, for example, by first growing unattached (17NFs 110. These are then coated with Silicon Layer 115 (or some other intercalation material) such that the intercalation material is generally in contact with the CNI(s 110 as a coatine layer. The coated CNTs 110 ate then mixed with Surface Effect Dominant SPes 1430 n Binder 1440 the xture is deposited on Substrate 1001031 FIG, 16 illustrates an electrode su Enhancement i 1320, non-aligned CINFs 110 and free Intercalation Material according to various t bodimen ention. In these embodiments, the Intercalation Material 1610 is not necessarily disposed round the CNF 110 as a coating. The Intercalation Material 1.610 is free in the ense that it is not restricted to the surface 01GM's 110, however it is still held in proximity to Substrate 105 by Binder 1440.

1001041 The embodiments illustrated in FIG. can be produced, for by mixing Binder 1440, Surface Effect Dominant Sites 1430, Intercalation Material 1610 and CNF 110 together (in any o The mixture is then applied to Substrate 105. In these embodiments, GNPs 1 10 may or may not be attached to Substrate 105 by means other than Binder 1440. Intercalation Material 1610 may and/or may not he in contact with CNN or Substrate 105. Likewise, Surface Dominan Sites 1430 are optionally in contact with Substrate 105, CNF 1'10 and/or Intercalation Material 1610. Intercalation Material 1610 optionally includes particles, suspens 0 clusters, and/or droplets of intercalation material with sizes of at least 0.1, 0.6, I, 1.5, 9, 3,5, 7, 9, 10, 13, 15, 18, 21 o 0 or any range there between. Other sizes are possibie in alternative embodiments.

I00105/ FIG. 17 illustrates an electrode surfaceace including Binder 1440, Surface Effect Dominant Sites 1430 and Intercalation v1ateriai 1610, without support filaments ieeordina, to various embodiments of the invention. In these embodiments Surt ffect Dominant Sites 1430 and ' Material 1610 are held in prom: Substrate 11005 by Binder 1440.

1001061 FIG. 18 illust lies an electrode surface Mar to that ismated in HO 15. However, bodiments left st fated FIG. IS Surface Effect Dominant Sites 1430 -c concentrated close proximity Lo Intercalation Material 1610. For example, in some embodiments at least 2%, 10%, % of Surface Effect Dominant Sites 1430 are on particles in contact with Intercalation Material 1610. Increased concentration of Surface Effect Dominantinant Sites1430 pro ttercalation Materi 1610 can be achieved using methods described elsewhere herein. This results in a greater concentration Surface Effect Dominant Sites 1430 at the surface of Intercalation Material 1610 relative to other volumes within Binder 1440.

[001071 FIGS. 14C, 19 and 20 illustrate lectrode surface similar to thal illustrated in FICis. 6 and 17 respective the embodiments illustrated by these s, Surfice Effect Dominant Sit 430 are disposed in close proximity to free intercalation material, neer:F(11m2 to various embodiments of the invention. As in the embodiments illustrated by FIG. 18, in some cmbodiirettts at least 2%, 10%, 25%, 0%, 75% or 85% of Surface Effect Dominant Sites 1430 ar et with Intercalation Material 1610. In some embodiments a higher concentration of nanopartteies inclucliug Surface Effect Dominant Sites 1430 are disposed within 5 nanometers of Intercalation Material 1610 surfaces than between 10 and 15 m utonaeters of these surfaces. Increased concentration of Surface Effect Dominant Sites I 430 proximate to Intercalation Mates ial16] 0 can be achieved by selecting appropriate Zeta potentials of the nanopartieles and Intercalation Material 1610 in solution so that the nauiop-articles fbrm an electrostatic double layer at the surface of Intercalation Material 1610. e Zeta potential is the elects c poten s1 in the lterfacial double laver at the 1-ration of the sumac e sus a the built hcmid away from the surface. The Lei i potentia':ptional itreater than (absolute). In other embodiments, the nail( articles are applied to the surfaces of intercalation vlate I 161t1 prior o the application appli atiosn of Binder 1440.

1001081 Intercalation 3, al 1610, as illustrated in. LI ' * 16-20, can include any single one or combination he materials discussed herein with respect to Silicon Lay 115 (including or lad it silicon). Likewise, CNE's 110, as t.^.din FIGS. 16-20 can include any ious types fibers discussed he (including or -eluding carbon nanofiber). For example, these CNFs 110 may include branched fiber multi walled fibers, wires, aerogel graphite, carbon, graphene, boron-nitride nanotubet it * The number of Surface Effect Dominant Sites 1430 and. CNF 110 shown in these figures and other figures herein is for a purposes only. For example, in practice the number of Surface Effect Dominant Sites 1430 can be much greater. Likewise the amount and size of intercalation Material 1610 and Silicon Layer 115 shown is for illustrative purpo es. Alternative cuts may include greater or lesser amounts and greater or lesser sizes. Likewise, he depth of PPM 1420 and the length of CNF 110 can vary from that shown in the figures.

1001091 in various embodiments, cum of nationarticies including Surface Effect Dominant Sites 1430 may be selected to so as to result in at least 0.1, 0.5, 0.7, 0.9, 1.1, 1,3, 1.5, 2, 3, 5, 10, 25, 50 or 100 (or any range there between) times a monolayer of the nanoparticles on the surface of intercalation Material 1610 or Silicon Layer 115 (as measured in a discharged state). As a ed herein, a 0.1 monolayer indicates 10% and a 10x monolayer monolayeris 10 monolayers. in various embodiments, the amount of nanoparticles including Saville° Elie tes 1430 may be se ue-ed to resrresultn at least 1. 5, 10, '0, 50, 100, 250 or 500 nanometet layer for any combination; there between) of nanotaarticles on the surface of Intercalation ischarged elate; 1610 (as measured Other ci a -de t s red in monolay-ers or depth are possible. As the coverage of the nanoparucies E that nclude Surface Liftect Dominant Sites 1430) approaches 1.0 in *-i the nanoparticles can form a ld cen the intercalation Material 1610 ss.

carriers of the elect ols.e that n -ate through Binder 1440.exampleti le in some embodiments the electrolytei 's lithium as a chargea i(Iro rgh Binder 1440 and undergo 0 faradaic reaction with Suriacc Dominant Sites 1430 in which an electron is donated to the lithium from one of Surface Effect Dominant Sites 1430, this electron has been transferred (du donated) from Substrate 105 to the inanoptutcle via Intercalation Material 1610. Because the narroparticles form a barrier, at this stage in a charging process, only a limited limi tealinto ire carrierreachns Intercalation - st.

Material 1610. Charging is dominated by reactions at the Surface Effect Dominant Sites 1430. In some embodiments, charging can be rapid because intercalation of he charge carrier into Intercalation Material 1610 is not necessary before the faradaic reaction with the charge career occurs. The pr.seace -'Surface Effect Dominant Sites 1430 greatly increases the surface area where the initial latradaic reaction can occur prior to intercalation. Surface Effect Dominant Sites 1430 catalyze the intercalation of charge carrier into Intercalation Material 1610, The charge carrier can be calated in the fttnn as received at Surface Effect Dominant Sites 1430 or intercalated in are alternate form such as a metal oxide. If.tercalated as a metal oxide, the oxygen of the oxide may be recycled back to the Surface Effect Dominant Site 1430 following the intercalation.

[NI BA In some embodiments, because the nano-particles form an nerlect barrier some charge still --h Intercalation Material 1610 at this stage of- (e.g., an initial staire of cltarg 71«, :} 11ii r storage deviced.e.'ice including the electrodes discussed here in).

Because Material 1610 of some embodiments, such ai silicon, expands when charge carrier t n occurs the surface area Intercalation Material 1610 also ses This reduces the surface coverage of nanoparticles the surface of Intercalation Material reduces the effccti= etkess of the ria pa doles in forming a barrier to charge cathers. :us, as h inng nrogresses greater nbers of charge earners per inn time can reach In ircalation Material 1610. This is optionally conttnutd u c is dominated by reactions within the lntereahati all 1610. The reduction in si may ncrrasz Cr,e at er z e fractr n,?T Sr>rface Effect Dominant Sites 1430 on each nanopart e that arc exposed to the electrolyte. As used her surface coverage sod to represent a nsity of a speck,s on a surface and may be measured as a number of motiolayers fraction thereo0, as a thickness, or as a concentration, etc. [00! 111 in some embodiments, the power storage at Surface Effect Dominant Sites 1430 occurs at potentials at which faradaic surface reactions occur but intercalation of charge carriers into the nano particles that include the Surface Effect Dominant Sites 1430 does not occur. This prevents degradation of the nanoparticies by repeated inters and de-intercalation of charge carrier and allows for a longer cycle lifetime. At the same electrode it s desirable to store power within intercalation Material 1610 via faradaic reactions that occur at a higher potentials, optionally including potentials that would. cause ion o of charge ca ers into the na having Surface Effect Dominant Sites 1430, This can occur in some embodiments of the invention because there is a potential drop between Substrate 105 and the Electrolyte 12 1001121 In one specific example, in which lithium c charge carrier, the Surface E;ffeet Dominant Sites 1430 are on Ti0_ aanoparticles and Intercalati i Material 1610 is pre tom inantiv siIleon. The particular voltages in other-embodiments will be understood to be dependent included in Surface Effect Dominant Sites 1430 and Intercalation 1610, and the reactions occurring during charging, etc in embodiments the po ce between Surface Effect Dominant Sites 1430 and Substrate 105 is at least 3, 0.4, 0,5, 0.6, 0.8, L.0, 1.3, 1.7, 2,0, 2.2, or 2.4V, or any range there between. As used herein the term "potential-is used an absolute value (c.a., of an electrostatic potential 1001131 FIG. 21 illustrates methods ofassembling an electrode surface. ascording to intents of the invention assentbled electrode surface rnr y be used.

example, as an anode in a battery, capacitor-or hybrid deg: ice. The methods illustrated in FIG, e optionally used to produce the vat ectrodes discussed re beret 1001141 In a Provide Substrate Step 2110 a conductive substrate is provided. Provide Substrate Step 10 is simillar to Provide Substrate Step 1310. In Provide Substrate Step 2110, Substrate 105 optionally suitable for growth of (NE's 110 or other support filaments is provided. As discussed herein, Substrate 1(15 may include a variety of materials, for example Cu, Au, Sn. etc. Substrate 105 optionally includes udeation sites as described elsewhere herein.

1001151 In an optional Provide GNP Step 2120, CM:. 110 (or any of the other support filaments described herein) are provided. Provide CNF Step 2120 is optional in embodiments in which electrodes that -k support filaments, such as those illustrated by Erns. 17 and 20, are produced. In some mbodiments the ONE 110 are provided by growing C.-NE 110 on Substrate 105. In some embodiments, CNF 110 are provided by adding CNF 110 to a aixture, that is later applied to Substrate 105. In sonic enibodimems CNF 110 are produced separate from Substrate LOS and later attached to Substrate 105.

1001161 In a Protiicde Intercalation Material Step 2130, IntercalationMaterial1610 is provided. In same embodiments, Intercalation Material 1610 is first applied to CNF 110. In various embodi intercalation Material 161 is applied as a colloidal suspension, tug vapor deposition, 0101 173 in a P e Effect Dominant Sites (SEDS} Ste 2140, Surface Effect Dominant Sites 1430 are pa As ssed elsewhere herein, the Surface Effect Dominant Sites 1430 may b ides or!artier structures arapherie or activated carbon. Surface 1,tfeGt Doi}iinant Sites 1430 can provided as a n susp ion in Binder 1140, or in a solvent, using ion using electro deposition, using evaporation as a sprayor if Itke Inembodiments potential of line on Material 1610 is selected such that Surface Effect Dominant Sites 1430 are concentrated. at 3 ac of intercalation Material. 16I 0.

100118) In an.pply Step 2150 Inl.;rcalation Material 1610, Surface Effect Dominant ices 1430 and optionally CNFs 110 are applied to Substrate 105. These materials can be applied in a w ide variety of orders and combinations. For example, Intercalation Material 1610 can he applied to CNFs 110 (perhaps already attached to Substrate 105) and then Surface Effect Dominant Sites 1430 can be then applied on top of the Intercalation Material 1610. Alternatively, free CNF 110, Intercalation Material 1610 may he first mixed, then Surface Effect Dominant Sites 1430 and Binder 1140 either alone or in combination are added. Based on the teachings herein, one of ordinary skill in the art will understand that in different embodiments, these components can be mixed or added in any order or combination. Further, the components can be mixed prior to or after being applied to Substrate 105. The Steps 2110-2150 can be performed in any order. Apply Step 2150 is optionally followed by Condition Step 1350.

100119] In some embodiments the method illustrated in FTC. 21 includes a intercalation Material 1610 and Surface Effect Dominant Sites 1430 in a suspension n a solvent 3). a sufficient amount of dispersion, The dispersion is optionally applied to C.NIEs 110. The solvent of the dispersion is then evaporated from the mixture resulting in a powder or coating on the CNEs 110. Binder 1440 can be added to the suspension before or after application to the CNFs 110. In some embodiments, the application of Surface Effect DominantSites 1430 occurs at _the tmal stage of Intercalation Material 1610 deposition by clanging the materials eing sputtered onto Substrate 105. in these efnbodiments,for example can cart Lae added to the spun stall? ealation Material 1610 is deposited. "Phis produces a sputtered layer of 1)0, as Surface Effect Dominant Sites 1430 on top of Intercalation Material 1610.

1001201 FIG. 22 illustrates methods of operating a charge storage device" according to various embodiments of the invention. This method may be used, tor example, when charging the charge storage device. In some embodiments the method includes attaching a ciliarging device to both an anode and cathode of the charge storage device. via wires. This charging storage device places potentials at the anode and cathode resulting in a potential gradient there between. The potential gradient drives electrons into the anode. The steps illustrated in FIG. 22 optionally occur contemporaneously, e.g., they can occur at the same or at overlapping times with respect to each other.

1001211 in an Establish Potential Step 2210 a potential is established at the charge storage device. This potential may be between an anode and a cathode of the charge device. Such a potential will result in a potential gradient between Substrate 105 and Electrolyte 125 within the charge storage device, The potential gradient can produce a potential difference between locations of Surface Effect Dominant Sites 1430 and Intercalation Material 1610. In various embodiments this potential difference is at least 0.001, 0.1, 0.3, 0.4, 0.5, 0.8, 1.0, 1.3, 1.7, 2.0, or 2.4 V, or any range there between.

I00122l In a Receive Lithium Step 2220 a charge carrier, of which Lithium is but one possible example, is received at one of Surface Effect Dominant Sites 1430. This charge carrier is optionally received through Binder 1440.

1001231 In a Transfer Electron Step 2230 an electron is transferred (e.g.. donated) from Surface Effect Dominant Site 1430 to the charge carrier received in Receive Lithium Step 2220. This transfer may comprise sharing of the electron between the Surface Effect Dominant Site 1430 and the charge carrier. The electron is transferred in a faradaic reaction and is typically conducted from Substrate 105. The Mut occurs white the charge carrier is at the surface of the Surface Effect Dominant Site 1430 and o occurs at the potential of that location. A reaction potential of the electron tra s for example, lependent on the reaction potential of the charge earn ition potential H ac Dominant Site 1430 The reaction potential can' an be dependent on both the Stu Dominant Site 1430 and the nearby Intercalation Material 1610. As used herein, the term -reaction potent used to refer to the potential at which a reaction occurs at an appreciable in a cyclic thltanunogram. In another example, the potentials required for the react Li or 2L1 MO 4,there M is any of the transition metals discussed herein) to occur in an electrochemical cell are the reaction potentials of these reactions. The reaction potential can be highly iendent on the environment in which the reaction occurs.

For example, the second reaction above may have a lower reaction o n settee 1402 nanoparticle having a diameter in the range of 2-10 nri. Likew 0 potential can be influenced by the energy required for intercalation or by the close proximity of Surface Effect Dominant Sites 1430 and intercalation Material 1610, 1001241 In an intercalate Lithium Step 2240 a charge carrier, of which Lithium is but one possible example, r intercalated within Intercalation Material 1610, This step may include migration of the charge carrier into the bulk of lite late gal 1610.

The charge carrier can he received at Intercalation Manila] 1610 as the same chemical species as received at the Surface Effect Dominant Sites 1430 rn Receive lithium Step 2220, or alternatively in as a chemical d ced at the Sufi pct Effect Dominant Sites 1430.

For example, the barge rier can be received at the Intercalation Material 1610 as an (e g., Li2. etc.) of the chemical species received at Surttee r f4ect Do in t Sites 1430.

1001251 in a Transfei Electron Step m electron from Interea Material lO10 to the charge ca-ter of Intercalate Lithium ep 2 240. The electron is paten al of a reaction can be illustrated by, for example, peaks transferred in a farm ion and is typically conducted it om Substrate 105. The transfer occurs l the charge carrierisintercalation Mater 1610 and occurs at th potential of that location. A reaction potential the electron transfe the reaction potential of the charge carrier and the reaction potential of the Intercalation Material 1610. The potential f this conduction hand can he influenced by both the Intercalation Material 1610 d nearby Surface Effect Dominant Sites 1430. Surface Dominant Sites 1430 can ta yze transfer of lithium from Electrolyte 125 to intercalation Material 1610. As discussed elsewhere herein, this transfer can occur 'a an intermediate oxide such as Ti20. The work (sanction of this electron transfer can be different than the work function of the electron transfer in Transfer Electron Step 2230. For example, in various embodiments the work function is at least 0.001, 0.1, 0.3, 0,4, 0 0 0, 1.3, 1 2.0 or 2.4V, or any combination there between. In some embodiments it is thermodynamically more favorable for lithium to be intercalated into Intercalation Material 1610 than into the bulk of nanopartides that include the Surface Effect Dominant Sites 1430. However, the presence of the Surface Effect Dominant Sites 1430 can catalyze intercalation of a charge carrier to Intercalation Material 1610.

261 If the charge canier is converted n Transfer Electron Step 2230 then, in ionic embodiments, Transfer Electron Step 2i 0include transferof an oxygen back from intercalation) Material 1610 back to Surface Effect Dominant Sites 1430. This oxygen received at intercalation vtateMaterial 1610 as the oxide of the charge carrier, and is r leased from the charge earner during intercalation. After being transferr Dominant Sites 410 this oxygen can then be used in further occurrences or Transfer Electron Step 2230, i.e.,recycled.

[001271description of FIG. 22 ah,e ass z,kcs that the charge carne rcce d in Receiy 2220 and the charge carrier. Intercalate L ithiumn Step 2240 are two different criers (that could be o e same type), in various mbochments steps 22 and 224t) can be nersonned n by the aindividual charge earners, For example, -mbodiments, Receive Lithium Step 2220 includes receiving a charrie arrier at one of S cant Sue-1430, Transfer Electron Step 2230 ilten includes a reaction in which the charge carrier reacts with the Surtnce Effect Dominant Site 1430 to produce an interne e compound. in stntic embodiment his reaction includes 21_ MO 4-2e --L120 + M is any of the transition: 's discussed herein and Li2O s the tine resulting intermediate compound). In Intercalate Lithium Step 2240 the intermediate compound (e.g., Lis()) is intercalated into Intercalation Material 1610, or one (or both) of the Li in the intermediate compound are transferred from the 0 of Lii0 to an atom of the Intercalation mated g., LixSi). This tra transfer may result in regeneration of the MO that was split 'Fransfer Electron Step 2230. Note that in this example the same dividual Li atom was involved in each of the Steps 2220-2230 and 2240. Transfer Electron Step 2250 is not required in these embodiments of the methods illustrated by FIG, 22, it is possible that in some embodiments both reaction sequences that include an intermediate such as and reaction sequences that do not include ant intermediate occur during a single charging cycle. Several embodiments embod ments arespecifically illustrated and/or described herein. However, it will be appreciateappreciated that modifications and variations are covered by the above icantl tad within ilte ticope of the ppended claims deparm intended scope thereof. For ca. p iseussed herein: been focused on CNFs having a stacked-con structure the teachings be adapted to other materials having similar or a_ternattve sti uctures. Like *-e while a C a Substrateand Li charge canners are discussed herein other substrates and charge carriers will be apparent to one of ordinary, skill in the art SiliconLayer 115 is optionally' formed of intercalation materials in addition to or as an alternate ample, tin, e -mansii,n carbon,hitt grapheme, silicon, other materials discusse r combinations thereof could be used as rtercafe tion matedal. Additionally, acrogels, nano vl ices, TiOs (titanium ti)" metal carbon wires, cr boron nano-fibers can be used in place of the carbon nano-fibers discussed ile rein.The relative concentrations of Di et 1440, Surface Eflect Dominant Sites I 430, Intercalation Material 1610 and ME 110 and other elements in the figures can vary significantly from that illustrated.

1001291 The electrodes taught herein tuay be included in a wide variety: o storage s incltuiing capacitors, batteries and hybrids thereof."These energy storage devices can he used in, bar example portable electronics, load balancing devices nication devices, backup power supplies, vehicles and computing devices.

The concepts taught herein can he, in many cases. applied to cathodes as well as anodes.

1001301 Details of VACYF Growth and Silicon Deposition, Microscopy and Spectroscopy Characterization, and Electrochemical Cell Assembly and Charge-Discharge Tests can be found in US provisional application' 1/667,876 filed Jul 7012 100131) The embodiments discussed herein are illustrative the present invention As these embodiments of the present invention are described with reference to illustrations, various modifications or adaptations of the iethods and or specific structures described may become apparent to those skilled in the art. All such modifications, adaptations, or variations that rely upon the teach s of the present (tian, andthrough which these teachings have advanced the CO within the spirit anti scope of the present iny eniio Hence, these descriptions d drawiri,gs should not be considered in a limitingas i1 1.s understood that the present invention is in no way limited to only the embodiments tustrated. -1-6

Aspects of the invention will now be described with reference to the following numbered clauses: 1. An energy storage system co nising: a conductive substrate, a carbon nanofiber connected to the conductive substrate, the carbon nanofber including a plurality of exposed nanoscale edges along the length of the carbon nariefibe and an intercalation material configured to form a shell over at least part of the carbon nanoli tier.

2. The system or method of clause 1, 29, 30 or 31, wherein each of the exposed nanoscale edges include edges of multiple graphitic sheets.

3. The system or method of clause 29, 30" 31, 1 or 2 wherein each of the exposed nanosc dges is configured to control growth of the intercalation material.

4 The system or method of clause 29, 30, 31, 1-2 or 3, wherein each of the exposed nanoscale edges is configured to provide a migration path for charge carriers to an interior of the carbon it-mliber.

5. The system or method of clause 29, 30, 31, 1-3 or 4, wherein each of the exposed nanoscale edges include multiple graphene edges.

6. An energy storage system comprising: a conductive substrate: a carbon nanofiber connected to the conductive substrate, the carbon nanoliber including a plurality of cup-like structures along the length of the carbon nanofiber-and an intercalation material configured to form a shell over at least part of the carbon nanofiber.

7. The system or method of clause 29, 30, 31, -5 Or 6, wherein each of the cup-like structures include walls having multiple aphitic sheets.

8. The system or method of clause 29, 30, 31 6 or 7, wherein each of the cup-like structures are configured to control growth of the ntercal on material.

9. An energy storage system comprising: a conductive substrate; a carbon nanofiber connected to the conductive substrate; and an intercalation material configured to form a shell over at least part of the carbon nanofiber, the intercalation material being disposed in a feather k-structure along a. length of the carbon nanofiber.

10. An ett stem comprising: er conductive substrate; a carbon nanofiber connected to the conductive substrate; and an interc ation material configured to form a shell over at least part of the carbon nanofiber,the intercalation material being configured such that expansion of the intercalation material is non-delaminating of the intercalation material from the carbon nanofiber.

11. The system or method of clause 29, 30, 31, 1t-9 or 10, wherein the expansion s radial to the carbon na otiber.

12. The system or method of clause 29, 30, 31, 1-10 or 11, wherein the expansion is between parts of the intercalation material disposed on the carbon nanofiber.

13. The system or method of clause 1-11 or 12, further comprising an electrolyte in contact with the intercalation material and including a charge ca rier 14. The system or method of clause 29, 30, 31, 13, wherein the electrolyte is a solid electrolyte.

15. The system or method of clause 29, 30, 31, 13 or 14, wherein the charge carrier includes lithium.

16. The system or method of clause 29, 30, 31, 1 -14 or 15, wherein the carbon nanofiber is one of a plurality of vertically aligned carbon nanofibers attached to the substrate.

17 The system or method of clause 29, 30, 31, 1-15 or 16, wherein the conductive substrate, carbon nanofiber and intercalation material are configured to function -an anode.

18. The method of clause 17, further comprising a cathode in contact with the electrolyte.

19. The system or 'ea d of clause 1-17 or 18, wherein the carbon nanofiber is directly attached to conductive substrate.

20. The system or method of clause 28, 29, 30,1-18 or 19, wherein the intercalation layer includes silicon.

21. The system or method of clause 29, 30, 31, 1-19 or 20 wherein the carbon nanofiber is configured to grow an intercalation material structure at the exposed edges of the carbon nanofiber.

22. The system or method of clause 29, 30, 31, 1-19 or 20, wherein the carbon nanofiber is indirectly attached to the conductsubstrate using ' der.

23. The system or method of clause 29, 30, 31, 1-21 or 22, wherein the cup-Like structures include spiral with cup-likt, cross-section.

24. The system or method of clause 1-22 or 23, wherein carbon nanofiber and the intercalation material result in an insertion capacity for Lit of between 2752 and 3650 mAlg-and at least a 85% retention of the n ertion capacity for 100 charge/ discharge cycles.

25. The system or method of clause 29, 30,31, 1-23 or 24, wherein the intercalation material is disposed in a layer having a no al thickness of between 0.1 and 4.0 um 26. The system or method of clause 29, 30, 31, 1-24 or 25, wherein the carbon nanofiber is is. 3 and 200 pm in length.

27. The system or method of clause 1-25 or 26, further corn sing a plurality of nanoparticies attached to the intercalation material, each of the nanoparticl s being configured to provide surface effect dominant sites configured barge carriers via faradaic interactions on surfaces of the na.noparticl es.

28. Theor method of clause 29, 30, 31, 1-26 or 27, wherein the conductive substrate, carbon nanofiber and intercalation material are configured such that an insertion capacity for Li' increases as a charge rate is increased from 2C to 8C.

nC) A method of producing an energy storage device, the method con icing: providing a conductive substrate; adding carbon nanofibers to the conductive substrate, the carbon nanofibers each including a plurality of exposed nanoscale edges along the length of the carbon nanofiber; and applying intercalation material to the carbon nanofibers, the intercalation material being configured for intercalation of charge carriers.

30. A method of producing an energy storage device, the method compels gi providing a conductive substrate; adding iarbon nanofibers to the conductive substrate, the carbon nanofibers each including a plurality of cup-like structures along the length of the carbon nanofiber and applying intercalation material to the carbon nanofibers, the intercalation material beingmfigured for intercalation of charge carriers.

31. A method of produci g n energy storage device, the method comprising: providing a conductive substrate; adding carbon nanofibers to the conductive substrate; and applying intercalation material to the carbon nar_*ofibers, the intercalation material being configured for intercalation of charge carriers, and the intercalation material being disposed in a feather-like structure along a length of the carbon nanotiber.

32. The method of clause 29, 30 or 31, further comprising adding an electrolyte in contact with the ercaa d including a ch earner 33. The method of clause 29-31 or 32, wherein the carbon nanofibers are vertically aligned carbon anofiber attached o duesubstrate.

34. The method of clause 29-32 or 33, wherein the conductive substrate, carbon anolibers and intercalation material are configured to function as an anode.

35. Tu method of clause 29-33 or 34" further comprising a cathode in contact with the electrolyte.

36. The hod of clause ( 34 or 3 wherein the carbon nanotibers are attached directly to the conductive substrate.

37. The method of clause 29-35 or 36, further comprising attaching a plurality of nanoparticies to the intercalation material, each of tlae nanoparticles being co to provide surface effect dominant sites configured to adsorb charge carriers via faradaic interactions on surfaces of the nanoparucl es.

38. The system or method of clause 1-27 or 28, wherein the intercalation material includes first silicon structure at a time of the carbon nanolther and a second silicon structure along a length of the carbon nanofiber.