CN101685860A - Cathode active material, preparation method thereof and cathode and battery containing same - Google Patents
Cathode active material, preparation method thereof and cathode and battery containing same Download PDFInfo
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- CN101685860A CN101685860A CN200810216386A CN200810216386A CN101685860A CN 101685860 A CN101685860 A CN 101685860A CN 200810216386 A CN200810216386 A CN 200810216386A CN 200810216386 A CN200810216386 A CN 200810216386A CN 101685860 A CN101685860 A CN 101685860A
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention provides a cathode active material, containing silica-based composite material. The silica-based composite material contains component A and component B; wherein component A is silicon oxide, and component B is one or more than one of FeO, Fe2O3 and Fe3O4 or one or more than one of lithium oxide, lithium chloride and lithium hydroxide. Cycle performance of battery prepared by cathodeactive material provided by the invention is greatly improved, and capacity of battery is improved in certain degree while initial charging/discharging circulation invisible capacity is greatly reduced.
Description
Technical field
The present invention relates to a kind of negative active core-shell material and preparation method thereof and contain the negative pole and the battery of this material.
Background technology
Lithium rechargeable battery is extensively used as the main flow power supply at electronic products such as mobile communication equipment, digital camera, notebook computers owing to have characteristics such as volume is little, energy density is big.The capacity of the secondary cell of at present traditional lithium cobalt oxygen/graphite system is near its theoretical peak capacity, is difficult to improve its volume energy density by the methods such as thickness that improve dressing density, reduce collector or barrier film.Along with the update of mobile electronic product, the particularly arriving in mobile phone 3G epoch has proposed urgent requirement to the appearance of ultra-high capacity battery.
In recent years, the negative material of silica-base material as lithium ion battery carried out extensively studying meticulously.Silica-base material has crystal and amorphous two kinds of forms, and is wherein preferable with the performance of amorphous silicon substrates material as negative material, in addition, be in crystal and amorphous between the crystallite attitude also can be used as negative material.In charge and discharge process, lithium can take off embedding in silica-base material.When lithium is inserted in the silicon, can form alloy with silicon.This silicium cathode material has high specific capacity, and theoretical capacity can reach 4200mA/g.
But silica-base material can produce huge change in volume before and after removal lithium embedded, and volume is expanded to original 4 times approximately behind the complete embedding lithium of silica-base material.Therefore, like this violent change in volume in charge and discharge process has caused a series of fatal problems, for example, the forfeiture of the removal lithium embedded ability that the fragmentation of negative material, efflorescence cause in the cyclic process, negative material comes off and the deterioration of the afflux characteristic that causes from collector, produces fold on the collector and the bulging of the coiling body electricity core that causes etc.Therefore, it is relatively poor that the extremely violent volume breathing of this silicium cathode causes adopting the cycle performance of battery of this negative pole.
Si oxide is during as the negative material of lithium rechargeable battery, and the change in volume that can slow down material cycle performance of battery is improved, but the irreversible capacity first of negative material is very big, and the specific capacity of battery is not high.
Summary of the invention
The irreversible capacity first that the objective of the invention is in order to overcome existing negative active core-shell material is big, the shortcoming that the specific capacity of battery is not high, provide a kind of capacity greatly, the charge irreversible capacity is low first, and can effectively slow down cyclic process volumetric expansion, the negative active core-shell material that cycle performance is high.
The inventor finds to add active component FeO, Fe unexpectedly in Si oxide
2O
3, Fe
3O
4In one or more, can not only improve the capacity of battery, the irreversible capacity of charge first of reduction battery, and reversible reaction can take place in this active component, its inert fraction that forms in charge and discharge process can play cushioning effect to the volumetric expansion of SiO, suppress the efflorescence of active material, improved the cycle performance of the battery that contains this negative active core-shell material.
The inventor also finds to add the inert fraction lithia in Si oxide, lithium chloride, in the lithium hydroxide one or more, not only these materials can the partially filled Si oxide micropore that enters, active material stability strengthens, and it is as the part of electrode material, phase film (SEI film or passivating film) elasticity is big in the middle of the solid electrolyte that these particle surfaces form, better kept the stability of SEI membrane structure to a certain extent, can better suppress the change in volume of silicon base compound, significantly improve the cycle performance of the battery that contains the silicon-based anode active material in embedding/when taking off lithium; And inert fraction of the present invention can be simultaneously as dispersant, the environment of elasticity and dispersion is provided for active particle, can increase conductivity, part has suppressed the reunion of particle again, increased the specific area of material, improved effective storage lithium space of material, irreversible capacity loss reduces, lithium is easier to take off embedding, thereby the capacity of battery is improved.
The invention provides a kind of negative active core-shell material, this negative active core-shell material contains silicon based composite material, and described silicon based composite material contains component A and B component, and described component A is a Si oxide; Described B component is FeO, Fe
2O
3, Fe
3O
4In one or more, or B component is in lithia, lithium chloride, the lithium hydroxide one or more.
The present invention provides the preparation method of above-mentioned negative active core-shell material simultaneously, and this method comprises component A and B component are mixed, and obtains silicon based composite material, and wherein, component A is a Si oxide; B component is FeO, Fe
2O
3, Fe
3O
4In one or more, or B component is in lithia, lithium chloride, the lithium hydroxide one or more.
The present invention provides the negative pole that contains above-mentioned negative active core-shell material simultaneously, and this negative pole comprises collector and coating and/or be filled in negative material on the collector that negative material comprises negative active core-shell material, conductive agent and adhesive.
The present invention provides the lithium rechargeable battery that contains above-mentioned negative pole simultaneously, and this battery comprises pole piece and nonaqueous electrolytic solution, and pole piece and nonaqueous electrolytic solution are sealed in the battery container, and pole piece comprises positive pole, negative pole and barrier film.
Among the present invention, by in Si oxide, adding FeO, Fe
2O
3, Fe
3O
4In one or more, or be in lithia, lithium chloride, the lithium hydroxide one or more, significantly improved negative active core-shell material cycle performance, improved the battery that contains this negative active core-shell material capacity, reduced the battery charge irreversible capacity first that contains this negative active core-shell material.For example, the battery D1-D4 that embodiment of the invention 1-4 makes is after 50 circulations, and the discharge capacitance of battery is all more than 60%, and the reference cell CD1 that Comparative Examples 1 makes is after 50 circulations, and the discharge capacitance of battery is less than 30%.
Embodiment
The invention provides a kind of capacity greatly, the charge irreversible capacity is low first, and can effectively slow down cyclic process volumetric expansion, the negative active core-shell material that cycle performance is high.This negative active core-shell material contains silicon based composite material, and wherein, silicon based composite material contains component A and B component, and component A is a Si oxide, and the present invention is preferably the inferior silicon of oxidation; B component is active component FeO, Fe
2O
3, Fe
3O
4In one or more, or in the B component inert fraction lithia, lithium chloride, lithium hydroxide one or more.
In the silicon based composite material, the content of component A and B component can in very large range change according to the present invention, and under the preferable case, the weight ratio of component A and described B component is 80: 20～50: 50; More preferably the weight ratio of component A and described B component is 80: 20～70: 30.In above-mentioned scope, can better suppress the change in volume of Si oxide in embedding/when taking off lithium, better improve the cycle performance of the battery that contains this negative active core-shell material; With the effective storage lithium space that can better improve material, reduce the battery irreversible capacity loss, improve battery capacity.
In the silicon based composite material, the specific area of material can in very large range change according to the present invention.The specific area of the preferred negative active core-shell material of the present invention is 4.1m
2/ g～9.6m
2/ g.In above-mentioned scope, the chemical property of negative active core-shell material is more excellent.
In the silicon based composite material, the amorphous degree of material can in very large range change according to the present invention.The general anode material adopts the amorphous silicon substrates material, and the unbodied structure of material can keep the stable of structure relatively in the silica-base material charge and discharge process, influences the chemical property of material.The amorphous degree of the preferred negative active core-shell material of the present invention is greater than 100%, and amorphous degree herein is based on the X-ray diffraction peak, according to formula
Amorphous degree=((the XRD main peak intensity of active material behind the ball milling)/(the XRD main peak intensity of active material before the ball milling)) * 100%
The inventor is unexpected to find that negative active core-shell material of the present invention is in charge and discharge process, the potential region that forms the SEI film is 0.6～1.2V, electrolyte is easier formation skin covering of the surface on the combination electrode surface, and the SEI film that forms has bigger elasticity, Stability Analysis of Structures has improved performances such as the cycle efficieny of the battery that contains this negative active core-shell material and reversible capacity.
Among the present invention, the mean particle diameter of negative active core-shell material can in very large range change, and the mean particle diameter of the preferred negative active core-shell material of the present invention is 0.5 μ m～20 μ m.
Negative active core-shell material of the present invention has above 10
-18Cm
2The Li ions diffusion speed of/s, Li ions diffusion speed is big more, easier insertion and deviating from the lithium ion composite material, be that lithium ion has good dispersal behavior in composite material, help charge transfer, promptly reduced the contact resistance between the active material particle, help electrochemical redox, improve the chemical property of the battery that contains this negative active core-shell material, reduced the irreversible capacity first of battery especially.
The present invention also provides the preparation method of this kind negative active core-shell material, and this method comprises component A and B component are mixed, and obtains silicon based composite material.Component A is a Si oxide; B component is FeO, Fe
2O
3, Fe
3O
4In one or more, or B component is in lithia, lithium chloride, the lithium hydroxide one or more.
According to the present invention, in the described silicon based composite material, the consumption of component A and B component can in very large range change, and under the preferable case, the weight ratio of described component A and described B component is 80: 20～50: 50; More preferably, the weight ratio of described component A and described B component is 80: 20～70: 30.
According to the present invention, the method of component A and B component mixing is had no particular limits,, for example can be the method for ball milling as long as component A and B component can be mixed, the condition of ball milling can comprise that the rotating speed of ball milling is 200～600 rev/mins, and the time of described ball milling is 5～50 hours.Among the present invention, the used dispersant of ball milling is an absolute ethyl alcohol.
In order to prevent negative active core-shell material oxidation when the ball milling, described ball milling carries out under inert gas atmosphere or vacuum environment.Wherein, described inert gas can be one or more in group 0 element gas and the nitrogen.The pressure of described vacuum environment is 1 * 10
-2Below the handkerchief.
The present invention also provides a kind of negative pole, and this negative pole comprises collector and coating and/or be filled in negative material on the collector that wherein, negative material comprises above-mentioned negative active core-shell material, conductive agent and adhesive.
Negative pole of the present invention is except the anticathode active material improves, and all the negative pole with conventional lithium ion battery is identical for other.
Wherein, conductive agent for example can be selected from acetylene black, conductive carbon black, graphite powder, the carbon nano-tube etc. one or more for well known to a person skilled in the art various conductive agents.
Adhesive is for well known to a person skilled in the art various binding agents.For example can be in fluorine resin, acrylic polymer, amine polymer and the polyolefin compound one or more, be preferably in polyvinylidene fluoride, polytetrafluoroethylene, vinylidene difluoride-hexafluoropropylene copolymer, polyamidoimide and the butadiene-styrene rubber one or more.The content of the adhesive in the negative material is conventionally known to one of skill in the art.For example, in negative material, the weight of relative negative active core-shell material, the content of described adhesive can be 0.1-15 weight %, is preferably 1-10 weight %.
Collector is conventionally known to one of skill in the art.For example can be stamped metal, metal forming, net metal, foamed metal, in specific embodiments of the present invention, use Copper Foil as negative current collector.
The preparation method of negative pole of the present invention is conventionally known to one of skill in the art.For example the slurry that contains negative active core-shell material, adhesive and solvent can be applied and/or be filled on the collector, drying is rolled or is not rolled.
Wherein, the content of the various compositions in the slurry and preparation method are conventionally known to one of skill in the art.For example, in the slurry, the weight of relative negative active core-shell material, the content of adhesive can be 1-10 weight %, the content of solvent can be 100-300 weight %.As long as slurry is with above-mentioned negative electrode active material, conductive agent, adhesive and solvent evenly.Solvent is conventionally known to one of skill in the art.For example can be in N-methyl pyrrolidone (NMP), dimethyl formamide (DMF), diethylformamide (DEF), dimethyl sulfoxide (DMSO) (DMSO), oxolane (THF) and the water one or more.
The drying condition of slurry and the method for calendering are conventionally known to one of skill in the art.In general, Gan Zao condition is generally temperature 80-150 ℃, 0.5-5 hour drying time.
The present invention also provides a kind of lithium rechargeable battery, and this battery comprises pole piece and nonaqueous electrolytic solution, and pole piece and nonaqueous electrolytic solution are sealed in the battery container, and pole piece comprises positive pole, negative pole and barrier film, and wherein, negative pole is above-mentioned negative pole.
Positive pole can be the positive pole that uses in the conventional lithium rechargeable battery.This positive pole comprises the positive electrode on plus plate current-collecting body and this collector, and positive electrode comprises positive active material, conductive agent and adhesive, and the kind of positive active material, conductive agent and adhesive and content are conventionally known to one of skill in the art.
Electrolyte consists of conventionally known to one of skill in the art, and in general, electrolyte contains nonaqueous solvents and is dissolved in electrolyte in this nonaqueous solvents, and electrolytical content is generally 0.3-2mol/l.
The kind of nonaqueous solvents is conventionally known to one of skill in the art, can use various known nonaqueous solventss, preferably uses the mixed solvent of chain acid esters and ring-type acid esters; The chain acid esters can be selected from dimethyl carbonate, diethyl carbonate, ethyl propyl carbonic acid ester, diphenyl carbonate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, dimethoxy-ethane, diethoxyethane with and fluorine-containing, sulfur-bearing and contain one of them or its mixture of the chain organosilane ester of unsaturated bond; The ring-type acid esters can be selected from ethylene carbonate, propene carbonate, vinylene carbonate, gamma-butyrolacton, sultone with and fluorine-containing, sulfur-bearing or contain one of them or its mixture of the ring-type organosilane ester of unsaturated bond.
Electrolytical kind is conventionally known to one of skill in the art, can use the lithium electrolyte that is generally used for nonaqueous electrolytic solution secondary battery, for example, electrolyte can be selected from one or more in the lithium salts of lithium perchlorate, chlorine lithium aluminate, lithium hexafluoro phosphate, LiBF4, lithium halide, fluorocarbon based fluorine oxygen lithium phosphate or fluorocarbon based sulfonic acid lithium.
The kind of barrier film is conventionally known to one of skill in the art, and for example, barrier film can be polypropylene (PP) film or polyethylene (PE) film.
Except the negative pole that negative pole use the present invention makes, the preparation method of described lithium rechargeable battery is conventionally known to one of skill in the art.This method comprises positive pole and the negative pole for preparing this battery, and positive pole, negative pole and barrier film are prepared into pole piece, the pole piece that obtains and electrolyte is sealed in the battery case get final product.
The present invention will be described in more detail below by embodiment.
Embodiment 1
Present embodiment illustrates negative electrode of lithium ionic secondary battery provided by the invention and contains the negative pole and the battery of this material.
(1) preparation of negative active core-shell material
With the raw silicon oxide (going up the marine clear world) of 80% weight portion, the raw material Fe of 20% weight portion
3O
4(going up the marine clear world) joins in the ball grinder of planetary ball mill (QM-3SP2 type, Nanjing Univ. Instrument Factory), and wherein, the ratio of the weight of abrading-ball and the total weight of raw material is 15: 1.With vacuumizing and charge into argon gas after the ball grinder sealing as protection gas, carry out ball milling, the rotating speed of ball milling is 300rpm, the time of ball milling is 5 hours, obtains negative active core-shell material A1.
Measuring the mean particle diameter that obtains negative active core-shell material A1 with laser particle size analyzer (Ms-2000 of Britain Ma Erwen Instr Ltd.) is 3 microns.
The specific area that obtains negative active core-shell material A1 with Monosorb type BET tester analysis-e/or determining is 7.2m
2/ g.
Change the diffraction main peak intensity that target X-ray diffractometer (Cu K α 1) analysis-e/or determining obtains negative active core-shell material A1 with Japan RigaKu D/max of science 2200pc+0.5kw, the amorphous degree that obtains negative active core-shell material that converts is 1.35.
Adopt LAND battery test system (model: CT2001A) at 25mAg
-1Current density discharge and recharge experiment, the film formed potential region of SEI that can be got negative active core-shell material A1 by the capacity differential curve of twice charge and discharge cycles is 0.78-1.1V.
Adopt German Zahner electrogenesis chem workstation (model IM6) to carry out ac impedance measurement, wherein composite material is a work electrode, and electrode and reference electrode are the lithium sheet, and range of scanned frequencies is 1M～0.001Hz, and sinusoidal wave amplitude is 5mV.
With real part of impedance Z
ReTo ω
-1/2Mapping can obtain a straight line, and the slope of straight line promptly is the size of s.The diffusion coefficient of lithium ion in electrode can calculate from the Warburg factor of diffusion impedance.
That is: D=R
2T
2/ 2A
2n
4F
4C
2s
2
N is the reaction electron number in the formula, and A is an electrode area, and C is an ion concentration.
The Li ions diffusion speed that obtains negative active core-shell material A1 is 2.9 * 10
-18Cm
2/ s.
(2) preparation of lithium rechargeable battery
The negative active core-shell material A1 that obtains of steps (1) and the 4 gram adhesive polytetrafluoroethylene of 100 grams are joined in the 40 gram N-methyl pyrrolidones, in de-airing mixer, stir then and form slurry stable, homogeneous.These slurries are coated on the Copper Foil equably, and drying is 0.5 hour under 120 ℃, rolls then, cuts into the negative plate of 416mm * 45mm, contains 2.8 gram negative active core-shell materials in each negative plate.
(Atuofeina Corp 761#PVDF) is dissolved in the 1350 gram N-N-methyl-2-2-pyrrolidone N-solvents and makes adhesive solution, adds 2895 gram LiCoO then in gained solution with 90 gram polyvinylidene fluoride
2(FMC Corp.'s commodity) fully mix and make anode sizing agent.This anode sizing agent is uniformly applied on the aluminium foil, and through 125 ℃ of dryings 1 hour, calendering then was cut into 424 * 44 millimeters positive plate, contains 6.1 gram positive active materials in each positive plate.
The polypropylene diaphragm of above-mentioned positive plate, 20 micron thickness and negative plate is overlapping successively and be wound into rectangular lithium ion battery electricity core, pack in the battery case, electrolyte is injected battery case with the amount of 3.8g/Ah, and LP053450 type lithium rechargeable battery D1 is made in sealing.Described electrolyte contains LiPF6 and nonaqueous solvents, LiPF described in the electrolyte
6Concentration be 1 mol, described nonaqueous solvents is an ethylene carbonate (EC) and diethyl carbonate (DMC) weight ratio is 1: 1 the ethylene carbonate and the mixed solvent of diethyl carbonate.
Embodiment 2
Present embodiment illustrates negative electrode of lithium ionic secondary battery provided by the invention and contains the negative pole and the battery of this material.
(1) preparation of negative active core-shell material
With the raw silicon oxide (going up the marine clear world) of 70% weight portion, the raw material Fe of 30% weight portion
3O
4And FeO (go up the marine clear world) joins in the ball grinder of planetary ball mill (ND7-2L type Nanda Tianzun Electronics Co., Ltd., Nanjing), and wherein, the ratio of the weight of abrading-ball and the total weight of raw material is 15: 1.With vacuumizing and charge into argon gas after the ball grinder sealing as protection gas, carry out ball milling, the rotating speed of ball milling is 350rpm, the time of ball milling is 10 hours, obtains negative active core-shell material A2.
Adopt the method for testing identical to record with embodiment 1:
The mean particle diameter of negative active core-shell material A2 is 2.1 microns.
The specific area of negative active core-shell material A2 is 8.25m
2/ g.
The amorphous degree of negative active core-shell material A2 is 1.4.
The film formed potential region of the SEI of negative active core-shell material A2 is 0.8-1.2V.
The Li ions diffusion speed of negative active core-shell material A2 is 3.53 * 10
-18Cm
2/ s.
(2) adopt the method identical to prepare lithium rechargeable battery, the negative active core-shell material that different is negative active core-shell material is embodiment 2 is prepared with embodiment 1.
Embodiment 3
Present embodiment illustrates negative electrode of lithium ionic secondary battery provided by the invention and contains the negative pole and the battery of this material.
(1) preparation of negative active core-shell material
Raw silicon oxide (going up the marine clear world) with 70% weight portion, the raw material lithium chloride of 30% weight portion (going up the marine clear world) joins in the ball grinder of planetary ball mill (ND7-2L type Nanda Tianzun Electronics Co., Ltd., Nanjing), wherein, the ratio of the total weight of the weight of abrading-ball and raw material is 15: 1.With vacuumizing and charge into argon gas after the ball grinder sealing as protection gas, carry out ball milling, the rotating speed of ball milling is 300rpm, the time of ball milling is 5 hours, obtains negative active core-shell material A3.
Adopt the method for testing identical to record with embodiment 1:
The mean particle diameter of negative active core-shell material A3 is 2 microns.
The specific area of negative active core-shell material A3 is 5.9m
2/ g.
The amorphous degree of negative active core-shell material A3 is 1.3.
The film formed potential region of the SEI of negative active core-shell material A3 is 0.75-1.0V.
The Li ions diffusion speed of negative active core-shell material A3 is 2.78 * 10
-18Cm
2/ s.
(2) adopt the method identical to prepare lithium rechargeable battery, the negative active core-shell material that different is negative active core-shell material is embodiment 2 is prepared with embodiment 1.
Embodiment 4
Present embodiment illustrates negative electrode of lithium ionic secondary battery provided by the invention and contains the negative pole and the battery of this material.
(1) preparation of negative active core-shell material
Raw silicon oxide (going up the marine clear world) with 70% weight portion, the feed hydrogen lithia of 30% weight portion (going up the marine clear world) joins in the ball grinder of planetary ball mill (ND7-2L type Nanda Tianzun Electronics Co., Ltd., Nanjing), wherein, the ratio of the total weight of the weight of abrading-ball and raw material is 15: 1.With vacuumizing and charge into argon gas after the ball grinder sealing as protection gas, carry out ball milling, the rotating speed of ball milling is 300rpm, the time of ball milling is 10 hours, obtains negative active core-shell material A4.
Adopt the method for testing identical to record with embodiment 1:
The mean particle diameter of negative active core-shell material A4 is 1.8 microns.
The specific area of negative active core-shell material A4 is 6.43m
2/ g.
The amorphous degree of negative active core-shell material A4 is 1.5.
The film formed potential region of the SEI of negative active core-shell material A4 is 0.7-1.0V.
The Li ions diffusion speed of negative active core-shell material A4 is 3.14 * 10
-18Cm
2/ s.
(2) adopt the method identical to prepare lithium rechargeable battery, the negative active core-shell material that different is negative active core-shell material is embodiment 2 is prepared with embodiment 1.
Comparative Examples 1
Adopt the method identical with embodiment 1 to prepare lithium rechargeable battery, different is that negative active core-shell material is that embodiment 1 does not have treated oxidation Asia silicon materials.
The cycle performance test
With 80 milliamperes of (0.1C) constant current charges 960 minutes, deboost was 4.2 volts, shelved after the charging 15 minutes, with 160 milliamperes of (0.2C) constant current discharges to 3.0 volts, used BS-9300R secondary cell device for detecting performance to measure the initial discharge capacity that obtains battery.Repeat the above-mentioned step 50 time of discharging and recharging, the discharge capacity after the record circulation 50 times is calculated the discharge capacitance of 50 circulation back batteries according to following formula.The result is as shown in table 1,
Discharge capacitance=50 time circulation back discharge capacity/initial discharge capacity * 100%.
Table 1
| Embodiment 1 | Embodiment 2 | Embodiment 3 | Embodiment 4 | Comparative Examples 1 | |
| Mean particle diameter (micron) | ??3 | ??2.1 | ??2 | ??1.8 | ??3.5 |
| Specific area (m 2/g) | ??7.2 | ??8.25 | ??5.9 | ??6.43 | ??4.68 |
| Amorphous degree (%) | ??1.35 | ??1.4 | ??1.3 | ??1.5 | ??1.2 |
| Potential region (V) | ??0.78-1.1 | ??0.8-1.2 | ??0.75-1.0 | ??0.7-1.0 | ??0.6-0.8 |
| Li ions diffusion speed (cm 2/s) | ??2.9×10 -18 | ??3.53×10 -18 | ??2.78×10 -18 | ??3.14×10 -18 | ??1.91×10 -19 |
| Discharge capacitance (%) | ??70 | ??75 | ??62 | ??66 | ??25 |
The cycle performance of the battery D1-D4 that makes of embodiment of the invention 1-4 all has significant improvement as can be seen from the above table, particularly battery is after 50 circulations, the discharge capacitance of battery is all more than 60%, and the reference cell CD1 that Comparative Examples 1 makes 50 times the circulation after, the discharge capacitance of battery is less than 30%.
Embodiment 5-8
Negative active core-shell material and polytetrafluoroethylene binding agent that embodiment 1-4 is made mixed by weight 9: 1, and the furnishing paste evenly is applied to about 1cm
2The stainless steel collector body on, in the oven dry down of 120 ℃ of vacuum drying chambers, make electrode slice with the 20MPa compressing tablet with DY-20 desktop electric tablet press machine.(H under the argon gas atmosphere in the MBRAUN glove box
2O and O
2The volume integral number average less than 10
-6) with above-mentioned electrode slice, lithium sheet (1.5cm * 1.5cm) and 8 milliliters LiPF
6Electrolyte (concentration is 1mol/L, and solvent is that volume ratio is the mixed solvent of 1: 1: 1 ethylene carbonate (EC), diethyl carbonate (DMC) and methyl ethyl carbonate (EMC)) is assembled into simulated battery.
Comparative Examples 2
Method according to embodiment 5-8 prepares simulated battery, and different is that negative active core-shell material is the active material that Comparative Examples 1 prepares.
The test of battery specific capacity
Under 25 ℃, adopt blue electricity (LAND) series battery test macro (model: the CT2001A) charge-discharge performance of specimen between 0～1.5V.The electrode slice of simulated battery is received the positive pole of tester, and the lithium sheet is received the negative pole of tester.
Battery is set to discharge condition, and discharge current density is 0.5mA/cm
2, discharge cut-off voltage is 0V, discharge finishes to be out of service and to calculate first discharge specific capacity according to following formula (1).The result is as shown in table 2.
The quality (1) of first discharge specific capacity (mAh/g)=discharge capacity/active material
After discharge finished first, battery was set to charged state again, and the density of charging current is 0.5mA/cm
2, the charging cut-ff voltage is 1.5V.Charging finishes the back and calculates initial charge specific capacity reversible specific capacity just according to following formula (2).The result is as shown in table 2.
The quality (2) of initial charge specific capacity (mAh/g)=charging capacity/active material
Calculate first charge-discharge efficiency according to following formula (3) then.The result is as shown in table 2.
First charge-discharge efficiency=initial charge specific capacity/first discharge specific capacity * 100% (3)
Table 2
| Embodiment 5 | Embodiment 6 | Embodiment 7 | Embodiment 8 | Comparative Examples 2 | |
| Initial charge specific capacity (MAH/gram) | ??1102 | ??1241 | ??954 | ??1080 | ??592 |
| First discharge specific capacity (MAH/gram) | ??1933 | ??1970 | ??1871 | ??2000 | ??1850 |
| First charge-discharge efficiency (%) | ??57 | ??63 | ??51 | ??54 | ??32 |
| Irreversible capacity (MAH/gram) | ??831 | ??729 | ??917 | ??920 | ??1258 |
The battery that makes of embodiment of the invention 5-8 is than Comparative Examples 2 as can be seen from the above table, and its specific capacity all has significant improvement, and first charge-discharge efficiency is all more than 50%, and the reference cell first charge-discharge efficiency that Comparative Examples 2 makes only 30%.The battery first charge-discharge irreversible capacity that embodiment of the invention 5-8 makes has reduction significantly, has well improved the chemical property of existing silicon based composite material, for the good battery of processability provides the basis.
Claims (12)
1, a kind of negative active core-shell material, this negative active core-shell material contains silicon based composite material, and described silicon based composite material contains component A and B component, and described component A is a Si oxide; Described B component is FeO, Fe
2O
3, Fe
3O
4In one or more, or B component is in lithia, lithium chloride, the lithium hydroxide one or more.
2, material according to claim 1 is characterized in that, the weight ratio of described component A and described B component is 90: 10～50: 50.
3, material according to claim 1 is characterized in that, the specific area of described negative active core-shell material is 4.1m
2/ g～9.6m
2/ g.
4, material according to claim 1 is characterized in that, having of described negative active core-shell material surpasses 100% amorphous degree.
5, material according to claim 1 is characterized in that, described negative active core-shell material forms the middle phase film of solid electrolyte in charge and discharge process potential region is 0.6～1.2V.
6, material according to claim 1 is characterized in that, the mean particle diameter of described negative active core-shell material is 0.5 μ m～20 μ m.
7, material according to claim 1 is characterized in that, described negative active core-shell material has above 10
-18Cm
2The Li ions diffusion speed of/s.
8, the preparation method of the described negative active core-shell material of claim 1, this method comprise component A and B component are mixed, and obtain silicon based composite material, and described component A is a Si oxide, and described B component is FeO, Fe
2O
3, Fe
3O
4In one or more, or B component is in lithia, lithium chloride, the lithium hydroxide one or more.
9, method according to claim 8, it is characterized in that, with the method for component A and B component mixing is ball milling, the condition of described ball milling comprises that the rotating speed of ball milling is 200～600 rev/mins, the time of described ball milling is 5～50 hours, and the weight ratio of described component A and described B component is 80: 20～60: 40.
10, a kind of negative pole, this negative pole comprises collector and coating and/or is filled in negative material on the collector, described negative material comprises negative active core-shell material, conductive agent and adhesive, it is characterized in that described negative active core-shell material is any described negative active core-shell material among the claim 1-7.
11, negative pole according to claim 10, it is characterized in that, described conductive agent is selected from one or more in acetylene black, conductive carbon black, graphite powder, the carbon nano-tube, and described binding agent is selected from one or more in polytetrafluoroethylene, polyvinylidene fluoride, vinylidene difluoride-hexafluoropropylene copolymer, the polyamidoimide.
12, a kind of lithium rechargeable battery, this battery comprises pole piece and nonaqueous electrolytic solution, and described pole piece and nonaqueous electrolytic solution are sealed in the battery container, and described pole piece comprises positive pole, negative pole and barrier film, it is characterized in that described negative pole is any described negative pole of claim 10-11.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103608952A (en) * | 2011-06-24 | 2014-02-26 | 丰田自动车株式会社 | Negative-electrode active material, and method for production of negative-electrode active material |
| CN105609318A (en) * | 2016-01-07 | 2016-05-25 | 上海展枭新能源科技有限公司 | Preparation method of lithium pre-embedded negative plate and obtained lithium pre-embedded negative plate |
| CN105990574A (en) * | 2015-02-11 | 2016-10-05 | 微宏动力***（湖州）有限公司 | Coated lithium-rich negative electrode material and preparation method thereof |
| CN108807952A (en) * | 2018-08-11 | 2018-11-13 | 苏州纳智航新能源科技有限公司 | A kind of preparation method of the sub- silicon/ferrous oxide composite negative pole material of lithium ion cell nano oxidation |
| CN111769261A (en) * | 2020-06-02 | 2020-10-13 | 杭州电子科技大学 | Ferroferric oxide/silicon oxide/multilayer graphene composite material and preparation method thereof |
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2008
- 2008-09-24 CN CN200810216386A patent/CN101685860A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103608952A (en) * | 2011-06-24 | 2014-02-26 | 丰田自动车株式会社 | Negative-electrode active material, and method for production of negative-electrode active material |
| CN105990574A (en) * | 2015-02-11 | 2016-10-05 | 微宏动力***（湖州）有限公司 | Coated lithium-rich negative electrode material and preparation method thereof |
| CN105609318A (en) * | 2016-01-07 | 2016-05-25 | 上海展枭新能源科技有限公司 | Preparation method of lithium pre-embedded negative plate and obtained lithium pre-embedded negative plate |
| CN105609318B (en) * | 2016-01-07 | 2018-05-11 | 上海展枭新能源科技有限公司 | The preparation method and the pre- embedding lithium cathode sheet of gained of a kind of pre- embedding lithium cathode sheet |
| CN108807952A (en) * | 2018-08-11 | 2018-11-13 | 苏州纳智航新能源科技有限公司 | A kind of preparation method of the sub- silicon/ferrous oxide composite negative pole material of lithium ion cell nano oxidation |
| CN111769261A (en) * | 2020-06-02 | 2020-10-13 | 杭州电子科技大学 | Ferroferric oxide/silicon oxide/multilayer graphene composite material and preparation method thereof |
| CN111769261B (en) * | 2020-06-02 | 2021-08-31 | 杭州电子科技大学 | Ferroferric oxide/silicon oxide/multilayer graphene composite material and preparation method thereof |
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