NL2030074B1

NL2030074B1 - Electrode with embeded pillar structure

Info

Publication number: NL2030074B1
Application number: NL2030074A
Authority: NL
Inventors: Augustinus Haverkate Lucas; Unnikrishnan Sandeep; Ameen Mahmoud
Original assignee: Lionvolt B V
Priority date: 2021-12-08
Filing date: 2021-12-08
Publication date: 2023-06-22

Abstract

The resent disclosure relates to an electrode; a method of manufacturing said electrode; and an energy storage device comprising said electrode. The electrode (1) that comprises an anode metal base (2) and a diffusion layer (3) including conductive pillars (4) With elongate interspace regions (5) therebetween. The pillars (4) are anchored in the metal base layer along an embedded portion (42) thereof, leaving a protruding portion (43) that extends outwardly from a face (21) of the anode metal base layer. The free terminal end faces (44) of the protruding ends can be aligned along plane.

Description

Title: ELECTRODE WITH EMBEDED PILLAR STRUCTURE

TECHNICAL FIELD AND BACKGROUND

The present disclosure relates to an energy storage device, in particular to an electrode comprising an anode metal base layer and a diffusion layer including a structure of electrically conductive pillars. The present disclosure relates to an energy device comprising said electrode and method of manufacturing the electrode.

Lithium metals are promising materials for electrode compositions in energy storage devices in regarding their high specific capacity , however safety issues regarding dendrite formation and rapid aging by electrolyte degradation and Lithium metal consumption hinder their commercialization. When lithium metal is cycled using state of the art liquid electrolytes, porous lithium is formed during plating, covered by a solid electrolyte interface (SEI) layer. Upon cycling not all lithium is reversible, and the SEI layer breaks and reforms on freshly deposited lithium. This results in both lithium metal loss, electrolyte degradation and increase of cell resistance due to the build-up of the resistive SEI layer.

Several types of lithium metal electrodes are known in the field.

Zhang et. al. (Nature Commun. 2018, 9:3729) discloses covering lithium with multiple layers carbon nanotubes (CNTs), each layer having a different concentration of Zn giving a gradient with high Zn concentration directly onto the CNTs, and a final layer with no Zn cover layer. The layers are casted onto Li metal using a DOL/CNT suspension. Disadvantages include distribution of pores and/or sites for Li metal plating. In addition electric field distribution, in particular at an interface between the layered electrode and electrolyte 1s not particularly well distributed, which can result in presence of preferential local lithium deposition sites, in particular in a direction towards the opposing electrode.

WO2017011052A2 discloses an electrode comprising: a plurality of vertically aligned carbon nanotubes; and a metal e.g. Lithium associated with the vertically aligned carbon nanotubes. Similar to the device disclosed by Zhang et. al. the electrode as disclosed allows room to improve electric filed field distribution, near an interface between the layered electrode and electrolyte. Further, distribution of Li sites and/or ion diffusion pathways between the pillars can be regarded as sub-optimal, leading to inhomogeneous lithium distribution along the length of the pillars. In addition electrical and/or mechanical interconnection between the carbon nanotubes and the carrier is not particularly established.

CN112176772 disclosed a method for preparing a lithiophilic carbon nanotube paper. The preparation method comprises the following: uniformly mixing carbon nanotube powder and lithiophilic nano material powder, and carrying out papermaking to form a film by using a wet papermaking process. Nanocellulose can be added to improve the film strength under low thickness. The composition is heated in an inert gas environment to combine the lithiophilic nano material and the carbon nanotubes so as to form a carbon nanofiber with a lithiophilic surface. Authors mention an improvement in lithium dendritic crystal growth over comparable uncoated nanomaterial. However, similar to

W02017011052A2 there remains room for improvement in one or more of: improving homogeneity of electric filed field distribution near an interface between the electrode and electrolyte; optimization of Li plating sites and/or ion diffusion pathways along the thickness of the paper; and the electrical and/or mechanical interconnection between the carbon nanotubes paper and the carrier.

SUMMARY

The present disclosure aims to mitigate one or more of the disadvantages associated to known electrodes. Thereto there is provided an electrode comprising structure of electrically conductive pillars whereby at least a portion of the pillars along a base portion thereof is embedded, anchored, in an anode metal base layer. The electrode can advantageously be applied as anode in an energy storage application, such as a secondary metal-ion battery, e.g. a lithium ion battery, comprising at least said electrode, a further electrode comprising a cathode material, and a separator separating the electrodes and comprising an electrolyte composition. The electrolyte can be a semi-solid electrolyte, e.g. gel, a solid- state electrolyte, or even liquid electrolyte benefiting from comparatively higher ion transport rates.

The anode metal base layer, in case of lithium ion battery, typically comprising lithium, serves as a buffer base layer. The anode metal base provides an excess of anode metal allowing a replenishment of metal ions lost during cycling of the battery. The electrically conductive pillars can simultaneously improve current distribution and field homogeneity within the anode, both in the anode metal base layer and in any anode metal plated onto the metal base and/or the pillars during battery operation.

Anchoring the pillars into the metal base layer advantageously proves a robust interconnection between the pillars and the metal. mitigating potential damaging of the protruding pillars portions, e.g. breaking off at the face of the anode metal base. In addition anchoring improves an electrical interconnection between pillar and the metal base and/or a current collector.

In a preferred embodiment, the structure of electrically conductive pillars is comprised of a vertically aligned carbon nanotubes (CNTs) having upstanding sidewalls. As will be explained in more detail herein below, the CNT structure can advantageously be manufactured with adjacent pillars being essentially vertically oriented with respect to a carrier substrate and with a variation in length that is within 0-5% of an average pillar length. Accordingly, there can advantageously be provided an anode metal electrode configured to mitigate dendritic as well as porous anode metal, for instance, in case of anode being based on lithium metal, typically mitigating Lithium-metal growth on top of the structure and/or reducing the electrolyte degradation and Li-consumption caused by irreversible cycling losses.

Aspects of the present disclosure relate to an electrode and to a method of manufacturing the electrode as disclosed herein.

The electrode comprises an anode metal base layer and a diffusion layer including a structure of electrically conductive pillars with elongate interspace regions between sidewalls of adjacent electrically conductive pillars, wherein each of the electrically conductive pillars is anchored in the metal base layer, generally from an embedded terminal end face of the electrically conductive pillar, along an embedded portion thereof, leaving a protruding portion that extends outwardly from a face of the anode metal base layer. In a preferred embodiment, the anode metal comprises or essentially consists of lithium, forming a lithium metal base layer.

Alternatively the anode metal can be formed of a composition, e.g. an alloy, comprising one or more of lithium, sodium, potassium, magnesium, indium, and zinc, e.g. a Li/Na alloy or a Na/K alloy or a Li-In alloy. Preferably the diffusion layer includes a structure of vertically aligned electrically conductive pillars with elongate interspace regions between upstanding sidewalls of adjacent electrically conductive pillars. Alternatively the diffusion layer can comprise slanted (non-vertically oriented) electrically conductive pillars or even randomly oriented pillars, such as nanowires (e.g.

CNTs, or metal, or conductive ceramic, or a conductive composite) as obtainable by vapor-phase or wet-chemical processing.

Advantageously, each of the electrically conductive pillars can be anchored in the metal base layer from an embedded terminal end face of the electrically conductive pillar along an embedded portion thereof, leaving a protruding portion that extends outwardly from a face of the anode metal base layer.

Aligning the terminal end faces of the electrically conductive pillars advantageously homogenizes the electrical field at the tips of the pillars, mitigating uneven anode metal (e.g. Li) plating.

In case of vertically aligned pillar structures, the free terminal 5 end faces of the protruding ends can advantageously be essentially along an alignment plane, whereby the level of alignment can advantageously be transferred from a first carrier (e.g. a pillar growth substrate), having a comparatively low level of height variations, e.g. surface roughness and/or bow, to a second carrier, e.g. an anode metal film or carrier foil with an anode metal cover layer, having a different, comparatively higher level of variation in roughness. Inventors inventively found the deviation of the free terminal ends from the alignment plane <5% or even below 0.5% from an average. In absolute deviation of the free terminal end from the alignment plane is < 2000 nm, preferably < 1500. Advantageously deviation can be < 200 nm, or even < 100 nm. In a preferred embodiment, embedding and high levels of alignment can be obtained by transferring the pillar structure from a first carrier substrate, e.g. a growth substrate, to a second substrate as comprised in the electrode, e.g. an anode metal foil or a current collector foil (e.g. copper) carrying a layer of anode metal. The better the alignment, the lower the deviations in the length of the protruding pillar portions, the better the field alignment at an interface between the electrode and a separator can be. In some embodiments, the protruding ends can be essentially aligned along a single plane. The better the alignment, the more homogeneous the field can be and the more homogeneous anode metal can plate onto the base and/or pillar structure during battery cycling, which improves battery safety and/or lifetime.

Advantageously the lithium metal base can be attached, e.g. directly or via an adhesion promotion layer, to a current collecting structure such as a metal foil or a metal coated carrier. The current collecting support structure can provide structural support, not only during battery operation,

but also during manufacturing including, but not limited, to delamination stages as explained herein below.

The vertically aligned pillars provide channels with low tortuosity for effective anode metal-ion transport kinetics. Additionally the vertically aligned pillars may have a coating layer on them, for further improving anode metal ion transport kinetics. Such a surface coating layer can advantageously form a passivation layer minimizing electrochemical reaction between the pillars (e.g. CNTs) and the electrolyte, which can lead to undesired SEI formation on the pillars. Excessive SEI formation can lead to a) poor (dis)charging speed and b) loss of Li from the anode and the electrolyte thereby lowering cycle-life. At the growth surface where anode metal is formed, the interspace favorably restricts the nucleation radius promoting homogeneous dense (non-porous) metal growth.

Provision of an electrode comprising an anode metal base layer and a diffusion layer including a structure of vertically aligned electrically conductive pillars can be realized by a method as disclosed. As will become clear in more detail, this method can advantageously realize the anchoring and alignment of the end faces of the protruding tips of the pillars.

The method of manufacturing an electrode comprising an anode metal base layer and a diffusion layer including a structure of electrically conductive pillars, with elongate interspace regions between sidewalls of adjacent electrically conductive pillars, comprises at least: anchoring each of the electrically conductive pillars in the metal base layer from an embedded terminal end face of the electrically conductive pillar along an embedded portion thereof, leaving a protruding portion that extends outwardly from a face of the anode metal base layer, wherein the anchoring comprises a processing step involving melt-processing anode metal.

In a preferred embodiment, the method comprises: forming on a face of an template substrate a structure of electrically conductive pillars with elongate interspace regions between sidewalls of adjacent electrically conductive pillars; contacting terminal end portions of the formed electrically conductive pillars with a layer of an anode metal heated to above a softening temperature; and delaminating, after cooling below a solidifying temperature the anode metal , the structure of vertically aligned electrically conductive pillars from the template substrate, to form the electrode whereby each of the electrically conductive pillars is anchored in the metal base layer from an embedded terminal end face of the electrically conductive pillar along an embedded portion thereof, leaving a protruding portion that extends outwardly from a face of the base layer.

By anchoring the pillars into the anode metal, e.g. an anode metal substrate or anode metal coated carrier, preferably an anode metal coated current collector, and delaminating the template substrate from the pillars, the pillars are effectively transferred from the template substrate to the metal base layer. Hereby the tips of the pillars as formed on the growth- substrate become anchored into the base, whereas the bases from the pillars as formed on the template from the protruding ends of the now anchored pillars, effectively inverting the pillar structure as formed and realizing the manufacture of the electrode, wherein the electrically conductive pillars are anchored in the metal base layer from an embedded terminal end face of the electrically conductive pillar along an embedded portion thereof, leaving a protruding portion that extends outwardly from a face of the base layer.

Transferring the pillars from a template structure mitigates height variations between the pillars as formed on the templated. Instead the height variation of the end faces of the pillars after transfer can be essentially governed by a topology of the template substrate, which can advantageously be essentially flat.

As an alternative to method above, also referred to as delamination-transfer route, the electrode can also be provided by a process referred to as melt-infiltration.

In a preferred embodiment, the melt-infiltration route comprises: forming, on a face of an template substrate, a structure of electrically conductive pillars with elongate interspace regions between sidewalls of adjacent electrically conductive pillars; contacting terminal end portions of the formed electrically conductive pillars with a quantity of an anode metal sufficient to at least partly fill the elongate interspace regions between sidewalls of adjacent electrically conductive pillars; and heating the anode metal above a flowing temperature, e.g. a melting temperature, and maintaining said condition for a period to infiltrate the interspace regions at along a base portion of the electrically conductive pillars with liquified anode metal. Alternatively, the template substrate comprising the pillars may be heated to an elevated temperature (>180°C) already during the contacting of the anode metal on the pillars, thereby enabling at least partial impregnation of the anode metal in between the pillars.

Of course melt-infiltration can also be combined with the delamination-transfer process. For example, an additional amount of lithium metal at the base of the embedded pillar structure as provided by delamination can be provided in a subsequent melt-infiltration process.

Addition of additional lithium metal increases the thickness of the metal base layer and increases a length along which the pillars are embedded, further strengthening adhesion of the pillars during battery operation.

Advantageously the protruding portions can be covered by a layer of an insulator, whereby insulator coverage is restricted to the end faces of the protruding portions. Covering the end faces of the protruding portions with an insulator, e.g. a metal oxide, hinders anode metal plating, e.g. Li plating, in a direction away from the end face of pillars and accordingly mitigates dendrite formation while promoting an open interspace structure (e.g. access to the base anode metal) by mitigating blockages at top portions of the pillar structure.

It will be appreciated that both the transfer method as well as the melt-infiltration methods as disclosed herein can advantageously result in the formation of protruding portions with appropriate insulator coverage.

For the transfer method in particular inventors found that material as comprised on the template substrate (e.g. an oxide or a nitride) can remain attached to the end faces of the pillars after delaminating the pillars from the template substrate. Since the pillars are formed, e.g. grown, from a face of the template the remnants of the template substrate are advantageously restricted to the terminal face of the pillar.

Restricting the insulator to the end face, keeps the underlying interspace regions open for electrolyte access and Li-ion transfer through the structure. The insulator layer prevents dendritic Li growth on top of the pillars and establishes stable Li metal cycling. Restricting insulator coverage to the end faces of the protruding portions of the pillars advantageously allows Li plating in a radial direction in the interspace regions between adjacent pillars, and on the metal base layer , optimizing energy density within the system while minimizing potential dendrite formation from the end face(s) of the pillar (s).

In a strongly preferred embodiment the pillars comprise, or essentially consist of, carbon nanotubes. Carbon nanotubes advantageously combine a high strength with advantageous electric properties and high surface area offering improved capacity to weight ratio as compared to microfabricated pillars having a comparatively lower surface to volume ratio at comparable lengths.

Carbon nanotubes can be conveniently formed, grown, from a template substrate yielding a structure of vertically aligned structure of vertically aligned electrically pillars with elongate interspace regions between upstanding sidewalls of adjacent electrically conductive nanotubes.

In a preferred embodiment, growing vertically aligned carbon nanotubes comprises providing catalytic seed particles along a surface of the template substrate, and growing the carbon nanotubes from the seed particles (e.g. by exposing the seed particles to a suitable gaseous/vapor carbon source as known in the field). In some embodiments, the catalytic seed particles are provided on a layer comprising a first insulator. In other embodiments the pillars can be grown from a conductive carrier, e.g. a copper foil.

The combination of carbon nanotube structure formation and at least partial embedding thereof in an anode metal base layer, offers in addition to improved electrical conductivity and provision of an anode metal buffer, a further synergetic benefit in case of lithium anode metals in that the carbon nanotubes already during manufacturing of the electrode are rendered less susceptible to electrochemical degradation reactions during subsequent use in a cell (such as SEI formation). Inventors find this benefit can be attributed to exposure of the nanotubes with lithium already during fabrication steps, referred to as melt-delamination and/or melt-infiltration, which pre-lithiates potential reactive sites.

In other or further strongly preferred embodiments, the upstanding sidewalls of the electrically conducting pillars are covered with a coat that has a high affinity to the anode metal. The coating is preferably at least provided along portions of the sidewalls that are embedded in the anode metal base. In some embodiments, the coat extends along at least part of the wall of the protruding portions of the pillars and laterally into the interspace regions between the pillars. Such a coating, in case of a

Lithium ion battery referred to as a lithiophilic coat, advantageously serves the purposes of increasing the adhesion of the pillar, e.g. a CNT pillar, to the metal base along the embedded portion and serves as a nucleation surface promoted anode metal plating, i.e lithium plating in case of lithium ion battery, near the pillar base during electrode operation, e.g. as part of a rechargeable battery device. Restricting the insulator to the end face, keeping the underlying interspace regions open and providing the lithiophilic coat along the protruding pillars prevents dendritic Li growth on top of the CNTs, establishes stable Li metal cycling whereby the lithiophilic layer promotes homogeneous lithium plating along the length of the interspace regions.

The lithiophilic coat is preferably provided before anchoring in a step comprising covering at least the terminal end portions of the pillars as provided on the template substrate with a lithiophilic coat, said lithiophilic coat extending laterally into the interspace regions between the adjacent electrically conductive pillars. The coat can be applied by suitable method including, but not limited to, electro plating, chemical vapor deposition (CVD), vapor deposition (PVD), and atomic layer deposition (ALD). In case of the delamination-transfer method, applying the coat before transfer can advantageously effectively improve performance of the electrode by providing the lithiophilic coat to those wall portions of the anchored pillars which are conventionally hard, or even impossible to coat, namely at or near the bottom of the elongate interspace regions between the pillars. Providing the lithiophilic coat before transfer further advantageously allows leaving the face that will later, after transfer, from the protruding end face free of a lithiophilic coat. Leaving the terminal end face of the protruding pillar portion free of a lithiophilic coat advantageously can mitigate or even eliminate a need for a subsequent step of applying a protective insulative coat to mitigate dendrite formation from the pillar end.

Inventors further found that applying the lithiophilic coat to the pillars before transfer, e.g. using vapor deposition, can advantageously provide a lithiophilic coat having a thickness gradient, whereby the thickness gradually decreases in a direction towards the terminal end face of the protruding portion. This gradiented deposition advantageously provides a higher density of lithiophilic material at positions towards the metal base resulting in optimized electrode performance of battery operation, which is believed to be a result of gradiented lithiophilic material distribution along the length of the pillars offering optimized diffusion pathway in the interspace regions and more homogeneous Li plating along the length of the CNT, e.g. mitigating dominant Li plating near the pillar tops hindering Li diffusion and deposition along lower portions of the pillar.

In case of the melt-infiltration method, the lithiophilic coat may be first applied on the CNTs subsequent to which a protective insulative coat may be applied on the pillar ends.

Preferably, the embedded portion is embedded in the anode metal base layer over a distance of at least 500 nm — 20 pm, preferably at least 2 pm. The more the pillars are embedded the higher the quantity of buffer anode metal that can be available for replenishing losses and the stronger interconnection to the pillars can remain during cycling. Optionally the embedded portion can be shorter e.g. at least 10 or 20 nm for at least some to the pillars, e.g. during use in a battery due to anode metal stripping, whereby stripping to a point below 1 or 2 nm is preferably avoided.

In some preferred embodiments, the protruding portion extends outwardly over a distance, defining a diffusion layer with a thickness between 1 pm and 50 pm. The elongate interspace regions between adjacent protruding pillar portions can advantageously define a volume for anode metal plating during battery cycling, whereby the range of 10-40 pm was found to offer a good balance between plating capacity and ion diffusion distance. Accordingly, in a preferred embodiment, the embedded portion is embedded in the anode metal base layer over a distance of at least 500 nm — 20 nm, preferably at least 2 pm, and wherein the protruding portion extends outwardly over a distance, defining a diffusion layer with a thickness between 1 pm and 50 pm.

In another embodiment the anode metal buffer layer essentially fills up the entire volume between the adjacent electrically conductive pillars. In some embodiments, the protruding portion can be as short as 1 or 2 nanometers or even entirely covered . As such the filled electrode structurer having can advantageously serve as a source, or base layer, for subsequent anode metal plating, e.g. lithium plating. Because the base layer comprises in embedded structure of electrically conductive pillars as disclosed herein, plating can be more homogeneous as compared to layers plated on bare metal anode layers, e.g. a lithium foil within embedded structure of vertically aligned carbon nanotubes. Embodiments whereby the anode metal base layer essentially fills up the entire volume adjacent vertically aligned pillars preferably comprise pillars having a total length in a range up to about 20 pm, e.g. 3-15 pm or 5-10 pm. Longer pillars, thicker buffer layers, are possible but less preferable from power per volume perspective and/or a total material cost for a given battery capacity.

In other or even further strongly preferred embodiments the electrode comprises an insulator capping layer. In a preferred embodiment, the insulator capping layer covers the sidewalls of the protruding portions of the pillars along a terminal end section thereof. In contrast to the lithiophilic coat the insulating capping layer is preferably applied after the transfer. This allows covering only the terminal ends of the anchored pillars.

The insulator capping mitigates lithium deposition along the tips of the pillars along a radial direction. Generally the insulator capping extends downward along the upstanding walls over a length in a range of 100 nm to 10 pm from the terminal end faces of the protruding ends. Mitigating lithium deposition along the terminal ends of the pillars improves electrode performance, in particular in terms of preventing excessive lithium deposition, dendrite formation, at the tips during abusive operation of the electrode, e.g. during an overcharging battery operation.

In some embodiments, the insulator capping layer extends along the upstanding walls over a length in a range of 100 nm - 10 pm. In some embodiments the insulator capping layer essentially the entire length of the protruding portions of the pillars. In some embodiments, the insulator capping layer conformally covers the sidewalls 45 along the protruding and embedded portion. In such embodiments, the insulator coated pillars structures, e.g. CNTs, act as a homogenous ion-guidance layer for further plating of anode metal during cell cycling, whereby plating along the pillars walls will be mitigated and plating will be predominantly or even exclusively onto the anode metal base layer.

In some embodiments, the insulator capping layer comprises or is essentially formed of an electrically insulating oxide composition. Preferably the insulator capping layer is formed of a high-k-dielectric composition, e.g. a composition having a dielectric constant in excess of 10, preferably higher, e.g. in excess of 100. In any case the insulator capping layer reduces Li nucleation in lateral direction between adjacent electrically conductive structures and/or reduced electrochemical near tips of the structure.

In some embodiments, the diffusion layer is not patterned resulting in a structure whereby the pillars are homogenously distributed along the metal base layer.

The packing density of the pillars, e.g. carbon nanotubes, grown can vary depending on the type of substrate, its roughness and thickness of any buffer layer, and in particular catalyst layer. For closed layers, carpets, inventors found that a packing density in a range of about 1-107 to 1-109 of is beneficial for electrode, anode, performance. A lower pillar packing density allows better penetration of the lithiophilic material with any dry deposition techniques such as ALD and PVD, promoting adhesion and lithium infiltration. In addition, the vertical pathways (i.e. interspace regions) between the pillars, e.g. carbon nanotubes, typically spaced in a range of 0-500 nm, preferably 10-300 nm, are more open, improving Li ion transport kinetics. Furthermore, a lower pillar density results in lower electrochemical SEI formation on the pillars when assembled and cycled in an electrochemical cell.

The thickness (length) of the diffusion layer can vary over a broad range, whereby higher pillars provide a comparatively larger surface area and an accompanied increased capacity and C-rate over short pillars.

Typically the protruding pillar portion has a length of at least 5 or 10 nm.

Preferably longer, e.g. in a range between 10-100 jun or more, e.g. between 50-250 pm or even up to 500 pm. A maximum height can be limited by practical limitations as to providing the structure of vertically aligned electrically conductive pillars on the template substrate. For CNTs a limit may be about 100 pm as based on practical growth conditions.

In some embodiments pillar structure can be a non-closed layer, e.g. containing holes or channels without pillars. Or in other words, the diffusion layer can include regions without pillars forming apertures that provide access towards the lithium metal base layer. The apertures may be uniformly dimensioned or may contain a distribution of different dimensions, e.g. periodically patterned or randomly distributed along the diffusion layer.

The apertures/channels promote electrolyte infiltration and Li-ion access in particular for high carbon nanotube structures, and/or facilitate infiltration of the lithiophilic material and lithium metal during electrode fabrication. In particular cases, where a solid electrolyte is deposited onto the pillar structure reducing access (e.g. almost closing) to the open space between the pillars, the channels / holes facilitate electrolyte access to the pillar structure from a sideways direction.

Inventors found that during battery cycling, Li metal can also be plated inside the apertures bordered with electrically conductive pillars. It was found that lithium mostly grows in the direction perpendicular from the pillar wall surface, which mitigates (dendritic) growth of Li-metal outward of the channel/holes at least so long as the system is operated outside abuse conditions, e.g. over-charging or over-discharging.

Other of further aspects of the present disclosure relate to an energy storage device. For example, a battery such as rechargeable Li- metal battery. The energy storage device, comprises the electrode as disclosed herein, a further electrode, and a separator separating the electrodes. During normal discharging operations the electrode as disclosed herein serves as an anode, whereas the further electrode acts as cathode.

During plating or charging operations these roles are reversed. The cathode may be a slurry coated particulate electrode comprising of typical metal oxides (such as Nickel-Manganese-Cobalt-Oxides (NMC), Nickel-Cobalt-

Aluminium-Oxides (NCA), Lithium-Nickel-Manganese-Oxide (LMNO) or phosphates e.g. Lithium-Iron-Phosphate (LFP) etc.

The separator comprises an electrolyte, typically an anode metal- ion electrolyte, e.g. Li-ion. The separator can comprise a mobile electrolyte such as a liquid electrolyte, an electrolyte solution or a semi-solid electrolyte such as a polymer gel based electrolyte, or it may comprise of a solid state electrolyte. If the separator comprises of a solid state electrolyte, then within the diffusion layer a semi-solid electrolyte may be applied between the pillars. Semi-solid electrolytes advantageously combine high ion mobility while retaining structure integrity to separate the electrodes. A gel electrolyte may be formed e.g. by solution casting of a solvent solution containing monomers, lithium salt, and solvents, followed by curing. The electrodes can e.g. be separated by porous separator membrane, a solid electrolyte membrane, and/or a hybrid or composite polymer membrane.

BRIEF DESCRIPTION OF DRAWINGS

These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawing wherein:

FIG 1A depicts a schematic cross-section side view of an electrode;

FIG 1B depicts a schematic cross-section side view of an electrode;

FIG 1C depicts a schematic cross-section side view of an electrode;

FIG 2A depicts a schematic cross-section detail side view of an electrode;

FIG 2B depicts a schematic cross-section side view of an electrode

FIG 2C depicts a schematic side view of an electrode;

FIG 3A depicts a schematic side view of an electrode;

FIG 3B depicts a schematic cross section side view of an electrode;

FIG 3C depicts a schematic side view of an electrode;

FIG 3D depicts a schematic exploded side view an energy storage device comprising an electrode;

FIG 4A depicts a schematic side view of an electrode;

FIG 4B depicts a schematic side view of an electrode;

FIG 4C depicts a schematic side view of an electrode;

FIG 4D depicts a schematic side view of an electrode

FIG 5A depicts a schematic representation of a method of manufacturing an electrode;

FIGs 5B and 5C schematically illustrate steps comprised in a method of manufacturing an electrode;

FIG 6A schematically illustrate steps comprised in a method of manufacturing an electrode;

FIG 6B schematically illustrates energy storage device; and

FIG 7A and 7B depict micrographs illustrating an electrode during stages of manufacturing.

DESCRIPTION OF EMBODIMENTS

Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and/or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a step of a method is referred to as subsequent to another step, it can directly follow said other step or one or more intermediate steps may be carried out before carrying out the particular step, unless specified otherwise. Likewise it will be understood that when a connection between structures or components is described, this connection may be established directly or through intermediate structures or components unless specified otherwise.

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity.

Embodiments may be described with reference to schematic and/or cross- section illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise.

As used herein the phrase ‘free terminal end faces of the protruding ends are essentially aligned along a single plane’ can be understood to relate to the protruding ends of the conductive pillar ends being essentially aligned with respect to each other, having the tips essentially aligned along a single plane. Typically the plane can be a flat plane, a 2D plane, whereby variations are defined by a roughness of the template substrate used forming the pillars. Advantageously, the template substrate can have a semi-conductor grade roughness. Advantageously, the template substrate can have a roughness ISO grade of N4 (Ra 200nm) or lower. More preferably the roughness (Ra) is below N3 grade (Ra 100 nm) or below N2 grade (Ra 50 nm). Most preferably the roughness (Ra) is even lower, e.g. <25nm (N1 grade) or even lower, e.g. <5 nm. The smoother the template substrate the better the alignment of the pillars and the more homogeneous the electric field can be during operation (charging/discharging) at the lithium metal electrode. Alternatively the pillars can be formed directly on a metal foil, e.g. a copper foil. Thus, the growth substrate may have long range height variations, e.g. a bow or a surface roughness above the semi-conductor grade roughness. Inventors found that length variations between individual carbon nanotubes, even when grown from a substrate having long range height variations, e.g. a bow or a surface roughness above the semi-conductor grade roughness, can bein a range having sufficient local alignment. Pillar transfer (transfer- delamination method) can nevertheless mitigate contributions to pillars length variations, e.g. variations due to uneven growth conditions (e.g. due local variations in growth speed, e.g. due to inhomogeneous in carbon source exposure).

Generally the insulator has a resistivity in excess of about 1011 ©Qm at 20°C. Generally, the insulator comprises oxides of a metal, oxides of a metalloid, or a combination thereof. Preferably, the insulator has a relative dielectric constant in excess of 3 or more e.g. 4 (about 3.9 for silicon dioxide).

The insulator can be a high-k dielectric. Preferred high-k-dielectric materials include but are not limited to: AlOx; S10x; TiOx; and metal titanate oxides, such as BaTiOx or SrTiOx; or combination thereof. The insulator and/or the lithiophobic capping layer generally have a thickness suitable for mitigating Li-plating. A thickness of at least 1 nm was found suitable. Preferably the thickness is in a range of 1-10 nm. Thicker layers are possible but provide little additional benefit in mitigating local lithium plating. Larger thicknesses are less preferred because the additional volume taken up thereby reduces the potential energy density per volume unit.

In some embodiments, the lithiophilic coat comprises or essentially consists of a solid state electrolyte (SSE) composition, such as lithium phosphorus oxynitride (LIPON) and lithium thiophosphates.

Suitable examples include: oxide-, sulfide- or phosphates-based SSE, including but not limited to LISICON (lithium superionic conductor) (e.g.

LGPS, LiSiPS, LiPS), argyrodite-like (e.g. Li6PS5X, X = CL, Br, I), garnets (LLZO), NASICON (sodium superionic conductor) (e.g. LTP, LATP, LAGP), lithium nitrides (e.g. Li3N), lithium hydrides (LiBH4), perovskites (e.g. lithium lanthanum titanate, "LLTO"), lithium halides (LYC, LYB) and

RbAg4I5. The thickness of the SSE is preferably at least 1 nm, preferably in a range of 1-30 nm.

The lLithiophilic coat generally comprises a composition known known for promoting Li metal nucleation. Suitable materials include but are not limited to Zn, In, Bi, Al, Au, and Sn. Preferably, the lithiophilic coat comprises or essentially consists of Zn, ZnO, or a combination thereof.

Inventors found that Zn and ZnO can advantageously be provided conformably along the pillars and in particular along outer sidewalls of carbon nanotubes, e.g. by dry vapor deposition methods such as ALD.

FIG 1A provides a schematic cross-section side view of an electrode 1 comprising a lithium metal base layer 2 and a diffusion layer 3 including a structure of vertically aligned electrically conductive pillars 4 with elongate interspace regions 5 between upstanding sidewalls 45 of adjacent electrically conductive pillars. As shown each of the electrically conductive pillars 4 is anchored in the metal base layer. The pillars are embedded form an embedded terminal end face 41 along an embedded portion 42 thereof, leaving a protruding portion 43 that extends outwardly from a face 21 of the lithium metal base layer. As shown the free terminal end faces 44 of the protruding ends are essentially aligned along a single plane “P”, or in other words the protruding portions protruded from the face 21 over an about equal distance. As shown the pillars generally protrude in an about perpendicular direction from the lithium metal base layer. About perpendicular can be understood to relate deviations of no more than 20°, preferably less, e.g. within a range up to 10° or even within 5°. Note that the anchoring depth of the pillars need not be, and typically is not identical, depending on a height variation of the pillars as formed on the template substrate 61 (see FIG 4B). Note that the top plane can essentially contain height variations as comprised on the surface of a growth substrate. Note that the anode metal base layer 2 can be provided along a support current collector 8, e.g. as shown in FIG 2B and 4A.

FIG 1B provides a schematic cross-section side view of an electrode. The embodiment includes the features described in relation to

FIG 1A. The electrode 1 additionally comprises an insulator 6 that covers the terminal end faces 44 of the protruding pillar portions. As shown insulator coverage 1s restricted to the end faces of the protruding portions, that 1s the insulator does not extend along the pillar wall in a direction towards the lithium metal base layer. As will be explained in more detail in regard to the method the insulator 6 can comprise delaminated remnants of a template substrate 61 use for providing, e.g. growing the pillars. In case the pillars are formed by carbon nanotubes the insulator 6 can further comprise catalyst seed particles.

FIG 1C provides a schematic cross-section side view of an electrode. The embodiment includes the features described in relation to

FIG 1A although the embodiment is represented without variations in anchoring depth. The electrode 1 as shown additionally comprises a

Lithiophilic coat 7. The lithiophilic coat 7 comprises a lithiophilic composition 71 and is provided over the upstanding sidewalls 45 along at least the embedded portion 42 of the electrically conducting pillar are covered with a lithiophilic coat 7 comprising a lithiophilic composition 71. The composition generally comprises, or essentially consists of, materials known for promoting Li metal nucleation as listed herein above. The lithiophilic coat 7 improves adhesion to the lithium metal base layer 2, in particular for carbon nanotubes.

As shown the lithiophilic coat 7 preferably also covers the upstanding sidewalls 45 along at least part 46 of the protruding portion.

Typically, at least 5% of the protruding portion. The lithiophilic coat can cover up to 20 or 30% of the protruding portion, e.g. in a range 5-30% or 20- 30%. The lithiophilic coat extends laterally into the interspace regions 5 between the adjacent electrically conductive pillars. In these areas the coat serves as a growth surface where lithium metal is formed/plated.

It will be appreciated that the embodiment as shown in FIG 1C can include the features described in relation to FIG 1B giving the combined benefit of improved Li metal plating inside the interspace regions 5 while mitigating lithium plating or even dendrite formation in a direction away from a top face 44 of one or more of the pillars 4.

In a preferred embodiment, the lithiophilic coat 7 has a minimum thickness “t7” along the embedded portion 42 of the electrically conductive pillars of > 1 nm, preferably > 100 nm, more preferably > 300 nm. Thicker layers were found to improve adhesion to lithium anode base layer, in particular during transfer process.

The lithiophilic coat preferably has maximum thickness < 1 pm, preferably < 700nm. Increasingly thick coats limit ion diffusion towards the pillar.

In another or further preferred embodiment, e.g. as shown, the lithiophilic coat 7 does not cover top portions 47 of the electrically conductive pillars and the free terminal end faces 44 of the protruding ends of the electrically conductive pillars. Leaving the tops of the pillars free of lithiophilic composition 71 reduces deposition of Li along top sections of the pillars, reducing lateral expansion of plated Li, and mitigating blockage of the interspace regions 5.

In a preferred embodiment, e.g. as illustrated in FIG 2A and 3B, the lithiophilic coat has a thickness gradient whereby the thickness gradually decreases in a direction towards the terminal end face of the protruding portion. Typically the thickness decreases from a range of about 100%-70% of the pillar interdistance at a base of the protruding portion (depending on pillar interspacing corresponding to approx. 500-20nm) to about zero nm towards the terminal end faces 44. Provision of a gradient lithiophilic coat 7 advantageously optimizes distribution of material for lithium plating. Preferably, the lithiophilic coat 7 is porous. Porosity increases the surface area for Li plating and limits the nucleation radius promoting lithium deposition.

Preferably, the lithiophilic coat 7 comprises nanoparticles 72. The nanoparticles comprise, essentially consists, or at least have an outer layer comprising the lithiophilic composition 71. The particles can advantageously be deposited using dry deposition methods such as PVD and ALD. The particles advantageously provide porosity in interspaces between adjacent particles, offering enhanced area for Li-plating. The particles typically have a maximum average cross section diameter below 1 nm, preferably below 500 nm, e.g. in a range of 50 — 250 nm.

The pillars need not necessarily be arranged in a continuous layer. The carbon nanotube structure can also be a non-closed layer, e.g. containing holes or channels. Accordingly, in some preferred embodiments, e.g. as shown in FIG 2B, the diffusion layer 3 is patterned to include regions without electrically conductive pillars 4 forming apertures 31 that provide access towards the lithium metal base layer 2.

In some embodiments, e.g. as shown in FIG 2B, a lithiophilic coat (7-1) along an interface between the support 8. The lithiophilic coat (7-1), e.g.

Zn, improves adhesion between the support (e.g. copper coil) and the lithium metal base layer 2.

The apertures/channels promote electrolyte infiltration and metal-ion access. For CNTs inventors confirmed that the apertures facilitate sideways infiltration of the lithiophilic material. In particular cases, where a solid electrolyte (e.g. LIPON using spatial ALD, CVD, or PVD) is deposited onto the CNT structure and (almost) closing the open space between the

CNTs, the channels / holes can further facilitate electrolyte access to the

CNT carpet in the region underneath the solid electrolyte layer, e.g. as schematically indicated by the dash-dot arrow.

Preferably, the apertures 31 have a cross section diameter “d31” in a range of 100 nm — 50 pm. Accordingly, in some embodiments, the apertures (31) have a cross section diameter (d31) in a range of 100 nm - 50 nm, preferably, in a range of 200 nm to 500 nm. Inventors found that for such separation energy density can be optimized, whereby lithium mostly grows in the direction away from the CNT wall surface, which results in minimal (dendritic) growth of Li-metal outward of the channel/holes, provided of course that plating stays within cycling capacity limits.

Advantageously the diffusion layer van be provided along more than one face of the lithium metal base layer 2. In a preferred embodiment, e.g. as shown in FIG 2C(left), a further one of the diffusion layer 3-2 is provided along a second face 22 of the lithium metal base layer 2. In more preferred embodiment (as shown in FIG2C-right), first and second electrode as provide along opposing faces 81,82 of a common current collector 8.

Alternatively two electrodes 1 can be assembled back to back (not shown).

The metal base layer can advantageously be a lithium foil.

Lithium foils are commercially available and can be handled with relative ease. Typically the foil has a thickness “d2” in a range of 50-500 pm.

Thinner self-standing foils can be harder to handle during the pillar transfer process. Thicker self-standing foils are possible but the added lithium content contributes comparably less to battery performance.

In some embodiments, e.g. as illustrated in FIGs 2C (right) and 3A, the metal base layer 2 is provided along a face 81 of a support foil 8. The support foil improves structural integrity during manufacturing while enabling the use of comparatively thinner anode metal layers, e.g. Li layers.

Preferably, the support is an electronically conductive support, preferably a copper foil support foil. The metal support can advantageously provide current collection and support during delamination process. Copper foil can advantageously further be used as a substrate from growing carbon nanotubes. Typically the support has a thickness between 1-50 pm. Thicker supports increase the relative amount of battery inactive materials in the electrode. In some embodiments, the support foil 8 is structured, e.g. with thinned regions 82, apertures or foam to decrease the relative weight contribution of support metal in the electrode 1. The anode metal base layer may be an alloy as well (e.g. with In, Sn, Zn, Na, K, Mg etc.). This can e.g. be achieved by embedding the pillars in an alloy and/or by co-melting an alloy layer into the pillar structure.

In some preferred embodiments, the electrode comprises an insulator capping layer, said the insulator capping layer covering the sidewalls of the protruding portions of the pillars along a terminal end section thereof. The insulator capping layer 9 advantageously provides reduced Li nucleation in a lateral direction between adjacent electrically conductive structures, while further homogenizing the electric field and/or reducing electrochemical activity near the capped tips of the pillars structure.

FIG 3B schematically illustrates an electrode comprising an insulator capping layer in combination with elements described in relation to FIGs 1A, 1B, and 2A. The embodiment includes a gradiented lithiophilic coat 7 that is provided along a bottom portion of the pillars 4 and an insulator capping layer 9 that covers the insulator 6 and that extends down into the interspace regions 5 along the sidewalls 45 of the pillars along a top portion 48 thereof. The lithiophilic capping extends along the upstanding walls over a distance of up to 30% of the height of the carbon nanotubes, typically 100 nm to 10 pm.

As described above the insulator capping layer 9 can be comprised, or essentially consist, of an electrically insulating oxide composition, preferably a high-k-dielectric such as: AlOx; SiOx; TiOx; and metal titanate oxides, such as BaTiOx, or a combination thereof. A thickness of about 1 nm was found sufficient to modify the electrochemical properties at the top portion 48 of the protruding pillars. Generally the thickness is in arange of 1 to about 10 nm. Thicker layers are believed to offer comparatively minimal improvement in lithiophobicity of the insulator.

In some embodiments, e.g. as shown lithiophilic capping layer 1s formed of a solid state electrolyte composition 91 , such as are lithium phosphorus oxynitride LIPON and lithium thiophosphates. In case the lithiophilic capping layer is formed of a solid state electrolyte composition the layer may be thicker than 10 nm. Optionally the layer may close or nearly close off the interspace regions 5 between adjacent pillars. Generally the thickness in a range of 1-30 nm.

FIG 3C schematically illustrates a variation of an electrode 1 wherein the pillars are formed by carbon nanotubes “CNT”, the tips of which are provided with an insulator 6 and an insulator capping layer 9 that extends downward towards the Li-metal base layer 2. the carbon nanotubes are anchored into the Li-metal base layer 2 whereby the embedded portions of the carbon nanotubes are coated with Zn, forming a Zn-sublayer 7.

FIG 3D provides schematic exploded sideview of an energy storage device 100. The device as shown forms a as rechargeable lithium metal battery that comprises the electrode 1 as disclosed herein; a separator 101, and further electrode 102. The separator separates the anode and the cathode. The separator comprises semi-solid electrolyte 103 including Li ions. that diffuse into and out of the diffusion layer of the electrode 1 during respective charging and discharging cycles of the battery.

Of course aspects explained in relation to structures as obtained by the transfer-delamination method can be equally applied to structures obtained by the melt-infiltration method, unless specified otherwise.

Whereby structures manufactured by the melt-infiltration method differ in that that the pillars are physically interconnected to the support current collector 8 and possibly in the level of alignment and deviation from plane P at the tops of the pillars other features including as pillar spacing, pillar, embedding depth and length of protruding portions can be essentially the same.

FIG 4A depicts a schematic side view of an electrode as manufactured by the melt-infiltration method as explained in more detail with reference to FIG 6A. As shown, such the electrode differs in that the pillars contact the support current collector 8 and in the relatively reduced level of pillar alignment (shown in exaggeration). It will however be appreciated that the electrode can contain any of the other features as disclosed in relation to FIGs 1B to 3C.

FIG 4D depicts a schematic side view of an electrode that differs from the embodiment shown in FIG 4A in that the pillars, e.g. carbon nanotubes, are randomly oriented. A random orientation can be suitably vapor-phase or wet-chemical processing. As for other embodiments the pillars 5 are embedded from one terminal end in an anode metal base layer 2. The embedding can be provided by melt-infiltration.

FIG 4B (left and right) depicts an embodiment of an electrode wherein the anode metal buffer layer 2 essentially fills up the entire volume between the adjacent electrically conductive pillars 4. The anode metal base layer may not necessarily be fully dense. The density can be controlled by tuning parameters like temperature, time, heating ramp and cooling ramp.

Also the surface energy of the CNTs and/or that of the support substrate (on which the CNTs are grown or transferred to) can affect the density.

The embodiment as shown on the left can be made with the melt- infiltration method as explained with reference to FIGs 5B and 5C. FIG 4B (right) depicts a corresponding embodiment as obtained by the embedding- transfer method as will be explained in more detail with reference to FIG 6A. The protruding portions 43 have a length in a range between about zero and 10%, typically below 5% or 2% of the length of the embedded portion 42.

For embodiments comprising a complete, or near complete, filling of anode metal the total length of the pillar 42+43 is generally below 15 pm, typically in a range of 5-10 pm. Accordingly, the length of the protruding portion 43 generally has a length <150nm, preferably in a range of 100-0 nm, e.g. about 50 nm, about 10 nm or even about 1 or 2 nm. Structures with longer pillars, containing a comparatively larger amount of anode metal buffer are possible but considered less preferable due to comparatively decreasing benefit of anode metal buffer.

FIG 4C depicts an embodiment, manufactured using the melt- infiltration route, wherein, the pillars 4 are covered with a conformal layer of a second insulator 6-2, said layer forming an insulator capping 9, wherein the insulator layer covers the sidewalls along the protruding and embedded portion 42, 43 of the pillars. The insulator coated pillars structures, e.g.

CNTs, can act as a guidance structure for anode metal ions (e.g. Li) during cell cycling, whereby metal plating (e.g. Li) along the pillars walls will be mitigated and plating will be predominantly or even exclusively onto the anode metal (e.g. Li) base layer 2, yielding a plated anode metal layer 2p (e.g. Li-metal layer) which is evenly distributed between the pillars.

Methods of manufacturing the electrode as disclosed herein will now be illustrated with reference to FIGs 5, 6A and7, wherein FIGs 5B-5C detail aspects relating to the transfer-delamination method and FIG 6Adetails aspects relating to the melt-infiltration method and FIG 7 depicts micrographs illustrating an electrode during stages of manufacturing.

Both methods can be used to manufacture an electrode comprising an anode metal base layer and a diffusion layer including a structure of electrically conductive pillars, with elongate interspace regions between sidewalls of adjacent electrically conductive pillars. In general both methods comprises anchoring the electrically conductive pillars in the metal base layer from an embedded terminal end face of the electrically conductive pillar along an embedded portion thereof, leaving a protruding portion that extends outwardly from a face of the anode metal base layer, wherein the anchoring comprises a processing step involving melt-processing anode metal.

FIG 5A provides a schematic representation of a transfer- delamination applied to manufacturing an electrode comprising a lithium metal base layer and a diffusion layer including a structure of vertically aligned electrically conductive pillars. It will be understood that electrodes comprising another anode metal composition as disclosed herein can be manufactured in an analogue way.

The method 200 the method comprises the steps of: forming 201 on a face of an template substrate 61 a structure of vertically aligned electrically conductive pillars 4 with elongate interspace regions5 between upstanding sidewalls 45 of adjacent electrically conductive pillars 4; anchoring 203 terminal end portions of the formed electrically conductive pillars in a lithium metal base layer 2; and delaminating 205, after solidifying the lithium metal base layer, the structure of vertically aligned electrically conductive pillars 4 from the template substrate 61, to form the electrode, wherein each of the electrically conductive pillars 4 is anchored in the metal base layer from an embedded terminal end face 41 of the electrically conductive pillar along an embedded portion 42 thereof, leaving a protruding portion 43 that extends outwardly from a face 21 of the base layer. Advantageously the insulator can comprise delaminated remnants of the template substrate.

The anchoring 203 generally includes positioning the structure of vertically aligned electrically conductive pillars with elongate interspace regions as formed on the template substrate opposite a face of the lithium metal base layer, whereby a face of the template substrate carrying the pillars and a top surface of the metal substrate are aligned. Preferably kept level within a range of 0 to 20°, more preferably within a range up to 10° or even within 5°. Most preferably within about 1° or even essentially level.

The better the alignment the more uniform the height of the pillars and/or the vertical alignment of the pillars after transfer will be.

To facilitate anchoring the template and/or metal substrate are preferably heated to a temperature above a softening temperature of the metal. For example for lithium heating to its melting temperature (about 181°C) or at least with a range of 5-100 °C above the melting temperature was found sufficient. Upon contacting the metal interpenetrates between the pillars. The embedding depth is generally at least 0.1 mm or about 1% of the initial pillar length. Typically the embedding depth is at least about 1 pm. Preferably the embedding depth is a range between about 1 and about 30 pm, which was found to offer a balance between offering sufficient anchoring strength while leaving a major portion of the pillars accessible for lithium plating. It will be understood that, the formed laminate is cooled to below a hardening temperature, e.g. to below 180°C, prior to delaminating 205. Alternatively the metal base layer can be formed on the tips of the pillars as formed on the template substrate, e.g. by electroplating or sputtering a layer of the metal.

Forming 201 the structure of vertically aligned electrically conductive pillars can comprise providing catalytic seed particles along a surface of the template substrate 61, and growing the carbon nanotubes from the seed particles. Details of growing vertically aligned carbon nanotubes are known. Reference can e.g. be made to methods disclosed in

WO20160178571 and the references cited therein which as hereby incorporated by reference.

Alternatively the structure of vertically aligned electrically conductive pillars can be provided by microfabrication methods including but not limited to additive manufacturing methods and microfabrication methods such as etching. For example, a structure of vertically aligned electrically conductive pillars can comprise manufacturing a high-aspect ratio structure of pillars formed in a metal substrate, as described relation to FIGs 1 to 3 in WO20150126248, which is hereby incorporated in full.

Advantageously the method can, prior to anchoring 203, comprise a step of covering 202 at least the terminal end portions of the pillars with a lithiophilic coat 7. Preferably covering includes deposition methods such as

CVD, PVD, and ALD. Alternatively the coat can be provided by wet methods including but not limited to electro- and electroless plating. Advantageously dry deposition methods can provide the coat in a controlled way without exposing the pillars forces, e.g. capillary force, associated to liquid processing method. If desired a base portion of the pillars on the template be left uncoated.

As explained the structure of pillars can be patterned.

Accordingly, the method can comprise patterning 204. Patterning can be suitably performed at any stage during the manufacturing process. For example, before forming the pillars, e.g. by patterning the template substrate 61 and/or the seed layer thereon. Alternatively or in addition patterning may be performed after pillar formation, e.g. prior or after embedding, e.g. as shown in FIG 4B.

In another or further preferred embodiment, the method comprises, after delaminating 205, depositing 206 an insulator capping layer, whereby the insulator capping layer covers the protruding portions of the pillars along a terminal end section thereof. Similar to the lithiophilic coat the capping is preferably provided by dry deposition methods.

In some embodiments, the step of anchoring 203 terminal end portions of the formed electrically conductive pillars is performed along two opposing faces of the lithium metal base layer, yielding an electrode having diffusion layers along to faces.

FIG 5B (left) schematically illustrates a structure of vertically aligned carbon nanotube pillars 4, with interspace regions 5 and apertures 31 without pillars, as formed on a template substrate 61 during a step of covering 202 the pillars with a Zn-based lithiophilic coat the coating is evaporated onto the pillars by PVD from a target comprising Zn-based composition 71. FIG 7A shows a micrography of a carbon nanotube 4 structure with apertures 31 on a template substrate after deposition of Zn.

The Zn covers the top portions of the nanotubes on the template. The Zn forms particles along top faces and sidewalls of the patterned nanotube structure.

FIG 5B (right) illustrates a process during anchoring 203 terminal end portions of the formed electrically conductive pillars in a lithium metal base layer 2.

As compared to the right figure the template substrate 61 with pillars is flipped over and a lithium foil 2 is assembled atop the pillars. The assembly is heated above a softening temperature of the lithium upon which the pillars become anchored into the metal. The embedding depth can be controlled by the temperature and applied force F between template substrate and metal base 2. Inventors found that a comparatively high pressure in a range of 100 N/m? can be applied without permanently damaging or bending the pillars, which is believed to be facilitated by the alignment and/or strength of the pillars. The pressure may also be near zero, e.g. a gravitational force or a fraction thereof.

FIG 5C schematic illustrates the process delaminating 205 the structure of vertically aligned electrically conductive pillars 4 from the template substrate 61, after solidifying the lithium metal base layer. Upon removing the template substrate 61 an embodiment of an electrode 1 is formed that includes: a structure of vertically aligned carbon nanotube pillars 4, with interspace regions 5 and apertures 31 without pillars; a lithiophilic coat 7, and an insulator 6. The pillars are anchored into the lithium metal base layer 2. As described in relation to FIG 1A, terminal ends of the protruding pillars portions are aligned, whereas the embedded terminal end faces need not be aligned. The coat 7 is provided along the pillars but the top comprises an insulator 6. The insulator 6 is formed of delaminated remnants of a template substrate 61. Although not shown in detail as in FIG 1B the insulator is restricted to terminal end faces 44 of the protruding ends forming an insulator capping 9 at the pillar tops.

FIG 7B (top left and top right) provide top view micrographs at two magnifications of an electrode after delamination. As can be seen the pillar tops are covered by insulator 6.

FIGs 7B (bottom left and bottom right) provide top view micrographs at two magnifications of the electrode after performing a lithium plating step in an electrochemical cell. As can be observed the plating of lithium in an outward direction away from the tops of the pillars is effectively mitigated. Instead lithium plating predominantly occurs within the interspace regions and apertures 31 in a lateral direction between opposing pillars walls, and also within the pillar walls.

FIG 6A provides a schematic representation of aspects relating to the transfer-delamination applied to manufacturing a patterned lithium metal electrode. As for the transfer method, it will be understood that similar principles apply when making non-patterned electrode and/or electrodes comprising a different anode metal, e.g. a Li/Na alloy.

The method comprises forming 201 on a face of a template substrate a structure of electrically conductive pillars 4 with elongate interspace regions 5 between sidewalls of adjacent electrically conductive pillars. In the melt-infiltration method the template can advantageously be a conductive support current collector 8, e.g. a copper foil.

Following formation terminal end portions of the formed electrically conductive pillars are contacted 203 with a quantity of an anode metal 2. The anode metal can be suitably brought in to contact with the pillar tips. For example, by covering the structure with an anode metal film 2, e.g. as shown. Alternatively, or in addition, an amount of anode metal can be disposed directly onto the pillars structure, preferably by a dry deposition method as mentioned above. In some embodiments the anode metal is carried by a carrier substrate, e.g. a high-melting metal substrate coated with a layer of lithium metal. In any case the amount of anode metal is sufficient to at least partly fill the elongate interspace regions 5 between sidewalls of adjacent electrically conductive pillars 4 (see. e.g. FIG 4A),

Subsequently the anode metal is heated to above a melting temperature for a period to infiltrate the interspace regions between adjacent electrically conductive pillars with liquified anode metal. For lithium metal the temperature can be 180°C — 500°C. Contact time 1s usually 1 min — 30 min. To control filling of the space between pillars temperature is typically ramped up at a rate of 1 °C/sec — 10 °C/sec. Cooling, back to a solidifying temperature is generally performed at a rate of 1 °C/sec — 10 °C/sec. A deposited amount and density of infiltrated anode metal (e.g. lithium) can be conveniently determined experimentally, e.g. by microscopy and differential mass determination. This enables associating a melt- infiltrated base layer thickness and/or density to a set of melt-infiltration conditions (temperature, time, and/or ramp up/down rate). It will be appreciated that any layers contacting the pillar tops after the melt- infiltrating step, e.g. remaining anode metal foil and/or carrier are preferably removed prior to cooling.

FIG 6B schematically illustrates an exploded view of an energy storage device 100. The storage device 100 comprises at least: the electrode 1 as disclosed herein; a further electrode 102; and a separator 101 separating the electrode and the further electrode. Electrode 102 forms a counter electrode and generally comprises a cathode material 102c. The separator 101 holds an electrolyte composition (103) comprising a corresponding anode meal 10n, e.g. Li-ions.

For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

For example, while embodiments were shown for carbon nanotube growth from a template substrate, also alternative ways can be envisaged by those skilled in the art having the benefit of the present disclosure for achieving a similar function and result. For example, inventors find that the invention can be applied in broader sense to any vertically aligned pillar, nano tubes, wires, provided that the pillars predominantly withstand the delamination procedure, which was, at least for homogeneous carpets confirmed when the average mutual distance between adjacent pillars is smaller than 500 nm.

The various elements of the embodiments as discussed and shown offer certain advantages, such as improved provision of an anode metal base- layer, alignment of pillar ends; reduced dendrite formation from pillar ends, improved distribution of lithiophilic material along the walls bounding the interspace regions between adjacent pillars; and directed lateral lithium plating from pillars walls. Of course, it is to be appreciated that any one of the above embodiments or processes may be combined with one or more other embodiments or processes to provide even further improvements in finding and matching designs and advantages. It is appreciated that this disclosure offers particular advantages to lithium metal electrodes and batteries and in general can be applied for any application concerning metal based electrode materials.

In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise. Where one claim refers to another claim, this may indicate synergetic advantage achieved by the combination of their respective features.

But the mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot also be used to advantage.

The present embodiments may thus include all working combinations of the claims wherein each claim can in principle refer to any preceding claim unless clearly excluded by context.

Claims

ConclusiesConclusions

1. Een elektrode (1) omvattende een anode-metalen basislaag (2) en een diffusielaag (3) die een structuur omvat van elektrisch geleidende pilaren (4) met langwerpige tussenruimtegebieden (5) tussen zijwanden (45) van aangrenzende elektrisch geleidende pilaren, waarin elk van de elektrisch geleidende pilaren (4) is verankerd in de metalen basislaag vanaf een ingebed terminaal eindvlak (41) van de elektrisch geleidende pilaar langs een ingebed gedeelte (42) daarvan, waarbij een uitstekend gedeelte (43) vrij blijft dat zich naar buiten uitstrekt vanaf een oppervlak (21) van de anode-metalen basislaag.An electrode (1) comprising an anode-metal base layer (2) and a diffusion layer (3) comprising a structure of electrically conductive pillars (4) with elongated spacing regions (5) between side walls (45) of adjacent electrically conductive pillars, wherein each of the electrically conductive pillars (4) is anchored in the metal base layer from an embedded terminal end face (41) of the electrically conductive pillar along an embedded portion (42) thereof, leaving free a protruding portion (43) extending towards extends outwardly from a surface (21) of the anode metal base layer.

2. De elektrode (1) volgens conclusie 1, waarin de structuur van elektrisch geleidende pilaren (4) verticaal uitgelijnde pilaren met opstaande zijwanden (45) omvat, bij voorkeur koolstofnanobuizen.The electrode (1) according to claim 1, wherein the structure of electrically conductive pillars (4) comprises vertically aligned pillars with upstanding side walls (45), preferably carbon nanotubes.

3. De elektrode (1) volgens conclusie 1 of 2, waarin vrije terminale eindvlakken (44) aan de uitstekende einden van aangrenzende elektrisch geleidende pilaren zijn uitgelijnd langs een uitlijnvlak, waarbij een afwijking van de vrije terminale eindvlakken tot het uitlijnvlak < 200 nm 1s, bij voorkeur < 100 nm.The electrode (1) according to claim 1 or 2, wherein free terminal end faces (44) at the protruding ends of adjacent electrically conductive pillars are aligned along an alignment plane, wherein a deviation of the free terminal end faces from the alignment plane < 200 nm 1s , preferably < 100 nm.

4. De elektrode volgens één van voorgaande conclusies, waarin vrije terminale eindvlakken (44) van de uitstekende einden individueel zijn bedekt met een eerste isolator (6-1), waarbij de dekking van de isolator 1s beperkt tot de eindvlakken van de uitstekende delen.The electrode according to any one of the preceding claims, wherein free terminal end faces (44) of the projecting ends are individually covered with a first insulator (6-1), the coverage of the insulator 1s limited to the end faces of the projecting parts.

5. De elektrode volgens één van de voorgaande conclusies 3-4, waarin de vrije terminale eindvlakken (44) van de uitstekende delen in wezen zijn uitgelijnd langs een enkel vlak (P).The electrode of any one of claims 3 to 4, wherein the free terminal end faces (44) of the projections are substantially aligned along a single plane (P).

6. De elektrode (1) volgens één van de voorgaande conclusies, waarin het ingebed gedeelte (42) in de anode-metalen basislaag (2) is ingebed over aan afstand van tenminste 500 nm — 15 nm, bij voorkeur ten minste 2 pm, en waarin het witstekende gedeelte (43) zich naar buiten uitstrekt over een afstand waarbij een diffusielaag wordt gedefinieerd met een dikte tussen 1 pm en 50 nm.The electrode (1) according to any one of the preceding claims, wherein the embedded portion (42) is embedded in the anode metal base layer (2) over a distance of at least 500 nm - 15 nm, preferably at least 2 µm, and wherein the whitening portion (43) extends outwardly for a distance defining a diffusion layer having a thickness between 1 µm and 50 nm.

7. De elektrode volgens één van de voorgaande conclusies 1-6, waarin de elektrisch geleidende pilaren (4) een lengte hebben van < 15 nm, bij voorkeur in een bereik van 3 — 10 nm, en waarin de pilaren in wezen geheel zijn ingebed in de anode-metalen basislaag (2).The electrode according to any one of the preceding claims 1-6, wherein the electrically conductive pillars (4) have a length of < 15 nm, preferably in a range of 3 - 10 nm, and wherein the pillars are substantially fully embedded in the anode metal base layer (2).

8. De elektrode volgens één van de voorgaande conclusies, waarin de opstaande zijwanden (45) langs tenminste het ingebed gedeelte (42) van de elektrisch geleidende pilaar zijn bedekt met een lithiofiele laag (7) die een lithiofiele samenstelling (71) omvat.The electrode according to any one of the preceding claims, wherein the upstanding side walls (45) along at least the embedded portion (42) of the electrically conductive pillar are covered with a lithiophilic layer (7) comprising a lithiophilic compound (71).

9. De elektrode volgens conclusie 8, waarin de lithiofiele laag (7) de zijwanden (45) bedekt langs tenminste een deel van het wtstekend gedeelte, waarbij genoemde lithofile laag zich zijwaarts uitstrekt in de tussenruimtegebieden (5) tussen de aangrenzende elektrisch geleidende pilaren.The electrode according to claim 8, wherein the lithiophilic layer (7) covers the side walls (45) along at least part of the protruding portion, said lithophilic layer extending laterally in the interspace regions (5) between the adjacent electrically conductive pillars.

10. De elektrode volgens één van de voorgaande conclusies 8-9, waarin de lithiofiele laag (7) een dikte gradiënt heeft, waarbij de dikte geleidelijk afneemt in een richting naar het terminale eindvlak (44) van het uitstekend gedeelte.The electrode according to any one of the preceding claims 8-9, wherein the lithiophilic layer (7) has a thickness gradient, the thickness gradually decreasing in a direction towards the terminal end face (44) of the projection.

11. De elektrode volgens één van de voorgaande conclusies 8-10, waarin de lithiofiele laag (7) topdelen van de elektrisch geleidende pilaren en de vrije terminale eindvlakken (44) van de uitstekende delen van de elektrisch geleidende pilaren niet bedekt.The electrode according to any one of the preceding claims 8-10, wherein the lithiophilic layer (7) does not cover top portions of the electrically conductive pillars and the free terminal end faces (44) of the projecting portions of the electrically conductive pillars.

12. De elektrode volgens één van de voorgaande conclusies 8-11, waarin de lithiofiele laag (7) nanodeeltjes (72) omvat welke een buitenlaag omvatten die de lithiofiele samenstelling (71) omvat.The electrode according to any one of the preceding claims 8-11, wherein the lithiophilic layer (7) comprises nanoparticles (72) comprising an outer layer comprising the lithiophilic compound (71).

13. De elektrode volgens één van of de voorgaande conclusies, waarin een terminaal einddeel (46) van het wtstekende gedeelte (43) van de pilaar is afgedekt met een conforme laag van een tweede isolator (6-2), zodat genoemde laag een isolerende afdoplaag (9) vormt.The electrode according to any one of the preceding claims, wherein a terminal end portion (46) of the protruding portion (43) of the pillar is covered with a conformal layer of a second insulator (6-2), so that said layer provides an insulating capping layer (9).

14. De elektrode volgens conclusie 13, waarin de conforme laag van de tweede isolator (6-2) de pilaar conform afdekt langs het uitstekende en ingebedde gedeelte (42,43).The electrode of claim 13, wherein the conformal layer of the second insulator (6-2) conformally covers the pillar along the protruding and embedded portion (42,43).

15. De elektrode volgens één van voorgaande conclusies, waarin de diffusielaag (3) is gepatroneerd om gebieden te omvatten zonder elektrisch geleidende pilaren (4) die openingen (31) vormen welke toegang verschaffen tot de anode-metalen basislaag (2) en die in een zijwaartse richting toegang verschaffen tot gebieden mét elektrisch geleidende pilaren (4).The electrode according to any one of the preceding claims, wherein the diffusion layer (3) is patterned to include areas without electrically conductive pillars (4) forming openings (31) which provide access to the anode-metal base layer (2) and which in provide sideways access to areas with electrically conductive pillars (4).

16. De elektrode volgens één van de voorgaande conclusies, waarin de metalen basislaag een lithium folie is, bij voorkeur een folie, met een dikte in een bereik van 10-500 nm.The electrode according to any one of the preceding claims, wherein the metal base layer is a lithium foil, preferably a foil, with a thickness in a range of 10-500 nm.

17. De elektrode volgens één van de voorgaande conclusies, waarin de metalen basislaag is voorzien langs een vlak (81) van een stroomcollector (8),The electrode according to any one of the preceding claims, wherein the metal base layer is provided along a face (81) of a current collector (8),

bij voorkeur een koperfolie.preferably a copper foil.

18. De elektrode volgens één van de voorgaande conclusies, waarin een verdere van de anode-metalen basislaag (2-2) is voorzien langs een tweede vlak (81) van de stroomcollector tegenover het eerste vlak (81), en waarbij een additionele elektrode laag is gevormd op deze tweede anode-metalen basislaag, daarbij resulterend in een stroom collector met elektroden aan weerszijden ervan.The electrode according to any one of the preceding claims, wherein a further of the anode metal base layer (2-2) is provided along a second face (81) of the current collector opposite the first face (81), and wherein an additional electrode layer is formed on this second anode-metal base layer, thereby resulting in a current collector with electrodes on either side thereof.

19. De elektrode volgens één van conclusies 17-18, waarin de stroomcollector (8) is gestructureerd om een relatieve gewichtsbijdrage van de stroomcollector (8) aan de elektrode (1) te verminderen.The electrode of any one of claims 17-18, wherein the current collector (8) is structured to reduce a relative weight contribution of the current collector (8) to the electrode (1).

20. Een energieopslagapparaat (100) omvattende de elektrode (1) volgens één van de voorgaande conclusies 1-19, een verdere elektrode (102) omvattende een kathode materiaal (102c), en een separator (101) omvattende een elektrolyt samenstelling (101e) die de elektrode (1) van de verdere elektrode (102) scheidt.An energy storage device (100) comprising the electrode (1) according to any one of the preceding claims 1-19, a further electrode (102) comprising a cathode material (102c), and a separator (101) comprising an electrolyte composition (101e) which separates the electrode (1) from the further electrode (102).

21. Een werkwijze (200) voor de vervaardiging van een elektrode (1) omvattende een anode-metalen basislaag (2) en een diffusielaag (3) omvattende een structuur van elektrisch geleidende pilaren (4), met langwerpige tussenruimtegebieden (5) tussen zijwanden (45) van aangrenzende elektrisch geleidende pilaren, omvattende het verankeren van elk van de elektrisch geleidende pilaren (4) in de metalen basislaag vanaf een ingebed terminaal eindvlak (41) van de elektrisch geleidende pilaar langs een ingebed gedeelte (42) daarvan, waarbij een uitstekend gedeelte (43) vrij blijft dat zich naar buiten uitstrekt vanaf een oppervlak (21) van de anode-metalen basislaag, waarin het verankeren een verwerkingsstap omvat de waarbij anodemetaal in de smelt wordt verwerkt.A method (200) for the manufacture of an electrode (1) comprising an anode-metal base layer (2) and a diffusion layer (3) comprising a structure of electrically conductive pillars (4), with elongated interspace regions (5) between side walls (45) of adjacent electrically conductive pillars, comprising anchoring each of the electrically conductive pillars (4) into the metal base layer from an embedded terminal end face (41) of the electrically conductive pillar along an embedded portion (42) thereof, forming a projecting portion (43) remains free extending outwardly from a surface (21) of the anode-metal base layer, in which the anchoring comprises a processing step of processing anode metal in the melt.

22. De werkwijze volgens conclusie 21, omvattende het vormen (201) van een structuur van elektrisch geleidende pilaren (4) met langwerpige tussenruimtegebieden (5) tussen zijwanden (45) van aangrenzende elektrisch geleidende pilaren (4) op een oppervlak van een template substraat (61), het in contact brengen (203) van terminale einddelen van de gevormde elektrisch geleidende pilaren met een laag van een anodemetaal welke is verwarmd tot boven een verwekingstemperatuur, het delamineren (205), na koelen tot onder een verhardingstemperatuur van het anodemetaal, van de structuur van elektrisch geleidende pilaren (4) van het template substraat (61), om de elektrode te vormen waarbij elk van de elektrisch geleidende pilaren (4) is verankerd in de metalen basislaag van een ingebed terminaal eindvlak (41) van de elektrisch geleidende pilaar langs een ingebed gedeelte (42) daarvan, waarbij een uitstekend gedeelte (43) vrij blijft dat zich naar buiten uitstrekt vanaf een oppervlak (21) van de basislaag.The method according to claim 21, comprising forming (201) a structure of electrically conductive pillars (4) with elongated interspace regions (5) between side walls (45) of adjacent electrically conductive pillars (4) on a surface of a template substrate (61), contacting (203) terminal end portions of the formed electrically conductive pillars with a layer of an anode metal heated above a softening temperature, delaminating (205), after cooling below a hardening temperature of the anode metal, of the structure of electrically conductive pillars (4) of the template substrate (61), to form the electrode with each of the electrically conductive pillars (4) anchored in the metal base layer of an embedded terminal end face (41) of the electrically conductive pillar along an embedded portion (42) thereof, leaving a protruding portion (43) extending outwardly from a surface (21) of the base layer.

23. De werkwijze volgens conclusie 21, omvattende het vormen (201) van een structuur van elektrisch geleidende pilaren (4) met langwerpige tussenruimtegebieden (5) tussen zijwanden (45) van aangrenzende elektrisch geleidende pilaren (4), op een oppervlak van een template substraat (61), het in contact brengen (203) van terminale einddelen van de gevormde elektrisch geleidende pilaren met een hoeveelheid van een anodemetaal voldoende om de langwerpige tussenruimtegebieden (5) tussen zijwanden (45) van aangrenzende elektrisch geleidende pilaren (4) tenminste deels te vullen,The method of claim 21, comprising forming (201) a structure of electrically conductive pillars (4) with elongated interspace regions (5) between side walls (45) of adjacent electrically conductive pillars (4), on a surface of a template substrate (61), contacting (203) terminal end portions of the formed electrically conductive pillars with an amount of an anode metal sufficient to at least partially cover the elongated interspace regions (5) between side walls (45) of adjacent electrically conductive pillars (4) to fill,

het verwarmen van het anodemetaal boven een smelttemperatuur voor een periode om te de tussenruimtegebieden (5) tussen aangrenzende elektrisch geleidende pilaren (4) te infiltreren met vloeibaar anodemetaal.heating the anode metal above a melting temperature for a period of time to infiltrate the interspace regions (5) between adjacent electrically conductive pillars (4) with liquid anode metal.

24. De werkwijze volgens één van de voorgaande conclusies 21-23, waarin de pilaren verticaal uitgelijnde koolstofnanobuizen zijn en waarbij het vormen (201) omvat het verschaffen van katalytische kiemdeeltjes langs een oppervlak van een template substraat, en het groeien van de koolstofnanobuizen vanuit de kiemdeeltjes.The method of any one of claims 21 to 23, wherein the pillars are vertically aligned carbon nanotubes and wherein the forming (201) comprises providing catalytic seed particles along a surface of a template substrate, and growing the carbon nanotubes from the germ particles.

25. De werkwijze volgens conclusie 24, waarin de katalytische kiemdeeltjes zijn voorzien op een laag omvattende een eerste isolator (6-1).The method according to claim 24, wherein the catalytic seed particles are provided on a layer comprising a first insulator (6-1).

26. De werkwijze volgens één van de voorgaande conclusies 21-25, waarin, voorafgaande aan het verankeren (203), de werkwijze omvat het bedekken (202) van tenminste de terminale einddelen van de pilaren met een lithiofiele laag (7), waarbij genoemde lithofile laag zich zijwaarts uitstrekt in de tussenruimtegebieden (5) tussen de aangrenzende elektrisch geleidende pilarenThe method according to any one of the preceding claims 21-25, wherein, prior to anchoring (203), the method comprises covering (202) at least the terminal end portions of the pillars with a lithiophilic layer (7), said lithofile layer extends laterally into the interspace regions (5) between the adjacent electrically conductive pillars

(4).(4).

27. De werkwijze volgens één van de voorgaande conclusies 21-26, verder omvattende het patroneren van het template substraat (61) en/of de gevormde structuur van elektrisch geleidende pilaren om een structuur van elektrisch geleidende pilaren te vormen die gebieden omvat zonder elektrisch geleidende pilaren (4) welke openingen (31) vormen die toegang verschaffen tot de lithium metalen bassislaag (2) en die toegang verschaffen in een zijwaartse richting tot gebieden mét elektrisch geleidende pilaren (4).The method according to any of the preceding claims 21-26, further comprising patterning the template substrate (61) and/or the formed structure of electrically conductive pillars to form an electrically conductive pillar structure comprising regions without electrically conductive pillars. pillars (4) forming openings (31) which provide access to the lithium metal base layer (2) and which provide access in a lateral direction to areas with electrically conductive pillars (4).

28. De werkwijze volgens één van de voorgaande conclusies 21-27, verder omvattende het afzetten (206) van een isolerende afdoplaag (9) welke de pilaren conform bedekt langs tenminste een terminaal einddeel (46) daarvan.The method according to any one of the preceding claims 21-27, further comprising depositing (206) an insulating capping layer (9) conformably covering the pillars along at least a terminal end portion (46) thereof.