Silicon anode, battery, and process for preparing such an anode and such a battery

Abstract

The invention relates to an anode comprising: (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate. It furthermore relates to the process to produce such anode. It also relates to the battery comprising at least one lithium-ion cell, wherein said lithium-ion cell comprises such anode, a cathode and at least one electrolyte situated in between the anode and the cathode.

Description

[0001] Silicon anode, battery, and process for preparing such an anode and such a battery

[0002] Field of the invention

[0003] The present invention relates to an improved anode comprising a conductive substrate and at least one active layer comprising silicon. The invention furthermore relates to a battery comprising such an anode and the use of such an anode in said battery. In addition, the invention relates to a process of preparing such an anode as well as to a process of preparing such a battery.

[0004] Background

[0005] The demand for high-performance energy storage solutions has driven significant advances in battery technology, particularly in the field of lithium-ion batteries over the recent years. Lithium-ion batteries are used in a variety of applications, including (but not limited to) portable electronics, electric vehicles and grid energy storage. One of the key areas of development in this field is aimed at investigation of alternative anode materials to improve the overall capacity and efficiency of these batteries. Among these materials, silicon-based anodes have attracted considerable attention due to their high theoretical capacity, which is approximately ten times greater than that of conventional graphite anodes. The use of lithium-ion batteries using silicon-based anode material is therefore rapidly growing. Although the energy density of lithium-ion batteries has increased with the use of silicon-based anode material, the silicon-based material is found to have limited cycle life compared to conventional graphite anodes based.

[0006] In the prior art solutions are presented to improve the stability and cycle life of the silicon anode.

[0007] For example, US2024154104A1 provides a battery cell that includes an arrangement of an anode active material, comprising silicon, on top of a current collector. The active material is configured on the surface of the current collector as such that exchange of lithium ions is possible. Empty spaces are formed in the anode active material in a predetermined pattern. The empty spaces accommodate Si expansion during charging and help to release stress. Other examples according to the prior art are provided in WO 2016163878.

[0008] Summary of the invention

[0009] This application addresses the problem of unsatisfactory cycle life in lithium- ion batteries utilizing silicon-based anodes. Batteries, and especially lithium-ion batteries, having a silicon-based anode allow for increased energy density in terms of cycle life. However, many solutions for silicon-based anodes batteries currently have unsatisfactory cycle life due to deterioration over time. This application seeks to find a solution to improve the cycle life of silicon-based lithium-ion batteries. The application also seeks to improve the silicon-based anode.

[0010] The disclosures of the background art were found to be prone to a limited cycle life due to deterioration of the anode material compared to the present disclosure.

[0011] Therefore, there remains a need for improved anodes for use in lithium-ion batteries and moreover a need to improve the cycle life of the known lithium-ion batteries. It is an objective of the invention to address one or more of the disadvantages, such as but not limited to the limited cycle life, faced in the prior art. It is another objective of the invention to provide an alternative to the existing silicon comprising anodes. A particular objective is to provide an efficient process for the production of the silicon comprising anodes. It is a further objective to use these anodes in rechargeable batteries.

[0012] During the first charge-discharge cycle of lithium-ion cell operation, the electrolyte can decompose to form a range of typically ill-defined lithium-containing compounds on the anode surface, producing a layer called the solid-electrolyte interphase (SEI). The SEI layer is a result of the reduction potential of the anode. During charging decreasing potentials at the anode can lead to electrochemical reduction of some of the components of the electrolyte at the surface. As the SEI layer is partially formed from lithium containing compounds, production of SEI growth reduces the total charge capacity of the cell by consuming some of the lithium that could otherwise be used to store charge. This is a degradation mechanism known as Loss of Lithium Inventory (LLI). The properties and evolution of the solid-electrolyte interphase layer fundamentally affects the overall performance of the lithium-ion cell. Reasons for this can include (but are not limited to): (i) that the solid-electrolyte interphase layers (im)permeability to lithium ions can limit the rate and / or amount of lithium that the anode can store; and (ii) that the solid-electrolyte interphase layers electronic resistivity affects the rate at which the solid-electrolyte interphase layer grows. SEI layer growth increases the LLI. In a lithium-ion cell with a silicon-comprising anode, the SEI plays an especially important role in capacity degradation, due to the large volumetric changes during cycling. Expansion and contraction of the anode material typically cracks the SEI layer that has formed on top of it, exposing more of the anode material to direct contact with the electrolyte, which results in further SEI production and further LLI. This decreases the commercially useful charge cycle life-span of lithium-ion cells when using a silicon-comprising anode. This problem of cracking of the SEI can be particularly acute for anodes comprising silicon with a nanostructured surface morphology, due to the surface area and shapes of silicon material at the anodeelectrolyte interphase.

[0013] Applicants have surprisingly found that the anode and battery presented provide for or have an improved cycle life. The improved cycle life is believed to be the result of the improved morphology or atomic structure of the silicon anode, that can be characterized using Raman spectroscopy. According to the prior art it is known to slightly improve the cycle life of battery with silicon containing anodes by optimizing the meso features and macro features (on nm-pm scale respectively) of the anode to release stresses. Contrary to the prior art solutions, the inventors have changed the atomic structure, other than the meso features and macro features as is done in the prior art. Changing the atomic structure of the anode is achieved by changing the process conditions in such a way that the silicon structure is substantially more organised and / or relaxed resulting in a higher cycle life. As indicated above, the obtained improved atomic structure of the anode can be determined or characterized by using Raman spectroscopy. Using Raman spectroscopy the structure of the silicon material can be determined by the bond angle distortion (BAD). The BAD is an indication to know if the material is close to crystalline Si. In this context, crystalline Si has negligible disorder and possesses the most structured form of the material. This crystalline material is normally accompanied with a less defective material and is considered more relaxed. The bond angle distortion values defined hereinafter correspond to pre-cycling of the battery according to some embodiments, and hence define the initial bond angle distortion values. After cycling, the values of the bond angle distortion may and typically will increase.

[0014] Another parameter that may be determined or calculated is the R* parameter, which is unrelated to the BAD value but is also in atomic scale like the BAD. The parameter R* comprises information about the voids on atomic scale. Both R* and BAD parameters relate to cycle life and may allow to identify improved cycle life.

[0015] In order to solve the objective, what is proposed is an anode, in particular a pristine anode, comprising (i) an electrically conductive substrate, and (ii) at least one layer, comprising at least 90 percent, preferably at least 95 percent by weight of silicon, applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy, In particular by using a Raman microscope or spectroscope, equipped with a 785 nm laser, in the range of from 6.60° up to 9.75°. Where reference is made to pristine this shall preferably be understood as prior to the formation and / or cycling and / or lithiation and / or de-lithiation process, and in particular directly after deposition of the active material. The bond angle distortion may be situated between 7.5° and 9.5°, more particularly between 8.0° and at least 9.0° (up to 9.75°), such as 9.01°, 9.1° and 9.71°. Particular but non- limitative examples of the bond angle distortion may be 8.5° and 8.9° and any value in between. Where reference in this document is made to a Bond Angle Distortion value this may be determined by using a Raman microscope or spectroscope, equipped with a laser (monochromatic light source) having a wavelength of 785 nm, in particular, use can be made of a Renishaw InVia Qontor Raman microscope or spectroscope, equipped with a 785 nm laser. To acquire the full spectral range from 100 cm-1to 3200 cm-1, a 1200 lines mm-1grating may be used, which is optionally rotated during the measurement, using Renishaw’s SynchroScan™ mode. The intensity of the laser is preferably limited to 10 % of the total available laser power, to avoid crystallization of the sample. The exposure time is preferably 10 seconds and three accumulations are preferably acquired per spectrum to increase the signal to noise ratio. Data may be recorded using a 50x Long Working Distance (LWD) objective. Yet, where reference is made to using a Raman microscope or spectroscope equipped with a 785 nm laser the Raman microscope or spectroscope may also or alternatively be equipped with a laser having another wavelengths. These values particularly correspond to the pristine material of the anode according to some embodiments. Pristine shall preferably be understood as prior to the formation and / or cycling and / or lithiation and / or de-lithiation process, and in particular directly after deposition of the active material. The bond angle distortion value of the anode applied in a battery may be higher after formation or one or more cycles compared to the bond angle distortion value of the pristine anode material. It is observed that the bond angle distortion of the non-pristine anode increases by approximately 3.0° to 5.0°, in particular 4.1 ° to 4.2° compared to the bond angle distortion of the pristine anode material. It was particularly found that after formation and / or one or more cycles the initial bond angle distortion values, i.e., of the pristine material, of 8.5° and 8.9° increased up to 12.6° and 13.1 ° respectively. Some embodiments of the invention also relate to an anode comprising (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480. The anode wherein the atomic structure is characterized by the microstructure parameter R* may further comprise one or more features according to the anode characterized by the bond angle distortion (ranges and values) as defined above.

[0016] The present invention, according to many non-limitative embodiments, further relates to a process for preparing an anode, in particular a pristine anode, comprising the steps of:

[0017] A) providing an electrically conductive substrate, optionally provided with nodules,

[0018] B) depositing onto the electrically conductive substrate at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon, such that an atomic structure of silicon is formed having a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75° and / or such that an atomic structure is formed having a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480. Optionally, the bond angle distortion is situated between 7.5° and 9.5°, more particularly between 8.0° and at least 9.0° (up to 9.75°). Yet, similar bond angle distortion values as disclosed in relation to the anode may be obtained.

[0019] The present invention, in many embodiments, also relates to a battery comprising at least one lithium-ion cell, wherein said lithium-ion cell comprises:

[0020] • an anode, in particular a pristine anode, comprising (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60 up to 9.75,

[0021] • at least one cathode, and

[0022] • at least one electrolyte, optionally a solid-state electrolyte, situated in between said at least one anode and said at least one cathode.

[0023] The invention, in some embodiments, also relates to a process for preparing a battery, in particular a battery according to some embodiments of the invention, and in particular for preparing for first use, comprising the steps of:

[0024] (i) providing an anode according to the invention, preferably produced by applying the anode preparation method according to the invention,

[0025] (ii) providing a cathode and an electrolyte comprising lithium,

[0026] (iii) combining the anode, the cathode, and the electrolyte to form a lithium-ion cell;

[0027] (iv) lithiating the anode;

[0028] (v) delithiating the anode, and

[0029] (vi) optionally repeating the lithiating step (iv) and delithiating step (v) at least once. The invention further relates to a battery as defined by some of the embodiments, wherein the battery is subjected to the preparation process as defined through at least steps (iv)-(v). Optionally wherein the atomic structure of the silicon based anode of said battery is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 10.2° to 13.95°.

[0030] It was particularly found that after formation and / or one or more cycles a bond angle distortion value of 8.5° and 8.9° may increase up to 12.6° and 13.1° respectively. Nevertheless a significant improvement of cycle life was observed for the pristine bond angle distortion values between 6.60° and 9.75°. According to some embodiments, the battery may comprise at least one enclosure and / or housing, wherein said housing is configured for, preferably in an isolated manner, accommodating one or more lithium-ion cells. Said housing may be isolated from the outside such that it is safe to be handled and transported. The housing or enclosure may accommodate a plurality of lithium-ion cells, which may optionally be mutually electrically connected in series and / or parallel to achieve a desired capacity.

[0031] Scientific disclosure

[0032] The present disclosure contributes to an increased cycle life of a battery or lithium-ion cell using the improved silicon-based anode material. The characterising improvement of pristine anode material properties were found through in-depth scientific study. The applicant herewith presents the relevant findings in terms of the scientific improvements proposed in this section.

[0033] In general, spectroscopy techniques like Fourier-Transformed Infrared spectroscopy and Raman spectroscopy are considered powerful tools to assess the characteristics of hydrogenated amorphous silicon materials.

[0034] A scientific article published in 2008 in the ‘Journal of applied physics’ (JOURNAL OF APPLIED PHYSICS 104, 073521 (2008), pages 073521 -1 to 7) describes the quantification of the bond-angle distortion by Raman spectroscopy and the strain energy of amorphous silicon. In the article a thorough critical analysis of the theoretical relationships between the bond-angle distortion (BAD) in amorphous silicon, A0, and the width of the transverse optical Raman peak, WTO, is presented. It is shown that the discrepancies between them are drastically reduced when unified definitions for A0 and WTO are used. From the transverse optical mode, the bond angle distortion, A0, sometimes also referred to as bond angle disorder or bond angle variation, can be calculated. A0 is defined as the root mean square deviation from the tetrahedral bond angle, which is 109.5°. Deviations from this angle occur due to impurities, stresses inside the network structure and point defects but also a lack of long range ordering of atoms. In other words, the bond angle distortion (BAD) represents an indirect measure of the intrinsic stresses that are present in the layer. A higher bond angle distortion means more deviation from the ideal angle and thus more stresses in the network structure. Although the bond angle distortion can directly be measured via X-ray or neutron scattering, these methods require precise experimenting and complex analysis. Raman spectroscopy provides an alternative and relatively easy way to assess the bond angle distortion. The BAD A0 can be estimated using the center wavenumber of the transverse optical mode (coTO), as follows: g _ 505.5-<DTO

[0035] (Equation 1 )

[0036] 2.5

[0037] From the width of the transverse optical mode of amorphous material (Acoa-Si), combined with the width of the transverse optical mode of crystalline material (Acoc- Si, typically 1 cm-1) the lattice stress within the silicon network can be estimated (Equation 2):

[0038] Stress = — 250 ■ (Ao)c-Sj — a)a-si) (Equation 2)

[0039] In the Raman spectrum, the set of peaks between 2000 and 2200 cm’1correspond to the hydrogenated form of silicon. The peak around 2000 cm’1, represents Si-H, whereas the peak around 2100 cm-1represents Si-H2. These bonds are typically found in closed-off pores, as Si-Hx bonds that are present on the surface are rapidly oxidized in ambient conditions. Si-H bonds are mostly found in small, closed-off pores of less than 2 nm in size, whereas Si-H2bonds are found in somewhat larger voids, between 2 and 4 nm in size. Note that these small, closed- off pores cannot be assessed via other techniques. The ratio between those two types of pores, i.e., the pores of less than 2 nm in size and the pores in the range from 2 nm to 4 nm, or larger, in size, is represented by Equation 3:

[0040] (Equation 3) in which A(SiH2) represents the area of the gaussian peak around 2100 cm-1and A(SiH) represents the area of the gaussian peak around 2000 cm’1.

[0041] Additionally, the total void fraction S* can be determined via Equation 4:

[0042] (Equation 4) in which A(SiH) and A(SiH2) have the same meaning as above, and A(Si) represents the area of the transverse optical mode around 480 cm’1. Detailed of the invention

[0043] Where the background art seems to focus on development of improving the productivity, which may for example be increased by increasing the silane flows during production of anodes causing a higher growth rate to speed up production of anodes the applicants found a solution going against this longstanding trend of increased productivity.

[0044] By studying the fundamental scientific characteristics the applicant found the performance of the anode to be related to the morphology of the silicon anode material. In particular a more relaxed, regular, or structured morphology may substantially increase battery performance. Such results are achieved by lowering the silane flow over plasma power ratio, contrary to increasing it. The innovative anode according to some embodiments of the invention comprises silicon with an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°. It was surprisingly found that the anode used in a battery and battery characterized by Raman spectroscopy with a BAD in the range of from 6.60° up to 9.75° have an improved cycle life. Optionally, the bond angle distortion is situated between 7.5° and 9.0°, more particularly between 8.0° and 9.0°. Particular examples of the bond angle distortion may be 8.5° and 8.9°. These values particularly correspond to the pristine material of the anode according to some embodiments. It is imaginable that the bond angle distortion value of the anode, in particular when provided in a battery , is higher after formation or one or more cycles. The Bond Angle Distortion value is characterized and / or determined by Raman spectroscopy, preferably with a spectral resolution of approximately 0.5°. Smaller spectral resolutions of approximately 0.1° or 0.05° are also conceivable depending on the set-up used. It is observed that the bond angle distortion of the non-pristine anode in the battery increases by approximately 3.0° to 5.0°, in particular 4.1° to 4.2° compared to the original pristine anode in said battery. It was particularly found that after formation and / or one or more cycles the initial bond angle distortion values for the pristine anode material of 8.5° and 8.9° increased up to 12.6° and 13.1° respectively for the non-pristine anode material.

[0045] Additionally or alternatively some embodiments of the invention relates to an anode comprising (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480. The anode wherein the atomic structure is characterized by the microstructure parameter R* may further comprising one or more features according to the anode characterized by the bond angle distortion.

[0046] The improved cycle life is believed to be the result of the improved, in particular more structured (regular) and / or more relaxed, morphology of the pristine silicon anode. The structure of the silicon material is close to an ideal structure with a low level of internal stress and / or disorder. This morphology has not been seen in prior art samples before and is achieved by the adapted manufacturing process. Some none-limitative examples to achieve the desired structure by adapting the manufacturing process, particular a PECVD process to deposit the active silicon material, are adjusting the plasma power, adjusting the gas flows as such, and / or the chamber design such as distance between plasma source and substrate. For example, the new morphology may be achieved by lowering the silane gas flow over plasma power ratio for a PECVD process. This is explained in more detail in the examples discussed in this document.

[0047] The indicated bond angle distortion range typically relates to a pristine (unused) anode material. In this respect, pristine and unused shall preferably be understood as prior to the formation and / or cycling and / or lithiation and / or de- lithiation process. The bond angle distortion will normally change, in particular increase, during operational use, to bond angle distortion values exceeding 9.75°. Experiments have shown that the bond angle distortion can reach values of between 12° and 13.5° after formation and / or a few cycles.

[0048] Therefore, the invention, according to a number of non-limitative embodiments, is directed to an anode comprising (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent by weight of silicon and, directly or indirectly, applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°. However, bond angle distortions in the range from 7.5° up to 9.0°, more particularly in the range from 8.0° up to 9.0° are conceivable for all embodiments provided in this document. Lower bond angle distortion (A9) (typically <6.60°) as measured by Raman spectroscopy is an indication that the silicon includes is substantially crystallized due to better ordering of the atomic bonds in the structure, which affects the cycle time. Crystalline Si anodes have a significantly lower cycle life since they are prone to cracking. Therefore, a negative impact on cycle life is expected to be seen if crystalline silicon based anode is used in the battery. Higher bond angle distortion (A0) (typically >9.75°) as measured by Raman spectroscopy is an indication that the silicon is less structured, meaning that there are undesired internal stresses in the material, due to lower ordering of the atomic bonds in the structure, which (also) affects the cycle life. Upon cycling, the material undergoes morphology changes due to lithiation and delithiation step, evidenced by higher BAD after few cycles. Not to be bounded with any particular theory, a material with less stress in the beginning will likely be able to sustain more stress during cycling, hence, offers better cycle life.

[0049] It is therefore preferred that the silicon comprising layer is at least partially amorphous. Due to the relatively high silicon content over 90 percent by weight of the anode material, preferably even more than 95 percent by weight of the anode material, the anode material may be and is preferably free of graphite, and / or may be free of any binder. It is imaginable that the at least one layer is exclusively composed out of silicon, however in practice some impurities may and often will be present in small amounts.

[0050] Suitably, the silicon of the anode may comprise an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 7.50° up to 9.50°, and even in the subrange of 8.50° to 8.90°.

[0051] Suitably, the anode comprises at least one layer comprising at least 95 percent by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 7.50° up to 9.50°.

[0052] In addition to the specified bond angle distortion range(s) specified above, or instead of the specified bond angle distortion ranges specified above, the silicon structure in the at least one layer may be characterised by microstructure parameter R*, which is a measure for the ratio of Si-H bonds that are mostly found in small, closed off pores of less than 2 nm in size, and Si-H2 bonds that are found in somewhat larger voids, between 2 and 4 nm in size. Suitably, the silicon in the anode comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480. This ratio has been calculated using equation (3):

[0053] (Equation 3)

[0054] This Raman structure R* may be considered a ratio between the closed pores / defects with size less than 2 nm and the total pores / voids with size from 2 nm to 4 nm. This indicates whether if silicon layer is dense or void-rich material. Hence, lowering the value of R* gives an indication of less voids presence in the material. In Equation 3, A(SiH2) represents the area of the gaussian peak around 2100 cm-1and A(SiH) represents the area of the gaussian peak around 2000 cm-1of the Raman spectroscopy results. Experiments have shown that for these R* values, in combination with and / or independent of the claimed BAD values, the results for improved cycle life are even more optimal.

[0055] The at least one layer comprising at least 90 percent by weight of silicon and applied onto the electrically conductive substrate according to the disclosure may be continuous or discontinuous. The layer may include areas where the current collector surface is exposed to the gaps. Preferably, the area where the current collector surface is exposed to the gaps is minimal. This is in order to maximize the amount of active material of the anode. Suitably, the active material may be arranged on both sides of the current collector. Suitably, the active material may be arranged on only one side of the current collector.

[0056] Possibly, the at least one layer comprising silicon comprises a plurality of adjacent columns extending perpendicularly with respect to a plane defined by the electrically conductive substrate. Said adjacent columns are typically separated by column boundaries extending in the perpendicular direction. Said columns may comprise at least 90 percent by weight of silicon, most preferably at least 95 percent by weight of silicon. In some embodiments, by using X-ray fluorescence (XRF) the amount of silicon (mg cm-2) can be measured, which in combination with the thickness and the weight measured by weighing, such as by using a high precision laboratory scale, allows for determining of the purity of the active anode material in %. The orientation of the columnar structures can be determined from a cross-sectional electron microscope image of the anode with a state of charge (SOC) of 0% to 10%, wherein the cross section is perpendicular to the - typically planar - plane defined by the current collector. Yet, it is also possible to use an optical microscope to determine the orientation of the columnar structures. Basic examples of a layer comprising silicon with such plurality of adjacent columns extending perpendicularly with respect to a plane defined by the electrically conductive substrate can be found in for example WO2023121462A1 , the disclosure of said document in relation to the columnar structure is hereby incorporated by reference. The variations of the columnar structure may be combined with the teachings of this document. Although the shape of the columnar structure can be made visual by SEM and / or Optical Microscopy, the molecular characteristics cannot be retrieved via SEM, and require the inventive characterisation.

[0057] Suitably, at least 95% of the regions may comprise a plurality of interconnected or adjoined columnar structures comprising silicon. Suitably, at least 96%, or at least 97%, or at least 98%, or at least 99%, or about 100%, or substantially 100% of the regions may comprise a plurality of interconnected or adjoined columnar structures comprising silicon. Adjoined columnar structure shall be understood as the neighbouring columnar structures not necessarily contacting. There may in such adjoining columnar structures be a small interruption between one columnar structure and the adjoining columnar structure causing the boundaries to be visible. The interconnected columnar structure shall be understood as the columnar structures directly abutting one another, which renders such interconnected columnar structures more difficult to visually distinguish from one another. Suitably, the columnar structures may extend in a substantially perpendicular direction from the surface plane of the current collector.

[0058] In some embodiments, the adjacent columns have a larger mutual distance at the interface of the silicon and the electrically conductive substrate (column base) compared to the column distance at the top of the column, in particular compared to the part of the columns at their maximum width.

[0059] Suitably, at least one column, and more preferably a plurality of columns have a non-constant width along the length direction of the column. This may be understood as the width said column being different at different points along the length of said column. The length of the column extends substantially perpendicular to the plane defined by the electrically conductive substrate.

[0060] Suitably, at least one column, and more preferably a plurality of columns comprise a base section, wherein a bottom surface of the base section is connected to the conductive substrate. The base section may comprise a top surface which may be an exposed surface. Said top surface may be flat, or convex, or concave. The base section may have an outwardly diverging cross-sectional shape from the bottom side of the base section towards the top side of the base section. Suitably, the outwardly diverging base section may be cone shaped. On top of said base section, such as on the top surface, a top section may be arranged. The base section and top section, if applied, may be integrally formed out of a single material. Suitably, the top section may have a convex shape. The convex shape may be a substantially hemispherical shape, or may be composed out of a plurality of flat interconnected surfaces forming a convex shape.

[0061] Suitably, at least one column, and more preferably a plurality of columns comprise a base section, wherein a bottom surface of the base section is connected to the conductive substrate. The base section may be an inwardly diverging cross-sectional shape from the bottom side of the base section towards the top side of the base section. Suitably, the outwardly diverging base section may be cone shaped. A combination of different types of columns as described herein may be applied in combination with one another.

[0062] Suitably, the electrically conductive substrate that has silicon applied onto it includes nodules for supporting said columns, wherein more preferably each column is support by a single nodule. Suitably, the nodules are preferably formed using electrodeposition or electroplating. These nodules are commonly formed by raised areas and / or bumps applied (purposively) onto the electrically conductive substrate during production in order to graft the silicon anode material onto said nodules, in particular to form a desired columnar silicon structure onto said substrate. Suitably, the nodules are formed by conductive material, preferably metal.

[0063] Suitably, the silicon comprises amorphous silicon, optionally further comprising nano crystalline silicon. Nano crystalline is a nanoparticle of Si which is in a cubic diamond structure. These particles may be a few nm to approximately 40 nm, typically having a maximum of 100 nm. The amorphous silicon may in some embodiments be free of nano crystalline silicon. Suitably, the amorphous silicon and / or nano-crystalline silicon, if present, may optionally further comprise silicon- containing compounds. A silicon-containing compound may be a compound comprising a silicon atom bound to another atom different from silicon. Suitably, the active material may have an amorphous structure, optionally wherein the amorphous structure has nano-crystalline regions. For ease of reference the term amorphous silicon used throughout this document to indicate that the silicon layer may optionally, but not necessarily, comprise amorphous silicon, in which nano-crystalline regions of the silicon layer may be present with a fraction of nanocrystalline silicon up to about 30%. The silicon layer according to the disclosure may comprise silicon oxide and / or hydrogenated silicon.

[0064] The layer comprising silicon may have a porosity of less than 50%. Suitably, the active material, in particular the silicon, may have a porosity of less than 30%. Suitably, the layer comprising silicon has a porosity in the range of from 0% up to 75%, preferably 0% up to 50%, more preferably 10% up to 50%. The porosity may be determined by means of microscopy and / or SEM and / or mass loading measurement. Alternative ways to obtain the porosity may also be conceivable.

[0065] Suitably, the layer comprising silicon may have a thickness of from 5 pm to 20 pm. Suitably, the layer comprising silicon may have a thickness of from 5 pm to 15 pm, or of from 8 pm to 20 pm.

[0066] By controlling the depositing of active material comprising silicon on the current collector different characteristics of an anode according to many embodiments of the invention may be obtained. Suitably, the layer comprising silicon may have a silicon mass loading of at least 1 mg cm-2. Suitably, the layer comprising silicon may have a mass loading of at least 1 .2 mg cm-2or 1 .3 mg cm-2. Suitably, the layer comprising silicon may have a mass loading from 1 mg / cm2to 10 mg cm-2. Suitably, the layer comprising silicon may have a mass loading from 1 mg cm-2to 3 mg cm-2or 5 mg cm-2. Suitably, the layer comprising silicon may have a mass loading from 1 .2 mg cm-2to 3 mg cm-2, or 5 mg cm-2, or 10 mg cm-2. Suitably, the layer comprising silicon may have a mass loading from 1 .3 mg cm-2to 3 mg cm-2, or 5 mg cm-2, or 10 mg cm-2. Suitably, the anode comprises the layer comprising silicon that has a mass loading from 0.8 mg cm-2to 4 mg cm-2, preferably of 1 mg cm’2to 3 mg cm’2.

[0067] Detailed aspects of the current collector

[0068] The current collector, in particular the electrically conductive substrate, of the anode may be preferably made of a material having good electrochemical stability, electrical conductivity, and mechanical strength. Suitably, the electrically conductive substrate may at least partially be composed of at least one material chosen from the group consisting of: copper, aluminium, nickel, titanium, carbon, iron, chromium, stainless steel, and an alloy of two or more of these materials. More preferably, the current collector comprises copper, nickel, or an alloy thereof. More preferably, the current collector comprises copper or an alloy thereof. More preferably, the current collector comprises copper.

[0069] An adhesion layer comprising a metal, metal alloy and / or metal salts and / or oxide attached to the current collector may advantageously increase the adhesion of the silicon to the current collector of the anode according to some embodiments of the present invention, see WO2021029769. The relevant disclosure from US2022328814A1 including the disclosure related to the use of metal alloys, salts, and / or oxides to increase adhesion is hereby incorporated herein by reference in its entirety. Such an interstitial adhesion layer is not essential. According to the present disclosure, the current collector comprising a metal, metal alloy and / or metal salts and / or oxide adhesion layer may suitably comprise an adhesion layer. This adhesion layer increases the adhesion between silicon material and the current collector material as different complexes of silicon are being formed on the interphase between the current collector material and the silicon. Such an adhesion layer preferably may comprise Chromium, and / or Chromium oxide, and / or nickel, and / or zinc, and / or tin, such as ZnO and / or SnO2. Hence, combinations thereof are also conceivable. The adhesion layer can be formed by coating or depositing the metal, metal alloy and / or metal salts and / or oxide on the current collector material. Preferably, the adhesion layer may be in a layer at a thickness of from 1 nm up to and including 5 nm, more preferably from 2 nm up to and including 5 nm. A thickness of approximately 0.1 nm may be considered as an average apparent thickness. It may be that the adhesion layer is not a continuous layer extending over the entire substrate, hence it may be that some parts do not contain adhesion layer.

[0070] Suitably, the electrically conductive substrate comprises a current collector, and an adhesion layer applied onto said current collector, wherein said adhesion layer is situated between the current collector and the layer comprising at least 90 percent by weight of silicon. More preferably, the adhesion layer comprises at least one additive selected from the group consisting of: nickel, zinc, tin, chromium, silane, nickel oxide, zinc oxide, tin oxide, and chromium oxide.

[0071] It was further found that a particular roughness of the electrically conductive substrate further increases the advantageous configuration of the anode according to several embodiments of the invention, specifically with regard to the shape of the lateral surfaces of the regions, the gap area, and the top surface area of the regions according to the some embodiments of the present invention.

[0072] Suitably, the current electrically conductive substrate may exhibit a surface roughness value selected from at least one of the following: an Sdr value of at least 40%; an Sz value of at least 4 pm; an Sq value of at least 0.43 pm; and an Sa value of at least 0.2 pm; or any combination thereof. Suitably, the electrically conductive substrate may exhibit a surface roughness having an Sdr value of at least 40%, an Sz value of at least 4 pm, an Sq value of at least 0.43 pm, and an Sa value of at least 0.2 pm as determined by white light interferometry according to ISO 25178(2012).

[0073] Therefore, in some embodiments, the electrically conductive substrate has a surface roughness value selected from at least one of the following:

[0074] • an Sdr value of more than 40%; and / or

[0075] • an Sdq value of more than 1 .0, as determined by white light interferometry according to ISO 25178(2012).

[0076] Suitably, the Sdr value may be at least 50%, at least 60%, at least 75%, at least 90%, at least 92%, at least 95%, at least 120%, at least 135%, at least 150%, or at least 160%. Suitably, the Sdr value may be of from 40% to 250%, of from 50% to 250%, of from 60% to 250%, of from 90% to 250%, of from 120% to 250%, of from 135% to 250%, of from 150% to 250%, or of from 160% to 250%. Suitably, the Sdr value may be of from 40% to 500%, of from 50% to 500%, of from 60% to 500%, of from 90% to 500%, of from 120% to 500%, of from 135% to 500%, of from 150% to 500%, or of from 160% to 500%.

[0077] Suitably, the Sq value may be at least 0.45 pm, at least 0.5 pm, at least 0.55 pm, at least 0.6 pm, at least 0.7 pm, at least 0.8 pm, or at least 0.85 pm. Suitably, the Sq value may be of from 0.43 pm to 2.5 pm, of from 0.45 pm to 2.5 pm, of from 0.5 pm to 2.5 pm, of from 0.55 pm to 2.5 pm, of from 0.6 pm to 2.5 pm, of from 0.7 pm to 2.5 pm, of from 0.8 pm to 2.5 pm, or of from 0.85 pm to 2.5 pm.

[0078] Detailed description of the process

[0079] In many embodiments, the bond angle distortion (BAD) of a silicon anode can be varied by changing the silane flow over plasma power ratio during the deposition process. In several embodiments the deposition process is a PECVD process. Non-limitative examples of a PECVD process are Microwave PECVD (MW-PECVD), RF PECVD (Radio Frequency), DC PECVD. In certain embodiments, lowering the silane flow over plasma power ratio leads to a decrease in the bond angle distortion (BAD). This appears to be a linear relationship. Lowering of the silane flow over plasma power ratio can be done in multiple ways, by steering the process parameters, such as process pressure and the flows of the reactive and supported gasses. Furthermore, the exact process conditions to yield the desired anode with the desired silicon structure depend on the layout and dimensions of the process chamber. Gas flows in PECVD are typically controlled by mass flow controllers (MFC’s) and flows are typically given is seem (standard cubic centimetre per minute) or SLM (standard litre per minute). The plasma power is given by W.

[0080] What is also presented is a process for preparing an anode, in particular an anode as described above, the process comprises the steps of: A) providing an electrically conductive substrate, optionally provided with nodules, followed by B) depositing onto the electrically conductive substrate at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon, such that an atomic structure of silicon is formed having a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75° or such that an atomic structure is formed having a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480.

[0081] Suitably, during step B) of the process at least one of the following deposition technologies is used: chemical vapour deposition (CVD), such as plasma-enhanced chemical vapour deposition (PECVD) and thermal CVD; physical vapour deposition (PVD), such as sputtering and / or evaporation; atomic layer deposition (ALD); and / or electrochemical deposition (ECD). The forming process of the silicon layer is preferably configured as such to create the nanostructured silicon thin film layer comprising a plurality of adjacent silicon columns and nanoparticle aggregates. As explained above, a nanostructured silicon thin film layer is capable of providing a significantly higher, e.g. 10-fold, energy storage capacity than prior art graphite anodes. During step B) a silane comprising gas may be used. Silane is converted into silicon using one of the above mentioned deposition techniques. More preferably, the silane comprising gas comprises at least one inert gas fraction, such as a nitrogen or argon fraction. Even more preferably, during step B) of the process a silane comprising gas flow over power ratio is applied which is in the range of from 0.65 down to 0.1 seem W-1, most preferably the silane comprising gas flow over power ratio is in the range of from 0.50 seem W’1down to 0.20 seem W1.

[0082] Besides the silane component in the silane comprising gas, optionally other gases such as argon and / or hydrogen are added to the process chamber.

[0083] Suitably, the silane of the silane comprising gas is at least one silane selected from the group consisting of: monosilane, disilane, trisilane and chlorosilanes.

[0084] The silane gas flow is preferably not too low, as the deposition rate decreases with decreasing gas flow. The silane flow recipe settings in the anode production process in accordance with many embodiments of the invention balance deposition rate (time) and product quality (related to cycle life in LIB applications).

[0085] Detailed description of the battery and manufacturing thereof

[0086] Batteries allow to power devices by moving electric charges between different materials to produce power. A battery may comprise an electrolyte, a cathode layer, a separator layer, and silicon material. When the battery is used, lithium ions move through the electrolyte from the silicon material to the cathode, creating an electric current that may power devices. The separator layer keeps the cathode and silicon material from touching but allows the ions to pass through, ensuring the battery works safely and efficiently. A separator may not be required in case of a solid state battery. The battery can be charged by applying an external electric current, which reverses the flow of lithium ions from the cathode back to the silicon material through the electrolyte. Batteries may have a limited cycle life, after which the battery may not be usable, or may be usable with significantly reduced capacity or performance compared to the initial capacity or performance. By changing the manufacturing process the BAD value of the anode can be adapted, which allows for production of improved batteries.

[0087] What is also presented is a battery comprising at least one lithium-ion cell, wherein said lithium-ion cell comprises:

[0088] • at least one anode comprising (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°;

[0089] • at least one cathode, and

[0090] • at least one electrolyte, optionally a solid-state electrolyte, situated in between said at least one anode and said at least one cathode.

[0091] It is imaginable that at least one electrolyte is a liquid electrolyte. Suitably, the electrolyte comprises a non-aqueous solvent or diluent, wherein the nonaqueous solvent or diluent more preferably, comprises a carbonate or a compound comprising an ether group, and wherein the electrolyte comprises at least one lithium salt, such as LiPF6, LiBF4, or l_iCIO4.

[0092] Preferably, the cathode of the battery comprises a lithium metal oxide, such as lithium cobalt oxide (LiCo02), lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), and / or lithium nickel manganese cobalt oxide (NMC).

[0093] The present invention according to some embodiments is also directed to the use of the anode in a battery as described above.

[0094] To assemble a battery, the silicon material is first prepared and applied as the anode, followed by the cathode. An electrolyte is then placed between the anode and cathode layers to facilitate ion movement. A separator layer is inserted between the anode and cathode to prevent direct contact, i.e. , maintaining physical separation of the anode and cathode, while allowing ion flow. These components are stacked or wound together in a specific order and may be encased in a suitable housing to form the complete battery. Yet, alternative process flows are not excluded by this possible example of the assembling process.

[0095] By improving the silicon anode prior to assembly, such as by adapting the processing parameters of forming the anode, a more relaxed or structured anode may be obtained which allows to improve the cycle life. It was found that the relaxed structure may be characterised by the bond angle distortion.

[0096] What is presented is a process for preparing a battery, in particular a battery as described above, comprising the steps of:

[0097] (i) providing an anode according to one or more embodiments of the invention as described above, preferably produced by applying the method according to many embodiment of the invention as described above,

[0098] (ii) providing a cathode and an electrolyte comprising lithium,

[0099] (iii) combining the anode, the cathode, and the electrolyte to form a lithium-ion cell; (iv) lithiating the anode;

[0100] (v) delithiating the anode, and

[0101] (vi) optionally repeating the lithiating step (iv) and delithiating step (v) at least once.

[0102] Suitably, during step iv) and / or step (v) and / or step (vi) the atomic structure of the silicon based anode changes such that the bond angle distortion (A0) as measured by Raman spectroscopy exceeds 9.75°. This battery may be understood as a lithiated battery.

[0103] The assembled battery may be subjected to a series of formation cycles to ensure proper functionality and performance. What is presented is a battery as defined by some of the embodiments, wherein the battery is subjected to the process according to the invention, in particular as specified above. Preferably, the atomic structure of the silicon based anode of said battery, after being subjected to the process, is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 10.2° to 13.95°, preferably from 10.7° to 13.85°.

[0104] It was particularly found that after formation and / or one or more cycles a bond angle distortion value of 8.5° and 8.9° of the pristine anode material may increase up to 12.6° and 13.1 ° respectively after formation and / or one or more cycles. Nevertheless a significant improvement of cycle life was observed for these pristine bond angle distortion values. According to some embodiments, the battery comprises at least one enclosure and / or housing, wherein said housing is configured for, preferably in an isolated manner, accommodating one or more lithium-ion cells. Said housing may be isolated from the outside such that it is safe to be handled and transported. It is imaginable that the housing or enclosure accommodates a plurality of lithium-ion cells, which may optionally be mutually electrically connected in series and / or parallel to achieve a desired capacity.

[0105] Non-limitative embodiments

[0106] Some embodiments of the present invention are set out in the following non- limitative clauses:

[0107] 1 . An anode, in particular a pristine anode, comprising:

[0108] (i) an electrically conductive substrate, and (ii) at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by, optionally one or more of: a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°; and / or a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480; and / or a relaxed, and / or regular, and / or structured silicon material.

[0109] 2. Anode according to clause 1 , wherein the bond angle distortion (A0) as measured by Raman spectroscopy is in the range of from 7.50° up to 9.50°.

[0110] 3. Anode according to clause 1 or 2, wherein the silicon comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480.

[0111] 4. Anode according to any of the previous clauses, wherein the layer comprising silicon comprises a plurality of adjacent columns extending perpendicularly with respect to a plane defined by the electrically conductive substrate, wherein said adjacent columns are preferably separated by column boundaries extending in the perpendicular direction.

[0112] 5. Anode according to clause 4, wherein at least 95% of the layer is formed by said plurality of adjacent columns.

[0113] 6. Anode according to clause 4 or 5, wherein said columns comprise at least 90 percent by weight of silicon, more preferably at least 95 percent by weight of silicon.

[0114] 7. Anode according to any of clauses 4-6, wherein the adjacent columns have a larger distance at the interface of the silicon and the electrically conductive substrate compared to the column distance at the top of the column. 8. Anode according to any of clauses 4-7, wherein at least one column, preferably a plurality of columns, is at least partially cone shaped

[0115] 9. Anode according to any of clauses 4-8, wherein at least one column, preferably a plurality of columns, has a substantially hemispherical terminal end portion.

[0116] 10. Anode according to any of clauses 4-9, wherein the electrically conductive substrate comprises nodules for supporting said columns, wherein preferably each column is support by a single nodule.

[0117] 11 . Anode according to any of the previous clauses, wherein the silicon comprises amorphous silicon, optionally further comprises nano-crystalline silicon.

[0118] 12. Anode according to clause 11 , wherein the amount of nano-crystalline silicon is in the range of from 1 to 10 percent by weight of the total amount of silicon.

[0119] 13. Anode according to any of the previous clauses, wherein the layer comprising silicon has a porosity in the range of from 10% up to 50%.

[0120] 14. Anode according to any one of the previous clauses, wherein the layer comprising silicon has a mass loading of 0.8 mg cm-2to 4 mg cm-2, preferably of 1 mg cm-2to 3 mg cm-2.

[0121] 15. Anode according to any of the previous clauses, wherein the electrically conductive substrate is at least partially composed of at least one material chosen from the group consisting of: copper, aluminium, nickel, titanium, carbon, iron, chromium, stainless steel, and an alloy of two or more of these materials.

[0122] 16. Anode according to any of the previous clauses, wherein the electrically conductive substrate comprises a current collector, and an adhesion layer applied onto said current collector, wherein said adhesion layer is situated between the current collector and the layer comprising at least 90 percent by weight of silicon. 17. Anode according to clause 16, wherein the adhesion layer comprises at least one additive selected from the group consisting of: nickel, zinc, tin, chromium, silane, nickel oxide, zinc oxide, tin oxide, and chromium oxide.

[0123] 18. Anode according to any of the previous clauses, wherein the electrically conductive substrate has a surface roughness value selected from at least one of the following:

[0124] • an Sdr value of more than 40%; and / or

[0125] • an Sdq value of more than 1 .0, as determined by white light interferometry according to ISO 25178(2012).

[0126] 19. Process for preparing an anode, in particular an anode according to any of the previous clauses, comprises the steps of:

[0127] A) providing an electrically conductive substrate, optionally provided with nodules,

[0128] B) depositing onto the electrically conductive substrate at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon, such that an atomic structure of silicon is formed having a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°.

[0129] 20. Process according to clause 19, wherein during step B) at least one of the following deposition technologies is used: chemical vapour deposition (CVD), such as plasma-enhanced chemical vapour deposition (PECVD) and thermal CVD; physical vapour deposition (PVD), such as sputtering and / or evaporation; atomic layer deposition (ALD); and / or electrochemical deposition (ECD).

[0130] 21 . Process according to clause 19 or 20, wherein during step B) a silane comprising gas is used.

[0131] 22. Process according to clause 21 , wherein said gas comprises at least one inert gas fraction, such as a nitrogen or argon fraction. 23. Process according to clause 22, wherein during step B) a silane comprising gas flow over power ratio is applied which is in the range of from 0.65 down to 0.1 sccm / W.

[0132] 24. Process according to clause 23, wherein the silane comprising gas flow over power ratio is in the range of from 0.50 down to 0.20 sccm / W.

[0133] 25. Process according to any of clauses 20-24, wherein the silane of the silane comprising gas is at least one silane selected from the group consisting of: monosilane, disilane, trisilane and chlorosilanes.

[0134] 26. Process according to clause 25, wherein the silane of the silane comprising gas is monosilane, wherein the silane comprising gas furthermore comprises hydrogen.

[0135] 27. A battery comprising at least one lithium-ion cell, wherein said lithium-ion cell comprises:

[0136] • at least one anode according to any of clauses 1 -18,

[0137] • at least one cathode, and

[0138] • at least one electrolyte, optionally a solid-state electrolyte, situated in between said at least one anode and said at least one cathode.

[0139] 28. Battery according to clause 27, wherein the electrolyte comprises a nonaqueous solvent or diluent, wherein the non-aqueous solvent or diluent preferably, comprises a carbonate or a compound comprising an ether group, and wherein the electrolyte comprises at least one lithium salt, such as LiPF6, LiBF4, or l_iCIO4.

[0140] 29. Battery according to clauses 27 or 28, wherein the cathode comprises a lithium metal oxide, such as lithium cobalt oxide (LiCo02), lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), and / or lithium nickel manganese cobalt oxide (NMC).

[0141] 30. Use of the anode according to any one of clauses 1 to 18 in a battery according to any of clauses 27-29. 31 . Process for preparing a battery, in particular a battery according to any of clauses 27-29, comprising the steps of:

[0142] (i) providing an anode according to any of clauses 1-18, preferably produced by applying the method according to any of clauses 19-26,

[0143] (ii) providing a cathode and an electrolyte comprising lithium,

[0144] (iii) combining the anode, the cathode, and the electrolyte to form a lithium-ion cell;

[0145] (iv) lithiating the anode;

[0146] (v) delithiating the anode, and

[0147] (vi) optionally repeating the lithiating step (iv) and delithiating step (v) at least once.

[0148] 32. Process according to clause 31 , wherein during step iv) and / or step (v) and / or step (vi) the atomic structure of the silicon based anode changes such that the bond angle distortion (A0) as measured by Raman spectroscopy exceeds 9.75°.

[0149] 33 Battery according to any of the clauses 27-29, wherein the battery is subjected to the process as defined in any of the clauses 31-32.

[0150] 34. Battery according to clause 33, wherein the battery wherein the atomic structure of the silicon based anode is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 10.2° to 13.95°.

[0151] 35. An anode comprising:

[0152] (i) an electrically conductive substrate, and at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480.

[0153] 36. Anode according to clause 35, further comprising one or more features according to any of clauses 1 -19. of inventive

[0154] The invention according to some embodiments describes a method for manufacturing a high-performance silicon anode, which may involve: A) Providing an electrically conductive substrate, optionally featuring nodules to enhance surface characteristics; B) Depositing onto this substrate at least one layer consisting of >90%, preferably >95% by weight of silicon. The properties of the conductive substrate, such as surface roughness (including roughness introduced by nodules) and mechanical characteristics, play an important role in determining the meso- and macro-scale features of the deposited silicon layer - such as the formation of a columnar structure. This invention focuses on achieving an enhanced morphology or atomic structure of the active silicon material. Such improvements were found to be realized by tuning the deposition parameters during step B. For instance, using a PECVD process, the silicon layer's structure can be optimized by adjusting factors like process chamber design, gas flow rates, and plasma power. A key example is the reduction of the silane gas flow to plasma power ratio, which has been shown to improve the silicon morphology and atomic structure, leading to better performance characteristics of the anode.

[0155] Brief introduction of the figures

[0156] The following, non-limiting examples and figures are provided to illustrate non-limitative embodiments.

[0157] Figure 1 illustrates schematically a lithium-ion battery comprising an improved anode;

[0158] Figure 2 illustrates schematically two different embodiments of the anode, which can be used in the battery as shown in figure 1 ;

[0159] Figure 3 illustrates schematically an anode comprising a silicon layer, which can be used in the battery as shown in figure 1 ;

[0160] Figure 4 illustrates a Raman spectrum of amorphous hydrogenated silicon; Figure 5 illustrates a measured relation between the bond angle distortion (BAD) and the silane flow divided by applied power to produce said improved anode; Figure 6 illustrates a measured relation between the bond angle distortion (BAD) and the cycle life of a battery using the improved (pristine) anode; Figure 7 illustrates a Raman spectrum of a sample before and after cycling of said battery;

[0161] Figure 8 illustrates the measured relation between the microstructure parameter R* and the silane flow to produce said improved anode;

[0162] Figure 9 illustrates the measured relation between the microstructure parameter R* and the cycle life of the battery;

[0163] Figure 10 illustrates a picture of a particular pattern on the (pristine) anode; and Figure 11 illustrates a schematic overview of formation of the anode according to a non-limitative embodiment.

[0164] Detailed description of the figures

[0165] In order to describe the detailed aspects of the invention it is important to provide a simplified schematic of a battery, for simple understanding. Figure 1 therefore shows a simple schematic representation of a lithium-ion battery (100). Lithium-ion batteries (LIBs) are widely used as rechargeable energy storage systems for many devices. LIBs typically consist of an anode (101 ) and a cathode (102) which may together be referred to as the electrodes, optionally, a separator (103) and at least one, but in the depicted embodiment two layers of electrolyte (104). If the anode according to this embodiment is used in a solid state battery, the separator (103) may not be required. Moreover, in the solid state battery case, the electrolyte (104) may be a solid layer between the anode (101) and cathode (102). During charging, lithium ions are released from the cathode (102) and move towards the anode (101 ), whereby an interaction between the lithium ions and the active material of the cathode (102) takes place. This process is reversed during discharge and electrons are released from the lithium atoms in the anode (101 ), leading to an electrical current. It is noted that the representation of the battery (100) in this figure is merely schematical, particular details of the anode (101 ) and cathode (102) as described in the specification are not depicted. It is nevertheless conceivable that the particular details as described are present in the shown battery (100).

[0166] In figures 2a and 2b a schematic representation of two different and non-limitative embodiments of an anode (101) are shown. It is noted that the two embodiments shown in this figure are not exhaustive and different configurations may be conceivable. In figure 2a a single sided anode (101 ) is depicted, wherein one side of the anode (101) is covered with a layer (106) comprising silicon. Said silicon comprising layer (106) is provided onto an anode base layer (105), which may throughout this publication alternatively be referred to as an anode carrier layer or the electrically conductive substrate or current collector. In figure 2b a double sided anode (101) embodiment is depicted, wherein two sides of the anode (101) are covered with a layer (106) comprising silicon. In this embodiment said silicon comprising layers (106) are each provided on different sides of the anode base layer (105). The two-sided anode (105) as shown in figure 2b might have twice the capacity of the single sided anode (101 ) as shown in figure 2a when used with two cathodes. This provides for improved capacity which may in certain applications be required and beneficial. It is appreciated that all of the anode configurations can be utilized in any of the batteries disclosed. The batteries in accordance with various embodiments of the invention are not limited to any specific anode configuration. A more detailed representation of the structure of an anode can be seen in figure 3. In figure 3 a schematic representation is given of an anode (101 ) comprising a silicon layer (106), the silicon layer (106) has a specific appearance as is earlier disclosed in WO2016163878, comprising a plurality of pillars 107 which form a pillar structure, the disclosure of US2023275211 A1 associated to the pillars and pillar structure is herewith incorporated by reference in its entirety. In this application the silicon anode (101) is produced using PECVD techniques. A silicon anode is deposited on a current collector material (105) which forms the electrically conductive substrate. On the current collector (105), nodules (108) are added. An example of the electrically conductive substrate (105) is a copper foil with copper nodules, but many different substrates and combinations are possible. This figure depicts the plurality of columns forming the silicon layer (106) to be composed out of a base section (112), which base section (112) in this non-limitative embodiment has an outwardly diverging cross section in a direction away from the conductive substrate (105). The base section (112) has a cone shaped form. In this embodiment a middle section (113) is presented which has a substantially consistent cross-section. On top of the middle section (113) a top section (114) is provided which top section (114) in this embodiment is formed by a partially hemispherical convex shape (114). It is possible to provide the hemispherical top (114) directly onto the base section (112), and hence not using such a middle section (112). The base section (112), middle section (113) and top section (114) are integrally formed out of a single material. Figure 4 shows a non-limitative example of a Raman spectrum to visualize characteristics of the anode silicon material. This figure allows to indicate the meaning of the different aspects of the Raman spectrum that may be relevant to the understanding of the silicon material. A non-limitative Raman spectrum of amorphous hydrogenated silicon, as shown in figure 4, may comprise (or even consist of) four peaks: one peak with its centre between 425 cm-1and 435 cm-1, one peak with its centre between 480 cm-1and 521 cm-1, and a set of two peaks of which one has its centre somewhere around 2000 cm'1and the other around 2100 cm-1. The peak between 425 cm-1and 435 cm-1corresponds to the Si-Oxpeak due to oxidation of Si in air after deposition. The peak between 480 cm-1and 521 cm-1corresponds to the transverse optical mode of the silicon peak (coTO). A center at 521 cm-1indicates that the material is entirely crystalline, whereas a center at 480 cm’1indicates that the sample is purely amorphous. In this case, the center value of the transverse optical mode never exceeds 484 cm’1, indicating that the material is amorphous. It is to be understood that the values may deviate under circumstances and hence the values of the peaks as shown in this non-limitative embodiment are merely an example.

[0167] In line with the current disclosure it was found that the bond angle distortion (BAD) in silicon anodes can be varied by changing the silane inflow during the deposition process, preferably the PECVD process. Lowering the silane over power ratio leads to a decrease in the bond angle distortion (BAD). This appears to be a linear relationship, at least within the measured range, as is shown in figure 5. The process can be varied by steering the process parameters, such as process pressure and the flows of the reactive and supported gasses. Furthermore, the exact process conditions to yield the desired anode with the desired silicon structure depend on the layout and dimensions of the process chamber. Gas flows in PECVD are typically controlled by mass flow controllers (MFC’s) and flows are typically given in seem (standard cubic centimetre per minute) or SLM (standard litre per minute).

[0168] Lowering of the bond angle distortion (BAD) has a positive effect on the cycle life of the silicon anode when applied in a lithium-ion battery, as is demonstrated in figure 6. Samples with a higher bond angle distortion display a lower cycle life when used in a LIB, whereas samples with a low bond angle distortion have a higher cycle life. It is thought that the enhanced cycle life of the samples with a lower bond angle distortion is the result of the following: during lithiation, lithium ions penetrate the silicon network, thereby disrupting its structure. This may for example be caused through alloy formation and / or alloying reactions. With repeating cycles of lithiation and delithiation, more defects are incorporated into the silicon network, until at some point, the structure becomes instable and loses its integrity entirely. In batteries or cells comprising silicon-based anodes, the SEI, as explained before, plays an important role in the capacity degradation due to the large volumetric changes during cycling. Expansion and contraction of the anode material typically cracks the SEI layer that has formed on top of it, exposing more of the anode material to direct contact with the electrolyte, which results in further SEI production and further LLI. This decreases the commercially useful charge cycle life-span of lithium-ion cells with a silicon-comprising anode. In a structure with a higher bond angle distortion to begin with, the introduction of more defects will result in a loss of performance sooner than a structure that has less defects when lithium is introduced. This explains why a lower bond angle is beneficial for cycle life of the anode when applied in lithium ion batteries.

[0169] Importantly, cycled anodes display a larger bond angle distortion compared to their pristine counterparts, as is shown in figure 7. This indicates that more defects are present in the silicon structure after continuous lithiation and delithiation cycles. The inventors found that a low BAD is beneficial for higher cycle life in LIB applications. A silicon material with a BAD of less than 6.6° is generally considered not feasible to produce, as lowering the silane flow over plasma power ratio has its limits with respect to production times and production costs. Thus for production reasons a higher BAD might be beneficial. More importantly a BAD value of less than 6.6 may be considered crystalline material. Crystalline silicon anodes are more prone to cracking during cycling which is not preferred. Lowering the silane flow over plasma power ratio results in lower growth rate of the anode material. The ideal silane flow over plasma power ratio and the ideal BAD is a balance between production time and production cost (growth rate) and quality reasons (cycle life in LIB applications).

[0170] The other feature that can be derived from the Raman spectra is the microstructure parameter R*. In various embodiments, it was found that a silicon anode material with a high R* is also beneficial. A material with a higher R* can be produced by lowering the silane over power ratio during the preferred PECVD process, see the results in figure 8. In figure 9 the relation between the microstructure parameter R* and the cycle life shows that values of R* in the range from 0.220 up to 0.5 are beneficial. R* can be calculated from the Raman spectrum and correlates to the ratio of Si-H and Si-H2bonds, as is previously discussed above. Figure 10 shows an anode (101 ) according to an embodiment of the present invention. From the figure it is apparent that a pattern has emerged on the anode. The pattern on the anode (101) has the appearance of interwoven waves.

[0171] Lowering the silane flow over plasma power ratio results in lower growth rate of the anode material but surprisingly found to improve the cycle anode according to the invention. Figure 11 depicts a non-limitative embodiment of the process for forming of the anode, showing the intermediate results under the blocks representing the steps. In step 109 a conductive substrate 105 is provided. During the optional step 110 the conductive substrate 105 is provided with a plurality of nodules 108, which in the schematically depicted intermediate product are shown as dots on the conductive substrate 105. It is optionally possible to provide an adhesion layer onto the current collector, as described throughout this disclosure, which is applied after step 110. Step 111 represents depositing of the silicon comprising layer 106 onto the conductive substrate 105. Here, the nodules 108 form the starting points for the formation of the pillars 107. Said pillars 107 form the silicon comprising layer 016. Hence, the wording “silicon comprising layer” shall encompass the structure as depicted in this non-limitative figure, i.e. , a plurality of adjacent pillars 107 which do not necessarily contact one another. The silicon comprising layer 106, formed by the pillar structure 107, is preferably relaced and / or regular. The silicon material may be characterized by an atomic structure having a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°. It is appreciated that the skilled person may depart from the particular form of the pillars 107 as depicted in this embodiment. The pillars in accordance with various embodiments of the invention are not limited to any specific pillar construction. 1 : Raman measurements

[0172] For the Raman measurement discussed in this example three different types of samples were produced by PECVD on a copper current collector. The ED current collector comprises nodules to enhance the roughness, different silane over power ratios were used for all three samples. It is noted that sample 3 reflects a comparative example according to the prior art having a higher silane over power ratio compared to samples 1 and 2, which latter two samples are samples according to the present invention. The silane over power ratios used for production of the shown examples are presented in Table 1. After characterizing said pristine anodes using Raman spectroscopy to determine the bond angle distortion of the pristine anodes according to each sample type. Using all sample types batteries were produced comprising non-aqueous electrolyte and a cathode. The batteries acquired with the anodes according to the different sample types have been cycled with one or more formation cycles. After some the cycles a group of each of the sample types was removed from the test and the BAD values have been measured to determine the post use BAD values. The remaining sample types were kept cycling to determine the cycle life thereof.

[0173] The data of pristine samples were acquired using a Renishaw InVia Qontor Raman microscope or spectroscope, equipped with a 785 nm laser. To acquire the full spectral range from 100 cm-1to 3200 cm-1, a 1200 lines mnr1grating was used, which was rotated during the measurement, using Renishaw’s SynchroScan™ mode. The intensity of the laser was limited to 10 % of the total available laser power, to avoid crystallization of the sample. The exposure time was 10 seconds and three accumulations were acquired per spectrum to increase the signal to noise ratio. Data was recorded using a 50x Long Working Distance (LWD) objective.

[0174] Post-mortem anodes of the Raman measurements were measured inside a custom-made air-tight cell that has a transparent CaF window. The measurement settings were similar to those of the pristine samples, except that for the window cells, a 40x objective with a numerical aperture (NA) of 0.6 was used, and an integration time of 100 seconds. For each spectrum, 100 accumulations were acquired. Here, post-mortem anodes refer to the process of analyzing anodes used in batteries, particularly lithium-ion batteries, after they have completed their lifecycle or failed during use. This analysis helps in understanding the degradation mechanisms and performance issues that the anodes undergo during battery operation.

[0175] All data was curve fitted in Renishaw’s WiRE 5.5 software. No baseline subtraction was applied prior to the fitting. In case of cosmic rays overlapping with the relevant peaks, these were removed using the Cosmic Ray Detection wizard of the WiRE software, with the Width of Features algorithm, in which only peaks were removed with a width parameter between 3 and 5 and a height parameter between 10 and 15. In all cases where cosmic ray removal was applied, the suggested peaks for removal were always first judged by eye.

[0176] The silicon peak around -480 cm-1was fitted using a Gaussian peak, assuming a linear baseline, for which an offset was allowed. The peak center, width and height were all allowed to shift without any restrictions, whereas the fitted area was restricted to between 400 cm-1and 580 cm-1. A maximum of 200 iterations was allowed to obtain a good fit of this peak, with a tolerance of 0.01 .

[0177] For the two SiHx-peaks between 1900 cm’1and 2100 cm’1, two Gaussian peaks were fitted, again assuming a linear baseline for which an offset was allowed. For the first peak, which is centred around 2000 cm-1, the center was restricted to lay between 1980 cm'1and 2020 cm'1. The width and height were unrestricted. The second peak, usually centred around 2100 cm-1, the center was restricted to lay between 2080 cm'1and 2120 cm'1, while the width was constrained between 50 cm’1and 95 cm’1. The height of the peak was allowed to shift. The total fitted area was restricted between 1910 cm-1and 2180 cm-1, and a maximum of 500 iterations was allowed to obtain a good fit, with a tolerance of 0.01 .

[0178] Table 1. Raman parameters for different pristine samples, as well as preparation conditions

[0179] In Table 1 , Samples 1 and 2 are samples according to the present invention, which have a BAD value situated within the range of 6.6°-9.75°. Sample 3 is a sample according to the prior art, wherein the BAD value of the pristine anode is situated at 10.1. From these samples it is evident that the present invention provides a significantly increased cycle life at 80% capacity retention.

[0180] Table 2. Comparison of Raman parameters between pristine and cycled anode material.

[0181] Table 2 shows the results comparing the results of the pristine anode bond angle distortion of three samples according to the invention with the bond angle distortion of said same three samples after formation or one or more cycles. Here, sample Z relates to a different plasma source based example. For each of the samples according to the invention, it was observed that the bond angle distortion increased after formation. From Table 2 it is concluded that the BAD values increase with approximately 4.1 to 4.2 after formation. This indicates that, after formation, a battery comprising an anode according to sample types 1 or 2 may typically have a BAD value after formation or one or more cycles which is situated in the range of 10.2° to 13.95°, preferably in the range of 10.7° to 13.85°.

[0182] Example porosity measurement

[0183] The porosity may be determined by the Barrett-Joyner-Halenda method pursuant to ISO 15901-2:2006. Gas accessible porosity and (average) pore size of the material according to the disclosure may be preferably determined according to the method specified by the ISO (International Organization for Standardization) standard: ISO 15901-2:2006 “Pore size distribution and porosity of solid materials by mercury porosimetry and gas adsorption — Part 2: Analysis of mesopores and macropores by gas adsorption” using nitrogen gas. Briefly, a N2adsorption-isotherm is measured at about -196°C (liquid nitrogen temperature). According to the calculation method of Barrett-Joyner-Halenda (Barrett, E. P.; Joyner, L.G.; Halenda, P. P. (1951), “The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms”, Journal of the American Chemical Society, 73 (1): 373-380) the pore size and pore volume can be determined. The calculation method is well-known in the art. A brief experimental test method to determine the isotherm can be described as follows: a test sample is dried, preferably at a high temperature, preferably between 40 and 180 degrees Celsius, preferably between 60 and 120 degrees Celsius, most preferably between 60 degrees Celsius and 100 degrees Celsius, and under an inert atmosphere. The samples may be dried for up to approximately 48 hours. The sample is then placed in the measuring apparatus. Next, the sample is brought under vacuum and cooled using liquid nitrogen. The sample is held at liquid nitrogen temperature during recording of the isotherm.

[0184] Concluding remarks

[0185] The present disclosure aims to provide improved cycle life for batteries having a silicon-based anode. It was found that by providing a more relaxed structure of the silicon anode material, which may be characterised by the bond angle distortion or the R* parameter it is possible to achieve improved cycle life compared to the background art.

[0186] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0187] The term “Raman spectroscopy” as used herein, includes a non-destructive chemical analysis technique which may provide detailed information about chemical structure, phase and polymorphy, crystallinity and molecular interactions. It is based upon the interaction of light with the chemical bonds within a material. Raman is a spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-frequency modes of systems may also be observed. Raman spectroscopy relies upon inelastic scattering of photons, known as the Raman scattering. A source of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range is used, although X-rays can also be used. The laser light interacts with molecular vibrations, phonons or other excitations in the system, resulting in the energy of the laser photons being shifted up or down. The shift in energy gives information about the vibrational modes in the system. Raman is furthermore a well know technique to characterize (amorphous) silicon. It is common practice in the solar cell industry to characterize the silicon structure of the solar cells.

[0188] The inventive concepts are described by several embodiments. It is conceivable that individual inventive concepts, including inventive details, may be applied without, in so doing, also applying other details of the described embodiments. It is not necessary to elaborate on examples of all conceivable combinations of the above-described inventive concepts, as a person skilled in the art will understand numerous inventive concepts can be (re)combined in order to arrive at a specific application and / or alternative embodiment.

[0189] The ordinal numbers used In this document, like “first”, “second”, and “third” are used only for identification purposes. Hence, the use of expressions like a “second” component, does therefore not necessarily require the co-presence of a “first” component. By “complementary” components is meant that these components are configured to co-act with each other. However, to this end, these components do not necessarily have to have complementary forms. The verb “comprise” and conjugations thereof used in this patent publication are understood to mean not only “comprise”, but are also understood to mean the phrases “contain”, “substantially consist of”, “formed by” and conjugations thereof.

Claims

Claims1 . An anode comprising:(i) an electrically conductive substrate, and(ii) at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°.

2. Anode according to claim 1 , wherein the bond angle distortion (A0) as measured by Raman spectroscopy is in the range of from 7.50° up to 9.50°.

3. Anode according to claim 1 or 2, wherein the silicon comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480.

4. Anode according to any of the previous claims, wherein the layer comprising silicon comprises a plurality of adjacent columns extending perpendicularly with respect to a plane defined by the electrically conductive substrate, wherein said adjacent columns are preferably separated by column boundaries extending in the perpendicular direction.

5. Anode according to claim 4, wherein at least 95% of the layer is formed by said plurality of adjacent columns.

6. Anode according to claim 4 or 5, wherein said columns comprise at least 90 percent by weight of silicon, more preferably at least 95 percent by weight of silicon.

7. Anode according to any of claims 4-6, wherein the adjacent columns have a larger distance at the interface of the silicon and the electrically conductive substrate compared to the column distance at the top of the column.

8. Anode according to any of claims 4-7, wherein at least one column, preferably a plurality of columns, is at least partially cone shaped9. Anode according to any of claims 4-8, wherein at least one column, preferably a plurality of columns, has a substantially hemispherical terminal end portion.

10. Anode according to any of claims 4-9, wherein the electrically conductive substrate comprises nodules for supporting said columns, wherein preferably each column is support by a single nodule.11 . Anode according to any of the previous claims, wherein the layer comprising silicon has a porosity in the range of from 10% up to 50%.

12. Anode according to any one of the previous claims, wherein the layer comprising silicon has a mass loading of 0.8 mg cm-2to 4 mg cm-2, preferably of 1 mg cm'2to 3 mg cm'2.

13. Anode according to any of the previous claims, wherein the electrically conductive substrate is at least partially composed of at least one material chosen from the group consisting of: copper, aluminium, nickel, titanium, carbon, iron, chromium, stainless steel, and an alloy of two or more of these materials.

14. Anode according to any of the previous claims, wherein the electrically conductive substrate comprises a current collector, and an adhesion layer applied onto said current collector, wherein said adhesion layer is situated between the current collector and the layer comprising at least 90 percent by weight of silicon.

15. Anode according to claim 14, wherein the adhesion layer comprises at least one additive selected from the group consisting of: nickel, zinc, tin, chromium, silane, nickel oxide, zinc oxide, tin oxide, and chromium oxide.

16. Anode according to any of the previous claims, wherein the electrically conductive substrate has a surface roughness value selected from at least one of the following:• an Sdr value of more than 40%; and / or• an Sdq value of more than 1 .0, as determined by white light interferometry according to ISO 25178(2012).

17. Process for preparing an anode, in particular an anode according to any of the previous claims, comprises the steps of:A) providing an electrically conductive substrate, optionally provided with nodules,B) depositing onto the electrically conductive substrate at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon, such that an atomic structure of silicon is formed having a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 6.60° up to 9.75°.

18. Process according to claim 17, wherein during step B) at least one of the following deposition technologies is used: chemical vapour deposition (CVD), such as plasma-enhanced chemical vapour deposition (PECVD) and thermal CVD; physical vapour deposition (PVD), such as sputtering and / or evaporation; atomic layer deposition (ALD); and / or electrochemical deposition (ECD).

19. Process according to claim 17 or 18, wherein during step B) a silane comprising gas is used.

20. Process according to claim 19, wherein said gas comprises at least one inert gas fraction, such as a nitrogen or argon fraction.21 . Process according to claim 20, wherein during step B) a silane comprising gas flow over power ratio is applied which is in the range of from 0.65 down to 0.1 sccm / W.

22. Process according to claim 21 , wherein the silane comprising gas flow over power ratio is in the range of from 0.50 down to 0.20 sccm / W.

23. Process according to any of claims 18-22, wherein the silane of the silane comprising gas is at least one silane selected from the group consisting of: monosilane, disilane, trisilane and chlorosilanes.

24. Process according to any of claims 23, wherein the silane of the silane comprising gas is monosilane, wherein the silane comprising gas furthermore comprises hydrogen.

25. A battery comprising at least one lithium-ion cell, wherein said lithium-ion cell comprises:• at least one anode according to any of claims 1 -16,• at least one cathode, and• at least one electrolyte, optionally a solid-state electrolyte, situated in between said at least one anode and said at least one cathode.

26. Battery according to claim 25, wherein the electrolyte comprises a nonaqueous solvent or diluent, wherein the non-aqueous solvent or diluent preferably, comprises a carbonate or a compound comprising an ether group, and wherein the electrolyte comprises at least one lithium salt, such as LiPF6, LiBF4, LiFSI, or l_iCIO4.

27. Battery according to claim 25 or 26, wherein the cathode comprises a lithium metal oxide, such as lithium cobalt oxide (LiCo02), lithium iron phosphate (LiFePO4), lithium manganese oxide (LiMn2O4), and / or lithium nickel manganese cobalt oxide (NMC).

28. Use of the anode according to any one of claims 1 to 16 in a battery according to any of claims 25-27.

29. Process for preparing a battery, in particular a battery according to any of claims 25-27, comprising the steps of:(i) providing an anode according to any of claims 1 -16, preferably produced by applying the method according to any of claims 17-24,(ii) providing a cathode and an electrolyte comprising lithium,(iii) combining the anode, the cathode, and the electrolyte to form a lithium-ion cell;(iv) lithiating the anode;(v) delithiating the anode, and(vi) optionally repeating the lithiating step (iv) and delithiating step (v) at least once.

30. Process according to claim 29, wherein during step iv) and / or step (v) and / or step (vi) the atomic structure of the silicon based anode changes such that the bond angle distortion (A0) as measured by Raman spectroscopy exceeds 9.75°.31 Battery according to any of the claims 25-27, wherein the battery is subjected to the process as claimed in any of the claims 29-30.

32. Battery according to claim 31 , wherein the battery wherein the atomic structure of the silicon based anode is characterized by a bond angle distortion (A0) as measured by Raman spectroscopy in the range of from 10.2° to 13.95°.

33. An anode comprising:(i) an electrically conductive substrate, and at least one layer comprising at least 90 percent, preferably at least 95 percent, by weight of silicon and applied onto the electrically conductive substrate, wherein the silicon comprises an atomic structure which is characterized by a microstructure parameter R* in the range of from 0.220 up to 0.5, preferably in the range of 0.230 up to 0.480.

34. Anode according to claim 33, further comprising one or more features according to any of claims 1-17.

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