High cycle life lithium ion cell having a nanostructured silicon-containing anode

Abstract

This application relates to a lithium-ion cell, which includes a silicon anode, a current collector layer and a silicon layer, the silicon layer including a plurality of columnar structures on the current collector, a cathode, a separator, and an electrolyte. The electrolyte contains 9 to 29% by mass of a lithium salt, a non-aqueous solvent, and a diluent, and has a molar ratio of lithium salt-solvent-diluent of 1:x:y (1.0 ≦ x ≦ 3 and 2.0 ≦ y ≦ 4.0).

Description

Technical Field

[0001] The present invention relates to a lithium - ion cell comprising: (i) a silicon anode including a silicon layer, the silicon layer including a plurality of columnar structures on a current collector; and (ii) an electrolyte including a lithium salt, a non - aqueous solvent, and a diluent, and to a battery of such a cell.

Background Art

[0002] A battery is a device consisting of one or more electrochemical cells having an external connection for converting stored chemical energy into electrical energy. Each cell has a positive electrode and a negative electrode, also referred to as a cathode and an anode, respectively. When the battery is connected to an external circuit, electrons flow from the anode to the cathode through the external circuit, supplying electrical energy to the circuit and any device connected to the circuit.

[0003] Primary batteries, such as alkaline batteries, are single - use batteries because the electrode materials change permanently during discharge. Secondary batteries, such as lithium - ion batteries, can be charged and discharged multiple times because the original composition of the electrode materials can be restored by applying a reverse current.

[0004] A cell is made from two half - cells connected in series by a conductive electrolyte material.

[0005] One of the half - cells includes a cathode, the other half - cell includes an anode, and the electrolyte is present in both half - cells. A separator may be present between the two half - cells. The separator prevents a short - circuit between the cathode and the anode while allowing ions to move across the separator between the two half - cells.

[0006] A particularly advantageous type of electrochemical cell is the lithium-ion cell. In a lithium-ion cell, during discharge, lithium ions move from the negative electrode, i.e., the anode, through the electrolyte to the positive electrode, i.e., the cathode, and vice versa during charging. Historically, lithium-ion cells have used a lithium compound inserted into the positive electrode and graphite for the negative electrode. Lithium-ion cells generally have a higher energy density than conventional lead-acid batteries, and advantageously have no memory effect and typically exhibit low self-discharge. Examples of electrolytes useful for lithium-ion cells are disclosed, for example, in U.S. Patent Application Publication No. 2018 / 254524.

[0007] In recent developments in lithium-ion cells, there has been a demand to use silicon for the anode material instead of graphite, which has been historically used. This is because silicon enables the realization of a maximum capacity that is much higher than the maximum capacity of about 370 mAh / g that can be obtained with graphite. For example, pure silicon can achieve a specific capacity of about 3600 mAh / g. Obtaining a higher charge capacity without a significant increase in mass is an important issue for improving the battery life of mobile phones, drones, or electric vehicles.

[0008] The factor that has delayed the widespread commercialization of lithium-ion cells having an anode containing silicon is that silicon typically exhibits a large volume change during lithium insertion, and an increase of up to 300 - 400% in volume can occur. Such a change in volume typically causes large anisotropic stresses within the anode, which can lead to breakage, crumbling, or peeling of the silicon material from the anode. The breakage, crumbling, or peeling of the silicon material from the anode reduces the charge capacity of the anode and the charge cycle life of the cell comprising such an anode.

[0009] To overcome these swelling problems, a series of three-dimensional silicon surface morphologies for use in anodes have been developed. One approach is to develop so-called nanostructured architectures, examples of which include three-dimensional thin films, nanowires, and nanotubes. Three-dimensional thin film silicon anodes use the shape most similar to conventional thin film batteries, where a thin film of silicon is deposited on a metal foil, and the metal foil functions as a current collector. Thin film "two-dimensional" batteries are typically limited to a film depth of 2-5 micrometers to avoid crack formation, collapse, and / or delamination of the silicon layer, and the areal capacity is limited to be significantly less than the areal capacity achievable with three-dimensional thin films. Three-dimensional thin films use a third dimension corresponding to depth to increase the electrochemically active area. Examples of such cells are disclosed, for example, in U.S. Patent Application Publication No. 2007031744.

[0010] One option for doing this is to etch holes in the silicon film by inductively coupled plasma etching in silicon. Another option is to deposit silicon by plasma enhanced chemical vapor deposition such that a thin film of silicon is deposited on a metal current collector foil, in which case the thin film is mostly formed of silicon pillars extending perpendicular to the surface of the metal foil. Such pillars typically have a diameter of several hundred nanometers. There are voids, i.e., a network of cavities, not only between the pillars but also inside the pillars. These nanostructured surface morphologies allow for swelling of the pillars, i.e., an increase in volume, which thereby spreads into the voids. This means that little or no pressure is exerted by one pillar on adjacent pillars during swelling, and overall, the bulk silicon material exerts little or no pressure parallel to the surface of the metal foil. This advantageously enables these materials with nanostructured surface morphologies to avoid crack formation, collapse, or delamination.

[0011] Another strategy is to structure silicon in the form of nanostructures such as nanoparticles, nanowires, nanotubes, or more complex 3D structures. These nanostructures provide sufficient space for silicon to accommodate volume expansion, reduce internal stress and breakage, while maintaining a high surface area for lithium-ion transport from the electrolyte to silicon. For example, International Publication No. 2010 / 129910 2 discloses a conductive substrate and silicon-containing nanowires substrate-rooted in this conductive substrate. International Publication No. 15 / 175509 extends this concept by having two silicon material layers coating a nanowire template embedded in the substrate, with the second silicon layer having a higher density than the first layer. Here, International Publication No. 15 / 175509 states that the first silicon layer forms a space into which silicon can expand when absorbing lithium, while the second silicon layer reduces the formation of the SEI layer.

[0012] One such example would be silicon nanowires grown on a steel current collector substrate by the vapor-liquid-solid growth method. The wires are bonded to the current collector material at one end, and the irregular network of silicon wires is thought to be able to accommodate large strains during expansion due to lithium incorporation. This advantageously enables these materials with nanostructured surface morphologies to avoid crack formation, crumbling, or delamination.

[0013] Overall, these silicon-containing anodes with a three-dimensional form have a relatively large surface area of the anode in contact with the electrolyte. This is advantageous on the one hand as they reduce the local current density.

[0014] In the first charge-discharge cycle of the operation of a lithium-ion cell, the electrolyte decomposes to form a typically ill-defined series of lithium-containing compounds on the anode surface, generating a layer called the solid electrolyte interface (SEI). The solid electrolyte interface layer is a result of the reduction potential of the anode. During charging, the potential of the anode decreases, which causes electrochemical reduction of some of the components of the surface electrolyte. Since the SEI layer is formed partially from lithium-containing compounds, the formation of SEI growth reduces the total charge capacity of the cell by consuming some of the lithium that would normally be available for charge storage. This is a degradation mechanism known as lithium inventory loss (LLI). The properties and development of the solid electrolyte interface layer fundamentally affect the overall performance of the lithium-ion cell. This is because (i) the (in)permeability of the solid electrolyte interface layer to lithium ions can limit the rate and / or amount of lithium that the anode can store, and (ii) the electronic resistance of the solid electrolyte interface layer affects the rate at which the solid electrolyte interface layer grows. Typically, the higher the electronic conductivity of the formed SEI layer, the faster the further electrolyte decomposition, and as a result, the faster the SEI layer grows. The growth of the SEI layer increases the lithium inventory loss (LLI).

[0015] In a lithium-ion cell having a silicon-containing anode, the SEI plays a particularly important role in capacity degradation due to the large volume changes during cycling. Typically, the expansion and contraction of the anode material form cracks in the SEI layer formed thereon, exposing more of the anode material to direct contact with the electrolyte, resulting in further SEI formation and further LLI. This reduces the commercially useful charge cycle life of the lithium-ion cell having a silicon-containing anode. This problem regarding SEI crack formation can be particularly severe in the case of anodes containing silicon with a nanostructured surface morphology due to the surface area and shape of the silicon material at the anode-electrolyte interface.

Prior Art Documents

Patent Documents

[0016] [Patent Document 1] U.S. Patent Application Publication No. 2018 / 254524 [Patent Document 2] U.S. Patent Application Publication No. 2007 / 031744 [Patent Document 3] International Publication No. 2010 / 129910 [Patent Document 4] International Publication No. 15 / 175509 [Patent Document 5] International Publication No. 21 / 029769 [Patent Document 6] International Publication No. 15 / 188959 [Non-Patent Document]

[0017] [Non-Patent Document 1] 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" [Non-Patent Document 2] Barrett, E. P.; Joyner, L.G.; Halenda, P. P., "The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms", Journal of the American Chemical Society, 73 (1), 1951, p.373-380 [Non-Patent Document 3] Brunauer, S.; Emmett, P. H.; Teller, E., “Adsorption of Gases in Multimolecular Layers”, Journal of the American Chemical Society, 60 (2), 1938, p.309-319

Summary of the Invention

Problems to be Solved by the Invention

[0018] An object of the present disclosure is to provide a lithium-ion cell including an anode, wherein the anode contains silicon and has an increased specific capacity and charge cycle stability.

Means for Solving the Problems

[0019] In view of the foregoing discussion, a first aspect of the present disclosure is a lithium-ion cell comprising: - a silicon anode, i. a current collector layer, ii. a silicon layer positioned on the current collector layer, wherein the silicon layer contains a plurality of columnar structures on the current collector, and the silicon anode; - a cathode, - a separator, - an electrolyte, i. 9 to 29% by mass of a lithium salt with respect to the electrolyte, ii. a non-aqueous solvent, iii. a diluent, wherein the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y (x is in the range of 1.0 to 3.0 and y is in the range of 2.0 to 4.0), relates to a lithium-ion cell provided with the above.

[0020] A further aspect of the present disclosure is a lithium-ion cell, comprising the following steps: (i) providing a lithium-ion cell according to the present invention; (ii) charging the cell to a voltage of at least 4.0 V; (iii) discharging the voltage to 3.0 V; It relates to a lithium-ion cell manufactured by a method including:

[0021] Another aspect of the present disclosure is a lithium-ion cell, comprising the following steps: (i) providing a lithium-ion cell according to the present invention; (ii) charging the cell at 0.01 C for 10 hours; (iii) charging the cell at 0.1 C until (i) 9 hours or (ii) 4.2 V is reached; (iv) discharging the cell at 0.1 C until 2.5 V is reached; (v) charging the cell at 0.2 C until 4.2 V is reached; (vi) discharging the cell at 0.2 C until 2.5 V is reached; (vii) charging the cell at 0.2 C for 90 minutes; It is a lithium-ion cell manufactured by a method including:

[0022] Another aspect of the present disclosure is a lithium-ion cell, - a silicon anode, i. a current collector layer, ii. a silicon layer on the current collector layer, iii. a solid electrolyte interface layer, comprising, wherein the silicon layer i. a plurality of columnar structures on the current collector, ii. primary voids having a width of 1 to 10 μm, iii. optionally, secondary voids having a width of 10 to 150 nm, a silicon anode comprising; - a cathode, - a separator, - an electrolyte, i. a lithium salt, ii. a non-aqueous solvent, iii. a diluent, an electrolyte comprising; Relates to a lithium ion cell comprising

[0023] In another aspect, the present disclosure relates to a battery comprising a lithium ion cell according to any of the foregoing aspects. Another aspect of the present disclosure is the use of a lithium ion cell according to any of the foregoing aspects as an energy storage and / or release device.

[0024] A further aspect of the present disclosure is - 9 to 29% by mass of lithium bis(fluorosulfonyl)imide, and - 1,2-dimethoxyethane, and - 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, An electrolyte comprising, wherein the electrolyte has a molar ratio of (lithium bis(fluorosulfonyl)imide):(1,2-dimethoxyethane):(1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether) of 1:x:y (1.3 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4.0).

[0025] The cells and batteries according to the present disclosure provide unexpected and outstanding cycle life and capacity characteristics.

Brief Description of the Drawings

[0026]

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MODE FOR CARRYING OUT THE INVENTION

[0027] [Definitions and Abbreviations] Hereinafter, the subject matter disclosed herein will be described more fully. However, the subject matter disclosed herein can be embodied in different forms and should not be construed as limited to the embodiments described in the following and the accompanying examples of this specification. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the embodiments to those skilled in the art.

[0028] All references listed herein, including but not limited to all patents, patent applications and their publications, and articles in scientific journals, are incorporated herein by reference in their entirety to the extent that they supplement, explain, provide background for, or teach the methodologies, techniques and / or configurations used herein.

[0029] The following terms are considered to be well understood by those skilled in the art, but the following definitions are provided to facilitate the description of the subject matter disclosed herein.

[0030] 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 the subject matter disclosed herein belongs.

[0031] In accordance with long - standing patent law practice, the terms "a", "an", and "the" as used in this application, including in the claims, refer to "one or more".

[0032] The term "and / or", when used to describe two or more items or conditions, refers to situations where all of the listed items or conditions are present or applicable, or where only one (or fewer than all) of the items or conditions is present or applicable.

[0033] Although this disclosure supports definitions that refer only to alternatives and "and / or", the use of the term "or" in the claims is used to mean "and / or" unless explicitly indicated to refer only to alternatives or unless the alternatives are mutually exclusive.

[0034] As used herein, "another" can mean at least two or more.

[0035] The term "comprising", which is synonymous with "including", "containing", or "characterized by", is inclusive or open - ended and does not exclude additional, unrecited elements or method steps.

[0036] "Comprising" is a term of art used in claim language where the recited elements are not meant to be essential, and other elements can be added and still form a composition within the scope of the claim.

[0037] As used herein, the phrase "consisting of" excludes any element, step, or ingredient not specified in the claim. When the phrase "consisting of" appears in the body of the claim rather than immediately following the preamble, it limits only the elements recited in that phrase, and other elements are not excluded from the claim as a whole.

[0038] As used herein, the phrase "consisting essentially of" limits the scope of a claim to the specified materials or steps and those that do not materially affect the basic and novel characteristics of the claimed subject matter. Unless otherwise indicated, all numerical values expressing quantities such as sizes, volumes, percentages (%) etc. used in the present specification and claims are to be understood as being modified in all instances by the term "about".

[0039] Accordingly, unless indicated to the contrary, the numerical parameters set forth in the present specification and the appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the subject matter disclosed herein.

[0040] Additive: As used herein, the term "additive" refers to components of electrolytes present in an amount of 0.01 to 10% by mass.

[0041] Amorphous silicon: As used herein, the term "amorphous silicon" is understood to include proto-crystalline silicon, which is a definition for amorphous silicon including a proportion of nano-crystalline silicon. This proportion can be up to about 30% of the silicon layer. For ease of reference, in the present specification, the term amorphous silicon is used to indicate that the silicon layer contains amorphous silicon and the nano-crystalline region of the silicon layer can be present in a proportion of nano-crystalline silicon up to about 30%.

[0042] Anode: As used herein, the term "anode" is understood as the electrode through which charge flows when entering an electronic device. In the context of an electrochemical perspective, anions, i.e., negatively charged ions, move towards the anode and / or cations, i.e., positively charged ions, move away from the anode to balance the electrons exiting the electrode and moving towards the electronic device. In a lithium-ion battery or a galvanic cell during discharge, the anode is the negative terminal from which electrons flow out. In a lithium-ion battery during charging or recharging, the anode becomes the positive terminal into which electrons flow from the electronic device.

[0043] Capacity: In this specification, the term "capacity" of a battery or cell is understood as the amount of charge that such a device can supply. Capacity is expressed in units of mAh or Ah and indicates the maximum constant current that a battery or cell can generate over one hour. For example, a battery with a capacity of 1 Ah can supply 1 A for one hour or a current of 100 mA for ten hours.

[0044] Cathode: In this specification, the term "cathode" is understood as the electrode through which charge flows out of an electronic device. In the context of an electrochemical perspective, anions (negatively charged ions) leave the anode and / or cations (positively charged ions) move towards the anode to balance the electrons entering the electrode from the electronic device. In a lithium-ion battery or galvanic cell during discharge, the cathode is the positive terminal into which electrons flow. In a lithium-ion battery during charging or recharging, the cathode is the negative terminal from which electrons flow into the electronic device.

[0045] Cell: In this specification, the term "cell" is understood as an electrochemical device used to generate voltage or current from a chemical reaction, or conversely, an electrochemical device in which an applied current induces a chemical reaction.

[0046] Coulombic Efficiency (CE): In this specification, the term "Coulombic Efficiency" is understood as the efficiency of transferring charge within a cell or battery. Coulombic Efficiency is defined as the amount of charge that exits the cell or battery during a discharge cycle divided by the amount of charge that entered the cell or battery during the previous charging cycle.

[0047] In this specification, DME represents 1,2-dimethoxyethane.

[0048] In this specification, DEC represents diethyl carbonate.

[0049] Doping: In this specification, the term "doping" is understood to mean introducing a trace amount of an element into a material to change its original electrical properties or to improve the crystal structure of a silicon material.

[0050] In this specification, EC represents ethylene carbonate.

[0051] In this specification, electrolyte represents a substance containing free ions that act as an ion-conductive medium. In the context of the disclosure of this specification, the electrolyte contains ions in solution.

[0052] In this specification, FEC represents fluoroethylene carbonate.

[0053] In this specification, fluoroalkyl represents an alkyl group in which at least one C-H bond is replaced by a C-F bond.

[0054] Fluoroalkyl ether: In the context of the disclosure of this specification, this term refers to a fluorinated ether having the general formula R 1 -O-R 2 (wherein at least one of R 1 and R 2 is independently selected from fluoroalkyl). The fluoroalkyl chain can be linear, cyclic or branched. The fluoroalkyl ether may be partially or fully fluorinated. R 1 and R 2 may be the same as or different from each other.

[0055] In this specification, LiFSI represents lithium bis(fluorosulfonyl)imide.

[0056] In this specification, perfluoroalkyl group represents an alkyl group in which all C-H bonds are replaced by C-F bonds.

[0057] As used herein, a silicon anode refers to an anode in which the majority of the mass, preferably at least 60% by mass, more preferably at least 70% by mass, and most preferably at least 80% by mass is silicon.

[0058] Areal capacity: As used herein, it represents the capacity per unit area of an electrode or an active material. The unit of areal capacity is mAh / cm 2 Is.

[0059] As used herein, the specific capacity represents the capacity per unit mass. In this patent, the mass specifically refers to the mass of the silicon active material in the anode. The specific capacity can be expressed in units of mAh / g.

[0060] As used herein, the solid electrolyte interface (SEI) represents a passive layer containing decomposition products resulting from the electrochemical decomposition of the electrolyte at the electrode / electrolyte phase boundary of the anode. This is typically formed during the first few cycles of a lithium-ion battery or cell.

[0061] As used herein, TTE represents 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0062] [Lithium-ion cell] The present invention relates to a lithium-ion cell, - A silicon anode, i. A current collector layer, and ii. A silicon layer Including, the silicon layer includes a plurality of columnar structures on the current collector, a silicon anode, - A cathode, - A separator, - An electrolyte, i. 9 to 29% by mass of a lithium salt with respect to the electrolyte, ii. A non-aqueous solvent, and iii. A diluent Including, having a molar ratio of lithium salt - solvent - diluent of 1:x:y (1.0 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4.0), an electrolyte, It is directed to a lithium ion cell comprising

[0063] Surprisingly, the lithium ion cell according to this aspect of the present disclosure exhibited excellent cycle life and current density.

[0064] [Anode] The lithium ion cell according to the present disclosure comprises a silicon anode. The silicon anode includes a silicon layer and a current collector layer.

[0065] [Current collector] Preferably, the current collector material according to the present disclosure has a thickness of 1 to 100 μm, preferably 5 or 10 to 50 μm, more preferably 10 to 15 μm or about 10 or 12 μm, respectively.

[0066] Advantageously, the current collector material according to the present disclosure may include copper, tin, chromium, nickel, titanium, stainless steel or silver, or alloys thereof, more preferably copper or nickel, or alloys thereof, most preferably copper.

[0067] The current collector material includes a sheet-like material manufactured by cold rolling or electroplating, and may also include an alloy of copper or titanium having elements such as magnesium, zinc, tin, phosphorus, and / or silver. This may be smooth, rough, or textured, and the tensile strength is preferably in the range of 150 - 600 MPa, and may include a passive layer deposited on the copper foil to protect the copper foil from oxidation in air. The sheet-like material manufactured by cold rolling or electroplating may have certain defects such as a rolling line, potential strain, impurities, and natural oxides, which may affect the quality of the active material layer. Therefore, the current collector material may be subjected to surface treatment. For example, by electroplating or the like, nodules of the current collector material or other metals can be bonded to the surface of the current collector material to increase the roughness of the foil to various degrees. Other surface treatment techniques known in the art include annealing, knurling, etching, liquefaction, physical polishing, and electrolytic polishing, and are used to improve the morphology of the current collector material before the deposition of the active material.

[0068] Preferably, the current collector material according to the present disclosure includes a metal, a metal alloy, and / or a metal salt and / or an oxide. The metal, metal alloy, and / or metal salt and / or oxide according to the present disclosure are preferably selected from aluminum, copper, nickel, tin, indium, and zinc, preferably nickel, ZnO or SnO2, most preferably ZnO, and preferably, the current collector includes a copper or nickel core layer, more preferably a core layer doped with an oxide or fluoride of zinc, aluminum, tin, or indium. Preferably, the metal, metal alloy, and / or metal salt and / or oxide, or the core layer is a layer with a thickness of 0.1 - 5 nm, more preferably 1 - 2 nm. Preferably, the current collector according to the present disclosure containing copper or nickel includes nickel, ZnO or SnO2.

[0069] [Optional intermediate adhesive layer] In International Publication No. WO 2021 / 029769, which is an international patent application filed by the applicant, it is disclosed that an adhesive layer containing a metal, a metal alloy, and / or a metal salt and / or an oxide bonded to a current collector material can advantageously improve the adhesion of the silicon material to the current collector material of the composite electrode. Such an intermediate adhesive layer is not essential. According to the present disclosure, a current collector material containing a metal, a metal alloy, and / or a metal salt and / or an oxide adhesive layer preferably includes an adhesive layer. This adhesive layer improves the adhesion between the silicon material and the current collector material because different composites of silicon are formed on the interface between the current collector material and silicon. Such an adhesive layer preferably contains nickel, zinc or tin, for example, ZnO or SnO2. The adhesive layer can be formed by coating or depositing a metal, a metal alloy, and / or a metal salt and / or an oxide on the current collector material. Preferably, the adhesive layer is a layer having a thickness of 0.1 to 5 nm, more preferably 1 to 2 nm.

[0070] [Silicon layer] The silicon layer of the silicon anode includes a plurality of columnar structures on the current collector. The silicon layer is present on the current collector layer.

[0071] The silicon layer according to the present disclosure is bonded to the current collector layer as a layer containing a plurality of adjacent pillars having a diameter of 0.5 to 100 μm, either directly or by bonding to an intermediate adhesive layer.

[0072] Preferably, the pillars have a diameter of 1 to 75 μm, more preferably 2 to 50 μm, even more preferably 3 to 25 μm, still more preferably 4 to 20 μm, even more preferably 5 to 15 μm, still more preferably 6 to 12 μm, and most preferably 8 to 10 μm.

[0073] Preferably, the pillars have an average diameter of 1 to 75 μm, more preferably 2 to 50 μm, even more preferably 3 to 25 μm, still more preferably 4 to 20 μm, even more preferably 5 to 15 μm, still more preferably 6 to 12 μm, and most preferably 8 to 10 μm.

[0074] Preferably, the pillars extend mainly in a direction perpendicular to the surface of the current collector layer. In this specification, adjacent pillars may preferably be separated by pillar boundaries that extend essentially in the perpendicular direction. This can be determined by cross-sectional electron microscopy.

[0075] Preferably, according to the present disclosure, at least one silicon layer has a thickness of 0.1 to 1,000 μm, preferably 0.5 to 500 μm, more preferably 1 to 100 or 200 μm, even more preferably 1 to 30 or 50 μm, still more preferably 3 μm to 20 μm, still more preferably 5 to 15 μm, and most preferably 6 to 10 μm. Alternatively, according to the present disclosure, at least one silicon layer preferably has a mass loading of 0.1 to 4.0 mg / cm 2 , more preferably 0.5 or 0.8 to 2.0 or 2.5 mg / cm 2 , or 2.5 to 3.5 or 4.0 mg / cm 2 , most preferably 1.0 to 2.0 mg / cm 2 . The mass loading relates to the mass loading of one silicon layer present on one side of the current collector layer.

[0076] Advantageously, at least one silicon layer according to the present disclosure has a porosity of 0% to 50%, more preferably 1%, 2%, 5% or 10% to 50%.

[0077] Preferably, the silicon layer according to the present disclosure has a porosity of 0% to 80%, preferably 5 to 60%, and even more preferably 10 to 40% as determined by the BJH method of ISO 15901-2:2006.

[0078] Preferably, the average pore diameter of the silicon layer is in the range of 0.5 to 40 nm, preferably 1 to 20 nm.

[0079] The porosity and (average) pore diameter according to the present disclosure are preferably determined by the method defined by the ISO (International Organization for Standardization) standard using nitrogen gas: 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”. Briefly speaking, the N2 adsorption isotherm is measured at about -196 °C (liquid nitrogen temperature). The pore diameter and pore volume can be determined by the calculation method of Barrett-Joyner-Halenda (Barrett, E. P.; Joyner, L.G.; Halenda, P. P., “The Determination of Pore Volume and Area Distributions in Porous Substances. I. Computations from Nitrogen Isotherms”, Journal of the American Chemical Society, 73 (1), 1951, p.373-380). The specific surface area can be determined from the same isotherm by the calculation method of Brunauer-Emmett-Teller (Brunauer, S.; Emmett, P. H.; Teller, E., “Adsorption of Gases in Multimolecular Layers”, Journal of the American Chemical Society, 60 (2), 1938, p.309-319). Both calculation methods are well-known in the art. A simple experimental test method for determining the isotherm can be described as follows: The test sample is dried under high temperature and an inert atmosphere. Then, the sample is dried and placed in the measuring device. Next, the sample is placed under vacuum and cooled using liquid nitrogen. The sample is maintained at liquid nitrogen temperature during the recording of the isotherm.

[0080] The silicon layer according to the present disclosure preferably has an amorphous structure in which nanocrystalline regions are present. More preferably, the silicon layer or pillars contain up to 30% nanocrystalline silicon. According to one embodiment, the silicon layer advantageously contains an n-type or p-type dopant in order to obtain silicon layers of n-type conductivity or p-type conductivity, respectively.

[0081] Advantageously, the silicon pillars may further contain a silicon alloy, which is preferably selected from the group comprising Si-C and / or Si-N. Preferably, the composite material according to the present disclosure contains carbon or an alloy containing carbon or silicon. The silicon alloy can be either an additive or an alternative to amorphous silicon. Thus, according to one aspect of the present disclosure, the material of the pillars comprises at least one material selected from amorphous silicon and amorphous silicon alloys.

[0082] According to a further aspect, the material of the pillars comprises amorphous silicon and a nanocrystalline silicon alloy. In some embodiments, the silicon alloy may be present as a nanocrystalline phase within the electrode layer. Also, the anode layer may contain a mixture of an amorphous material and a nanocrystalline phase. For example, a mixture of amorphous silicon and nanocrystalline silicon, or a mixture of amorphous silicon and a nanocrystalline silicon alloy, or a mixture of silicon and a silicon-based alloy mainly in an amorphous state containing a proportion (up to about 30%) of a mixture in a nanocrystalline state. According to the present disclosure, the amorphous silicon pillars preferably extend perpendicularly from the anode surface, i.e., the interface between the anode layer and the electrolyte layer, and a plurality of silicon pillars are arranged adjacent to each other and are separated by an interface extending perpendicularly to the anode surface.

[0083] The silicon layer according to the present disclosure may advantageously contain silicon oxide. The silicon layer according to the present disclosure can be positioned on the current collector layer in various configurations. The silicon can be on a nanowire template bonded to a substrate such as a current collector layer or an adhesive layer. As used herein, the term "nanowire" is understood to mean a branched or unbranched wire-like structure having at least one dimension with a length up to about 1 μm. The nanowire is a conductive material containing, for example, carbon, metal, or a metal silicide such as nickel silicide, copper silicide, silver silicide, chromium silicide, cobalt silicide, aluminum silicide, zinc silicide, titanium silicide, or iron silicide, preferably containing at least one nickel silicide phase containing Ni2Si, NiSi, or NiSi2. The nanowire can be the same material as the current collector such as nickel, copper, or titanium. Alternatively, the nanowire may be a material and layer different from the current collector material such as a copper current collector coated with a nickel layer. One or more layers of active material such as silicon can be deposited on the nanowire via, for example, PVD, CVD, or PECVD. The silicon layer may contain carbon, copper, sulfide, metal oxide, fluorine-containing compound, polymer, or lithium phosphate nitride. The silicon layer may be a layer containing carbon, copper, sulfide, metal oxide, fluorine-containing compound, polymer, or lithium phosphate nitride, and preferably may be coated with a carbon layer having a thickness of 1 nm to 5 μm, preferably 10 nm to 1 μm.

[0084] [Optional electrode tab] In a preferred embodiment, the lithium ion cell according to the present disclosure further comprises an electrode tab. More preferably, the lithium ion cell according to the present disclosure further comprises an electrode tab containing nickel or copper, or an alloy containing nickel, copper, tin, silicon, an alloy containing copper and nickel, an alloy containing copper and tin, or an alloy containing copper and silicon. Most preferably, the tab material contains nickel.

[0085] The tab is preferably a sheet-like material containing a metal having a thickness of 1 μm to 1 mm, more preferably 10 to 500 μm, 20 to 200 μm, 50 to 150 μm, or about 100 μm.

[0086] [Cathode] The cell according to the present disclosure includes a cathode. Cathodes suitable for use in the present disclosure are known to those skilled in the art and are commercially available.

[0087] Preferably, the cathode, or the positive electrode, or the material essentially constituting these is selected from the following: Carbon / sulfur composite, or air electrode, in particular, a carbon-based electrode containing graphite carbon and, optionally, a metal catalyst such as Ir, Ru, Pt, Ag, or Ag / Pd; carbon monofluoride; CuO (copper(II) oxide); Cr2O5; Cr3O8; iron disulfide; Li2M 2 SiO4 (M 2 = Mn, Fe, or Co), Li2M 2 SO4 (M 2 = Mn, Fe, or Co), LiM2SO 4 m F (M2 = Fe, Mn, or Co), Li 2-x (Fe 1-y Mn y )P2O7 (0 ≦ x ≦ 1; 0 ≦ y ≦ 1), Li3V 2-x M1 x (PO4)3 (M1 = Cr, Co, Fe, Mg, Y, Ti, Nb, or Ce; 0 ≦ x ≦ 1); Li 4-x M x Ti5O 12 (M = Mg, Al, Ba, Sr, or Ta; 0 ≦ x ≦ 1); LiCoO2; LiFePO4 (LFP); LiMC1 x MC 2 1-x O2 (MC1 and MC2 are independently Fe, Mn, Ni, Co, Cr, Ti, Mg, or Al; 0 ≦ x ≦ 1); LiMC1 x MC2 1-x PO4 (MC1 or MC2 = Fe, Mn, Ni, Co, Cr, or Ti; 0 ≦ x ≦ 1); LiMC1 x MC2 y MC3 1-x-yO2 (MC1, MC2 and MC3 are independently Fe, Mn, Ni, Co, Cr, Ti, Mg or Al; 0≦x≦1; 0≦y≦1, 0≦x+y≦1); LiMn2O4 (LMO); LiMn 2-y X y O4 (X=Cr, Al or Fe, 0≦y≦1); LiNi 0.5 Mn 1.5 O4 Spinel; LiNi 0.5-y X y Mn 1.5 O4(X=Fe, Cr, Zn, Al, Mg, Ga, V or Cu;0≦y<0.5);LiNi 0.8 Co 0.15 Al 0.05 O2(NCA);LiNi x Mn y Co z O2 (NMC, x+y+z=1), Li rich Li 1+w Ni x Mn y Co z O2(x+y+z+w=1, 0≦w≦0.25);LiV3O8;LiVPO4F;MnO2;Thionyl chloride;V2O5;V6O1; x Li2MnO3(1-x)LiM 1 y M 2 M 3 1-y-z O2 (in the formula, M 1 , M 2 and M 3 are independently Mn, Ni, Co, Cr, Fe, or mixtures thereof, and x=0.3-0.5; y≦0.5; z≦0.5).

[0088] In a preferred embodiment, the cathode is a lithium conversion compound such as Li2O2, Li2O, Li2S, or LiF. More preferably, the cathode is LiNi x Mn y Co z O2 (in the formula, x≧0.6) (NMC) or LiNi x Mg y Ti 1-x-y O2 (wherein 0.9≦x<1) (NMT, e.g., LiNi 0.96 Mg 0.02 Ti 0.02 O2).

[0089] In a particularly preferred embodiment, the cathode is selected from one or more high-voltage cathodes, which means a cathode that can operate at 4.3 to 4.6 V.

[0090] [Separator] The cell according to the present disclosure comprises a separator. The separator is present to prevent a short circuit from occurring between the cathode and the anode while still allowing ions to flow between both electrodes.

[0091] The separator can be suitably selected from (i) glass fiber, (ii) a porous polymer film with or without a ceramic coating such as a polyethylene-based or polypropylene-based material, or (iii) a composite material (e.g., a porous film of inorganic particles and a binder). One exemplary polymer separator is Celgard (C) K1640, which is a polyethylene (PE) membrane. Another exemplary polymer separator is Celgard (C) 2500, which is a polypropylene membrane. Another exemplary polymer separator is Celgard (C) 3501, which is a polypropylene membrane coated with a surfactant.

[0092] Another set of exemplary porous polymer films with a ceramic coating are the PE and PP separators available from Gelon. An example of such a separator is the 16-μm-thick PE battery separator from Gelon, which includes a 12-μm-thick polyethylene polymer film coated on both sides with a 2-μm-thick ceramic alumina layer to provide a separator with a porosity of 38%.

[0093] The separator may optionally be infused with an electrolyte.

[0094] [Electrolyte] The cell according to the present disclosure includes an electrolyte. This electrolyte i. 9 to 29% by mass of a lithium salt with respect to the electrolyte, and ii. A non-aqueous solvent, iii. A diluent, and the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y (1.0 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4.0).

[0095] [Lithium salt] The electrolyte contains 9 to 29% by mass of lithium salt based on the electrolyte.

[0096] The lithium salt, or a combination of lithium salts, is involved in the charging and discharging processes of the cell.

[0097] Preferably, the lithium salt is LiAsF6, Li2SO4, LiBF4, LiBr, LiCF3SO3, LiCl, LiClO4, LiI, LiNO2, LiNO3, LiSCN, lithium 2-trifluoromethyl-4,5-dicyanoimidazole (CAS: 761441-54-7), lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide (LiFTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluoro(oxalato)borate (LiDFOB CAS: 409071-16-5), lithium trifluoromethanesulfonate (LiTf), LiPF6 or any combination thereof.

[0098] More preferably, the electrolyte contains 9 to 29% by mass of a lithium salt selected from LiAsF6, Li2SO4, LiBF4, LiBr, LiCF3SO3, LiCl, LiClO4, LiI, LiNO2, LiNO3, LiSCN, lithium 2-trifluoromethyl-4,5-dicyanoimidazole (CAS: 761441-54-7), lithium (fluorosulfonyl)(trifluoromethylsulfonyl)imide (LiFTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(oxalato)borate (LiBOB), lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium difluoro(oxalato)borate (LiDFOB CAS: 409071-16-5), lithium trifluoromethanesulfonate (LiTf), LiPF6 or any combination thereof.

[0099] Most preferably, the lithium salt consists essentially of lithium bis(fluorosulfonyl)imide.

[0100] [Non-aqueous solvent] The electrolyte contains a non-aqueous solvent. The non-aqueous solvent is preferably selected such that the lithium salt has a solubility of at least 3 M (mol / dm 3 3) at 25 °C and 1 atm in the selected solvent.

[0101] Preferably, the non-aqueous solvent is selected such that the lithium salt has a solubility of at least 4 M, more preferably at least 5 M at 25 °C and 1 atm in the selected solvent.

[0102] Without being bound by theory, it is considered that statistically, solvent molecules in the electrolyte according to the present disclosure are most likely to closely bind to lithium ion salts to form aggregates. Furthermore, these solvent-lithium salt aggregates are considered to be suspended in the continuous phase of the diluent.

[0103] Preferably, the non-aqueous solvent is selected from non-aqueous solvents containing at least one of the following components: (i) esters, (ii) sulfur-containing solvents, (iii) phosphorus-containing solvents, (iv) ethers, (v) nitriles, or (vi) any combination thereof.

[0104] [Ester solvent] Preferably, the ester is selected from diethyl carbonate (DEC), difluoroethylene carbonate (DFEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), methyl 2,2,2-trifluoroethyl carbonate (MFEC), propylene carbonate (PC), trifluoroethylene carbonate (TFEC), trifluoropropylene carbonate (TFPC), 2,2,2-trifluoroethyl trifluoroacetate, 2,2,2-trifluoroethyl acetate, alkyl carboxylic acid esters such as ethyl acetate, ethyl propionate, ethyl trifluoroacetate, methyl butyrate, or any combination thereof.

[0105] More preferably, the ester is selected from 2,2,2-trifluoroethyl trifluoroacetate, 2,2,2-trifluoroethyl acetate, ethyl acetate, ethyl propionate, ethyl trifluoroacetate, methyl butyrate, and / or any combination thereof.

[0106] [Sulfur-containing solvent] Preferably, the sulfur-containing solvent is selected from sulfone solvents, sulfoxide solvents, or any combination thereof. More preferably, the sulfur-containing solvent is selected from dimethyl sulfone, ethyl methyl sulfone (EMS), ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS, sulfolane), dimethyl sulfoxide, ethyl methyl sulfoxide, ethyl methyl sulfone (EMS), ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS, sulfolane), dimethyl sulfoxide, ethyl methyl sulfoxide, or any combination thereof.

[0107] [Phosphorus-containing solvent] Preferably, the phosphorus-containing solvent is selected from organic phosphorus compounds (organic phosphates, phosphites, phosphonates, phosphoramides, etc.), phosphazenes (organic or inorganic), or any combination thereof. These phosphorus-containing solvents are generally flame-retardant.

[0108] More preferably, the phosphorus-containing solvent is selected from bis(2,2,2-trifluoroethyl)methyl phosphate, tributyl phosphate, triethyl phosphate (TEPa), trimethyl phosphate (TMPa), triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite, dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phenyl phosphonate, bis(2,2,2-trifluoroethyl)methyl phosphonate, hexamethylphosphoramide, hexamethoxyphosphazene (CAS: 957-13-1), hexamethoxycyclotriphosphazene (CAS: 6607-30-3), hexafluorophosphazene (CAS: 15599-91-4), or any combination thereof.

[0109] [Ether solvent] Preferably, the ether solvent is selected from 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (diglyme, DEGDME), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), 1,3-dioxolane (DOL), allyl ether, or any combination thereof.

[0110] [Nitrile solvent] Preferably, the nitrile solvent is selected from acetonitrile, propionitrile, succinonitrile, adiponitrile (CAS: 111-69-3), or any combination thereof.

[0111] The electrolyte preferably contains a non-aqueous solvent selected from dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethylene carbonate (EC), propylene carbonate (PC), difluoroethylene carbonate (DFEC), trifluoroethylene carbonate (TFEC), trifluoropropylene carbonate (TFPC), methyl 2,2,2-trifluoroethyl carbonate (MFEC), ethyl acetate, ethyl propionate, methyl butyrate, ethyl trifluoroacetate, 2,2,2-trifluoroethyl acetate, 2,2,2-trifluoroethyl trifluoroacetate, dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS), dimethyl sulfoxide, ethyl methyl sulfoxide, trimethyl phosphate (TMPa), triethyl phosphate (TEPa), tributyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) methyl phosphate, trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite, dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phenyl phosphonate, bis(2,2,2-trifluoroethyl) methyl phosphonate, hexamethylphosphoramide, hexamethoxyphosphazene, hexamethoxycyclotriphosphazene, hexafluorophosphazene, 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (diglyme, DEGDME), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), 1,3-dioxolane (DOL), allyl ether, acetonitrile, propionitrile, succinonitrile, adiponitrile (CAS: 111-69-3) or any combination thereof.

[0112] More preferably, the non-aqueous solvent is selected from ethyl acetate, ethyl propionate, methyl butyrate, ethyl trifluoroacetate, 2,2,2-trifluoroethyl acetate, 2,2,2-trifluoroethyl trifluoroacetate, dimethyl sulfone (DMS), ethyl methyl sulfone (EMS), ethyl vinyl sulfone (EVS), tetramethylene sulfone (TMS), dimethyl sulfoxide, ethyl methyl sulfoxide, trimethyl phosphate (TMPa), triethyl phosphate (TEPa), tributyl phosphate, triphenyl phosphate, tris(2,2,2-trifluoroethyl) phosphate, bis(2,2,2-trifluoroethyl) methyl phosphate, trimethyl phosphite, triphenyl phosphite, tris(2,2,2-trifluoroethyl) phosphite, dimethyl methyl phosphonate, diethyl ethyl phosphonate, diethyl phenyl phosphonate, bis(2,2,2-trifluoroethyl) methyl phosphonate, hexamethylphosphoramide, hexamethoxyphosphazene (cyclotris(dimethoxyphosphonitrile), hexamethoxycyclotriphosphazene), hexafluorophosphazene (hexafluorocyclotriphosphazene), 1,2-dimethoxyethane (DME), diethylene glycol dimethyl ether (DEGDME, i.e., diglyme), triethylene glycol dimethyl ether (triglyme), tetraethylene glycol dimethyl ether (tetraglyme), 1,3-dioxolane (DOL), allyl ether, acetonitrile, propionitrile or any combination thereof.

[0113] Most preferably, the solvent is 1,2-dimethoxyethane (DME).

[0114] [Diluent] The electrolyte contains a diluent. The diluent is preferably selected such that the lithium salt has a solubility of less than 0.3 M (mol / dm 3 ) at 25 °C and 1 atm in the selected solvent.

[0115] Preferably, the diluent is selected such that the lithium salt has a solubility of less than 0.2 M, more preferably less than 0.1 M, even more preferably less than 0.05 M, and most preferably less than 0.01 M in the selected diluent at 25 °C and 1 atm.

[0116] Preferably, the diluent is selected from diluents containing one or more of fluoroalkyl ethers, fluorinated orthoformates, fluorinated carbonates, fluorinated borates, or combinations thereof.

[0117] More preferably, the diluent is selected from fluoroalkyl ethers, fluorinated orthoformates, fluorinated carbonates, fluorinated borates, or combinations thereof.

[0118] Even more preferably, the diluent is 1,1,2,2 - tetrafluoroethyl - 2,2,2,3 - tetrafluoropropyl ether (TTE), 1,1,2,2 - tetrafluoroethyl - 2,2,2 - trifluoroethyl ether (TFTFE), 1,2,2,2 - tetrafluoroethyl trifluoromethyl ether, 1H,1H,5H - octafluoropentyl 1,1,2,2 - tetrafluoroethyl ether (OTE), bis(2,2,2 - trifluoroethyl) carbonate, bis(2,2,2 - trifluoroethyl) ether (BTFE), bis(2,2,2 - trifluoroethyl) methyl orthoformate (BTFEMO), ethoxynonafluorobutane (EOFB), heptafluoroisopropyl methyl ether, methoxynonafluorobutane (MOFB), tris(2,2,2 - trifluoroethyl) borate, tris(2,2,2 - trifluoroethyl) orthoformate (TFEO), tris(2,2,3,3,3 - pentafluoropropyl) orthoformate (TPFPO), tris(2,2,3,3 - tetrafluoropropyl) orthoformate (TTPO), tris(2,2 - difluoroethyl) orthoformate (TDFEO), tris(hexafluoroisopropyl) orthoformate (THFiPO), or any combination thereof.

[0119] More preferably, the diluent is selected from 1,1,2,2-tetrafluoroethyl-2,2,2,3-tetrafluoropropyl ether (TTE), 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE), 1H,1H,5H-octafluoropentyl 1,1,2,2-tetrafluoroethyl ether (OTE), bis(2,2,2-trifluoroethyl) ether (BTFE), bis(2,2,2-trifluoroethyl) methyl orthoformate (BTFEMO), ethoxynonafluorobutane (EOFB), methoxynonafluorobutane (MOFB), tris(2,2,2-trifluoroethyl) orthoformate (TFEO), tris(2,2,3,3,3-pentafluoropropyl) orthoformate (TPFPO), tris(2,2,3,3-tetrafluoropropyl) orthoformate (TTPO), tris(2,2-difluoroethyl) orthoformate (TDFEO), tris(hexafluoroisopropyl) orthoformate (THFiPO) or any combination thereof.

[0120] Most preferably, the diluent is 1,1,2,2-tetrafluoroethyl-2,2,2,3-tetrafluoropropyl ether (TTE).

[0121] [Electrolyte composition ratio] The electrolyte according to the present disclosure has a molar ratio of lithium salt-solvent-diluent of 1:x:y (1.0 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4.0).

[0122] Preferably, the electrolyte has a molar ratio of lithium salt-solvent-diluent of 1:x:y, where 1.1 ≤ x ≤ 2.5 and 2.2 ≤ y ≤ 3.8, more preferably 1.2 ≤ x ≤ 2.0 and 2.4 ≤ y ≤ 3.6, even more preferably 1.2 ≤ x ≤ 1.8 and 2.6 ≤ y ≤ 3.4, and most preferably x = 1.2 and y = 3.0.

[0123] More preferably, the electrolyte is such that the lithium salt is lithium bis(fluorosulfonyl)imide, the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y, where 1.1 ≦ x ≦ 21.5 and 2.2 ≦ y ≦ 3.8, more preferably 1.2 ≦ x ≦ 2.01.4 and 2.4 ≦ y ≦ 3.6, even more preferably 1.2 ≦ x ≦ 1.84 and 2.6 ≦ y ≦ 3.4, and most preferably x = 1.2 and y = 3.0.

[0124] Even more preferably, the electrolyte is such that the lithium salt is lithium bis(fluorosulfonyl)imide, the non-aqueous solvent is 1,2-dimethoxyethane, the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y, where 1.1 ≦ x ≦ 21.5 and 2.2 ≦ y ≦ 3.8, more preferably 1.2 ≦ x ≦ 2.01.4 and 2.4 ≦ y ≦ 3.6, even more preferably 1.2 ≦ x ≦ 1.84 and 2.6 ≦ y ≦ 3.4, and most preferably x = 1.2 and y = 3.0.

[0125] Even still more preferably, the electrolyte is such that the diluent is 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y, where 1.1 ≦ x ≦ 21.5 and 2.2 ≦ y ≦ 3.8, more preferably 1.2 ≦ x ≦ 2.01.4 and 2.4 ≦ y ≦ 3.6, even more preferably 1.2 ≦ x ≦ 1.84 and 2.6 ≦ y ≦ 3.4, and most preferably x = 1.2 and y = 3.0.

[0126] Most preferably, the electrolyte is such that the lithium salt is lithium bis(fluorosulfonyl)imide, the non-aqueous solvent is 1,2-dimethoxyethane, the diluent is 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, the electrolyte has a molar ratio of lithium salt-solvent-diluent of 1:x:y, where 1.1 ≦ x ≦ 21.5 and 2.2 ≦ y ≦ 3.8, more preferably 1.2 ≦ x ≦ 2.01.4 and 2.4 ≦ y ≦ 3.6, even more preferably 1.2 ≦ x ≦ 1.84 and 2.6 ≦ y ≦ 3.4, and most preferably x = 1.2 and y = 3.0.

[0127] [Additive] Preferably, the electrolyte according to the present disclosure further comprises an additive. The additive has a composition different from (i) the lithium salt, (ii) the solvent and (iii) the diluent. Optionally, the additive is a flame retardant.

[0128] Preferably, the additive comprises 4-fluoro-1,3-dioxolan-2-one (FEC, CAS: 114435-02-8), 1,3-dioxol-2-one (VC, vinylene carbonate, CAS: 872-36-6), 1,4-dicyanobutane (adiponitrile, CAS: 111-69-3), lithium difluorophosphate (LiDFP), 4,5-dimethylene-1,3-dioxolan-2-one, 1,3,2-dioxathiolane-2-oxide (CAS: 3741-38-6), 1,3,2-dioxathiolane-2,2-dioxide (CAS: 1072-53-3), 1,3,2-dioxathiane-2,2-dioxide (DTD, CAS: 1072-53-3), 3-methyl-1,4,2-dioxazol-5-one (CAS: 854849-14-2), tris(2,2,2-trifluoroethyl) phosphite (TTFEPi, CAS: 370-69-4), 1,3,2-dioxathiane 2-oxide (CAS: 4176-55-0), 1-methylsulfonylethene (CAS: 3680-02-2), 1-ethenylsulfonylethene (CAS: 77-77-0) or a combination thereof.

[0129] [Method for producing an electrolyte] In another aspect, the present disclosure is a method for producing an electrolyte according to the previous aspect, the method comprising the steps of: dissolving 9 to 29% by mass of lithium bis(fluorosulfonyl)imide in a non-aqueous solvent, 1,2-dimethoxyethane, with respect to the electrolyte; adding a diluent of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether to the solution containing the lithium salt; and mixing the diluent / solution mixture until a homogeneous suspension is obtained.

[0130] Without being bound by theory, the resulting electrolyte is believed to have advantageous electrolyte properties.

[0131] [Fabrication of a lithium ion cell] Another aspect of the present disclosure is a method for fabricating a lithium ion cell according to any of the previous aspects or specific embodiments, the method comprising: - providing a silicon anode, the silicon anode comprising: (i) a silicon layer; and (ii) a current collector layer; wherein the silicon layer comprises a plurality of columnar structures on the current collector; - placing a separator on the silicon anode; - placing a cathode on the separator to form a stack; - connecting the cathode and the anode to electrode tabs; - inserting the stack of the anode, the separator, and the cathode into a cell housing; - adding an electrolyte, the electrolyte comprising: (i) 9 to 29% by mass of a lithium salt with respect to the electrolyte; (ii) a non-aqueous solvent; and (iii) a diluent; wherein the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y (1.0 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4); - sealing the cell housing to prevent the electrolyte from exiting the cell housing. Relates to a method, including

[0132] In the context of this aspect of the present disclosure, (i) the silicon anode, (ii) the separator, (iii) the cathode, and (iv) the electrolyte can be as described in any of the foregoing aspects or specific embodiments.

[0133] Preferably, the cell housing is a pouch. More preferably, the cell housing is a laminated aluminum pouch.

[0134] Preferably, the step of sealing the cell housing is performed in a dry atmosphere. More preferably, the step of sealing the cell housing is performed under an inert atmosphere. By way of non-limiting example, such an inert atmosphere can be nitrogen gas or argon gas.

[0135] Another aspect of the present disclosure is a method of manufacturing a lithium-ion cell according to any of the foregoing aspects or specific embodiments, - A step of providing a silicon anode, wherein the silicon anode (i) a first silicon layer, (ii) a second silicon layer, (iii) a current collector layer, and the silicon layer includes a plurality of columnar structures on the current collector, - A step of placing a first separator on the first silicon layer of the silicon anode, - A step of placing a second separator on the second silicon layer of the silicon anode, - A step of placing a first cathode on the first separator, - A step of placing a second cathode on the second separator to form a stack, - A step of connecting the cathode and the anode to the electrode tabs, - A step of inserting the stack of the anode, the separator, and the cathode into the cell housing, - A step of adding an electrolyte, wherein the electrolyte (i) 9 to 29% by mass of a lithium salt with respect to the electrolyte, (ii) A non-aqueous solvent, (iii) A diluent, comprising a lithium salt-solvent-diluent molar ratio of 1:x:y (1.0 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4), and a step, - A step of sealing the cell housing to prevent the electrolyte from leaking out of the cell housing, relates to a method.

[0136] In the context of this aspect of the present disclosure, (i) the silicon anode, (ii) the separator, (iii) the cathode, and (iv) the electrolyte can be as described in any of the previous aspects or specific embodiments.

[0137] Preferably, the cell housing is a pouch. More preferably, the cell housing is a laminated aluminum pouch.

[0138] Preferably, the step of sealing the cell housing is performed in a dry atmosphere. More preferably, the step of sealing the cell housing is performed under an inert atmosphere. As a non-limiting example, such an inert atmosphere can be nitrogen gas or argon gas.

[0139] The lithium-ion cell according to this aspect of the present disclosure surprisingly has excellent cycle life and capacity.

[0140] [Method for forming a solid electrolyte interface layer in a lithium-ion cell] Another aspect of the present disclosure is a method for forming a solid electrolyte interface layer in a lithium-ion cell according to any of the previous aspects or embodiments, the following steps in the following order: (i) A step of providing a lithium-ion cell according to any of the previous claims, (ii) A step of charging to at least 4.0 V, (iii) A step of discharging to 3.0 V, relates to a method.

[0141] Preferably, this method comprises the following steps in the following order: (i) Providing a lithium-ion cell according to any one of the preceding claims; (ii) Charging to at least 4.2 V; (iii) Discharging to 2.5 V; and including.

[0142] More preferably, this method comprises the following steps in the following order: (i) Providing a lithium-ion cell according to any one of the preceding aspects or embodiments; (ii) Charging to at least 4.2 V; (iii) Discharging to 2.5 V; (iv) Charging to at least 4.2 V; and including.

[0143] Even more preferably, this method comprises the following steps in the following order: (i) Providing a lithium-ion cell according to any one of the preceding aspects or embodiments; (ii) Charging to at least 4.2 V; (iii) Discharging to 2.5 V; (iv) Charging to at least 4.2 V; (v) Discharging to 2.5 V; and including.

[0144] Still more preferably, this method comprises the following steps in the following order: (i) Providing a lithium-ion cell according to any one of the preceding aspects or embodiments; (ii) Charging to at least 4.2 V; (iii) Discharging to 2.5 V; (iv) Charging to at least 4.2 V; (v) Discharging to 2.5 V; (vi) Charging to at least 4.2 V; and including.

[0145] Preferably, the first charging step to at least 4.0 V, more preferably 4.2 V, is - charging at a rate of 0.001 C to 0.1 C for 1 to 24 hours, and - optionally, increasing the charging rate to 0.1 C until 4.2 is reached, and includes.

[0146] More preferably, the first charging to at least 4.0 V, even more preferably 4.2 V, is - charging at a rate of 0.002 C to 0.05 C for 2 to 18 hours, and - optionally, increasing the charging rate to 0.1 C until 4.2 V is reached, and includes.

[0147] Even more preferably, the first charging to at least 4.0 V, still more preferably 4.2 V, is - charging at a rate of 0.005 C to 0.02 C for 4 to 12 hours, and - optionally, increasing the charging rate to 0.1 C until 4.2 V is reached, and includes.

[0148] Still more preferably, the first charging to at least 4.2 V is - charging at a rate of 0.01 C for 6 to 10 hours, and - increasing the charging rate to 0.1 C until 4.2 V is reached, and includes.

[0149] Preferably, the first discharge to 3.0 V, more preferably 2.5 V, is at 0.02 to 0.2 C, more preferably 0.05 to 0.15 C, still more preferably 0.08 to 0.12 C, and most preferably 0.1 C.

[0150] Preferably, the second charging to at least 4.0 V, more preferably 4.2 V, is at 0.05 C to 0.4 C, more preferably 0.1 to 0.3 C, still more preferably 0.15 to 0.25 C, and most preferably 0.2 C.

[0151] Preferably, the second discharge to 3.0 V, more preferably to 2.5 V, is 0.05 C to 0.4 C, more preferably 0.1 to 0.3 C, even more preferably 0.15 to 0.25 C, and most preferably 0.2 C.

[0152] Preferably, the third charge to at least 4.0 V, more preferably to 4.2 V, is 0.05 C to 0.4 C, more preferably 0.1 to 0.3 C, even more preferably 0.15 to 0.25 C, and most preferably 0.2 C.

[0153] A particularly preferred embodiment of this aspect of the present disclosure is a method of forming a solid electrolyte interface layer in a lithium-ion cell according to any of the foregoing aspects or embodiments, the following steps in the following order: (i) providing a lithium-ion cell according to any one of claims 1 to 7; (ii) charging at 0.01 C for 10 hours; (iii) charging at 0.1 C until (i) 9 hours or (ii) 4.2 V is reached; (iv) discharging at 0.1 C until 2.5 V is reached; (v) charging at 0.2 C until 4.2 V is reached; (vi) discharging at 0.2 C until 2.5 V is reached; (vii) charging at 0.2 C for 90 minutes; relating to a method comprising.

[0154] The lithium-ion cell according to this aspect of the present disclosure surprisingly has excellent cycle life and current density.

[0155] [Product-by-Process] Another aspect of the present disclosure relates to a lithium-ion cell obtainable by the method described hereinbefore. The lithium-ion cell according to this aspect of the present disclosure surprisingly had excellent cycle life and capacity.

[0156] [A lithium-ion cell comprising a silicon anode including a primary void and a solid electrolyte interface layer] Another aspect of the present disclosure is a lithium-ion cell, - a silicon anode, i. a current collector layer, ii. a silicon layer on the current collector layer, iii. a solid electrolyte interface layer, and the silicon layer includes, i. a plurality of columnar structures on the current collector, ii. primary voids having a width of 1 to 10 μm, iii. optionally, secondary voids having a width of 10 to 150 nm, and the silicon anode, - a cathode, - a separator, - an electrolyte, i. a lithium salt, ii. a non-aqueous solvent, iii. a diluent, and the electrolyte, and relates to a lithium-ion cell comprising the same.

[0157] The lithium-ion cell according to this aspect of the present disclosure surprisingly has excellent cycle life and current density.

[0158] The current collector and the plurality of columnar structures on the current collector are as described above for the first and further aspects of the present disclosure.

[0159] [Primary void] The term "primary void" or "primary void structure" in the context of the present disclosure means a region within the silicon layer that does not contain components of a composite electrode such as a silicon layer or an SEI layer. The primary voids are preferably filled with an electrolyte. Without being bound by theory, the primary voids are thought to provide a space that allows silicon to expand (parallel to the surface of the current collector layer) during use of the composite electrode material, reducing the amount of crack formation, ablation, or delamination of the silicon layer. Further, it is thought that the electrolyte is present within the primary voids during use of the lithium-ion cell and can increase the surface area available for lithium-ion transport. Typically, such primary voids are only seen after cycling and / or use of the lithium-ion cell.

[0160] Preferably, the primary voids have a width of 2 to 9 μm, more preferably 3 to 8 μm, even more preferably 4 to 6 μm, and most preferably 5 μm.

[0161] Preferably, the primary voids have an orientation that is substantially perpendicular to the surface plane of the current collector material. The orientation can be determined from a cross-sectional electron microscopy image perpendicular to the surface plane of the current collector material. The determination of the dimensions of the primary void or primary void structure can be carried out by analysis of a cross-sectional or top surface image of a layer of anode material having 0% SOC by electron microscopy, where the cross-section is perpendicular to the surface plane of the current collector layer. The width of the primary void or primary void structure is preferably determined over a continuous region of the void space or structure by analysis of a cross-sectional image of the layer or material.

[0162] The width in this context means being parallel to the surface of the current collector at half the height of the silicon layer.

[0163] The height of the silicon is the average height of the silicon columns measured perpendicular to the surface of the current collector layer.

[0164] [Secondary voids] In the context of this disclosure, the term "secondary void" or "secondary void structure" refers to a region within a silicon layer that does not contain components of a composite electrode such as a silicon layer or an SEI layer and has a width of less than 10 nm. Without being bound by theory, it is believed that the secondary voids provide a space that allows silicon to expand (parallel to the surface of the current collector layer) during the use of the composite electrode material, reducing the amount of crack formation, abrasion, or delamination of the silicon layer.

[0165] Preferably, the secondary voids have a width of 20 - 140 nm, more preferably 30 - 130 nm, even more preferably 40 - 120 nm, even more preferably 50 - 110 nm, still more preferably 60 - 100 nm, and most preferably 70 - 90 nm.

[0166] Preferably, the secondary voids have an orientation that is substantially perpendicular to the surface plane of the current collector material. The orientation can be determined from a cross-sectional electron microscopy image perpendicular to the surface plane of the current collector material. Preferably, the secondary void structure surrounds the outer curved surface of each of the plurality of columnar structures. Preferably, the secondary void structure extends from the bottom to the top of each silicon layer, surrounds the columnar structure, and preferably surrounds it continuously, thereby defining the individual columnar structures.

[0167] The determination of the dimensions of the secondary voids or primary void structure can be carried out by analyzing a cross-sectional image of a layer of the anode material having 0% SOC by electron microscopy, and the cross-section is perpendicular to the surface plane of the current collector layer. The width of the primary voids or primary void structure is preferably determined across a continuous region of the void space or structure by analyzing the cross-sectional image of the layer or material.

[0168] The width in this context means being parallel to the surface of the current collector at half the height of the silicon layer.

[0169] The height of the silicon is the average height of the silicon pillars measured perpendicular to the surface of the current collector layer.

[0170] [Solid Electrolyte Interface Layer] This can be any solid electrolyte interface layer formed by charging and discharging the anode in the presence of an electrolyte containing a lithium salt.

[0171] Preferably, the solid electrolyte interface layer is formed by charging and discharging the anode in the presence of an electrolyte according to any embodiment of the first aspect of the present disclosure.

[0172] [Battery] In another further aspect, the present disclosure relates to a battery comprising at least one lithium ion cell according to any embodiment of any of the foregoing aspects. An advantage of such a battery is that the mass of such a battery can be made smaller than the mass of the prior art, while still having the same nominal voltage and capacity. In the context of the present disclosure, a battery may comprise one or more lithium ion cells.

[0173] [Battery shape] Examples of such batteries are cylindrical, prismatic, pouch and coin cells. It is also possible to combine multiple configurations of lithium ion cells. For example, a coin cell can have an internal cylindrical configuration (as disclosed in International Publication No. WO 2015 / 188959, which is an international patent application), or a pouch cell can have an internal prismatic configuration.

[0174] Generally, a lithium ion secondary battery is manufactured as follows. First, a positive electrode and a negative electrode are provided. Then, a plurality of positive electrode plates and a plurality of negative electrode plates are stacked with a separator sandwiched between the positive electrode plate and the negative electrode plate respectively to manufacture a battery cell having a predetermined shape. Then, the battery cell is placed in a battery case and an electrolyte is supplied into the battery case. Next, the battery case is usually sealed, whereby a battery such as a battery pack is obtained.

[0175] The electrode leads are connected to a general electrode assembly. Each electrode lead has one end connected to the electrode assembly and the other end exposed outside the battery case. The battery case in which the electrode assembly is placed is sealed by an adhesive layer such as a sealant layer at the portion of the battery case where the electrode lead extends outside the battery case, and is configured to have such a structure.

[0176] Furthermore, the electrode assembly is provided with electrode tabs. Each current collector plate of the electrode assembly includes a coated portion coated with an electrode active material and a terminal portion (hereinafter referred to as "non-coated portion") that may not be coated with the electrode active material. Each electrode tab can be formed by connecting the non-coated portions, or preferably by connecting a separate conductive tab connected to the electrode, and more preferably by ultrasonic welding. These electrode tabs may protrude in one direction, so that the electrode tabs are formed to be arranged side by side in the electrode assembly. Alternatively, the electrode tabs may protrude in opposite directions. Then, each electrode tab conveniently functions as a path for electrons to move between the inside and outside of the battery. Also, each electrode lead is preferably connected to the corresponding electrode tab by spot welding.

[0177] The electrode leads may extend in the same direction or in opposite directions depending on the positions where the positive and negative tabs are formed. The positive and negative electrode leads can be made of different materials. Finally, the electrode leads are electrically connected to the external terminals via their terminal components.

[0178] The pouch-shaped covering member encloses the electrode assembly in a sealed state such that a part of each electrode lead, for example, the terminal component of each electrode lead, is exposed from the pouch-shaped covering member. As described above, an adhesive layer such as a sealant layer is sandwiched between each electrode lead and the pouch-shaped covering member. The pouch-shaped covering member is provided with a sealing region at its edge. The horizontal slit of each electrode lead is spaced apart from the sealing region toward the joint portion. That is, when each electrode lead is formed to have an inverted T shape, the leg portion of the T shape protrudes outside from the pouch-shaped covering member, and a part of the head portion of the T shape is located within the sealing region.

[0179] [Prismatic battery] In a preferred embodiment, the battery has a substantially rectangular shape with a height of 48.5 mm, a length of 26.5 mm, and a width of 17.5 mm. Preferably, the battery has a nominal voltage of 9 volts. Preferably, the battery is rechargeable.

[0180] In a further embodiment, the present disclosure relates to a rectangular battery comprising a cell according to any of the embodiments of any of the foregoing aspects. Preferably, the rectangular battery is selected from a 4.5-volt lantern battery, a 6-volt (spring or screw joint) lantern battery, a 7.5-volt lantern battery, a 12-volt lantern battery, or a 9-volt battery.

[0181] [Cylindrical battery] The cylindrical lithium-ion secondary battery typically includes a spirally wound electrode assembly including a cathode and an anode spirally wound with a separator therebetween, and a pair of insulating plates, within a substantially hollow cylindrical battery can. In a preferred embodiment, the battery is a cylindrical battery with a diameter of 17 mm and a height of 34.5 mm. Preferably, the battery has a nominal voltage of 3.6 volts. More preferably, the battery has a nominal voltage of 3.6 volts and a capacity of 700 mAh. Preferably, the battery is rechargeable.

[0182] In a preferred embodiment, the battery has a cylindrical shape with a diameter of 15.6 mm and a length of 27 mm. Preferably, the battery has a nominal voltage of 3.6 volts. More preferably, the battery has a nominal voltage of 3.6 volts and a capacity of 600 or 800 mAh. Preferably, the battery is rechargeable.

[0183] In a preferred embodiment, the battery is a cylindrical battery with a diameter of 17 mm and a height of 34.5 mm. Preferably, the battery has a nominal voltage of 3.6 volts. More preferably, the battery has a nominal voltage of 3.6 volts and a capacity of 700 mAh.

[0184] [Double cylindrical battery] In a preferred embodiment, the battery has a double cylindrical shape with a height of 52.20 mm, a length of 28.05 mm, and a width of 14.15 mm. More preferably, the battery has a nominal voltage of 3.6 volts and a capacity of 1,300 mAh.

[0185] [Button-type battery] Button-type cells, commonly also referred to as coin-type cells, are thin compared to their diameter. In a preferred embodiment, the battery is a button type with a diameter of 9.5 mm and a height of 2.7 mm. Preferably, the battery has a nominal voltage in the range of 2.8 to 4.0 volts, preferably 3.0 to 3.8 volts, preferably 3.2 to 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.3, 3.4, 3.5, or 3.6 volts, and a capacity of 30 mAh at a constant discharge up to 2.0 volts per cell.

[0186] In a preferred embodiment, the battery is a button type with a diameter of 10 mm and a height of 2.5 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 30 mAh at a constant discharge up to 2.0 volts per cell.

[0187] In a preferred embodiment, the battery is a button type with a diameter of 11.5 mm and a height of 3.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 70 mAh with a constant discharge up to 2.0 volts per cell.

[0188] In a preferred embodiment, the battery is a button type with a diameter of 11 mm and a height of 10.8 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 160 mAh with a constant discharge up to 2.0 volts per cell.

[0189] In a preferred embodiment, the battery is a button type with a diameter of 12.5 mm and a height of 1.6 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 25 mAh with a constant discharge up to 2.0 volts per cell.

[0190] In a preferred embodiment, the battery is a button type with a diameter of 12.5 mm and a height of 2.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 35 - 40 mAh with a constant discharge up to 2.0 volts per cell.

[0191] In a preferred embodiment, the battery is a button type with a diameter of 12.5 mm and a height of 2.5 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 50 mAh with a constant discharge up to 2.0 volts per cell.

[0192] In a preferred embodiment, the battery is a button type with a diameter of 16 mm and a height of 1.6 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 50 - 55 mAh with a constant discharge up to 2.0 volts per cell.

[0193] In a preferred embodiment, the battery is a button type with a diameter of 16 mm and a height of 2.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 75 to 78 mAh at a constant discharge up to 2.0 volts per cell.

[0194] In a preferred embodiment, the battery is a button type with a diameter of 16 mm and a height of 3.2 mm.

[0195] Preferably, the battery has a nominal voltage of 3.0 or 3.2, 3.4 or 3.6 volts.

[0196] More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 140 mAh at a constant discharge up to 2.0 volts per cell.

[0197] In a preferred embodiment, the battery is a button type with a diameter of 20 mm and a height of 1.2 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 55 mAh at a constant discharge up to 2.0 volts per cell.

[0198] In a preferred embodiment, the battery is a button type with a diameter of 20 mm and a height of 1.6 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts and a capacity of 90 mAh at a constant discharge up to 2.0 volts per cell. In a preferred embodiment, the battery is a button type with a diameter of 20 mm and a height of 2.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 115 to 125 mAh at a constant discharge up to 2.0 volts per cell.

[0199] In a preferred embodiment, the battery is a button type with a diameter of 20 mm and a height of 2.5 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 160 - 165 mAh with a constant discharge up to 2.0 volts per cell.

[0200] In a preferred embodiment, the battery is a button type with a diameter of 20 mm and a height of 3.2 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 225 mAh with a constant discharge up to 2.0 volts per cell. Preferably, the battery has a maximum discharge current of 3 mA. Preferably, the battery has a maximum pulse discharge current of 15 mA. Preferably, the battery has a mass of less than 3.0 g, more preferably less than 2.9 g, and even more preferably less than 2.8 g.

[0201] In a preferred embodiment, the battery is a button type with a diameter of 20 mm and a height of 4.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 280 mAh with a constant discharge up to 2.0 volts per cell.

[0202] In a preferred embodiment, the battery is a button type with a diameter of 23 mm and a height of 2.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 350 mAh with a constant discharge up to 2.0 volts per cell.

[0203] In a preferred embodiment, the battery is a button type with a diameter of 23 mm and a height of 2.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts and a capacity of 110 - 175 mAh with a constant discharge up to 2.0 volts per cell.

[0204] In a preferred embodiment, the battery is a button type with a diameter of 23 mm and a height of 2.5 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts and a capacity of 165 - 210 mAh with a constant discharge up to 2.0 volts per cell. In a preferred embodiment, the battery is a button type with a diameter of 23 mm and a height of 3.0 mm.

[0205] Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts and a capacity of 265 mAh with a constant discharge up to 2.0 volts per cell.

[0206] In a preferred embodiment, the battery is a button type with a diameter of 23 mm and a height of 3.5 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts and a capacity of 165 mAh with a constant discharge up to 2.0 volts per cell.

[0207] In a preferred embodiment, the battery is a button type with a diameter of 23 mm and a height of 5.4 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 560 mAh at a constant discharge up to 2.0 volts per cell. In a preferred embodiment, the battery is a button type with a diameter of 24 mm and a height of 1.2 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 100 mAh at a constant discharge up to 2.0 volts per cell. In a preferred embodiment, the battery is a button type with a diameter of 24 mm and a height of 3.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 270 - 290 mAh at a constant discharge up to 2.0 volts per cell.

[0208] In a preferred embodiment, the battery is a button type with a diameter of 24 mm and a height of 5.0 mm. Preferably, the battery has a nominal voltage of 3.0 volts to 3.8 volts, for example, 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 or 3.2 volts and a capacity of 610 - 620 mAh at a constant discharge up to 2.0 volts per cell.

[0209] In a preferred embodiment, the battery is a button type with a diameter of 24 mm and a height of 7.7 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4 or 3.6 volts and a capacity of 1000 mAh at a constant discharge up to 2.0 volts per cell. In a preferred embodiment, the battery is a button type with a diameter of 26.2 mm and a height of 1.67 mm.

[0210] In a preferred embodiment, the battery is button-shaped with a diameter of 30 mm and a height of 3.2 mm.

[0211] Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 or 3.2, 3.4, or 3.6 volts and a capacity of 500 - 560 mAh at a constant discharge up to 2.0 volts per cell.

[0212] In a preferred embodiment, the battery is button-shaped with a diameter of 30 mm and a height of 3.2 mm. Preferably, the battery has a nominal voltage of 3.0 volts or 3.2, 3.4, or 3.6 volts. More preferably, the battery has a nominal voltage of 3.0 or 3.2, 3.4, or 3.6 volts and a capacity of 500 - 560 mAh at a constant discharge up to 2.0 volts per cell.

[0213] [Flat or pouch shape] The design of individual batteries around the high-energy cathode active material can provide high-capacity batteries within practical formats. Pouch batteries are generally substantially rectangular parallelepipeds, excluding connection tabs and other potential features around the edges, and are characterized by a thickness (t) and a planar area having a width (w) and a height (h), where the thickness is generally significantly smaller than the linear dimensions (width and height) defining the planar area (w h), as schematically shown in FIG. 2. In particular, the battery can have a thickness in the range of about 7 mm to about 18 mm. The area of the pouch battery can be in the range of about 25,000 mm 2 ~ about 50,000 mm 2 and the linear dimensions of the width and height defining the area are generally in the range of about 50 mm to about 750 mm.

[0214] The individual batteries obtained can generally have a discharge energy density of at least about 160 Wh / kg when discharged from 4.5 V to 2.0 V. In some advantageous embodiments, the batteries obtained can have a discharge energy density of at least about 200 Wh / kg when discharged from 4.5 V to 2.0 V, and in other embodiments from about 250 Wh / kg to about 400 Wh / kg. In further embodiments, the batteries can have a volumetric discharge energy density of at least about 300 Wh / l. In other advantageous embodiments, the batteries obtained can have a volumetric discharge energy density of at least about 500 Wh / l to 1150 Wh / l when discharged from 4.5 V to 2.0 V.

[0215] In the above embodiments, prismatic type, cylindrical type, laminated film type, coin type or button type or batteries having a wound spiral configuration have been described. However, the batteries according to the present invention can be applicable to other shapes in which the battery elements have other configurations such as a laminated structure.

[0216] [Use of a cell or battery according to any of the foregoing aspects] A further aspect of the present disclosure is the use of a cell or battery according to any of the foregoing aspects or embodiments of the previous disclosure as an energy storage and / or release device.

[0217] As used herein, the term "energy storage and / or release device" is understood to mean a secondary battery including an electrode assembly of a cathode / separator / anode structure mounted within a suitable battery case. Such batteries are excellent in terms of providing high energy density and high capacity, and in terms of their use in a secondary battery module including a plurality of secondary batteries typically connected in series with each other to form a battery pack that can be incorporated into a casing to form a module, including lithium ion secondary batteries.

[0218] [Specific electrolyte] In another aspect, the present disclosure is - 9 to 29% by mass of lithium bis(fluorosulfonyl)imide, and - 1,2-dimethoxyethane and, - 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether, and An electrolyte comprising, wherein the electrolyte has a molar ratio of 1:x:y of (lithium bis(fluorosulfonyl)imide):(1,2-dimethoxyethane):(1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether), 1.2 ≦ x ≦ 3.0 and 2.0 ≦ y ≦ 4.0, preferably 1.2 ≦ x ≦ 2.5 and 2.2 ≦ y ≦ 3.8, more preferably 1.2 ≦ x ≦ 2.0 and 2.4 ≦ y ≦ 3.6, even more preferably 1.2 ≦ x ≦ 1.8 and 2.8 ≦ y ≦ 3.2, most preferably x = 1.2 and y = 3.0, Relating to an electrolyte.

[0219] Without being bound by theory, the electrolyte according to this aspect has advantageous electrolyte properties and it is considered possible to obtain a longer cycle life for a lithium ion cell containing such an electrolyte.

[0220] [Detailed Description of the Drawings] Hereinafter, the present disclosure will be discussed with reference to the drawings showing preferred exemplary embodiments of the disclosure of the subject matter.

[0221] FIG. 1 schematically illustrates a conventional silicon anode material in an initially non-lithiated state (top), a fully lithiated state (center), and a fully delithiated state (bottom).

[0222] FIG. 2 schematically illustrates a conventional silicon anode material during SEI formation of a silicon anode material in an initially non-lithiated state (top), a fully lithiated state (center), and a fully delithiated state (bottom).

[0223] Figure 3 schematically illustrates a silicon anode material in which a silicon layer includes a plurality of columnar structures on a current collector. This schematically illustrates the silicon anode material in a first non-lithiated state (top), a fully lithiated state (center), and a fully delithiated state (bottom).

[0224] Figure 4 schematically illustrates a silicon anode material in which a silicon layer includes (i) a plurality of columnar structures on a current collector and (ii) an SEI. This schematically illustrates the silicon anode material in a first non-lithiated state (top), a fully lithiated state (center), and a fully delithiated state (bottom).

[0225] Figure 5 schematically illustrates a silicon anode material within a lithium cell according to the present invention. This schematically illustrates the silicon anode in a first non-lithiated state (top), a fully lithiated state (center), and a fully delithiated state (bottom).

[0226] Figure 6A is a resulting top surface scanning electron microscopy image of an anode including a silicon layer, the silicon layer including a plurality of columnar structures.

[0227] Figure 6B is a resulting cross-sectional scanning electron microscopy image of an anode including a silicon layer, the silicon layer including a plurality of columnar structures.

[0228] Figure 7A is a graph of areal capacity (mAh / cm 2 ) versus cycle number experimentally obtained for a material according to the present disclosure (Example 3) and a comparative example (Example 3A).

[0229] Figure 7B is a graph of capacity retention rate (%) versus cycle number experimentally obtained for a material according to the present disclosure (Example 3) and a comparative example (Example 3A).

[0230] Figure 7C is a graph of cumulative specific capacity (Ah / g) versus cycle number experimentally obtained for a material according to the present disclosure (Example 3, straight line, solid line) and a comparative example (Example 3A, curve, solid line).

[0231] Figure 8A is a graph of the capacity retention rate (%) versus the number of cycles experimentally obtained for the material according to the present disclosure (Example 6, upper line) and the comparative example (Example 6A, curve, solid line).

[0232] Figure 8B is a graph of the Coulomb efficiency (%) versus the number of cycles experimentally obtained for the material according to the present disclosure (Example 6, upper line) and the comparative example (Example 6A, lower line).

[0233] Figure 9A is an SEM image of the anode surface of Example 3 (left) and Comparative Example 3A (right) after performing Method 6 at a 0% state of charge. As can be seen, the surface morphology of the anode of the lithium-ion cell according to the present disclosure is significantly different from the surface morphology of the anode of a lithium-ion cell fabricated using a conventional carbonate-based electrolyte. The surface morphologies of both the lithium-ion cell according to the present disclosure and the lithium-ion cell fabricated using a conventional carbonate-based electrolyte after performing the methods of Example 6 and Example 6A are characterized by islands of columnar silicon separated by cracks. Visually, these resemble mad cracks.

[0234] Figure 9B is an SEM image of the anode surface of Example 3 (left) and Comparative Example 3A (right) after performing Method 6 at a 50% state of charge. As can be seen, the surface morphology of the anode of the lithium-ion cell according to the present disclosure is significantly different from the surface morphology of the anode of a lithium-ion cell fabricated using a conventional carbonate-based electrolyte. The surface morphologies of both the lithium-ion cell according to the present disclosure and the lithium-ion cell fabricated using a conventional carbonate-based electrolyte after performing the methods of Example 6 and Example 6A are characterized by islands of columnar silicon separated by cracks. Visually, these resemble mad cracks.

Examples

[0235] The following non-limiting examples illustrate the products and processes according to the present disclosure.

[0236] (Example 1) [Preparation of Electrolyte Solution According to the Present Disclosure] Lithium bis(fluorosulfonyl)imide (187 g, 1.0 mol), which is a lithium salt, was added to 1,2-dimethoxyethane (108 g, 1.2 mol), which is a non-aqueous solvent, while continuously stirring at 22°C. After all the lithium salt was completely dissolved, 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (696 g, 3.0 mol), which is a diluent, was added while further stirring at 22°C. The obtained electrolyte was evaluated and exhibited advantageous electrolyte characteristics.

[0237] (Example 2) [Preparation of Anode Material [Silicon Having a Nanoscale Columnar Morphology]] A roll of roughened copper foil current collector material (determined by the standard method ISO25178, Sa 0.51 μm, Sq 0.65 μm, Sz 5.9 μm, Sds 0.77 μm -2 , Ssc 16.2 μm -2 , Sdq 2.1 μm, Sdr 157%) was sent to a plasma enhanced chemical vapor deposition (PECVD) device equipped with an unwind chamber, two deposition chambers, and a rewind chamber. These chambers are all connected and are usually operated under vacuum (0.05 - 0.2 mbar). The foil was transported by a system of a tension roll and two heating drums that control the temperature of the foil. The first silicon layer was deposited on the same side of the copper substrate by PECVD at a substrate temperature of 100 - 300°C. In this method, a gas mixture containing a silicon precursor gas and a carrier gas was excited using magnetron radiation having a frequency of 2.45 GHz. Silane (SiH4) was the source of silicon, but argon (Ar) and hydrogen (H2) were added to stabilize the plasma, affect the material structure, and improve the deposition rate. The gas was injected through a "gas shower" that evenly distributes the gas.

[0238] Magnetron (microwave) radiation was introduced into the vacuum chamber by an antenna. To ensure homogeneous plasma, both sides of the antenna are connected to the magnetron radiation source. Thus, the magnetron heads are located on each side of the antenna. These magnetron heads are connected to the antenna. Gas is injected through a gas shower near the magnetron heads. The antenna is protected from the reaction environment by a quartz tube. The plasma is confined by a magnetic field generated by an array of permanent magnets.

[0239] The production rate of silicon was determined by the process conditions, the power input per source, and the number of microwave sources in operation. The gas flow was adjusted with an MW power input of 800 - 6000 W / m. Ten antennas or sources of power input were used.

[0240] Figure 6A is a top - surface scanning electron microscopy (SEM) image of the obtained material. Figure 6B is a cross - sectional scanning electron microscopy (SEM) image of the obtained material. The bar represents 10 μm, and each scale division corresponds to 1 μm.

[0241] By cross - sectional SEM (Figure 6B), it was confirmed that the deposited silicon layer had a thickness of 8 - 9 μm. By BET analysis, it was determined that this material had a surface area of 79.9 m 2 / g, a porosity of 15.73%, and an average pore diameter of 4.01 nm. By XRF analysis, a mass loading of 1.27 - 1.29 mg / cm 2 was revealed. The deposited material had a CIELAB lightness value L of 42.07 - 42.98 * .

[0242] (Example 3) [Preparation of Pouch Lithium - Ion Cells According to the Present Disclosure] The pouch cell was constructed by stacking (i) the anode material prepared in the previous [Example 2], (ii) a ceramic-coated separator (a 12-μm polymeric polypropylene coated on both sides with a 2-μm alumina layer supplied by Gelon LIB Group, China), and (iii) a cathode material (lithium nickel manganese cobalt oxide NMC622 of 3.5 mAh / cm 2 commercially available from CUSTOMCELLS). Both the cathode and the anode were connected to an external circuit by electrode tabs welded to the electrodes by conventional means. The tabbed and stacked units were placed inside a commercially available laminated aluminum pouch material with three sides sealed. The electrolyte prepared according to Example 1 was added to the laminated aluminum pouch under a dry atmosphere and then vacuum-sealed.

[0243] (Comparative Example 3A) [Preparation of Conventional Pouch Lithium-Ion Cells] The pouch cell was constructed by laminating (i) the anode material prepared in the previous [Example 2], (ii) using, as a ceramic separator, a 12-μm polymeric polypropylene film coated on both sides with a 2-μm alumina layer supplied by Gelon LIB Group, China, and (iii) using, as a cathode material, lithium nickel manganese cobalt oxide NMC622 of 3.5 mAh / cm 2 commercially available from CUSTOMCELLS. Both the cathode and the anode were connected to an external circuit by electrode tabs welded to the electrodes by conventional means. The tabbed and stacked units were placed inside a laminated aluminum pouch material with three sides sealed. A commercially available electrolyte was added to the laminated aluminum pouch under a dry atmosphere and vacuum-sealed. The commercially supplied electrolyte was a solution of LiPF6 (1 M) in a 1:1 volume ratio mixture of 1,3-dioxolan-2-one (ethylene carbonate, EC) and diethyl carbonate (DEC), which further contained 5 wt% fluoroethylene carbonate, 2 wt% vinylene carbonate and 2 wt% adiponitrile (AN).

[0244] (Example 4) [Cycle Life / Capacity Retention Analysis] The cells according to the present disclosure prepared according to Example 3 and the comparative cells prepared according to Example 3A were evaluated for their capacity retention characteristics.

[0245] The cycle conditions used were at 25 °C, C / 2 rate, 3 V to 4.2 V (constant voltage [CV] step of 4.2 V up to C / 20 rate).

[0246] The results are shown in FIGS. 7A, 7B, and 7C.

[0247] From the results, the lithium ion cells according to the present disclosure - retained a higher areal capacity over a significantly greater number of charge cycles than the comparative examples, and - retained a higher capacity retention rate over a significantly greater number of charge cycles than the comparative examples, and - retained a substantially linear cumulative specific capacity relationship over a significantly greater number of charge cycles and retained a higher cumulative specific capacity up to 80% of the initial capacity of life, was demonstrated.

[0248] Thus, the lithium ion cells according to the present disclosure showed an improvement in capacity retention rate and thus an improvement in cycle life compared to lithium ion cells fabricated using conventional carbonate-based electrolytes. The number of cycles required for the cumulative specific capacity (which is a measure of how much capacity, normalized to the mass of silicon in this case, is supplied) before the capacity drops to 80% of the initial capacity of life is approximately twice that of lithium ion cells fabricated using conventional carbonate-based electrolytes for the lithium ion cells according to the present disclosure.

[0249] (Example 5) [Cycle Life / Capacity Retention Analysis without Constant Voltage Step] The lithium-ion cell according to the present disclosure prepared by Example 3 and the comparative lithium-ion cell prepared by Example 3A were evaluated for their capacity retention characteristics.

[0250] The cycling conditions used were C / 2 rate at 25 °C, 3 V to 4.2 V.

[0251] The results are shown in Figure 8A. As can be seen from Figure 8A, the lithium-ion cell according to the present disclosure can undergo about 200 cycles before the capacity retention rate drops to 93%, while the lithium-ion cell fabricated using a conventional carbonate-based electrolyte can only undergo about 50 cycles before the capacity retention rate drops to 93%. Figure 8B shows that the lithium-ion cell according to the present disclosure achieves a higher Coulombic efficiency (over 99.9%), while the lithium-ion cell fabricated using a conventional carbonate-based electrolyte achieves a maximum of 99.8%.

[0252] From the results, it was demonstrated that the lithium-ion cell according to the present disclosure - exhibits a better capacity retention rate than the lithium-ion cell fabricated using a conventional carbonate-based electrolyte, and - has a higher Coulombic efficiency (over about 99.9%) than the lithium-ion cell fabricated using a conventional carbonate-based electrolyte (about 99.8%).

[0253] The higher Coulombic efficiency indicates that the lithium-ion cell according to the present disclosure undergoes fewer side reactions and lithium inventory losses than the lithium-ion cell fabricated using a conventional carbonate-based electrolyte.

[0254] (Example 6) [Method for forming solid electrolyte interface according to the present disclosure] A lithium-ion cell was prepared according to Example 3 and subjected to the following steps: - Stand still for 1 hour - Charge at 0.01C for 10 hours - Charge at 0.1 C until (i) 9 hours or (ii) 4.2 V is reached. - Let stand for 30 minutes. - Discharge at 0.1 C until 2.5 V is reached. - Let stand for 30 minutes. - Charge at 0.2 C until 4.2 V is reached. - Let stand for 30 minutes. - Discharge at 0.2 C until 2.5 V is reached. - Let stand for 30 minutes.

[0255] The solid electrolyte interface was formed during the formation of a lithium - ion cell held within a pressure clamp (initially at about 350 psi).

[0256] (Comparative Example 6A) [Method for forming a solid electrolyte interface according to the present disclosure] A lithium - ion cell was prepared according to Example 3A and subjected to the following steps: - Let stand for 1 hour. - Charge at 0.01 C for 10 hours. - Charge at 0.1 C until (i) 9 hours or (ii) 4.2 V is reached. - Let stand for 30 minutes. - Discharge at 0.1 C until 2.5 V is reached. - Let stand for 30 minutes. - Charge at 0.2 C until 4.2 V is reached. - Let stand for 30 minutes. - Discharge at 0.2 C until 2.5 V is reached. - Let stand for 30 minutes.

[0257] The solid electrolyte interface was formed in a lithium - ion cell held within a pressure clamp (initially at about 350 psi).

[0258] (Example 7) [Analysis of charge cycles and anode surface morphology after full discharge] The lithium - ion cells according to the present disclosure prepared according to Example 3 and the comparative lithium - ion cells prepared according to Example 3A were evaluated for their morphological characteristics after formation (all cycles ending in a discharged state).

[0259] The cycling conditions used were those of Example 6A and terminated at 2.5 V and 0% state of charge (SOC).

[0260] The lithium-ion cell was then disassembled under inert conditions and analyzed by scanning electron microscopy (SEM). Representative SEM images are reproduced in FIG. 9A. As can be seen, the surface morphology of the anode of the lithium-ion cell according to the present disclosure is significantly different from that of the anode of a lithium-ion cell fabricated using a conventional carbonate electrolyte. The surface morphologies of both the lithium-ion cell according to the present disclosure and the lithium-ion cell fabricated using a conventional carbonate electrolyte after carrying out the methods of Example 6 and Example 6A are characterized by islands of columnar silicon separated by cracks. Visually, these resemble mud cracks.

[0261] After carrying out the method of Example 6 or Comparative Example 6A, the surface morphology of the lithium-ion cell according to the present disclosure is unexpectedly different from that of the lithium-ion cell fabricated using a conventional carbonate electrolyte in that the crack density is significantly lower, the islands are significantly larger, and the cracks are significantly wider.

[0262] The exact mechanism that enables morphology control of the anode surface by the electrolyte of the present disclosure is not known.

[0263] Without being bound by theory, a lithium-ion cell exhibiting a surface morphology characterized by a lower crack density, larger islands, and wider cracks unexpectedly enables a reduction in surface area, and thus a reduction in parasitic decomposition of the electrolyte, and thus a reduction in solid electrolyte interphase formation, which is thought to contribute to an increase in the cycle life of such lithium-ion cells.

[0264] (Example 8) [Analysis of Anode Surface Morphology after Charge Cycles and Partial Charging] The lithium - ion cells according to the present disclosure prepared by Example 3 and the comparative lithium - ion cells prepared by Example 3A were evaluated for their capacity retention characteristics.

[0265] The cycling conditions used were as follows: - Stand still for 1 hour - Charge at 0.01C for 10 hours - (i) Charge at 0.1C for 9 hours or (ii) until reaching 4.2V - Stand still for 30 minutes - Discharge at 0.1C until reaching 2.5V - Stand still for 30 minutes - Charge at 0.2C until reaching 4.2V - Stand still for 30 minutes - Discharge at 0.2C until reaching 2.5V - End at 2.5V - Stand still for 30 minutes - Charge at 0.2C until 50% state of charge (SOC).

[0266] Next, the lithium - ion cells were disassembled under inert conditions and analyzed by scanning electron microscopy (SEM). Representative SEM images are reproduced in FIG. 9B. As can be seen, the surface morphology of the anode of the lithium - ion cell according to the present disclosure is significantly different from that of the anode of a lithium - ion cell fabricated using a conventional carbonate - based electrolyte. After implementing the method outlined above, the surface morphologies of both the lithium - ion cell according to the present disclosure and the lithium - ion cell fabricated using a conventional carbonate - based electrolyte are characterized by islands of columnar silicon separated by voids (cracks). Visually, these resemble mud cracks.

[0267] After implementing the method outlined above, the surface morphology of the lithium - ion cell according to the present disclosure is unexpectedly different from that of the lithium - ion cell fabricated using a conventional carbonate - based electrolyte in that the void (crack) density is significantly lower, the islands are significantly larger, and the voids (cracks) are significantly wider.

[0268] The exact mechanism that enables the morphology control of the anode surface by the electrolyte of the present disclosure is not known.

[0269] Without being bound by theory, lithium-ion cells having a surface morphology characterized by lower void (crack) density, larger islands, and wider voids (cracks) unexpectedly enable a reduction in surface area, and thus a reduction in parasitic decomposition of the electrolyte, and thus a reduction in solid electrolyte interface formation, and as a result, contribute to an increase in the cycle life of such lithium-ion cells.

Explanation of Signs

[0270] 1 Silicon anode 2 Current collector layer 3 Silicon layer 4 Cracks in the silicon layer 5 Ablated silicon (collapsed silicon) 6 Peeled silicon 7 Solid electrolyte interface (SEI) layer 8 Cracks in both the SEI and the silicon layer 9 Ablated SEI and silicon 10 Peeled silicon layer 11 Ablated SEI 12 Columnar structure 13 Excessive SEI deposition 14 Internal peeling of the SEI from the wall of the columnar structure 15 Peeling of the SEI from the top of the columnar structure 16 Ablation of the SEI from the top of the columnar structure 17 Ablation of the SEI from the wall of the columnar structure 18 Islands of columnar structure of silicon connected by the SEI 19 Secondary voids 20 Primary voids a Direction of the force acting due to the expansion of silicon b Direction in which the action of the force is suppressed by the structure

Claims

1. A lithium-ion cell, comprising: - a silicon anode, comprising: i. a current collector layer; and ii. a silicon layer; wherein the silicon layer comprises a plurality of columnar structures on the current collector, and - a cathode; - a separator; and - an electrolyte, comprising: i. a lithium salt in an amount of 9 wt% or more and 29 wt% or less based on the electrolyte; ii. a non-aqueous solvent; and iii. a diluent; wherein the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y (1.0 ≤ x ≤ 3.0 and 2.0 ≤ y ≤ 4.0). A lithium-ion cell comprising the above components.

2. The lithium-ion cell according to Claim 1, wherein the silicon layer has a depth of 1 μm or more and 200 μm or less, preferably 2 μm or more and 100 μm or less, more preferably 4 μm or more and 75 μm or less, even more preferably 5 μm or more and 50 μm or less, and most preferably 5 μm or more and 30 μm or less.

3. The silicon layer of the lithium-ion cell according to Claim 1 or 2, comprises: i. a plurality of columnar structures on the current collector, wherein the columnar structures mainly extend in a direction perpendicular to the surface of the current collector layer; ii. primary voids having a width of 1 μm or more and 10 μm or less; and optionally iii. secondary voids having a width of 10 nm or more and 150 nm. A lithium-ion cell according to Claim 1 or 2.

4. The lithium-ion cell according to any one of Claims 1 to 3, wherein the electrolyte has a molar ratio of lithium salt - solvent - diluent of 1:x:y, where 1.1 ≤ x ≤ 2.5 and 2.2 ≤ y ≤ 3.8, more preferably 1.2 ≤ x ≤ 2.0 and 2.4 ≤ y ≤ 3.6, even more preferably 1.2 ≤ x ≤ 1.8 and 2.6 ≤ y ≤ 3.4, and most preferably x = 1.2 and y = 3.

0.

5. The lithium-ion cell according to any one of Claims 1 to 4, wherein the lithium salt is lithium bis(fluorosulfonyl)imide.

6. i. The non-aqueous solvent is 1,2-dimethoxyethane. A lithium-ion cell according to any one of Claims 1 to 5.

7. i. The diluent is 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether. A lithium-ion cell according to any one of Claims 1 to 6.

8. The lithium ion cell according to any one of claims 1 to 7, wherein the silicon layer has a porosity of 0% or more and 80% or less, preferably 5% or more and 60% or less, and more preferably 10% or more and 40% or less, as determined by the BJH method of ISO 15901-2:2006.

9. A lithium ion cell according to any one of claims 1 to 8, comprising the following steps in the following order: (i) providing a lithium ion cell according to any one of claims 1 to 8; (ii) charging the cell to at least 4.0 V; (iii) discharging the cell to 3.0 V; A lithium ion cell obtainable by a method comprising.

10. A lithium ion cell according to any one of claims 1 to 9, comprising the following steps in the following order: (i) providing a lithium ion cell according to any one of claims 1 to 8; (ii) charging at 0.01 C for 10 hours; (iii) charging at 0.1 C for either (i) 9 hours or (ii) until reaching 4.2 V; (iv) discharging at 0.1 C until reaching 2.5 V; (v) charging at 0.2 C until reaching 4.2 V; (vi) discharging at 0.2 C until reaching 2.5 V; (vii) charging at 0.2 C for 90 minutes; A lithium ion cell obtainable by a method comprising.

11. A lithium ion cell, - a silicon anode, i. a current collector layer; ii. a silicon layer on the current collector layer; iii. a solid electrolyte interface layer; comprising, wherein the silicon layer iv. a plurality of columnar structures on the current collector, the columnar structures extending mainly in a direction perpendicular to the surface of the current collector layer; v. optionally, primary voids having a width of 1 μm or more and 10 μm or less; vi. optionally, secondary voids having a width of 10 nm or more and 150 nm or less; a silicon anode comprising; - a cathode; - a separator; - an electrolyte, i. a lithium salt; ii. a non-aqueous solvent; iii. a diluent; an electrolyte comprising; A lithium ion cell comprising.

12. The lithium ion cell according to any one of claims 1 to 11, wherein the lithium ion cell is operable at a voltage of 2.5 V or more and 4.6 V or less, more preferably 3.0 V or more and 4.5 V or less, and even more preferably 3.2 V or more and 4.2 V or less.

13. A battery comprising the lithium ion cell according to any one of claims 1 to 12.

14. Use of the lithium ion cell according to any one of claims 1 to 11 or the battery according to claim 12 as an energy storage and / or release device.

15. A method for manufacturing the lithium ion cell according to any one of claims 1 to 8.

16. (i) A step of providing the lithium ion cell according to any one of claims 1 to 12; (ii) A step of charging to at least 4.0 V; (iii) A step of discharging to 3.0 V. The method according to claim 15, comprising the above steps.

17. a. A step of charging at 0.01 C for 10 hours; b. A step of charging at 0.1 C for either (i) 9 hours or (ii) until reaching 4.2 V; c. A step of discharging at 0.1 C until reaching 2.5 V; d. A step of charging at 0.2 C until reaching 4.2 V; e. A step of discharging at 0.2 C until reaching 2.5 V; f. A step of charging at 0.2 C for 90 minutes. The method for manufacturing the lithium ion cell according to claim 15, further comprising the above steps.

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