Solution-deposited electrode coatings for thermal runaway mitigation in rechargeable battery packs

Abstract

Provided herein are battery cells comprising an artificial solid-electrolyte interface (SEI) layer for use as a protective coating on an electrode. The SEI layer is produced by liquid phase deposition (LDP). The battery cell can comprise an anode, a cathode, an electrolyte disposed between the anode and the cathode, a polymer separator disposed between the anode and the cathode, and a housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein at least one of the anode or cathode comprises an SEI layer produced by a LDP method.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 934,522, filed November 13, 2019, which is incorporated herein by reference for all purposes. Technical Field

[0003] Embodiments of this disclosure generally relate to methods, systems, and materials for coating a protective film onto the surface of battery pack electrodes to produce battery packs that demonstrate improved safety and thermal stability. Background Technology

[0004] Rechargeable battery packs often experience catastrophic failures due to the uncontrolled self-heating of a series of internal chemical reactions (commonly known as "thermal runaway"). For example, in the case of lithium-ion battery packs, a series of autocatalytic exothermic reactions occur in the range of 60-300°C, which ultimately leads to mechanical battery failure, anode-to-cathode short circuits, and combustion of flammable electrolytes.

[0005] However, in order to trigger these reactions, the lithium-ion battery pack must first be heated to a temperature >60°C, and its tendency to complete the full reaction chain, including thermal runaway, can also depend on its state of charge. The temperature at which thermal runaway begins is typically observed by calorimetry of the lithium-ion battery pack in an adiabatic chamber. As the temperature of the battery pack rises, the net positive measurement of heat indicates the exothermic process within the battery. A monotonically increasing amount of heat observed from the battery in the absence of any further heat being added to the adiabatic chamber indicates thermal runaway.

[0006] One example of a potential thermal runaway scenario is when the anode and cathode of a highly charged lithium-ion battery pack come into electrical contact with each other due to a mechanical failure of the polymer separator. In this situation, a large current flows through the contact point when the battery discharges. This current causes Joule heating of the surrounding materials, raising the internal temperature of the battery pack above 60°C (and locally, potentially much higher), thus triggering a thermal runaway reaction chain that can ultimately lead to catastrophic failure, such as a fire.

[0007] However, it has also been shown that an electrical short circuit is not necessary to trigger thermal runaway. Lithium-ion battery packs have also been observed to experience thermal runaway when the ambient temperature simply rises to 60°C or higher. Under these conditions, even without an electrical short circuit, the lithium-ion battery pack may experience thermal runaway due to sufficiently high temperatures, triggering the first exothermic reaction.

[0008] Recent literature has focused on understanding the key reactions leading to thermal runaway in lithium-ion battery packs, and it has been determined that the decomposition of electrode surface degradation products (often referred to as the “SEI” or solid-electrolyte interface) is the first exothermic reaction occurring within a temperature window of 60–90 °C. The SEI typically forms at the beginning of the cycle life of a lithium-ion battery pack and is a consequence of the electrochemical instability of the electrolyte on both the anode and cathode surfaces at or near full charge. Under these conditions, electrolyte reduction and oxidation products (on the anode and cathode, respectively) combine with available lithium to deposit a solid layer on all electrochemically active surfaces. This layer then acts as a kinetic barrier to further electrolyte decomposition.

[0009] For example, for graphite anodes, LiNi x Mn y Co z In existing lithium-ion battery packs, which use an O2 cathode and an electrolyte comprising a blend of LiPF6 salt and ethylene carbonate / ethyl methyl carbonate solvent, the majority of the SEI formed on the anode typically consists of LiF, Li2CO3, LiEDC ((CH2OCO2Li)2), and alkyl lithium carbonate (ROCO2Li, where R can contain various alkyl groups). Literature has indicated that both LiEDC and alkyl lithium carbonate can react with the remaining electrolyte at temperatures as low as 55°C to produce a variety of reaction products, including CO2 gas, LiF, HF, ethers, phosphates, and fluorophosphates. Many of these reactions are exothermic. Furthermore, the decomposition of the existing SEI can lead to the formation of a new SEI, which is also known to be exothermic. If the heat generated by such a combination of reactions is sufficient to raise the local battery temperature to 100°C or higher, there is a high probability that the mechanical integrity of the polymer anode-cathode separator will be compromised. Under such conditions, an electrical short circuit between the anode and cathode may also occur, leading to further temperature increases and further detrimental reactions.

[0010] For many lithium-ion cathode materials, temperatures exceeding approximately 160°C can cause a rapid release of oxygen from the host lattice. For example, with the common commercial cathode material LiCoO2, temperatures exceeding 180°C cause oxygen loss. The combination of oxygen with heat and a flammable electrolyte provides the necessary conditions for combustion, leading to catastrophic failure.

[0011] As a result, any technology that can prevent SEI decomposition or the decomposition of the electrode material itself can greatly improve the thermal runaway resistance of lithium-ion battery packs.

[0012] Recent research has attempted to improve the thermal stability of lithium-ion battery packs by applying thin-film coatings deposited on the anode and cathode surfaces using atomic layer deposition (ALD). Such coatings are often referred to as "artificial SEI". Coatings applied to the anode via ALD have resulted in an increase in the onset temperature of self-heating characteristics, an indicator of thermal runaway, and have also demonstrated reduced degradation of the cathode material.

[0013] Unfortunately, the introduction of roll-to-roll (R2R) ALD methods into conventional high-capacity lithium-ion production lines is unsustainable, primarily due to the fact that ALD is a slow, capital-intensive vacuum method.

[0014] Therefore, there is an industrial need to apply thin-film coatings to the electrodes of lithium-ion battery packs to produce battery packs with improved thermal stability, while also being able to do so in a way that can be extended to R2R high-capacity manufacturing.

[0015] For decades, high-quality conformal thin films of oxides and chalcogenides have been deposited using techniques other than ALD (Alternating Layer Deposition), such as chemical bath deposition (CBD), sequential ion layer adsorption and reaction (SILAR), and layer-by-layer sol-gel. In CBD, an aqueous solution of a complexed metal precursor is typically mixed with a chalcogenide or oxide ion source. Such techniques have also been widely implemented in a continuous R2R manner. The temperatures of these methods are generally moderate, well below the decomposition temperatures of the cell electrode materials, binders, or separators. CBD is well known for depositing high-quality CdS or ZnS as n-type junction partners on CdTe or CIGS thin-film solar cells. This technique has been used for many years, setting world records for the efficiency of these types of solar cells. They produce high open-circuit voltages, high diode ideality, and high shunt resistance, indicating excellent film quality and conformability. CBD methods have also been commercialized in high-capacity thin-film solar cell production lines.

[0016] A useful variant of CBD technology is SILAR. In this case, the substrate is alternately exposed to solutions of cationic and anionic reactants, with rinsing steps in between. While this technique results in slower film growth, its benefit lies in the elimination of homogeneous nucleation (precipitation) from the mixing of the two reactants, which significantly improves material utilization. Given that the tunneling limit of good dielectrics is on the order of 1–2 nm, SILAR technology is feasible for depositing passivation layers on the surface of battery pack electrodes. Thickness control in the SILAR method is also better than in the CBD method; for example, thickness control of the passivation layer on the battery pack electrodes is crucial for preventing undesirable barriers to lithium diffusion while maintaining the electron tunneling barrier.

[0017] Solution-based techniques also exist that utilize the same types of organometallic compounds used in gas-phase ALD to demonstrate layer-by-layer sol-gel coating. For example, an Al₂O₃ monolayer can be grown by immersing the substrate in a suitable aluminum alkoxide solution. Adsorption of the organometallic precursor followed by an oxidation step (e.g., hydrolysis) produces an oxide monolayer. These steps are repeated, with rinsing steps in between, to produce a monolayer-to-monolayer coating. The metal alkoxide precursor is typically soluble to very high molar concentrations in standard organic solvents such as 2-propanol. In recent years, high-quality Al₂O₃, SiO₂, and ZrO₂ composite barrier layers have been grown on TiO₂ dye-sensitized solar cells using this technique.

[0018] US PGPUB 2016 / 0090652 proposes a liquid-phase ALD method similar to the one described above, in which discrete wafer substrates are continuously exposed to a solution of a metal-organic precursor, a rinsing solvent for removing excess metal-organic compounds, an oxidizing solution, and another rinsing. These four steps are repeated to produce a film of any desired thickness. The wafer is attached to a spin-coating apparatus; after each step, the wafer is immediately rotated to remove excess fluid. While this technique works well for wafer-like substrates, it cannot be used to coat continuous substrates, such as foil rolls.

[0019] Therefore, there is a need for alternative deposition methods to ALD and other conventional approaches that are faster, more efficient, safer, and more cost-effective for creating conformal coatings on the surfaces of battery pack electrodes to mitigate thermal runaway. To date, no solution deposition apparatus has been demonstrated for conformal deposition growth of thin films on rolls of battery pack electrodes at a commercial scale. Examples of key challenges that remain to be addressed include homogeneous nucleation during film growth, cross-contamination of the precursor solution, and film thickness uniformity at all locations within the film. Summary of the Invention

[0020] In some aspects, this disclosure provides a battery pack comprising: an anode; a cathode; an electrolyte disposed between the anode and the cathode; a polymer separator disposed between the anode and the cathode; and a housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing allows electrical contact with the anode and the cathode, and wherein at least one of the anode or cathode comprises an artificial solid-phase electrolyte interface (SEI) layer produced by a liquid phase deposition method.

[0021] In some embodiments, the anode has the artificial SEI layer. In some embodiments, the cathode has the artificial SEI layer. In some embodiments, both the anode and the cathode have artificial SEI layers. In some embodiments, the battery pack is rechargeable.

[0022] In some embodiments, the artificial SEI is produced by a liquid phase deposition method, the method comprising: providing a battery pack electrode (e.g., an anode or cathode) to a transfer device; transferring the electrode via the transfer device to a first reaction chamber containing a first liquid solution, the first liquid solution comprising at least a first reagent; exposing the electrode to the first liquid solution in the first reaction chamber via the transfer device to produce a layer of the artificial SEI partially coated with the at least first reagent chemically bonded to the surface of the battery pack electrode; rinsing the layer in the first reaction chamber with a first rinsing solution comprising a first solvent to remove unreacted first reagent; transferring the electrode via the transfer device to a second reaction chamber containing a second liquid solution, the second liquid solution comprising at least a second reagent; exposing the electrode to the second liquid solution in the second reaction chamber via the transfer device, wherein the at least second reagent reacts with the at least first reagent chemically bonded to the surface of the electrode to produce a monolayer of the artificial SEI comprising a compound generated by the reaction of the at least second reagent with the first reagent; and rinsing the coating in the second reaction chamber with a second rinsing solution comprising a second solvent to remove unreacted second reagent. In some implementations, the aforementioned steps are repeated to produce the continuous growth of multiple stacked monolayers, thereby producing a thin film coating with a total thickness between 0.5 nanometers (nm) and 100 micrometers (µm).

[0023] In some embodiments, the thickness of the anode and / or cathode is from 100 nm to 1,000 µm before the artificial SEI is coated. In some embodiments, the anode and / or cathode in (a) have pores ranging in size from 0.1 nm to 100 µm. In some embodiments, the membrane porosity of the anode and / or cathode in (a) is 1-99%.

[0024] In some embodiments, the artificial SEI is engineered to withstand exposure to temperatures up to 100°C, 200°C, or 300°C without exothermic decomposition. In some embodiments, the artificial SEI is engineered to withstand exposure to temperatures up to 100°C, 200°C, or 300°C without exothermic reactions with any physically adjacent electrolyte, separator, or other battery pack components.

[0025] In some embodiments, the anode is composed of graphite, Si, Sn, Si-graphite composite, Sn-graphite composite, or lithium metal. In some embodiments, the cathode is composed of LiNi. x Mn y Co z O2, LiNi x Co y Al zO2, LiMn x Ni y O z It is composed of LiMnO2, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiV2O5, sulfur or LiCoO2, where x, y and z are stoichiometric coefficients.

[0026] In some embodiments, the conveying apparatus for the liquid phase deposition method includes a series of rollers for guiding the battery pack anode or cathode and partially coated battery pack anode or cathode to the first and second reaction chambers, respectively. In some embodiments, the anode, cathode, partially coated anode, and / or partially coated cathode are exposed to the first and second liquid solutions by a method selected from immersion, spraying, slot die coating, and gravure roller coating. In some embodiments, the first and second liquid solutions for the liquid phase deposition method are nonionic.

[0027] In some embodiments, the liquid phase deposition method further includes rinsing the partially coated battery pack anode or cathode with a first rinsing solution containing a first solvent to produce a saturated first layer on the partially coated battery pack anode or cathode, and a first residual solution containing the first solvent and an unreacted first reagent. In some embodiments, the liquid phase deposition method further includes passing the first residual solution through a first filtration step to separate the unreacted first reagent from the first solvent. In some embodiments, the liquid phase deposition method further includes rinsing the fully coated battery pack anode or cathode with a second rinsing solution containing a second solvent to produce a saturated monolayer film on the fully coated battery pack anode or cathode, and a second residual solution containing the second solvent and an unreacted second reagent. In some embodiments, the liquid phase deposition method further includes passing the second residual rinsing solution through a second filtration step to separate the unreacted second reagent from the second solvent. In some embodiments, the liquid phase deposition method further includes recycling the recovered unreacted first or second reagent back to the first or second liquid solution, respectively; and recycling the recovered first or second solvent back to the first or second rinsing solution, respectively.

[0028] In some embodiments, the filtration step of the liquid phase deposition method is performed using membrane separation, chemical precipitation, ion exchange, electrochemical removal, physical adsorption, flow filtration chromatography, or a combination thereof. In some embodiments, the first liquid solution of the liquid phase deposition method contains more than one reagent. In some embodiments, the second liquid solution contains more than one reagent. In some embodiments, the first and second reagents are organometallic precursors. In some embodiments, the first and second reagents are cationic or anionic. In some embodiments, the first and second liquid solutions further contain an organic solvent, water, or a mixture of both.

[0029] In some embodiments, the compound produced by the liquid phase deposition method is selected from one of the following: A x O y A type of binary oxide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal, or metalloid, and x and y are stoichiometric coefficients; A x B y O z A type ternary oxide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and x, y, and z are stoichiometric coefficients; A w B x C y O z A type quaternary oxide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients; A x B y Type II halide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, B is a halogen, and x and y are stoichiometric coefficients; A x B y C z A type ternary halide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, C is a halogen, and x, y, and z are stoichiometric coefficients; A w B x C y D z A type quaternary halide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, D is a halogen, and w, x, y, and z are stoichiometric coefficients; A x N y A type binary nitride, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal, or metalloid, and x and y are stoichiometric coefficients; A x B y N zA type ternary nitride, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and x, y, and z are stoichiometric coefficients; A w B x C y N z A type quaternary nitride, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients; A x B y Type II chalcogenides, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal, or metalloid, B is a chalcogenide, and x and y are stoichiometric coefficients; A x B y C z A type ternary chalcogenide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, C is a chalcogenide, and x, y, and z are stoichiometric coefficients; A w B x C y D z A quaternary chalcogenide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, D is a chalcogenide, and w, x, y, and z are stoichiometric coefficients; A x C y A binary carbide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal, or metalloid, and x and y are stoichiometric coefficients; A x B y O z Type II halide oxides, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, B is a halogen, and x, y and z are stoichiometric coefficients; A x As y A type of binary arsenide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal, or metalloid, and x and y are stoichiometric coefficients; A x B y As z A type ternary arsenide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and x, y, and z are stoichiometric coefficients; A w B x C y As z A type quaternary arsenide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients; A x (PO4) yType diphosphate, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal, or metalloid, and x and y are stoichiometric coefficients; A x B y (PO4) z Type III triphosphate, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and x, y, and z are stoichiometric coefficients; and A w B x C y (PO4) z A type tetraphosphate, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients.

[0030] In some embodiments, the anode or cathode of the battery pack further comprises a substrate. In some embodiments, the substrate is in the form of a foil, sheet, or film.

[0031] In some embodiments, the monolayer produced by the liquid-phase deposition method comprises at least one or more metalcones. In some embodiments, the one or more metalcones are generated by a reaction between a first reagent comprising an organometallic compound and a second reagent comprising an organic molecule. In some embodiments, the first reagent is an organometallic compound comprising an organic moiety and a metal comprising Al, Zn, Si, Ti, Zr, Hf, Mn, and / or V, and the second reagent is an organic molecule comprising ethylene glycol, glycerol, erythritol, xylitol, sorbitol, mannitol, butylene glycol, pentanediol, hydroquinone, hexanediol, lactic acid, triethanolamine, p-phenylenediamine, glycidyl ether, caprolactone, fumaric acid, aminophenol, and / or diaminodiphenyl ether.

[0032] In some embodiments, the monolayer produced by the liquid phase deposition method is composed of one or more organic materials. In some embodiments, the one or more organic materials are polymers comprising polyamides, polyimides, polyureas, polymethylimides, fluorinated elastomers, or any combination thereof.

[0033] In some embodiments, the battery pack cells undergo self-heating at temperatures higher than those observed in corresponding battery pack cells without an artificial SEI on the anode and / or cathode. In some embodiments, the battery pack cells release CO2, O2, H2, or any other gas at temperatures higher than those observed in corresponding battery pack cells without an artificial SEI on the anode or cathode.

[0034] In some embodiments, the anode and / or cathode comprises one or more of the following: graphite, Si, Sn, Ge, Al, P, Zn, Ga, As, Cd, In, Sb, Pb, Bi, SiO, SnO2, Si, Sn, lithium metal, LiNi x Mn y Co z O2, LiNi x Co y Al z O2, LiMn x Ni y O z LiMnO2, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiV2O5, sulfur or LiCoO2, where x, y and z are stoichiometric coefficients.

[0035] In some embodiments, the electrolyte comprises a salt and a solvent. In some embodiments, the salt is LiPF6, LiClO4, LiTFSI, or LiNO3. In some embodiments, the solvent comprises one or more of the following: ethylene carbonate, methyl ethyl carbonate, dimethyl carbonate, fluorinated ethylene carbonate, or propylene carbonate.

[0036] In some aspects, this disclosure provides a battery pack comprising: an anode; a cathode; an electrolyte disposed between the anode and the cathode; a polymer separator disposed between the anode and the cathode; and a housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing provides electrical contact with the anode and the cathode, wherein the anode, the cathode, and / or both contain an artificial SEI coating, and wherein the battery pack emits CO2, O2, H2, or any other gas at a temperature higher than that observed in a corresponding battery pack without an artificial SEI on the anode or cathode.

[0037] In some aspects, this disclosure provides a battery pack comprising: an anode; a cathode; an electrolyte disposed between the anode and the cathode; a polymer separator disposed between the anode and the cathode; and a housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing provides electrical contact with the anode and the cathode; wherein the anode, the cathode, and / or both comprise an artificial SEI coating, and wherein the battery pack experiences self-heating at a temperature higher than that in a corresponding battery pack without an artificial SEI on the anode or cathode. Attached Figure Description

[0038] Figure 1This is a general flowchart of an embodiment of the method according to the present disclosure. The method includes a rinsing / washing step and a filtration step.

[0039] Figure 2 This is a schematic diagram of one embodiment of a system for coating a thin film onto the surface of a battery pack electrode according to the present disclosure.

[0040] Figures 3A-3B This is a 60kX magnified image of the graphite electrode surface, showing the difference in surface morphology between raw, uncoated graphite (Fig. 3A) and graphite coated according to the method of this disclosure (Fig. 3B).

[0041] Figure 4 It is a scatter plot showing the unidirectional first cycle loss of the coated electrode and the uncoated electrode.

[0042] Figure 5 The t-test plot shows that, due to the presence of the coating, the first-cycle capacity loss between coated and uncoated anodes is significantly different at a 95% confidence level.

[0043] Figure 6 It is a graph showing the change in voltage between the charge difference / voltage difference (dQ / dV) of the uncoated graphite anode (600) and the coated graphite anode (601).

[0044] Figure 7 This describes a battery pack electrode with an artificial SEI according to the present disclosure coated on the top of a foil substrate.

[0045] Figure 8 This is a description of a battery pack containing electrodes coated with an artificial SEI layer according to the present disclosure. Detailed Implementation

[0046] This disclosure provides a battery pack comprising an artificial SEI layer as a protective coating on the electrodes. These films are produced by a reaction of two or more reagents during a liquid-phase deposition process. The artificial SEI layer acts as a protective coating on the electrode constituent particles, while allowing the particles to maintain electrical and physical contact with each other, thereby maintaining the power capacity of the battery pack. Furthermore, the protective coating reduces the tendency of the battery pack to experience a sequential cascade of exothermic reactions, typically described as “thermal runaway.”

[0047] To date, techniques for forming conformal coatings (<10 micrometers (μm) thick) on substrates with microstructures exhibiting high porosity, tortuosity, and / or a large number of high aspect ratio features (i.e., “non-planar” microstructures) have been either ineffective (due to the “line of sight” limitation of physical vapor deposition) or expensive and time-consuming (conventional atomic layer deposition (ALD)). Therefore, this disclosure provides methods and systems for achieving cost-effective means of forming uniform conformal layers on non-planar microstructures. Specifically, this disclosure focuses on forming uniform conformal layers on the surfaces of non-planar battery electrode arrays.

[0048] exist Figure 8 The image shows an example embodiment of a battery pack according to the present disclosure, comprising an artificial SEI layer formed by a liquid phase deposition method. The battery pack 800 includes a housing 802 containing electrodes 804 (anode) and 806 (cathode). Each electrode has an electrical contact 814a-b extending out of the housing 802. An electrolyte 808 is located between the two electrodes and separated by a separator 810. Artificial SEI layers 812a-b are coated on the surface of each electrode.

[0049] The electrode comprises a porous coating on top of a substrate (e.g., foil or sheet). The electrode is fully formed. A fully formed electrode refers to a standard sequence of electrode formation methods, including but not limited to casting a slurry of active and inactive material components onto a foil substrate to form the electrode, followed by drying the electrode, and then rolling the electrode. In some embodiments, full electrode formation does not include rolling. In some embodiments, the battery pack electrode comprises graphite, Si, Sn, silicon-graphite composites, Sn-graphite composites, or lithium metal. In some cases, the battery pack electrode comprises LiNi. x Mn y Co z O2, LiNi x Co y Al z O2, LiMn x Ni y O z The anode and / or cathode may contain one or more of the following: LiMnO2, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiV2O5, sulfur, or LiCoO2, where x, y, and z are stoichiometric coefficients. In some embodiments, the anode and / or cathode may contain one or more of the following: graphite, Si, Sn, Ge, Al, P, Zn, Ga, As, Cd, In, Sb, Pb, Bi, SiO, SnO2, Si, Sn, or lithium metal.

[0050] In some embodiments, the substrate may be a continuous substrate, typically in the form of foil or sheet. As used herein, "continuous substrate" means a substrate having an aspect ratio of at least 10:1 between its two largest dimensions and being sufficiently flexible to be wound onto itself in a roll. It can be made of a variety of materials, including but not limited to metals such as copper, aluminum, or stainless steel, or organic materials such as polyimide, polyethylene, polyetheretherketone (PEEK), or polyester, polyethylene naphthalate (PEN).

[0051] The battery pack also includes an electrolyte disposed between the electrodes. The electrolyte typically consists of an organic solvent and a salt. In some embodiments, the solvent comprises one or more of the following: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, γ-butyrolactone, ethyl acetate, fluorinated ethylene carbonate, propylene carbonate, or any other organic chemical known in the art as a suitable battery pack solvent. In some embodiments, the salt comprises one or more of the following: LiPF6, LiTFSI, LiFSI, LiClO4, LiNO3, or any other lithium salt known in the art as a suitable battery pack salt.

[0052] Separators (e.g., polymer separators) are typically located between electrodes. Polymer separators consist of a single layer or multiple layers stacked together in any combination of the following: polyethylene, polypropylene, polyvinylidene fluoride, polylactic acid, polyimide, polyamide, polyethylene oxide, or any other polymer known in the art as suitable battery pack separators. In some embodiments, glass fiber is used as a separator in place of or as a supplement to the polymer separator. In some embodiments, the polymer separator may also be coated with a film of other polymers or oxides, including but not limited to: cellulose, polyethylene oxide, aromatic polyamides, polymethyl methacrylate, polyamide, polyaryl ether ketone, polyvinylidene fluoride, polyimide, alumina, or silicon oxide.

[0053] The battery pack further includes a casing or housing containing electrodes, separators, and electrolyte. The battery pack casing is typically made of 304 or 316 grade stainless steel. In some embodiments, the battery pack casing may be made of aluminum. For coin, cylindrical, and prismatic battery forms, the casing is typically made of metal, including but not limited to 304 stainless steel, 316 stainless steel, or aluminum. For pouch battery forms, the casing is typically made of polymer, including but not limited to polyethylene, polyimide, and polyamide. In some embodiments, the pouch battery casing is laminated with a sheet of metal (e.g., aluminum).

[0054] exist Figure 7The image shows an example of an embodiment of a coated battery pack electrode according to the present disclosure. The coated battery pack electrode 700 includes electrode constituent particles (i.e., active layer) 702 coated with an artificial SEI 703 produced by a liquid phase deposition method as described herein. The thickness of the artificial SEI 703 can be between 0.5 nm and 100 μm. The electrode constituent particles 702 are located on top of a foil substrate 701.

[0055] In some respects, this disclosure provides methods and systems for generating an artificial SEI layer in a battery pack, said SEI layer being more resistant to dissolution than current SEIs, having sufficient adhesion to the material or component to be coated and sufficient mechanical stability, having appropriate resistance to prevent electrolyte decomposition, while conducting ions (such as lithium ions in the case of a battery pack), and having substantially no interparticle internal resistance. Furthermore, the artificial SEI, alone or in combination, performs any of the following operations: reducing heat released by exothermic reactions within the battery pack, reducing gases released from the anode and / or cathode as the battery pack temperature rises, reducing the dissolution of active materials, and / or increasing the onset temperature of thermal runaway.

[0056] The methods described herein for generating artificial SEIs are liquid-phase deposition methods. Artificial SEIs are used to coat the surfaces of components in electrochemical instruments, such as battery packs. In particular, applications that can benefit from the coatings described herein, such as those for battery packs, including high-voltage cathodes, fast-charging electrodes, silicon-containing anodes, less expensive electrolytes, and nanostructured electrodes, may include these. Therefore, in some embodiments, thin films can be coated onto the electrodes (e.g., cathodes or anodes) of the battery pack.

[0057] exist Figure 1 A simplified flowchart of an embodiment of the method according to this disclosure is shown. Although Figure 1 The implementation scheme relates to a method for coating artificial SEI onto the surface of battery pack electrodes. This description represents only the components deposited using the methods and systems provided herein and should not be construed as being limited in any way.

[0058] refer to Figure 1 For example, the battery electrode may be exposed in 100 to a first liquid solution containing one or more first reagents in a first reaction chamber to produce a layer containing one or more adsorbed first reagents on the surface of the electrode.

[0059] The first liquid solution contains at least a first reagent. The first reagent can be any compound capable of reacting with the material of the electrode (i.e., the part to be coated) to form a self-confining layer. In some embodiments, the first reagent is an organometallic compound. Examples of such organometallic compounds include, but are not limited to, aluminum trisec-butoxide, titanium ethoxide, niobium ethoxide, trimethylaluminum, and zirconium tert-butoxide. In another embodiment, the first reagent comprises an aqueous solution containing an ionic compound. Examples include, but are not limited to, zinc acetate, cadmium chloride, zinc chloride, zirconium chloride, and zinc sulfate. In some embodiments, the pH of the first solution can be varied. In some embodiments, the first liquid solution can be a solution comprising both a cation and anion precursor that react to form a solid film; in this case, film growth is limited by film-forming reaction kinetics. In some embodiments, the first liquid solution can be a solution comprising both an organometallic compound and an oxidizing precursor that react to form a solid film; in this case, film growth is limited by film-forming reaction kinetics.

[0060] In embodiments where the first reagent is an organometallic compound, the first liquid solution may further contain a solvent for dissolving or complexing the first reagent. Preferred solvents include organic solvents, such as alcohols (e.g., isopropanol or ethanol), alcohol derivatives (e.g., 2-methoxyethanol), slightly less polar organic solvents (e.g., pyridine or tetrahydrofuran (THF)), or nonpolar organic solvents (e.g., hexane and toluene).

[0061] In one embodiment, the first liquid solution is contained within a first reaction chamber. The reaction chamber must be a sufficiently large instrument to accommodate the receiving electrode and contain the amount of liquid solution used for the reaction to produce the self-confining layer. Such instruments that can be used as reaction chambers include, but are not limited to, tanks, baths, pans, beakers, etc.

[0062] The electrodes can be transferred to the first reaction chamber via a transfer device. As described in more detail below, the transfer device can be adapted and positioned in such a way as to guide or direct the electrodes in and out of the first chamber.

[0063] In some embodiments, the electrodes may be fully or partially immersed in the first and second liquid solutions in the first and second reaction chambers, respectively. In other embodiments, the electrodes may be sprayed with the first and second liquid solutions in the first and second reaction chambers, respectively.

[0064] In another embodiment, the electrode can be conveyed below a slit-die coater, from which a first liquid solution is continuously dispensed to produce a two-dimensional liquid film. The electrode conveying speed and the fluid flow rate through the die determine the thickness of the liquid film. The solvent can then simply evaporate to form a solid film of dissolved components, or the liquid film can react to deposit a thin film on the electrode surface. The resulting solid film can be as thin as an atomic monolayer or as thick as 100 micrometers. The reaction can take place while the solvent is still present or after the solvent has evaporated. If residual solvent remains until after the coating process is complete, it can be removed using various techniques, such as blade scraping, air knife, metering knife, or similar techniques. The entire slit-die coating process can then be repeated to produce a new film with a different chemical composition or simply a thicker coating with the same chemical composition. In this case, the reaction chamber simply contains the area where the slit-die coater is located and does not necessarily resemble the enclosed space implied by the term "chamber."

[0065] In another embodiment, the electrode can be conveyed through a tank containing a coating solution and a gravure roller. In this embodiment, the gravure roller continuously transfers fluid from the immersion tank to the adjacent substrate due to the preferential surface tension (wetting) of the coating solution on the substrate and roller. As in slot die coating, the result is initially a two-dimensional liquid film on the electrode surface. For example, the specific composition of the solution, substrate, and roller may affect the surface tension of the fluid on both the substrate and the roller, thus affecting the coating efficiency of the method. The solvent can then simply evaporate to form a solid film of dissolved components, or the liquid film may have reactants to precipitate a thin film on the electrode surface. The resulting solid film can be as thin as an atomic monolayer or as thick as 100 micrometers. The reaction can take place while the solvent is still present or after the solvent has evaporated. If residual solvent remains until after the coating process is complete, it can be removed by various techniques such as blade scraping, air knife, metering knife, or similar techniques. The entire gravure coating method can then be repeated to produce a new film with a different chemical composition or simply to produce a thicker coating with the same chemical composition.

[0066] Multiple sequential, repetitive steps of the same method (i.e., slot die or gravure coating) can be performed using the same or different solutions. Solutions can be separated (e.g., in a first solution, a second solution, etc.) to avoid cross-contamination, for example, or to prevent homogeneous nucleation when a heterogeneous film-forming reaction is preferred.

[0067] The electrode is exposed to the first liquid solution for a sufficient time (“residence time”) to allow one or more first reagents to adsorb onto the electrode surface and form a continuous layer (i.e., a self-confined layer). Examples of method variables that can affect this step include solution and electrode temperatures, residence time, and reagent concentration.

[0068] The advantages of this method and system are that the solvents used have different specific heat capacities and can also be used as a medium for both heat transfer and precursor transfer, resulting in faster and more efficient electrode heating. Compared to their pure analogues, the precursors dissolved in solution are also much more stable in terms of exposure to air, resulting in improved safety and easier handling.

[0069] Optionally, the electrode may undergo a first rinsing / washing step 102, thereby removing excess first reagent from step 100 with a solvent. Here, most or all of the unadsorbed first reagent is removed from the electrode surface before moving the electrode to the next method step. Key method variables include solvent temperature, electrode temperature, and residence time. 102 in Figure 1 The step is shown as a single step; however, in some embodiments, the step may be repeated or may have additional rinsing / washing steps to improve the removal of the first reagent.

[0070] The rinsing step leaves exactly a saturated (i.e., purified) first layer on the electrode and a residual solution in the reaction chamber containing the first solvent, one or more unreacted first reagents, and other reaction byproducts.

[0071] As an optional step, to recover the solvent and any unreacted reagents used in the rinsing step, the residual solution can be passed to filtration step 103. The filtration step separates the solvent from unreacted reagents (and any reaction byproducts). The filtration step also prevents cross-contamination between chambers and avoids slow contamination of the rinsing solution by reagents during operation. A continuous filtration rinsing bath not only maintains the purity of the rinsing solvent but can also be used as a material recovery system, thereby improving the material utilization efficiency of the method. Any filtration technique known in the art can be used. Preferred techniques include, but are not limited to, membrane separation, chemical precipitation, ion exchange, electrochemical removal, physical adsorption, and flow filtration chromatography.

[0072] The separated solvent can be recycled back to rinsing step 102 for reuse. Similarly, the filtered unreacted one or more first reagents can be recycled back to step 100 for further use in the method (not shown).

[0073] Then, in 104, the battery pack electrode, which has a partially coated layer containing the adsorbed first reagent (i.e., a self-restricting layer), can be exposed to a second liquid solution containing the second reagent in the second reaction chamber.

[0074] In some embodiments, the second liquid solution may contain an oxidizing agent, such as an oxide or sulfide source, examples of which include, but are not limited to, water, thioacetamide, and sodium sulfide. A solvent may also be present, which may contain polar or nonpolar organic solvents or may be water alone. In other embodiments, the second liquid solution may also contain a nitrogen-containing reagent, such as ammonia or hydrazine. In some embodiments, the pH of the second solution may also be varied.

[0075] The second reagent has a different and unique composition compared to the first reagent. The second reagent is selected to react with the adsorbed first reagent to produce a complete monolayer of thin film compound coated on the electrode.

[0076] In some implementations, the entire membrane can be formed solely from the reagents exposed to the electrodes from the first liquid solution. In this case, the second solution can be completely skipped.

[0077] In some embodiments, the resulting compound may contain metal oxides, such as Al2O3 and TiO2.

[0078] In other embodiments, the resulting compound may comprise a transition metal dichalcogenide (TMD). Typical examples of such materials follow the general chemical formula MX2, where M is a transition metal, such as Mo, W, Ti, etc., and X is S or Se.

[0079] In some embodiments, the compound consists of any combination of the following polymers: polyethylene oxide (PEO), polyvinyl alcohol (PVA), polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS), and polyvinylpyrrolidone (PVP). When combined with lithium salts (e.g., especially LiClO4, LiPF6, or LiNO3), such polymers can produce solid polymer electrolyte films.

[0080] In some embodiments, the compound may contain sulfides or selenides of, for example, Mo, Ti, or W. These materials vary widely in their electronic properties (e.g., band gap) and can therefore be used to form custom semiconductor heterojunctions that, for example, block electron transfer necessary for degradation reactions during lithium-ion battery pack operation. Specifically, such mechanisms can be used to block degradation reactions on both the anode and cathode surfaces.

[0081] In some implementation schemes, the resulting compound may be selected from:

[0082] (a) A x O y Type 2 binary oxide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, and x and y are stoichiometric coefficients;

[0083] (b) Ax B y O z Type ternary oxides, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, and x, y and z are stoichiometric coefficients;

[0084] (c) A w B x C y O z A type quaternary oxide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients;

[0085] (d) A x B y Type II halide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, B is a halogen, and x and y are stoichiometric coefficients;

[0086] (e) A x B y C z Type ternary halide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, C is a halogen, and x, y and z are stoichiometric coefficients;

[0087] (f) A w B x C y D z A type quaternary halide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, D is a halogen, and w, x, y, and z are stoichiometric coefficients;

[0088] (g) A x N y Type II nitride, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, and x and y are stoichiometric coefficients;

[0089] (h) A x B y N z Type ternary nitrides, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, and x, y and z are stoichiometric coefficients;

[0090] (i) A w B x C y N zA type quaternary nitride, wherein A, B and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, and w, x, y and z are stoichiometric coefficients;

[0091] (j) A x B y Type II chalcogenides, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, B is a chalcogenide, and x and y are stoichiometric coefficients;

[0092] (k) A x B y C z A type of ternary chalcogenide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, C is a chalcogenide, and x, y and z are stoichiometric coefficients;

[0093] (l) A w B x C y D z A type quaternary chalcogenide, wherein A, B and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, D is a chalcogenide, and w, x, y and z are stoichiometric coefficients.

[0094] (m) A x C y Type II binary carbides, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, and x and y are stoichiometric coefficients;

[0095] (n) A x B y O z Type II halide oxides, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, B is a halogen, and x, y and z are stoichiometric coefficients;

[0096] (o) A x As y Type II arsenide, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, and x and y are stoichiometric coefficients;

[0097] (p) A x B y As z Type ternary arsenide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals or metalloids, and x, y and z are stoichiometric coefficients;

[0098] (q) A w B x C y Asz A type quaternary arsenide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients;

[0099] (r) A x (PO4) y Type diphosphate, wherein A is an alkali metal, alkaline earth metal, transition metal, half-metal or metalloid, and x and y are stoichiometric coefficients;

[0100] (s) A x B y (PO4) z Type III triphosphates, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and x, y, and z are stoichiometric coefficients; and

[0101] (t) A w B x C y (PO4) z A type tetraphosphate, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, half-metals, or metalloids, and w, x, y, and z are stoichiometric coefficients.

[0102] In reactions involving nonionic precursors (e.g., organometallic compounds) and oxidants, such as in the hydrolysis of trimethylaluminum, the organic portion is removed and replaced by metal-oxygen-metal bonds until all bonds are fully saturated. In reactions involving two ionic solutions, such as in the hydrolysis of Cd... 2+ and S 2- In reactions between solutions of ions, the high solubility product constant of the reaction promotes the precipitation of ionic compounds (in this case, CdS), where the electrode promotes the formation of a heterogeneous film by minimizing surface energy.

[0103] Similar to step 102, the electrode from step 104 is then directed to a second rinsing / washing step 106 to remove unadsorbed / unreacted second reagent.

[0104] In some embodiments, the thickness of the film can be from about 0.5 nm to 100 µm. For example, the thickness of the film can be in the range of 0.5 nm-10 nm, 10 nm-50 nm, 50 nm-100 nm, 100 nm-500 nm, 500 nm-1 µm, 1 µm-10 µm, 10 µm-50 µm, or 50 µm-100 µm.

[0105] In some embodiments, the process can be repeated 100 to 106 times until a thin film coating of the desired thickness is formed on the electrode. This process is indicated by step 108, in which the electrode coated with the film is guided back to step 100 for further processing (ring formation). In some embodiments, these steps are repeated with different precursors to produce a stack of coatings comprising films containing various compounds.

[0106] Additionally, during steps 102 and 106, the solvent can be continuously or periodically filtered, rinsed, or washed to separate and recover unreacted one or more reagents from the solvent. This filtration step is indicated in steps 103 and 105, respectively. Both the precursor and the solvent can then potentially be recycled back into the method. Here, solvent recycling is indicated by a return arrow. These filtration steps will save significant material costs over the life of the equipment. A filtration step can be incorporated into the design for each washing and rinsing step. The filtration technique is preferably tailored to the type of reagent used in steps 100 and 104. For example, aqueous ionic solutions may require adequate filtration of the type of filter column used in the deionizer. However, organometallic compounds can be better removed by tangential flow filtration systems, such as those that exclude by molecular weight.

[0107] exist Figure 2 The diagram shows a schematic representation of an embodiment of a system for coating a thin film onto an electrode surface. Figure 2 In this context, the reaction chamber is shown as a tank or bath containing a sequence of reaction solutions; electrodes are transferred into the reaction chamber with the aid of a conveying device. Although Figure 2 The embodiments described herein relate to methods for coating thin films onto the surfaces of battery pack electrodes. This description represents only the components coated using the methods and systems provided herein and should not be construed as limiting in any way.

[0108] Figure 2 The conveying equipment is particularly suitable and adapted to guide or direct the battery pack electrodes in a sequential manner into and out of the first and second reaction chambers.

[0109] The preferred automated conveying equipment comprises a series of rollers, such as tension rollers, positioned to guide or direct the electrodes in and out of the first and second reaction chambers. This allows the system to provide a continuous liquid deposition method for coating a thin film onto the electrode surface. The series of rollers 202a-i is driven by a conveying motor (not shown). The rollers 202a-i are operated and oriented in such a way that the electrode 201 can be conveyed through the system, as discussed in more detail below. The system 200 also includes a series of chambers 205, 207, 215, and 217.

[0110] In some embodiments, the first and second reaction chambers may include sensors for determining or measuring the volume of the first or second liquid solution in the respective reaction chamber or the precursor concentration in each respective reaction chamber. Additionally, the first and second reaction chambers may also include regulating valves electrically driven by the sensors. When the sensor (e.g., a float switch) determines that the liquid solution is too low, the valve opens, allowing more liquid solution to flow into the reaction chamber from another source. In some cases, a pump (e.g., a peristaltic pump) is used to drive the liquid solution into the reaction chamber. When the sensor determines that the liquid solution is at a desired level, the valve closes, preventing excess liquid solution from flowing into the reaction chamber. In some cases, if the sensor determines that the liquid solution in the reaction chamber is too high, the valve opens, allowing excess liquid to flow out of the reaction chamber. In cases where the sensor detects a precursor concentration, the valve can expose the tank to a reserve solution with a high precursor concentration if a low precursor solution concentration is detected, and vice versa. An example of such a sensor is an ion-selective electrode.

[0111] In a further embodiment, the system includes a first rinsing chamber located between the first and second reaction chambers. The first rinsing chamber contains a first rinsing solution comprising a first solvent for rinsing electrodes conveyed to the first rinsing chamber by a conveying device to produce a saturated first layer on the electrodes, and a first residual solution comprising the first solvent and unreacted first reagent.

[0112] Similarly, the system may also include a second rinsing chamber located after the second reaction chamber. The second rinsing chamber contains a second rinsing solution containing a second solvent, used to rinse the electrodes conveyed to the second rinsing chamber by the conveying device to produce a thin film coated on the electrodes.

[0113] Chamber 205 is a first reaction chamber containing a first liquid solution comprising a first reagent and a solvent.

[0114] Chamber 207 is a first rinsing chamber located after the first reaction chamber 205, containing a first rinsing solution comprising a first solvent. A first filtration device 209 is connected to the first rinsing chamber 207. The first filtration device 209 has a residue tube 213 and a permeate collection tube 211 connected to the first rinsing chamber 207.

[0115] Another chamber 215 is a second reaction chamber located after the first rinsing chamber 207, and contains a second liquid solution comprising a second reagent and a solvent.

[0116] Chamber 217 is a second rinse chamber located after the second rinse chamber 215. The second rinse chamber 217 contains a second rinse solution containing a solvent. A second filter device 219 is connected to the second rinse chamber 217. The second filter device 219 has a residue tube 223 and a permeate collection tube 221 connected to the second rinse chamber 217.

[0117] System 200 further includes valves 225a-d located in each of chambers 205, 207, 215, and 217, respectively. Valves 225a-d are connected to a replenishment source (not shown) that, when needed, provides additional first liquid solution, second liquid solution, first reagent, second reagent, or solvent, as in the case of first chamber 215 and second chamber 215, or additional first or second rinse solution, as in the case of first rinse chamber 207 and second rinse chamber 217. Valves 225a-d may be electrically actuated and opened by triggering a sensor (not shown) adapted to monitor or measure the volume or concentration of the liquid solution in the chamber. The sensor may be immersed in the liquid solution in each chamber.

[0118] In operation, a first portion of electrode 203 is initially placed on a first roller 202a, which is part of the conveying device 201. Typically, the first portion is attached, for example by adhesive or tape, to guide material that passes through the remaining portions of rollers 202b-i. In this way, the guide material can guide the electrode through the conveying device 201 during the process. Once the portion of the electrode placed on roller 202a has been conveyed to roller 202i, or when the coating of the entire electrode is complete, the guide material can then be removed from the electrode. Examples of such guide material can come from previous rolls of electrode. Prior to coating a particular electrode, a previous roll of electrode may have already had a long tail length without active material (only foil). Once the previous roll has been processed, this residue is left on the conveying device, and the active material can be cut and removed. The remaining portion is then used as a guide to guide the next roll of electrode through the conveying device.

[0119] Therefore, the first portion of electrode 203 is also conveyed into the first reaction chamber 205 by the movement of the second roller 202b located within the first reaction chamber 205. The first portion of electrode 203 is exposed to the first liquid solution within the first reaction chamber 205 to produce a self-restricted layer containing an adsorbed first reagent on the surface of the first portion of the electrode. The first portion of electrode 203 remains in the first reaction chamber 205 for a certain period of time to allow a reaction to occur. Once the reaction is substantially complete, the first portion of electrode 203 is removed from the first reaction chamber 205 by moving upwards to the third roller 202c.

[0120] When this occurs, a second portion of electrode 203 is transferred to the first reaction chamber 205. The transfer device operates continuously until the required amount of electrode is coated with a thin film.

[0121] The first portion returns to electrode 203 and is then conveyed to the first rinse chamber 207 by the movement of the fourth roller 202d located within the first rinse chamber 207. The first rinse chamber 207 contains a first rinse solution containing a first solvent for rinsing electrode 203 to produce a saturated first layer on the electrode, and a first residual solution containing the first solvent and unreacted first reagent.

[0122] The system may also include a filtration device for separating unreacted reagents from the solvent in the first and second wash solutions. The filtration device can be any instrument capable of performing such a separation. Preferably, the filtration device is selected from one of the following: membrane, filter column or chromatographic column, chemical or electrochemical separation tank, or adsorption column.

[0123] When needed, the first rinse solution is passed to the first filter device 209 to separate the unreacted first reagent from the first solvent. Compared to the first rinse solution, the first filter device 209 produces a permeate stream rich in unreacted first reagent and lean in first solvent, and a residual stream rich in first solvent and lean in unreacted first reagent. The permeate stream is collected in the permeate collection tube 211, which can be recycled or returned to the first reaction chamber 205. The residual stream is recycled back to the first rinse chamber 207 via the residual tube 213. The filter device 209 can be operated periodically or continuously. From the first rinse chamber 207, the first portion of the electrode 203 is removed from the first rinse chamber 207 by moving upwards to the fifth roller 202e.

[0124] The first portion of electrode 203 is then transferred into the second reaction chamber 215 by moving downwards to the sixth roller 202f located within the second reaction chamber 215. The second reaction chamber 215 contains a second liquid solution containing at least a second reagent. Within the second reaction chamber 215, electrode 203 is exposed to the second liquid solution, which reacts with the first adsorbed reagent to produce a monolayer film coated on the electrode surface. After the reaction is substantially complete, the first portion of electrode 203 is removed from the second reaction chamber 215 by moving upwards to the seventh roller 202g.

[0125] Next, the first portion of electrode 203 is also transferred to the second rinsing chamber 217 by moving downwards to the eighth roller 202h located within the second rinsing chamber 217. The second rinsing chamber 217 contains a second rinsing solution containing a second solvent for rinsing the electrode to produce a purified monolayer film coated on the surface of electrode 203, and a second residual solution containing the second solvent and unreacted second reagent.

[0126] Similar to the first rinse solution, the second rinse solution can be sent to the second filtration device 219. Compared to the second rinse solution, the second filtration device 219 produces a permeate stream rich in unreacted second reagent and lean in second solvent, and a residual stream rich in second solvent and lean in unreacted second reagent. The permeate stream is collected in the permeate collection tube 221 and can be recycled or sent back to the second reaction chamber 215. The residual stream is recycled back to the second rinse chamber 217 via the residual tube 223. The filtration device 219 can be operated periodically or continuously.

[0127] Finally, the first portion of electrode 203 is removed from the second rinsing chamber 217 of the ninth roller 202i, which is conveyed upwards. From here, the first portion can be collected or rolled up until the remaining desired portion of the electrode is coated with a thin film.

[0128] and Figure 2 Similar embodiments to those described in this disclosure may include replacing bath-deposition reaction chambers 205 and 215 with a slot die or gravure coating reaction chamber (not shown). In such embodiments, rinsing chambers 207 and 217 may or may not be present, depending on the requirements of the rinsing step. In such embodiments, or even in Figure 2 In the embodiments described herein, excess solution removal techniques (e.g., air knives, scrapers, metering knives, or similar techniques) can be used instead of a rinsing step. In another similar embodiment, 215 may be completely absent, as the entire deposition reaction can take place in 205. Therefore, the apparatus of this disclosure can be considered modular in both its deposition and transport aspects and can be assembled in any particular manner to facilitate a specific solution deposition method.

[0129] The methods disclosed herein can be implemented using or by means of a computer system. The computer system can be involved in many different aspects of the operation of the method, including, but not limited to, regulating various aspects of the delivery device, such as guiding the movement of the delivery device by moving the part to be coated in and out of the reaction chamber; controlling the opening and closing time of valves; guiding liquids (e.g., reagents and buffer solutions) into the reaction chamber by detecting liquid volume via sensor readings; and regulating pumps. In some aspects, the computer system is implemented to automate the methods and systems disclosed herein.

[0130] The methods and systems provided above are now further described by way of the following embodiments, which are intended to be illustrative and not to limit the scope or basic principles in any way. Example

[0131] Example 1: Deposition of TiO2

[0132] First, titanium isopropoxide is dissolved in a suitable anhydrous solvent (e.g., dry isopropanol) and adsorbed onto the electrode surface. Then, excess unadsorbed titanium isopropoxide is removed from the part to be coated (e.g., the electrode) using a rinsing solvent. Next, the electrode is introduced into a solution of an oxidant (e.g., water) dissolved in a suitable solvent (e.g., isopropanol). Hydrolysis causes the loss of the alkoxide ligand to 2-propanol, leaving the adsorbed portion with the added hydroxyl group. In a fourth step, excess water and solvent are removed from the solution by rinsing solvent. A single monolayer of titanium oxide is produced. This process can be repeated to produce increased thickness.

[0133] Example 2: Deposition of CdS

[0134] Cadmium sulfate (CdSO4) first dissolves in an aqueous solution, producing Cd adsorbed on the electrode surface. 2+ Ions. Remove excess unadsorbed Cd from the electrode. 2+ The electrode is then introduced into an aqueous solution containing anionic sulfur precursors (e.g., thiourea or Na₂S). The pH of the precursor solution can be varied to control the reaction rate. The high solubility product constant of CdS in this reaction results in a single monolayer of CdS precipitating on the electrode surface, where surface energy is minimized to promote nucleation.

[0135] Example 3: Deposition of TiN

[0136] Immerse or expose the electrode (or other component to be coated) in an anhydrous ethanol solution of dissolved titanium ethoxide. Remove excess precursor from the electrode. Expose the electrode to a solution containing a nitrogen precursor, such as ammonia in pyridine or hydrazine in THF. The reaction of the precursor with adsorbed titanium ethoxide produces a single monolayer of TiN.

[0137] Example 4: Coating a thin film on a graphite anode

[0138] A coating method was performed on a graphite anode. The presence of the coating was confirmed using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). SEM images showed a significant change in the morphology of the graphite anode surface from before to after coating. Figures 3A-3B Then, EDX measurements of local Al and O signals confirmed that the coating material was indeed Al2O3. The approximately 0.9 atomic% Al measured by EDX was within the range of EDX signals for Al observed in graphite anodes coated with approximately 1 nm ALD, as documented in the literature. Therefore, it can be concluded from the literature that solution-coated Al2O3 is within the range of coating thicknesses deposited via ALD.

[0139] Example 5: Production of a graphite-lithium half-cell

[0140] A coated graphite anode is paired with a lithium foil to generate a graphite-Li half-cell. The half-cell is ideal for generating accurate data on the irreversible capacity loss due to SEI formation on the graphite. A rapid learning cycle is also possible, considering that only one charge-discharge cycle is required to measure the capacity loss in the first cycle. Figure 4-5 As shown in Table 1, when comparing the Al2O3-coated anode with the control, the average first cycle loss showed a statistically significant difference of 1.37% (to 95% confidence level).

[0141] Table 1

[0142]

[0143] By plotting the charge difference / voltage difference (dQ / dV) relative to the half-cell voltage, the amount of charge transferred during the typical SEI formation voltage of approximately 0.6–0.8 V can be accurately identified. Figure 6 It can be seen that the coated half-cell (601) has a lower charge difference in SEI generation compared to the uncoated half-cell (600), which clearly indicates that SEI generation is suppressed by the coating.

[0144] It should be understood from the foregoing that, although specific embodiments have been described and illustrated, various modifications are possible and contemplated herein. This disclosure is also not intended to be limited by the specific examples provided in the specification. While certain embodiments have been described with reference to the foregoing specification, the description and illustration of preferred embodiments herein are not intended to be construed as limiting. Furthermore, it should be understood that all aspects of this disclosure are not limited to the specific descriptions, configurations, or relative proportions presented herein, and depend on a variety of conditions and variables. Various modifications in form and detail of the embodiments will be apparent to those skilled in the art. Therefore, this disclosure is also intended to cover any such modifications, variations, and equivalents.

Claims

1. Battery pack, comprising: anode; cathode; An electrolyte disposed between the anode and the cathode; A polymer separator disposed between the anode and the cathode; and A housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing provides electrical contact with the anode and the cathode, and At least one of the anodes or cathodes comprises an artificial solid-electrolyte interface layer, i.e., an artificial SEI layer, produced by a liquid-phase deposition method, the liquid-phase deposition method comprising: (a) Supplying the battery pack anode and / or cathode to the conveying equipment; (b) The anode or cathode of the battery pack is transferred by the conveying device to a first reaction chamber containing a first liquid solution, the first liquid solution containing at least a first reagent, the first reagent containing an organic portion and Si and / or a metal containing Al, Zn, Ti, Zr, Hf, Mn and / or V; (c) Exposing the battery pack anode and / or cathode to the first liquid solution in the first reaction chamber via the conveying device to produce an artificial SEI battery pack anode or cathode partially coated by the layer formed by the at least first reagent chemically bonded to the surface of the battery pack anode or cathode; (d) The layer is rinsed in the first reaction chamber with a first rinsing solution containing a first solvent to remove unreacted first reagent; (e) The anode or cathode of the battery pack from (d) is transferred via the conveying device to a second reaction chamber containing a second liquid solution, the second liquid solution comprising at least a second reagent, the second reagent including ethylene glycol, glycerol, erythritol, xylitol, sorbitol, mannitol, butylene glycol, pentanediol, hydroquinone, hexanediol, lactic acid, triethanolamine, p-phenylenediamine, glycidyl ether, caprolactone, fumaric acid, aminophenol and / or diaminodiphenyl ether; (f) Exposing the battery pack anode and / or cathode to the second liquid solution in the second reaction chamber via the conveying device, wherein the at least second reagent reacts with the at least first reagent chemically bonded to the surface of the battery pack anode and / or cathode to produce a fully coated battery pack anode and / or cathode having an artificial SEI layer comprising a monolayer coating on the surface of the battery pack anode or cathode, the monolayer comprising at least one or more metalcones, the metalcones being compounds generated by the reaction of the at least second reagent with the first reagent; and (g) Rinse the coating in the second reaction chamber with a second rinsing solution containing a second solvent to remove unreacted second reagent; and The steps of the liquid phase deposition method are repeated to produce the continuous growth of multiple stacked monolayers.

2. The battery pack according to claim 1, wherein the anode has the artificial SEI layer.

3. The battery pack according to claim 1, wherein the cathode has the artificial SEI layer.

4. The battery pack according to claim 1, wherein both the anode and the cathode have an artificial SEI layer.

5. The battery pack according to any one of claims 1-4, wherein the artificial SEI layer comprises a thin film coating with a total thickness between 0.5 nanometers (nm) and 100 micrometers (µm).

6. The battery pack according to any one of claims 1-5, wherein the thickness of the anode or cathode of the battery pack in (a) is from 100 nm to 1,000 µm.

7. The battery pack according to any one of claims 1-6, wherein the anode or cathode of the battery pack in (a) has pores ranging in size from 0.1 nm to 100 µm.

8. The battery pack according to any one of claims 1-7, wherein the membrane porosity of the anode or cathode of the battery pack in (a) is 1-99%.

9. The battery pack according to any one of claims 1-8, wherein the anode and / or cathode comprises one or more of the following: graphite, Si, Sn, Ge, Al, P, Zn, Ga, As, Cd, In, Sb, Pb, Bi, SiO, SnO2, lithium metal, LiNi x Mn y Co z O2, LiNi x Co y Al z O2, LiMn x Ni y O z LiMnO2, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiV2O5, sulfur or LiCoO2, where x, y and z are stoichiometric coefficients.

10. The battery pack according to any one of claims 1-8, wherein the anode of the battery pack in (a) is composed of graphite, Si, Sn, Si-graphite composite, Sn-graphite composite or lithium metal.

11. The battery pack according to any one of claims 1-10, wherein the cathode of the battery pack in (a) is made of LiNi x Mn y Co z O2, LiNi x Co y Al z O2, LiMn x Ni y O z It is composed of LiMnO2, LiFePO4, LiMnPO4, LiNiPO4, LiCoPO4, LiV2O5, sulfur or LiCoO2, where x, y and z are stoichiometric coefficients.

12. The battery pack according to any one of claims 1-11, wherein the conveying device comprises a series of rollers for guiding the battery pack anode or cathode and the partially coated battery pack anode or cathode to the first and second reaction chambers, respectively.

13. The battery pack according to any one of claims 1-12, wherein the anode, cathode, partially coated anode and / or partially coated cathode are exposed to the first and second liquid solutions by a method selected from immersion, spraying, slot die coating and gravure roller coating.

14. The battery pack of claim 1, wherein the first and second liquid solutions are nonionic.

15. The battery pack of claim 1, wherein the method further comprises: The partially coated anode or cathode of the battery pack is rinsed with a first rinsing solution containing a first solvent to produce a saturated first layer on the partially coated anode or cathode of the battery pack, and to produce a first residual solution containing the first solvent and an unreacted first reagent.

16. The battery pack of claim 15, wherein the liquid phase deposition method further comprises: The first residual solution is passed through a first filtration step to separate the unreacted first reagent from the first solvent.

17. The battery pack of claim 1, wherein the liquid phase deposition method further comprises: The fully coated battery anode or cathode is rinsed with a second rinsing solution containing a second solvent to produce a saturated monolayer film on the fully coated battery anode or cathode, and to generate a second residual solution containing the second solvent and an unreacted second reagent.

18. The battery pack of claim 17, wherein the liquid phase deposition method further comprises: The second residual rinsing solution is passed to a second filtration step to separate the unreacted second reagent from the second solvent.

19. The battery pack of claim 16 or claim 18, wherein the liquid phase deposition method further comprises: The recovered unreacted first or second reagent is recycled back into the first or second liquid solution, respectively. and The recovered first or second solvent is recycled back to the first or second rinsing solution, respectively.

20. The battery pack of claim 16 or claim 18, wherein the filtration step of the liquid phase deposition method is performed using membrane separation, chemical precipitation, ion exchange, electrochemical removal, physical adsorption, flow filtration chromatography, or a combination thereof.

21. The battery pack of claim 1, wherein the first liquid solution of the liquid phase deposition method comprises more than one reagent.

22. The battery pack of claim 1, wherein the second liquid solution comprises more than one reagent.

23. The battery pack of claim 1, wherein the first and second reagents are organometallic precursors.

24. The battery pack of claim 1, wherein the first and second reagents are cations or anions.

25. The battery pack of claim 1, wherein the first and second liquid solutions further comprise an organic solvent, water, or a mixture of both.

26. The battery pack of claim 1, wherein the compound produced is selected from one of the following: (a) A x O y Type II binary oxide, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, and x and y are stoichiometric coefficients; (b) A x B y O z Type ternary oxides, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals or metalloids, and x, y and z are stoichiometric coefficients; (c) A w B x C y O z Type quaternary oxides, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, or metalloids, and w, x, y, and z are stoichiometric coefficients; (d) A x B y Type II halide, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, B is a halogen, and x and y are stoichiometric coefficients; (e) A x B y C z Type ternary halide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals or metalloids, C is a halogen, and x, y and z are stoichiometric coefficients; (f) A w B x C y D z A type quaternary halide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, or metalloids, D is a halogen, and w, x, y, and z are stoichiometric coefficients; (g) A x N y Type II nitride, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, and x and y are stoichiometric coefficients; (h) A x B y N z Type ternary nitrides, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals or metalloids, and x, y and z are stoichiometric coefficients; (i) A w B x C y N z A type quaternary nitride, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, or metalloids, and w, x, y, and z are stoichiometric coefficients; (j) A x B y Type II chalcogenides, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, B is a chalcogenide, and x and y are stoichiometric coefficients; (k) A x B y C z A type ternary chalcogenide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals or metalloids, C is a chalcogenide, and x, y and z are stoichiometric coefficients; (l) A w B x C y D z A type quaternary chalcogenide, wherein A, B and C are any combination of alkali metals, alkaline earth metals, transition metals or metalloids, D is a chalcogenide, and w, x, y and z are stoichiometric coefficients; (m) A x C y Type II binary carbides, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, and x and y are stoichiometric coefficients; (n) A x B y O z Type II halide oxides, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, B is a halogen, and x, y and z are stoichiometric coefficients; (o) A x As y Type II arsenide, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, and x and y are stoichiometric coefficients; (p) A x B y As z Type ternary arsenide, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals or metalloids, and x, y and z are stoichiometric coefficients; (q) A w B x C y As z A type of quaternary arsenide, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, or metalloids, and w, x, y, and z are stoichiometric coefficients; (r) A x (PO4) y Type diphosphate, wherein A is an alkali metal, alkaline earth metal, transition metal or metalloid, and x and y are stoichiometric coefficients; (s) A x B y (PO4) z Type III triphosphates, wherein A and B are any combination of alkali metals, alkaline earth metals, transition metals, or metalloids, and x, y, and z are stoichiometric coefficients; and (t) A w B x C y (PO4) z Type tetraphosphate, wherein A, B, and C are any combination of alkali metals, alkaline earth metals, transition metals, or metalloids, and w, x, y, and z are stoichiometric coefficients.

27. The battery pack of claim 1, wherein the anode or cathode further comprises a substrate.

28. The battery pack battery of any one of claims 1-27, wherein the battery pack battery undergoes self-heating at a temperature higher than that in a battery pack battery that does not have an artificial SEI on the anode and / or cathode.

29. The battery pack battery according to any one of claims 1-28, wherein the battery pack battery releases CO2, O2, H2 or any other gas at a temperature higher than that observed in a corresponding battery pack battery that does not have an artificial SEI on the anode or cathode.

30. The battery pack according to any one of claims 1-29, wherein the electrolyte comprises a salt and a solvent.

31. The battery pack according to claim 30, wherein the salt is LiPF6, LiClO4, LiTFSI or LiNO3.

32. The battery pack of claim 30 or claim 31, wherein the solvent comprises one or more of the following: ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, fluorinated ethylene carbonate, and propylene carbonate.

33. A battery pack, comprising: anode; cathode; An electrolyte disposed between the anode and the cathode; A polymer separator disposed between the anode and the cathode; and A housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing provides electrical contact with the anode and the cathode. The anode, cathode, and / or both contain an artificial SEI coating, which is prepared by liquid phase deposition using a conveyor system with a series of rollers. The artificial SEI coating comprises a monolayer composed of at least one or more metalcones, the metalcones being generated by a reaction between a first reagent and a second reagent. The first reagent comprises an organic portion and Si and / or a metal, the metal including Al, Zn, Ti, Zr, Hf, Mn, and / or V. The second reagent includes ethylene glycol, glycerol, erythritol, xylitol, sorbitol, mannitol, butylene glycol, pentanediol, hydroquinone, hexanediol, lactic acid, triethanolamine, p-phenylenediamine, glycidyl ether, caprolactone, fumaric acid, aminophenol, and / or diaminodiphenyl ether. The battery packs described therein release CO2, O2, H2, or any other gas at temperatures higher than those observed in corresponding battery packs that do not have an artificial SEI on the anode or cathode.

34. A battery pack, comprising: anode; cathode; An electrolyte disposed between the anode and the cathode; A polymer separator disposed between the anode and the cathode; and A housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing provides electrical contact with the anode and the cathode; The anode, the cathode, and / or both contain an artificial SEI coating, which is prepared by liquid phase deposition using a conveyor system with a series of rollers. The artificial SEI coating comprises a monolayer composed of at least one or more metalcones, the metalcones being generated by a reaction between a first reagent and a second reagent. The first reagent comprises an organic portion and Si and / or a metal, the metal including Al, Zn, Ti, Zr, Hf, Mn, and / or V. The second reagent includes ethylene glycol, glycerol, erythritol, xylitol, sorbitol, mannitol, butylene glycol, pentanediol, hydroquinone, hexanediol, lactic acid, triethanolamine, p-phenylenediamine, glycidyl ether, caprolactone, fumaric acid, aminophenol, and / or diaminodiphenyl ether. The battery cells described therein undergo self-heating at a temperature higher than that of the corresponding battery cells that do not have an artificial SEI on the anode or cathode.

35. The battery pack battery of any one of claims 1-34, wherein the battery pack battery is rechargeable.

36. A battery pack, comprising: anode; and cathode; At least one of the anodes or cathodes comprises an artificial SEI coating produced by a liquid phase deposition method, the method comprising: At least one of the anode or cathode is provided to the transmission device; and At least one of the anodes or cathodes is transferred via the conveying device to one or more reaction chambers, the reaction chambers containing one or more liquid solutions comprising at least two different reagents; and The active material of at least one of the anodes or cathodes is exposed to the one or more liquid solutions via the conveying device, wherein the at least two different reagents react to produce a fully coated battery electrode comprising a monolayer film on the surface of its active material, the monolayer film comprising one or more organic materials generated by the reaction of the at least two different reagents, wherein the one or more organic materials include polyamide, polyimide, polyurea, polyoxymethylene, fluorinated elastomers, or any combination thereof.

37. The battery pack of claim 36, wherein the liquid phase deposition method comprises: (a) Supplying the battery pack anode and / or cathode to the conveying equipment; (b) The anode or cathode of the battery pack is transferred by the conveying device to a first reaction chamber containing a first liquid solution, the first liquid solution containing at least a first reagent; (c) Exposing the anode and / or cathode to the first liquid solution in the first reaction chamber via the conveying device to produce a partially coated anode or cathode having a layer formed by the at least first reagent chemically bonded to the surface of the battery pack anode or cathode; (d) The layer is rinsed in the first reaction chamber with a first rinsing solution containing a first solvent to remove unreacted first reagent; (e) The anode or cathode of the battery pack from (d) is transferred via the conveying device to a second reaction chamber containing a second liquid solution, the second liquid solution containing at least a second reagent; (f) The battery pack anode and / or cathode are exposed to the second liquid solution in the second reaction chamber via the conveying device, wherein the at least second reagent reacts with the at least first reagent chemically bonded to the surface of the battery pack anode and / or cathode to produce the artificial SEI comprising a monolayer on the surface of the battery pack anode or cathode, the monolayer comprising a compound generated by the reaction of the at least second reagent with the first reagent; and (g) Rinse the coating in the second reaction chamber with a second rinsing solution containing a second solvent to remove unreacted second reagent.

38. The battery pack of claim 36 or claim 37, wherein the battery pack is rechargeable.

39. A battery pack, comprising: anode; cathode; An electrolyte disposed between the anode and the cathode; A polymer separator disposed between the anode and the cathode; and A housing containing the anode, the cathode, the electrolyte, and the polymer separator, wherein the housing provides electrical contact with the anode and the cathode, and At least one of the anodes or cathodes comprises an artificial solid-electrolyte interface layer, i.e., an artificial SEI layer. The artificial SEI coating comprises a monolayer composed of at least one or more metalcones, the metalcones being generated by a reaction between a first reagent and a second reagent. The first reagent comprises an organic portion and Si and / or a metal, the metal including Al, Zn, Ti, Zr, Hf, Mn and / or V. The second reagent includes ethylene glycol, glycerol, erythritol, xylitol, sorbitol, mannitol, butylene glycol, pentanediol, hydroquinone, hexanediol, lactic acid, triethanolamine, p-phenylenediamine, glycidyl ether, caprolactone, fumaric acid, aminophenol and / or diaminodiphenyl ether. The artificial SEI layer is capable of withstanding exposure to temperatures up to 100°C without exothermic decomposition, and the artificial SEI layer is prepared by a liquid phase deposition method using a conveyor with a series of rollers.

40. The battery pack of claim 39, wherein the artificial SEI layer is capable of withstanding exposure to temperatures up to 200°C without exothermic decomposition.

41. The battery pack of claim 39, wherein the artificial SEI layer is capable of withstanding exposure to temperatures up to 300°C without exothermic decomposition.

42. The battery pack according to any one of claims 39-41, wherein the artificial SEI layer does not react exothermically with any physically adjacent electrolyte, polymer separator or other battery pack components.

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