PRE-LITHIATED THERMALLY STABLE SEPARATOR

Abstract

Pre-lithiated separator for use in an electrochemical cell. The pre-lithiated separator comprises a base film, which is a polymer with a melting point above 180 °C, a ceramic that is in direct contact with the base film, and lithium on an outer surface of the pre-lithiated separator.

Description

INTRODUCTION

[0001] The present disclosure relates to batteries and methods for their manufacture. More particularly, the present disclosure relates to pre-lithiated separators with improved electrochemical and mechanical properties and methods for their manufacture.

[0002] A battery is a device that converts chemical energy into electrical energy using electrochemical reduction-oxidation (redox) reactions. In secondary or rechargeable batteries, these electrochemical reactions are reversible, allowing the batteries to undergo multiple charge and discharge cycles.

[0003] Lithium secondary batteries may contain one or more electrochemical cells that operate by the reversible passage of lithium ions between a negative and a positive electrode. The negative and positive electrodes may be disposed on opposite sides of a porous polymeric separator, and each of the negative and positive electrodes is typically supported by or connected to a metallic current collector. The negative and positive electrodes and the polymeric separator are infiltrated with an ionically conductive electrolyte, which provides a medium for the conduction of lithium ions through the electrochemical cell between the negative and positive electrodes.An electrochemical potential can be established between the negative and positive electrodes of the electrochemical cell by connecting their respective current collectors via an interruptible external circuit. During discharge, the electrochemical potential established between the negative and positive electrodes leads to spontaneous redox reactions within the electrochemical cell and the release of lithium ions and electrons at the negative electrode. The released lithium ions migrate from the negative electrode to the positive electrode through the ion-conducting electrolyte, and the electrons migrate from the negative electrode to the positive electrode via the external circuit, generating an electric current.After the lithium of the negative electrode is partially or completely depleted, the electrochemical cell can be recharged by connecting the negative and positive electrodes to the external power source, which causes non-spontaneous redox reactions within the electrochemical cell and the release of lithium ions and electrons from the positive electrode.

[0004] During the initial charging of a lithium secondary battery, an electrically insulating and ionically conductive layer, called a solid electrolyte interlayer (SEI), may form on a negative electrode surface at the interface between the negative electrode and the electrolyte. This native SEI is believed to naturally form due to the low reduction potential of the electrochemically active material of the negative electrode, which promotes the reduction of the electrolyte at the negative electrode surface. The SEI forms an ionically conductive (allowing the transport of Li +-ions) and electrically insulating barrier between the negative electrode and the electrolyte. The formation of a stable SEI on the negative electrode can help prevent further physical contact and unwanted side reactions between the negative electrode material and the electrolyte during battery operation.

[0005] Chemical reactions between the negative electrode material and the electrolyte that occur during SEI formation are parasitic and can consume active lithium, leading to irreversible capacity loss and reduced battery cycle life. Accordingly, it is desirable to provide separators that enable a rechargeable lithium-ion battery containing them to exhibit improved first cycling efficiency, higher energy density, and longer cycle life. SUMMARY

[0006] In an exemplary embodiment, the present disclosure provides a pre-lithiated separator for use in an electrochemical cell. The pre-lithiated separator may comprise a base film containing a polymer with a melting point greater than 180°C, a ceramic in direct contact with the polymer, and lithium on an outer surface of the pre-lithiated separator.

[0007] In addition to one or more of the features described herein, the polymer having a melting point above 180 °C may include a polyaramid, a polyimide, polyethylene terephthalate, polytetrafluoroethylene, a polyimide nanofiber nonwoven, a nanoscale Al2O3 and a poly(lithium 4-styrenesulfonate) coated polyethylene membrane, a SiO2-coated polyethylene, a co-polyimide-coated polyethylene, a polyetherimide, bisphenol acetone diphthalic anhydride, para-phenylenediamine, expanded polytetrafluoroethylene reinforced polyvinylidene fluoride hexafluoropropylene, or a combination thereof.

[0008] In another exemplary embodiment, the ceramic may contain Al2O3, SiO2, ZrO2, TiO2, lithium titanate, lithiated zeolite, zeolite, MgO, boehmite, or a combination thereof.

[0009] In another exemplary embodiment, the thickness of the lithium may compensate for the capacity loss during a first cycle of an electrochemical cell containing the pre-lithiated separator.

[0010] In yet another exemplary embodiment, the lithium may be located on a surface of the base film.

[0011] In yet another exemplary embodiment, the ceramic that is in direct contact with the polymer may include a mixture of the ceramic and the polymer.

[0012] In yet another exemplary embodiment, the ceramic directly in contact with the polymer may comprise a ceramic layer directly on the base film; and the lithium on the outer surface of the pre-lithed separator may comprise lithium directly on the ceramic layer.

[0013] In yet another exemplary embodiment, the ceramic layer directly on the base film may comprise a first ceramic layer directly on a first surface of the base film and a second ceramic layer directly on a second surface of the base film, wherein the second surface of the base film is opposite the first surface of the base film; and the lithium directly on the ceramic layer may comprise a first lithium layer directly on the first ceramic layer and a second lithium layer directly on the second ceramic layer.

[0014] In yet another exemplary embodiment, the ceramic layer may be exposed at an edge of the base film.

[0015] In an exemplary embodiment, the present disclosure provides a method for forming a pre-lithiated separator. The method may include directly depositing a ceramic onto a base film containing a polymer with a melting point greater than 180°C and directly depositing lithium onto the ceramic to form the pre-lithiated separator.

[0016] In addition to one or more of the features described herein, the deposition of lithium may be accomplished by thermal evaporation, sputtering, ion beam deposition, or a combination thereof.

[0017] In another exemplary embodiment, the deposition of lithium may occur at a processing temperature that is below the melting point of the polymer.

[0018] In yet another exemplary embodiment, the polymer having a melting point above 180°C may include a polyaramid, a polyimide, polyethylene terephthalate, polytetrafluoroethylene, a polyimide nanofiber nonwoven, a nanoscale Al2O3 and a poly(lithium 4-styrenesulfonate) coated polyethylene membrane, a SiO2 coated polyethylene, a co-polyimide coated polyethylene, a polyetherimide (PEI), bisphenol acetone diphthalic anhydride (BPADA), para-phenylenediamine, expanded polytetrafluoroethylene reinforced polyvinylidene fluoride hexafluoropropylene, or a combination thereof.

[0019] In yet another exemplary embodiment, the ceramic may include Al2O3, SiO2, ZrO2, TiO2, lithium titanate, lithiated zeolite, zeolite, MgO, boehmite, or a combination thereof.

[0020] In yet another exemplary embodiment, depositing the lithium directly onto the ceramic may include depositing the lithium to a calculated thickness to compensate for capacity loss during a first cycle of an electrochemical cell including the pre-lithiated separator.

[0021] In yet another exemplary embodiment, depositing the lithium directly onto the ceramic may comprise depositing the lithium onto a surface of the base film.

[0022] In yet another exemplary embodiment, directly depositing the ceramic onto a base film may comprise depositing a first ceramic layer directly onto a first surface of the base film and depositing a second ceramic layer directly onto a second surface of the base film, wherein the second surface of the base film is opposite the first surface of the base film; and directly depositing lithium onto the ceramic may comprise depositing a first lithium layer directly onto the first ceramic layer and depositing a second lithium layer directly onto the second ceramic layer.

[0023] In yet another exemplary embodiment, depositing the lithium directly onto the ceramic may include leaving an exposed portion of the ceramic layer at an edge of the base film.

[0024] In an exemplary embodiment, the present disclosure provides a method for forming a pre-lithiated separator. The method may include forming a base film containing a polymer having a melting point greater than 180°C and a ceramic, and depositing lithium directly onto an outer surface of the base film to form the pre-lithiated separator.

[0025] In addition to one or more of the features described herein, the polymer having a melting point above 180°C may include a polyaramid, a polyimide, polyethylene terephthalate, polytetrafluoroethylene, a polyimide nanofiber nonwoven, a nanosized Al2O3 and a poly(lithium 4-styrenesulfonate) coated polyethylene membrane, a SiO2 coated polyethylene, a co-polyimide coated polyethylene, a polyetherimide, bisphenol acetone diphthalic anhydride, para-phenylenediamine, expanded polytetrafluoroethylene reinforced polyvinylidene fluoride hexafluoropropylene, or a combination thereof; and the ceramic material may include Al2O3, SiO2, ZrO2, TiO2, lithium titanate, lithiated zeolite, zeolite, MgO thereof.

[0026] The above features and advantages, as well as other features and advantages of the disclosure, will be readily apparent from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Further features, advantages and details are listed only as examples in the following detailed description, which refers to the drawings in which: Fig. 1 schematically shows a disassembled isometric view of a prismatic battery cell including an anode, an electrolytic material, a separator, and a cathode, according to the disclosure; Fig. Figure 2 contains photos of the separators of Comparative Example 1 and Example 1; Fig. 3 is a graphical illustration showing the open circuit voltage of a cell including the separator of Comparative Example 2 (also referred to herein as “cell of Comparative Example 2”) and a cell with the separator of Example 1 after pre-lithiation (also referred to herein as “cell of Example 1”); Fig. 4 is a graphical illustration showing the first cycling efficiency and voltage profile of the cell of Comparative Example 2 and the cell of Example 1; Fig. 5 is a graphical illustration showing the cycling performance of the cell of Comparative Example 2 and the cell of Example 1; Fig. 6A is a graphical illustration showing the cycling performance of the cell of Comparative Example 2 and the cell of Example 1; and Fig. Figure 6B is a graphical illustration showing the cycling performance of the cell of Comparative Example 2 and the cell of Example 1. DETAILED DESCRIPTION

[0028] The following description is merely exemplary and is not intended to limit the present disclosure, its application, or uses. It should be understood that corresponding reference numerals indicate like or corresponding parts and features throughout the drawings.

[0029] A lithium secondary battery may comprise a battery case and an electrochemical cell enclosed within the battery case. The battery case may contain a metal, such as aluminum or steel, or the battery case may contain a foil bag material with multiple laminated layers of metal, plastic, or a combination thereof. The electrochemical cell may contain a stack of positive and negative electrodes electrically separated from each other by porous separators. The positive and negative electrodes and the porous separators of the electrochemical cell may be infiltrated with an ionically conductive electrolyte, for example, by filling the battery case with the electrolyte.

[0030] Batteries can be incorporated into energy storage devices such as rechargeable lithium-ion batteries, which can be used in automotive transport applications (e.g., motorcycles, boats, tractors, buses, camper vans, caravans, and tanks). However, the present technology can also be used in other electrochemical devices, for example (but not limited to) aerospace components, consumer goods, appliances, buildings (e.g., houses, offices, sheds, and warehouses), office equipment and furniture, and machinery for industrial equipment, agricultural equipment, farm machinery, or heavy machinery. The present disclosure provides a pre-lithiated separator with which a rechargeable lithium-ion battery incorporating it can achieve improved first cycling efficiency (e.g.,mitigating an initial irreversible capacity loss that occurs during a first cycle), higher energy density and longer cycle life.

[0031] With reference to the drawings, in which like reference numerals correspond to the same or similar components in the different figures, Fig. 1 schematically illustrates an embodiment of a prismatic-shaped lithium-ion battery cell 10 comprising an electrode pair 15 having a cathode 20, a separator 40, and an anode 30 arranged in a stack and sealed within a flexible pouch 60 containing an electrolyte material 62. In one embodiment of the battery cell, a reference electrode may be disposed between the anode and the cathode. A first, positive battery cell tab 26 and a second, negative battery cell tab 36 protrude from the flexible pouch 60. The terms "anode" and "negative electrode" are used interchangeably. The terms "cathode" and "positive electrode" are used interchangeably. A single electrode pair 15 having an assembly of cathode 20, separator 40, and anode 30 is shown.It can be seen that, depending on the application of the battery cell 10, several pairs of electrodes 15 can be arranged in the flexible bag 60 and electrically connected.

[0032] The cathode 20 includes a first electroactive material 22 disposed on a cathode current collector 24, and the cathode current collector 24 may include a foil portion 25 extending from the first electroactive material 22 to form the second battery cell tab 26.

[0033] The anode 30 includes a second electroactive material 32 disposed on an anode current collector 34. The anode current collector 34 may be a metallic substrate with a foil portion 35 extending from the second electroactive material 32 to form the first battery cell tab 36.

[0034] The cathode and anode current collectors 24, 34 may be plate-shaped metal elements that are in contact with the first and second electroactive materials 22, 32, respectively, over a significant interfacial area. The purpose of the cathode and anode current collectors 24, 34 is to exchange free electrons with the respective first and second electroactive materials 22, 32 during discharging and charging.

[0035] For certain battery cell chemistries, such as those using nanostructured silicon, including silicon nanoparticles, silicon nanowires, porous silicon, or a combination thereof, initial cycling efficiency may be low, e.g., due to the formation of a significant amount of SEI on the large surface area of ​​the anodes, and significant irreversible capacity loss may occur. Compensating for capacity losses can maintain the desired energy density.

[0036] For other anode materials, such as anodes on SiO x -Base, the first cycling efficiency may also be low due to the structural conditions that lead to the formation of nanoscale silicon domains embedded in lithium silicate. Lithium silicate is a non-active material for Li, meaning it cannot absorb or release additional Li during the charge and discharge process. The Li consumed during the formation of lithium silicate may not be reversible, and irreversible capacity loss may occur. To counteract the capacity loss, pre-lithiation can compensate for the Li loss in the system.

[0037] The term "pre-lithiated" (e.g., pre-lithiated separator) used herein means that the separator is lithiated during separator manufacturing and prior to battery assembly and initial cycling of the battery. The excess lithium in the pre-lithiated separator can compensate for the loss of active lithium in the battery's electrochemical cell(s), which may occur, for example, during initial or repeated cycling of the battery due to various lithium-consuming parasitic chemical reactions within the battery's electrochemical cell(s). The disclosed pre-lithiated separator can help increase the reversible capacity and cycle life of lithium secondary batteries.

[0038] The pre-lithiated separator provides electrical isolation (e.g., to prevent physical contact) between the negative electrode and the positive electrode. The pre-lithiated separator also provides a minimal resistance path for the internal conduction of lithium ions. The pre-lithiated separator may comprise a base film containing a polymer with a melting point greater than 180°C, a ceramic in direct contact with the polymer, and lithium on an outer surface of the pre-lithiated separator.

[0039] The pre-lithiated separator may, for example, include a microporous polymeric separator. The polymer has a melting point of more than 180 °C. The polymer may, for example, include a polyaramid, a polyimide, polyethylene terephthalate, polytetrafluoroethylene, a polyimide nanofiber nonwoven, a polyethylene membrane coated with nanoscale Al2O3 and poly(lithium 4-styrenesulfonate), a SiO2-coated polyethylene, co-polyimide-coated polyethylene, polyetherimide (PEI), bisphenol acetone diphthalic anhydride (BPADA), para-phenylenediamine, expanded polytetrafluoroethylene-reinforced polyvinylidene fluoride hexafluoropropylene, or a combination thereof. The thermal deformation of the pre-lithiated separator during manufacturing can be reduced or avoided by using a thermally stable polymer (e.g., with a melting point above 180 °C) as its base film.

[0040] The pre-lithiated separator also contains a ceramic that is in direct contact with the polymer. The ceramic can contain Al2O3, SiO2, ZrO2, TiO2, lithium titanate, lithiated zeolite, zeolite, MgO, boehmite, or a combination thereof. The ceramic can serve as a preventative measure against potential short circuits.

[0041] The base film may contain a mixture of ceramic and polymer. The base film may contain the ceramic (e.g., the ceramic filler), for example, in the form of particles embedded in a polymer matrix. The ceramic may be present in an amount of, for example, 5 wt.% to 70 wt.%, based on the total weight of ceramic and polymer. The ceramic (e.g., the filler or the particles) may be uniformly distributed in the polymer matrix. The ceramic filler may be mixed with precursors for base film formation to form a ceramic-filled polymer separator base film.

[0042] The pre-lithiated separator may contain a ceramic layer directly on the polymer (e.g., the ceramic layer may be sandwiched between the polymer base film and the lithium). The ceramic layer may be disposed on one or more sides of the base film. The ceramic may be deposited on one surface of the base film or on two opposing surfaces of the base film. The ceramic coating may be produced by a casting process in which ceramic powder is mixed with a polymer binder and a solvent to form a slurry, which is then cast onto a polymer separator base film. In the coating process, the binder may first be dissolved in a solvent, and then the ceramic powder may be added to the solution to form a slurry. The slurry may be cast onto both sides of a polymer separator base film.The thickness of the cast slurry can be 0.5 micrometers (µm) to 10 µm or 2 µm to 3 µm.

[0043] Lithium is located on an outer surface of the pre-lithiated separator. The lithium can be deposited on the ceramic layer (e.g., directly on the ceramic layer) or on the base film containing the ceramic (if present). Lithium can be deposited, for example, by thermal evaporation, sputtering, ion beam deposition, or a combination thereof. Lithium can be deposited on one surface of the separator or on two opposing surfaces of the separator, for example, when the ceramic is deposited on two opposing surfaces of the base film.

[0044] The thickness of the lithium can compensate for the capacity loss during the first cycle of an electrochemical cell with a pre-lithiated separator. For example, 5 µm thick lithium with an area of ​​1 square centimeter (cm 2 ) with a capacity of 1 milliampere hour per square centimeter (mAh / cm 2 ). With an anode charge (original design capacity) of 5 mAh / cm 2 and a first cycling efficiency of 80%, the lithium loss is 20% × 5 mAh / cm 2 = 1 mAh / cm 2 A deposition of at least 5 µm thick lithium should fully compensate for the lithium loss.

[0045] The ceramic layer may be exposed at an edge of the base film, or the base film containing ceramic (e.g., ceramic filler) may be exposed at an edge of the base film. Controlled surface coverage with lithium to retain a portion of the ceramic layer exposed at an edge of the base film, or the base film containing a ceramic filler exposed at an edge of the base film, may prevent a short circuit at a pole tab (further disclosed herein) after assembly of an electrochemical cell by preventing lithium from directly contacting another electrode tab after the pre-lithiated separator is folded or deformed.

[0046] When assembling an electrochemical cell containing the pre-lithiated separator, the pre-lithiated separator can be laminated or wound onto a surface of the negative electrode. The lamination process could be achieved by pressing the pre-lithiated separator onto (e.g., against) the anode by (e.g., using) a roller of a rolling machine. The lithium surface of the pre-lithiated separator can face either the positive or negative electrode in an assembled electrochemical cell.

[0047] One method for forming the pre-lithiated separator comprises depositing a ceramic layer directly onto a base film containing a polymer with a melting point greater than 180°C, and depositing lithium directly onto the ceramic to form the pre-lithiated separator. The deposition of the lithium can be performed at a processing temperature below the melting point of the polymer.

[0048] A method for forming the pre-lithiated separator may include preparing (e.g., forming) a base film (e.g., a composite base film) comprising a polymer having a melting point greater than 180°C and a ceramic (e.g., wherein ceramic particles are present as fillers in a polymer having a melting point greater than 180°C), and directly depositing lithium onto the base film to form the pre-lithiated separator. The deposition of the lithium may occur at a processing temperature below the melting point of the polymer.

[0049] The battery can generate an electric current during discharge through reversible electrochemical reactions that occur when the external circuit is closed (connecting the negative and positive electrodes) and when the negative electrode has a lower potential than the positive electrode. The difference in chemical potential between the negative and positive electrodes drives electrons generated at the negative electrode by a reaction, such as the oxidation of intercalated lithium, through the external circuit toward the positive electrode. At the same time, lithium ions, also generated at the negative electrode, are transported through the electrolyte toward the positive electrode.The electrons flow through the external circuit, and the lithium ions migrate through the electrolyte to the positive electrode, where they can be plated, reacted, or intercalated. The electric current flowing through the external circuit can be harnessed and passed through the load device (in the direction of the arrows) until the lithium in the negative electrode is depleted and the battery's capacity is reduced.

[0050] The battery can be recharged or repowered at any time by connecting an external power source (e.g., a charger) to the battery to reverse the electrochemical reactions that occur when the battery discharges. The external power source that can be used to recharge the battery depends on the size, design, and specific use of the battery. Example external power sources include, but are not limited to, an alternating current (AC) to direct current (DC) converter connected to an AC mains supply via a wall outlet and a vehicle alternator. Connecting the external power source to the battery promotes a reaction, such as non-spontaneous oxidation of intercalated lithium, at the positive electrode to produce electrons and lithium ions.The electrons flowing back toward the negative electrode through the external circuit and the lithium ions moving back toward the negative electrode through the electrolyte recombine at the negative electrode, replenishing it with lithium to be consumed during the battery's next discharge cycle. A full discharge followed by a full charge is considered a cycle, in which lithium ions cycle between the positive and negative electrodes.

[0051] The negative electrodes may be "double-sided," meaning that each of the negative electrodes includes discrete first and second layers of electrochemically active negative electrode material disposed on opposite sides of a negative electrode current collector. Each of the negative electrodes may also include a lithium metal layer, which may be disposed between the first and second negative electrode active material layers or on a major surface of either the first or second negative electrode active material layers.

[0052] The positive and negative electrodes located at the ends of the electrochemical cell may be single-sided, meaning that the electrodes each contain a single layer of electrochemically active material for the negative or positive electrode disposed on one side of a metal current collector. A positive electrode located at a first end of the electrochemical cell may contain a positive electrode active material layer disposed on a positive electrode current collector, and a negative electrode located at an opposite second end of the electrochemical cell may contain a negative electrode active material layer disposed on a negative electrode current collector.The negative and positive electrodes disposed between the single-sided positive and negative electrodes may be double-sided, meaning that the electrodes each comprise two discrete layers of electrochemically active negative or positive electrode material disposed on opposite sides of a metal current collector. A double-sided negative electrode may comprise a first negative electrode active material layer on a first side of a negative electrode current collector and a second layer of electrochemically active negative electrode material on an opposite second side of the negative electrode current collector.A double-sided positive electrode may comprise a first positive electrode active material layer on a first side of a positive electrode current collector and a second layer of electrochemically active positive electrode material on an opposite second side of the positive electrode current collector.

[0053] A battery may include a double-sided negative electrode and a double-sided positive electrode spaced from a double-sided negative electrode by a separator. The battery may include multiple repeating units of double-sided negative and positive electrodes separated by separators. The positive and negative electrodes and separators may be assembled in a stack, e.g., by circular winding, prismatic winding, single-sheet stacking, Z-folding, or other cell stacking processes. The current collectors for the positive electrode may be electrically connected to a positive pole tab, and the current collectors for the negative electrode may be electrically connected to a negative pole tab. The positive and negative polarity tabs may extend outside the battery case and be coupled to a power source or load via an external circuit.

[0054] Before hermetically sealing the electrochemical cell in a battery casing, the positive and negative electrodes and the separator(s) can be infiltrated with the ion-conductive electrolyte. After infiltration with the electrolyte, each adjacent pair of positive and negative electrode active material layers can form an electrochemical cell of the battery. A first electrochemical cell can be defined by a positive electrode active material layer disposed on a positive electrode current collector and a first negative electrode active material layer disposed on a first side of a negative electrode current collector.A second electrochemical cell may be defined by a second negative electrode active material layer disposed on a second side of the negative electrode current collector and a first positive electrode active material layer disposed on a first side of the positive electrode current collector, and a third electrochemical cell may be defined by a second positive electrode active material layer disposed on a second side of the positive electrode current collector and a negative electrode active material layer disposed on a negative electrode current collector.

[0055] An electrolyte may infiltrate the first and second negative electrode active material layers, creating an ion-conductive pathway for the transport of lithium ions from the lithium metal layer to the first negative electrode active material layer, to the second negative electrode active material layer, or to a combination thereof prior to initial cycling and battery operation. The lithium metal layer may be referred to as "ionically coupled" via the electrolyte to the first negative electrode active material layer, the second negative electrode active material layer, or a combination thereof.

[0056] A double-sided negative electrode may be configured to supply one or both of its associated electrochemical cells with a stoichiometric excess of lithium prior to initial charging and operation of the battery. The negative electrode may comprise a lithium metal layer having a first major surface and an opposite second major surface. A double-sided negative electrode may be configured such that, when the negative electrode is infiltrated with the electrolyte, the lithium metal layer is in physical contact with the electrolyte and is ionically coupled via the electrolyte to the first negative electrode active material layer, the second negative electrode active material layer, or a combination thereof. The electrolyte may be in physical contact with the first major surface of the lithium metal layer, the second major surface of the lithium metal layer, or a combination thereof.The electrolyte can facilitate the transport of lithium ions from the lithium metal into the first negative electrode active material layer, the second negative electrode active material layer, or a combination thereof prior to initial cycling and battery operation. The lithium metal layer can be disposed between the first and second negative electrode active material layers, or the lithium metal layer can be disposed on a major surface of either the first or second negative electrode active material layer.

[0057] Separators may be disposed between facing or opposing surfaces of adjacent pairs of positive and negative electrode active material layers. For example, in a first electrochemical cell, an opposing or facing surface of the positive electrode active material layer may be spaced from an opposing or facing surface of a negative electrode active material layer by a separator.

[0058] When the negative electrode is infiltrated with an electrolyte, the electrolyte can penetrate the pores of the porous first and second negative electrode active material layers and come into direct physical contact with the lithium metal layer(s). When the electrolyte comes into physical contact with the lithium metal layer(s), an ion-conductive pathway can be established within the negative electrode, enabling the transport of lithium ions from the lithium metal layer into the first negative electrode active material layer, the second negative electrode active material layer, or a combination thereof. Lithium ions released from the lithium metal layer and intercalated into the negative electrode active material layers can supply the associated electrochemical cells with a stoichiometric excess of active lithium, which participates in the electrochemical reactions within the cells.

[0059] After the lithium ions are released from the lithium metal layer, the lithium ions can be intercalated into the negative electrode active material layers, dissolved in the electrolyte, intercalated into the positive electrode active material layers, or a combination thereof. The lithium ions released from the lithium metal layer cannot return there. After the initial charge, repeated cycling of the battery, or a combination thereof, the lithium ions in the lithium metal layer can be completely consumed by the electrochemical reactions within the electrochemical cell(s).

[0060] A double-sided negative electrode may include a negative electrode current collector in the form of a non-porous metal foil having a first side and an opposite second side thereof. A first lithium metal layer may be formed on the first side of the negative electrode current collector, and a second lithium metal layer may be formed on the second side of the negative electrode current collector. The first and second lithium metal layers may be non-porous and may be in the form of non-porous lithium metal foils. A first negative electrode active material layer may be formed on the first side of the negative electrode current collector over the first lithium metal layer, and a second negative electrode active material layer may be formed on the second side of the negative electrode current collector over the second lithium metal layer.

[0061] A first current collector may be positioned at or near the negative electrode. The first current collector may be a metal foil, a metal grid or screen, or expanded metal comprising copper or another suitable electrically conductive material. A second current collector may be arranged at or in the region of the positive electrode. The second current collector may be a metal foil, a metal grid or screen, or expanded metal comprising aluminum or another suitable electrically conductive material. The first current collector and the second current collector may be identical or different. The first current collector and the current collector associated with the second electrode each collect free electrons and move them to and from an external circuit.For example, an interruptible external circuit and a load device may connect the negative electrode (via the first current collector) and the positive electrode (via the second current collector).

[0062] The first current collector, the negative electrode, the separator, the positive electrode, and the second current collector can be fabricated as relatively thin layers (e.g., with a thickness of a few micrometers to one millimeter or less) and assembled in layers connected in a series arrangement to provide a suitable electrical energy, battery voltage, and power package, for example, to form a "SECC" (Series-Connected Elementary Cell Core). The battery can further comprise electrodes connected in parallel to provide suitable electrical energy, battery voltage, and power, for example, to form a "PECC" (Parallel-Connected Elementary Cell Core).

[0063] The electrolyte can facilitate the transport of lithium ions between the adjacent pairs of active material layers of the positive and negative electrodes within the battery's electrochemical cell. The electrolyte can be a non-aqueous, liquid electrolyte solution containing a lithium salt dissolved in a non-aqueous, aprotic organic solvent or a mixture of non-aqueous, aprotic organic solvents.

[0064] Examples of lithium salts are lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClQ4), lithium tetrachloroaluminate (LiAlCl4), lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF4), lithium tetraphenylborate (LiB(C6H5)4), lithium bis(oxalato)borate (LiB(C2O4)2) (LiBOB), lithium difluorooxalatoborate (LiBF2(C2O4)), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethane)sulfonylimide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LiSFI) or a combination thereof.

[0065] Examples of non-aqueous aprotic organic solvents include alkyl carbonates, e.g. B. cyclic carbonates (e.g. ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), fluoroethylene carbonate (FEC)), linear carbonates (e.g. dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylic acid esters (e.g. methyl formate, methyl acetate, methyl propionate), γ-lactones (e.g. γ-butyrolactone, γ-valerolactone), ethers with a chain structure (e.g. 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane), cyclic ethers (e.g. tetrahydrofuran, 2-methyltetrahydrofuran), 1,3-dioxolane), sulfur compounds (e.g. sulfolane) or a combination thereof.

[0066] The electrolyte may comprise solid electrolyte particles having an average particle diameter of greater than or equal to about 0.02 µm to less than or equal to about 20 µm, optionally greater than or equal to about 0.1 µm to less than or equal to about 10 µm, and optionally greater than or equal to about 0.1 µm to less than or equal to about 1 µm. The solid electrolyte particles may have an average particle diameter of greater than or equal to about 0.02 µm to less than or equal to 20 µm, greater than or equal to 0.1 µm to less than or equal to 10 µm, and optionally greater than or equal to 0.1 µm to less than or equal to 1 µm. The solid electrolyte particles may comprise, for example, sulfide-based particles, halide-based particles, hydride-based particles, or other solid electrolyte particles containing, for example, low grain boundary resistance, or a combination thereof.

[0067] The sulfide-based particles may contain a pseudobinary sulfide system, a pseudoternary sulfide system, a pseudoquaternary sulfide system, or a combination thereof. Examples of pseudobinary sulfide systems include Li2S-P2S5 systems (such as Li3PS4, Li7P3S 11 and Li 9,6 P3S 12 ), Li2S-SnS2 systems (such as Li4SnS4), Li2S-SiS2 systems, Li2S-GeS2 systems, Li2S-B2S3 systems, Li2S-Ga2S3 systems, Li2S-P2S3 systems, and Li2S-Al2S3 systems. Examples of pseudoternary sulfide systems include Li2O-Li2S-P2S5 systems, Li2S-P2S5-P2O5 systems, Li2S-P2S5-GeS2 systems (such as Li 3,25 Ge 0,25 P 0,75 S4 and Li 10 GeP2S 12 (LGPS)), Li2S-P2S5-LiX systems (where X is F, Cl, Br or I) (such as Li6PS5Br, Li6PS5Cl, L7P2S8I, and Li4PS4I), Li2S-As2S5-SnS2 systems (such as Li 3,833 Sn 0,833 Ace 0,166S4), Li2S-P2S5-Al2S3 systems, Li2S-LiX-SiS2 systems (where X is F, Cl, Br or I), 0.4 Lil · 0.6 Li4SnS4, and Li 11 Si2PS 12 Examples of pseudoquaternary sulfide systems include Li2O-Li2S-P2S5-P2O5 systems, Li 9,54 Si 1,74 P 1,44 S 11,7 Cl 0,3 , Li7P 2,9 Mn 0,1 S 10,7 I 0,3 and Li 10,35 [Sn 0,27 Si 1,08 ]P 1,65 S 12 .

[0068] The halide-based particles can be, for example, Li3YCl6, Li3InCl6, Li3YBr6, LiIl, Li2CdC 14 , Li2MgCl4, LiCdI4, Li2ZnI4, Li3OCl, or a combination thereof; and the hydride-based particles may comprise, for example, LiBH4, LiBH4-LiX (where x = Cl, Br or I), LiNH2, Li2NH, LiBH4-LiNH2, Li3AlH6, or a combination thereof.

[0069] The electrolyte may be a polymeric gel. For example, a cell may comprise a positive electrode layer, a silicon anode layer (e.g., columnar silicon) (e.g., negative electrode), the exposed pre-lithiated separator, and a current collector for each of the positive electrode layer and the silicon anode layer. The polymeric gel electrolyte may be present in all layers (e.g., the positive electrode layer, the silicon anode layer, and the separator layer).

[0070] The polymeric gel electrolyte can be used to wet the particle-to-particle interfaces in an SSB to improve cell performance. For example, a cell may contain a positive electrode layer, solid electrolyte particles in the positive electrode layer, a silicon anode layer, the exposed pre-lithiated separator between the positive electrode layer and the silicon anode layer, and a current collector of both the positive electrode layer and the silicon anode layer. The polymeric gel electrolyte can be present in all layers (e.g., the positive electrode layer, the silicon anode layer, and the separator layer). The polymeric gel electrolyte can wet (e.g., fill) 5% to 100%, e.g., 80%, of the porosity of the solid electrolyte layer containing solid electrolyte particles.

[0071] The negative electrode may be formed from a lithium host material capable of functioning as the negative terminal of a lithium-ion battery. For example, the negative electrode may be defined by a plurality of negative electroactive solid particles. The negative electrode may be a composite material containing a mixture of the negative electroactive solid particles and the solid electrolyte particles disclosed herein. The negative electrode may be in the form of a layer having a thickness of greater than or equal to about 10 µm to less than or equal to about 5,000 µm, for example, greater than or equal to about 10 µm to less than or equal to about 500 µm, and optionally greater than or equal to about 10 µm to less than or equal to about 100 µm, for example, about 20 µm.

[0072] The negative electrode may contain greater than or equal to about 30 wt% to less than or equal to about 98 wt%, and optionally greater than or equal to about 50 wt% to less than or equal to about 95 wt% of negative electroactive solid particles and greater than or equal to 0 wt% to less than or equal to about 50 wt%, and optionally greater than or equal to about 5 wt% to less than or equal to about 20 wt% of solid electrolyte particles. The negative electrode may contain greater than or equal to 30 wt% to less than or equal to 98 wt%, and optionally greater than or equal to about 50 wt% to less than or equal to 95 wt% of negative electroactive solid particles and greater than or equal to 0 wt% to less than or equal to about 50 wt%, and optionally greater than or equal to about 5 wt% to less than or equal to 20 wt% of solid electrolyte particles.

[0073] The negative electroactive solid particles can be lithium-based, for example, based on a lithium alloy or a lithium metal. The negative electroactive solid particles can be silicon-based, including, for example, a silicon alloy, a silicon-graphite mixture, or a combination thereof. The negative electrode can be a carbon-containing anode, and the negative electroactive solid particles can contain a negative electroactive material such as graphite, graphene, hard carbon, soft carbon, carbon nanotubes (CNTs), or a combination thereof. The negative electrode can contain a negative electroactive material such as lithium titanium oxide (Li4Ti5O 12), a metal oxide such as TiO2, V2O5, or a combination thereof, a metal sulfide such as FeS, or a combination thereof. The negative electroactive solid particles may contain lithium, graphite, graphene, hard carbon, soft carbon, carbon nanotubes, silicon, a silicon-containing alloy, a tin-containing alloy, other lithium-accepting materials, or a combination thereof.

[0074] The negative electrode may further comprise a conductive additive, a binder material, or a combination thereof. For example, the negative electroactive solid particles, the solid electrolyte particles, or a combination thereof may optionally be mixed with an electrically conductive material that provides an electron conduction path, a polymeric binder material that improves the structural integrity of the negative electrode, or a combination thereof.

[0075] For example, the negative electroactive solid particles, the solid electrolyte particles, or a combination thereof can optionally be blended with binders such as sodium carboxymethylcellulose (CMC), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), PVDF, PTFE, ethylene-propylene-diene monomer (EPDM) rubber, nitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), polyethylene glycol (PEO), a lithium polyacrylate (LiPAA) binder, or a combination thereof. Electrically conductive materials can be, for example, carbon-based materials or a conductive polymer. Carbon-based materials may include, for example, graphite particles, acetylene black (e.g., KETCHEN™ black or DENKA™ black), carbon nanofibers and nanotubes, graphene (e.g., graphene oxide), carbon black (e.g., Super P), or a combination thereof.Examples of a conductive polymer may include polyaniline, polythiophene, polyacetylene, and polypyrrole. Blends of a conductive additive, a binder, or a combination thereof may also be used.

[0076] The negative electrode may comprise greater than or equal to 0 wt% to less than or equal to about 30 wt%, and optionally greater than or equal to about 2 wt% to less than or equal to about 10 wt% of the electrically conductive additive, and greater than or equal to 0 wt% to less than or equal to about 20 wt%, and optionally greater than or equal to about 1 wt% to less than or equal to about 10 wt% of the binder. The negative electrode may comprise greater than or equal to 0 wt% to less than or equal to 30 wt%, and optionally greater than or equal to 2 wt% to less than or equal to about 10 wt% of the electrically conductive additive, and greater than or equal to 0 wt% to less than or equal to 20 wt%, and optionally greater than or equal to about 1 wt% to less than or equal to about 10 wt%.

[0077] The positive electrode may be formed from a lithium-based electroactive material capable of undergoing lithium intercalation and deintercalation while functioning as the positive terminal of the battery. For example, the positive electrode may be defined by a plurality of the positive electroactive solid particles. The positive electrode may be a composite material containing a mixture of positive electroactive solid particles and solid electrolyte particles as disclosed herein. The positive electrode may be in the form of a layer having a thickness of greater than or equal to about 10 µm to less than or equal to about 5,000 µm, for example, greater than or equal to about 10 µm to less than or equal to about 500 µm, and optionally greater than or equal to about 10 µm to less than or equal to about 100 µm, for example, about 40 µm.

[0078] The positive electrode may comprise greater than or equal to about 30 wt. % to less than or equal to about 98 wt. % and optionally greater than or equal to about 50 wt. % to less than or equal to about 95 wt. % of the positive electroactive solid particles and greater than or equal to 0 wt. % to less than or equal to about 50 wt. % and optionally greater than or equal to about 5 wt. % to less than or equal to about 20 wt. % of solid electrolyte particles. The negative electrode may comprise greater than or equal to 30 wt. % to less than or equal to 98 wt. % and in certain aspects optionally greater than or equal to 50 wt. % to less than or equal to 95 wt. % of the negative electroactive solid particles and greater than or equal to 0 wt. % to less than or equal to 50 wt. % and in certain aspects optionally greater than or equal to 5 wt. % to less than or equal to 20 wt. % of the second plurality of solid electrolyte particles.

[0079] The positive electrode can be a layered oxide cathode, a spinel cathode, or a polyanion cathode. The cathode can be, for example, a layered oxide cathode (e.g., rock salt layered oxides), and the positive electroactive solid particles can be a positive electroactive material made of LiCoO2, LiNi x Mn y Co 1-x-y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), Li-Ni x Mn y Al 1-x-y O2 (where 0 < x ≤ 1 and 0 < y ≤ 1), LiNi x Mn 1-x O2 (where 0 ≤ x ≤ 1), Li 1+x MO2 (where 0 ≤ x ≤ 1) or a combination thereof for solid-state lithium-ion batteries. The spinel cathode may comprise a positive electroactive material, such as LiMn2O4 and LiNi 0,5 Mn 1,5O4. The polyanion cation may, for example, comprise a phosphate such as LiFePO4, LiVPO4, LiV2(PO4)3, Li2FePO4F, Li3Fe3(PO4)4, or Li3V2(PO4)F3 for lithium-ion batteries, a silicate such as LiFeSiO4, or a combination thereof for lithium-ion batteries. The positive electroactive solid particles may comprise a positive electroactive material of LiCoO2, LiNi x Mn y Co 1-x-y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi x Mn 1-x O2 (where 0 ≤ x ≤ 1), Li 1+x MO2 (where 0 ≤ x ≤ 1), LiMn2O4, LiNi x Mn 1.5O4, LiFePO4, LiVPO4, LiV2(PO4)3, Li2FePO4F, Li3Fe3(PO4)4, Li3V2(PO4)F3, LiFeSiO4, or a combination thereof. The positive electroactive solid particles can be coated (e.g., with LiNbO3, Al2O3, or a combination thereof), the positive electroactive material can be doped (e.g., with aluminum, magnesium, or a combination thereof), or a combination thereof. The positive electroactive material can be nickel manganese cobalt 811 (NMC811), nickel manganese cobalt 622 (NMC622), lithium cobalt oxide (LiCoO2), lithium iron phosphate (LiFePO4), high-energy nickel manganese cobalt oxide (HENMC) (e.g., overlithiated layered oxide cathode or lithium-rich NMC); Contain lithium manganese nickel oxide (LMNO); or a combination thereof.

[0080] The positive electrode may further comprise a conductive additive, a binder material, or a combination thereof. For example, the positive electroactive solid particles, the solid electrolyte particles, or a combination thereof may optionally be mixed with an electrically conductive material that provides an electron conduction path, a polymeric binder material that improves the structural integrity of the positive electrode, or a combination thereof.

[0081] For example, the positive electroactive solid particles, the solid electrolyte particles, or a combination thereof can optionally be blended with binders such as sodium CMC, SEBS, SBS, PVDF, PTFE, EPDM rubber, NBR, SBR, PEO, a LiPAA binder, or a combination thereof. Electrically conductive materials can be, for example, carbon-based materials or a conductive polymer. Carbon-based materials can include, for example, graphite particles, acetylene black (e.g., KET-CHEN™ Black or DENKA™ Black), carbon nanofibers and nanotubes, graphene (e.g., graphene oxide), carbon black (e.g., Super P), or a combination thereof. Examples of a conductive polymer can include polyaniline, polythiophene, polyacetylene, and polypyrrole. Blends of a conductive additive, a binder material, or a combination thereof can also be used.

[0082] The positive electrode may comprise greater than or equal to 0 wt% to less than or equal to about 30 wt%, and optionally greater than or equal to about 2 wt% to less than or equal to about 10 wt% of the electrically conductive additive, and greater than or equal to 0 wt% to less than or equal to about 20 wt%, and optionally greater than or equal to about 1 wt% to less than or equal to about 10 wt% of the binder. The positive electrode may comprise greater than or equal to 0 wt% to less than or equal to 30 wt%, and optionally greater than or equal to 2 wt% to less than or equal to about 10 wt% of the electrically conductive additive, and greater than or equal to 0 wt% to less than or equal to 20 wt%, and optionally greater than or equal to about 1 wt% to less than or equal to 10 wt% of the binder.

[0083] The positive electrode current collectors and the positive pole tab can be made of aluminum (Al) or another suitable electrically conductive material. The negative electrode current collectors and the negative pole tab can be made of copper, nickel or an alloy thereof, stainless steel, or another suitable electrically conductive material. The positive and negative electrode current collectors can be porous or non-porous. In some cases, the positive and negative electrode current collectors can be in the form of non-porous metal foils, perforated metal foils, porous metal mesh, or a combination thereof.

[0084] The lithium metal layer may comprise a layer of lithium (Li) metal or a lithium metal alloy. The negative electrode material layer may consist essentially of lithium metal and contain more than 97 wt% lithium, or preferably more than 99 wt% lithium. The lithium metal layer may be porous or non-porous. The lithium metal layer may, for example, be in the form of a non-porous metal foil, a perforated (porous) metal foil, or a porous metal mesh. The lithium metal layer may have a thickness in the range of 20 micrometers (µm) to 40 µm.

[0085] The first current collector may be a first bipolar current collector, the second current collector may be a second bipolar current collector, or a combination thereof. For example, the first bipolar current collector, the second bipolar current collector, or a combination thereof may be a clad foil, where, for example, one side (e.g., the first side or the second side) of the current collector comprises a metal (e.g., a first metal) and another side (e.g., the other side of the first side or the second side) of the current collector comprises a different metal (e.g., a second metal). For example, the clad foil may comprise aluminum-copper (Al-Cu), nickel-copper (Ni-Cu), stainless-steel-copper (SS-Cu), aluminum-nickel (Al-Ni), aluminum-stainless steel (Al-SS), and nickel-stainless steel (Ni-SS). The first bipolar current collector, the second bipolar current collector or a combination thereof may be pre-coated, e.g.with graphene or carbon-coated aluminum current collectors.

[0086] The size and shape of the battery can vary depending on the specific applications for which it is designed. Battery-powered vehicles and portable consumer electronics devices are two examples where the battery would most likely be designed to different size, capacity, voltage, energy, and power specifications. The battery can also be connected in series or parallel with other similar lithium-ion cells or batteries to produce higher output voltage, energy, and power when required by the load device. The battery can generate an electric current for the load device, which can be operatively connected to the external circuit. The load device can be fully or partially powered by the electric current flowing through the external circuit as the battery discharges.While the load device may be any suitable electrically powered device, some specific non-limiting examples of power-consuming devices include an electric motor for a hybrid or all-electric vehicle, a laptop computer, a tablet computer, a mobile phone, and cordless power tools or appliances. The load device may also be a power-generating device that charges the battery for electrical energy storage purposes.

[0087] Certain features of the present technology are further illustrated by the following non-limiting examples. ExamplesComparison Example 1

[0088] The separator of Comparative Example 1 comprised an Al2O3-coated polyethylene separator with a melting point of 130 °C. The coating thickness was approximately 3 micrometers (µm), and the base film thickness was approximately 9 µm. Example 1

[0089] The separator of Example 1 comprised a lithiated, zeolite-coated polyaramid separator. The coating thickness was approximately 3 µm, and the base film thickness was approximately 9 µm. Thermal evaporation of lithium

[0090] Approximately 10 grams of lithium ingot were placed in a tantalum crucible, which was then firmly mounted and connected between two electrical poles. Directly above the crucible was the separator of Comparative Example 1 or Example 1, which was attached to a Mo plate covered with copper foil, within a vacuum chamber. Before the deposition process, the chamber was thoroughly evacuated to a pressure of 10 -7Torr. An electric current was then applied to the crucible, heating the lithium inside. The heating power was precisely controlled at 20%. Throughout the deposition process, the thickness of the deposited lithium was closely monitored using a quartz crystal microbalance. The final thickness of the lithium layer was approximately 2 µm.

[0091] Fig. Figure 2 shows photographs of the separators of Comparative Example 1 (labeled "Al2O3", referring to the Al2O3-coated polyethylene separator) and Example 1 (labeled "LiZ" (lithiated zeolite, referring to the lithiated zeolite-coated separator)) before thermal evaporation of lithium (left image) and after thermal evaporation of lithium (right image). The ceramic-coated polyaramid separator of Example 1 underwent minimal deformation during thermal evaporation of lithium, while the Al2O3-coated separator underwent extensive deformation during thermal evaporation of lithium. Comparison example 2

[0092] The separator of Comparative Example 2 contained a lithiated zeolite-coated polyaramid separator similar to that contained in the separator of Example 1 before pre-lithiation. The separator of Comparative Example 2 was not pre-lithiated, as was the separator of Example 1. Cell performance

[0093] The formation of button cells (2032) was carried out using the separator of Comparative Example 2 or the separator of Example 1 after pre-lithification, a positive electroactive material of nickel-manganese-cobalt 622 (NMC622), a negative electroactive material of micrometer-sized Si and an electrolyte of 1 mol per liter (mol (M)) lithium hexafluorophosphate (LiPF6) in ethyl methyl carbonate (EMC)) / fluoroethylene carbonate (FEC)) in a weight ratio of 1:4, NMC622 loading of 3.75 milliampere hours per square centimeter (mAh / cm 2), a negative to positive ratio (N / P) of 2. The anode diameter was 14 millimeters (mm) and the cathode diameter was 13.5 mm.

[0094] Fig. Figure 3 is a graphical illustration showing the first cycling efficiency of the cell with the separator of Comparative Example 2 (also referred to herein as "Comparative Example 2 cell") and the cell with the separator of Example 1 after pre-lithiation (also referred to herein as "Example 1 cell"), where the x-axis represents the test time (seconds (s)) and the y-axis represents the voltage (volts (V)). Curve 201 represents the cell of Comparative Example 2 and Curve 202 represents the cell of Example 1. The open circuit voltage (OCV) of the cell of Example 1 after assembly is 2.5 V compared to 0.25 V for the cell of Comparative Example 2, indicating the presence of metallic Li on the separator. A slightly lower charge capacity for the first cycle suggests that the silicon was pre-lithiated during the OCV hold time.

[0095] Fig. 4 is a graphical illustration showing the first cycling efficiency of the cell of Comparative Example 2 and the cell of Example 1, where the x-axis represents capacity (ampere-hours (Ah)) and the y-axis represents voltage (V), with curve 303 representing the cell of Comparative Example 2 and curve 304 representing the cell of Example 1. Fig. 4 indicates a higher state of charge for the cell of Example 1 compared to the cell of Comparative Example 2.

[0096] Fig. Figure 5 is a graphical illustration showing the cycling performance of the cell of Comparative Example 2 and the cell of Example 1. The x-axis represents the cycle number and the y-axis represents the capacity (Ah). Curve 405 represents the charge capacity of the cell of Comparative Example 2. Curve 406 represents the discharge capacity of the cell of Comparative Example 2. Curve 407 represents the charge capacity of the cell of Example 1. Curve 408 represents the discharge capacity of the cell of Example 1. A higher discharge capacity for the cell of Example 1 indicates that the capacity loss caused by the formation of a solid electrolyte interlayer (SEI) has been compensated. As a result of Li compensation for the irreversible capacity loss during the first cycle, the battery exhibits a higher charge / discharge capacity during normal operation.

[0097] Fig. 6A and Fig.6B are graphical illustrations showing the cycling performance of the cell of Comparative Example 2 and the cell of Example 1, where the x-axis represents the cycle number and the y-axis represents the cycling efficiency (CE) (in percent (%)), curve 509 represents the cell of Comparative Example 2, and curve 510 represents the cell of Example 1. The first cycling efficiency of the cell of Example 1 was 85%, and the first cycling efficiency of the cell of Comparative Example 2 was 75%. The cycling efficiency can be further improved by applying a Li coating.

[0098] The terms “ein”, “einer”, “eine”, “eines” and their declension forms do not imply a limitation of quantity, but indicate the presence of at least one of the named items. The term “or” means “and / or” unless the context clearly indicates otherwise. Whenever “an aspect” is mentioned throughout the description, this means that a particular element (e.g. a feature, structure, step or property) described in connection with the aspect is included in at least one of the aspects described here and may or may not be present in other aspects. It is further understood that the elements described in the various aspects can be combined in any suitable way.

[0099] When an element such as a layer, film, region, or base film is described as lying "on top of" another element, it may lie directly on top of the other element, or there may be intervening elements. In contrast, when an element is described as lying "directly on top of" another element, there are no intervening elements.

[0100] Unless otherwise indicated herein, all examination standards are the most recent standard in effect as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the examination standard appears.

[0101] Unless otherwise defined, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0102] While the above disclosure has been described with reference to exemplary embodiments, it will be appreciated by those skilled in the art that various changes may be made and equivalents may be substituted for elements without departing from the scope thereof. Furthermore, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, the present disclosure is not intended to be limited to the particular embodiments disclosed, but is intended to include all embodiments falling within its scope.

Claims

[1] A pre-lithiated separator for use in an electrochemical cell, the pre-lithiated separator comprising: a base film comprising a polymer having a melting point of more than 180 °C; a ceramic that is in direct contact with the polymer; and Lithium on an outer surface of the pre-lithiated separator. [2] The pre-lithiated separator of claim 1, wherein the polymer having a melting point above 180°C comprises a polyaramid, a polyimide, polyethylene terephthalate, polytetrafluoroethylene, a polyimide nanofiber nonwoven, a nanoscale Al2O3 and a poly(lithium 4-styrenesulfonate) coated polyethylene membrane, a SiO2 coated polyethylene, a co-polyimide coated polyethylene, a polyetherimide, bisphenol acetone diphthalic anhydride, para-phenylenediamine, expanded polytetrafluoroethylene reinforced polyvinylidene fluoride hexafluoropropylene, or a combination thereof. [3] The pre-lithiated separator of claim 1, wherein the ceramic comprises Al2O3, SiO2, ZrO2, TiO2, lithium titanate, lithiated zeolite, zeolite, MgO, boehmite, or a combination thereof. [4] The pre-lithiated separator of claim 1, wherein a thickness of the lithium compensates for capacity loss during a first cycle of an electrochemical cell comprising the pre-lithiated separator. [5] The pre-lithiated separator of claim 1, wherein the ceramic in direct contact with the polymer comprises a mixture of the ceramic and the polymer. [6] Pre-lithiated separator according to claim 1, wherein the ceramic in direct contact with the polymer comprises a ceramic layer directly on the base film; and the lithium on the outer surface of the pre-lithiated separator comprises lithium directly on the ceramic layer. [7] A method of forming a pre-lithiated separator, the method comprising: Depositing a ceramic directly onto a base film comprising a polymer having a melting point of more than 180 °C; and Depositing lithium directly onto the ceramic to form the pre-lithiated separator. [8] The method of claim 7, wherein depositing the lithium comprises thermal evaporation, sputtering, ion beam deposition, or a combination thereof. [9] The method of claim 7, wherein the deposition of the lithium occurs at a processing temperature below the melting point of the polymer. [10] A method of forming a pre-lithiated separator, the method comprising: Forming a base film comprising a polymer having a melting point of more than 180 °C and a ceramic; and Depositing lithium directly onto an outer surface of the base film to form the pre-lithiated separator.

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