Electrode precursor composition, electrode, battery, device and method

Abstract

An electrode precursor composition for an alkali metal ion secondary battery is described. The electrode precursor composition comprises a polymer-electrolyte gel matrix phase comprising a blend of at least a first polymer and a second polymer and a liquid electrolyte comprising an organic solvent and an alkali metal salt, and a dispersed phase comprising an electrochemically active material. The first polymer comprises at most 10% by volume of the total volume of the blend. Also described are an electrode comprising or produced from the electrode precursor composition, the use of the first polymer, a method of producing an electrode, an electrochemical secondary battery comprising the electrode, and an electrochemical energy storage device comprising the electrochemical secondary battery.

Description

Electrode precursor compositions, electrodes, batteries, devices, and methods Background Technology

[0001] Lithium-ion rechargeable batteries are used in a wide range of applications, from small personal devices to electric vehicles. Lithium-ion batteries can exhibit high energy density, long cycle life, and other properties. They can contain multiple lithium-ion rechargeable cells; lithium-ion rechargeable batteries are an example of alkali metal-ion rechargeable batteries.

[0002] Lithium-ion battery components, such as electrodes, can be manufactured using a solvent casting process with sacrificial solvents. A liquid electrolyte can be used within the lithium-ion battery to provide conductivity of lithium ions between the solid, solvent-cast anode and cathode.

[0003] Different methods involve the use of gel electrodes. These electrodes can be formed from compositions prepared by mixing necessary components such as electrochemically active materials, polymers, and liquid electrolytes, and subsequently subjecting the composition to treatments such as heat treatment. Some gel electrode compositions contain a small amount of liquid electrolyte to aid in the gelation of the polymer. Summary of the Invention

[0004] This document provides an electrode precursor composition for alkali metal ion secondary batteries. The composition comprises a polymer-electrolyte gel matrix phase, which includes a polymer blend and a liquid electrolyte. The polymer blend consists of a blend of polymers, comprising a first polymer having a content of at least 1 x 10⁻⁶. 5 The composition comprises polymethyl methacrylate (PMMA) with a weight-average molecular weight of Da. The polymer blend also includes a second polymer containing at least 75 mol% vinylidene fluoride (VDF) as a constitutive monomer. The liquid electrolyte comprises an organic solvent and an alkali metal salt. The polymer-electrolyte gel matrix phase comprises a first polymer in an amount of 0.1 vol% to 10 vol% of the total volume of the polymer blend, i.e., the total volume of the first polymer, the second polymer, and any optional additional polymers. In addition to the polymer-electrolyte gel matrix phase, the composition also comprises a dispersed phase containing an electrochemically active material.

[0005] In solvent casting processes used to produce components such as electrodes, the use of sacrificial solvents such as N-methylpyrrolidone (NMP) is an energy-intensive step. Gel electrodes of the type produced using the compositions described herein avoid such additional costs, thereby significantly reducing battery production costs.

[0006] Using a small amount of liquid electrolyte means that the gel can be formed more easily, and the processability of the gel electrode is improved, thereby reducing manufacturing costs. However, in prior art compositions, this, in turn, makes the finished gel electrode more susceptible to dissolution in the electrolyte present between the electrodes within the finished battery, thus reducing the battery's operational life. In contrast, polymers with poor solubility in the electrolyte ensure that the gel electrode is not degraded by the electrolyte present in the battery once assembled. However, such electrodes can be difficult to manufacture due to poor gelation between the polymer and the electrolyte. To balance factors such as electrode processability, battery performance, and lifespan, this gel precursor composition employs a first polymer that acts as a processing aid. The first polymer typically has relatively high solubility in the selected electrolyte and can help form a more processable gel during gel electrode manufacturing without compromising battery performance or battery life. In some embodiments, the first polymer may not form a gel. In some embodiments, the first polymer may form a liquid in the selected electrolyte in a selected amount, or in some embodiments, it may dissolve in situ from the gel.

[0007] Furthermore, the inventors have discovered that using an added amount of highly soluble (first) polymer can reduce or eliminate the risk of introducing battery instability, which can occur, for example, when using a larger fraction of the first polymer. Even so, adding such a small amount of the first polymer to the electrode composition improves processability without having a detrimental effect on electrochemistry. That is, this electrode precursor composition contains only a relatively small amount of the first polymer, meaning that the structural stability and battery performance imparted by the second polymer and any other polymers remain almost unchanged, while still exhibiting a significant improvement in processability.

[0008] Another benefit of this electrode precursor composition is that the concentration of the alkali metal salt throughout the composition is higher than it would be possible without the first polymer in the polymer blend. The higher salt concentration increases the conductivity of the gel electrode, improving the electrochemical performance of the battery. Due to the presence of the first (more soluble) polymer in the blend, a larger amount of liquid electrolyte can be incorporated into the electrode precursor composition. This larger amount of liquid electrolyte implies a higher salt concentration and thus improved electrode performance, without a noticeable impact on the stability of the electrode structure.

[0009] The first polymer is polymethyl methacrylate (PMMA). Therefore, the first polymer is a homopolymer containing only methyl methacrylate (MMA) as a constituent monomer. The first polymer has a density of at least 1 x 10⁻⁶. 5 Da has a high weight-average molecular weight. Such polymers are believed to have particularly high solubility in typical liquid electrolytes used to prepare gel electrodes, thus facilitating the aforementioned improvements in processability, battery performance, and lifespan.

[0010] In some embodiments, the first polymer comprises at least 0.5% by volume, at least 1.0% by volume, or at least 2.0% by volume of the total volume of the polymer blend, i.e., the total volume of the first, second, and optionally additional polymers. In some embodiments, the first polymer is present in an amount up to 9.8% by volume, up to 9.5% by volume, or up to 9.0% by volume of the total volume of the polymer blend. These are considered particularly useful amounts of the first polymer for observing the aforementioned effects.

[0011] In some embodiments, the first polymer accounts for 0.5% to 9.8% of the total volume of the polymer blend, i.e., the total volume of the first, second, and optionally additional polymers, for example, 1.0% to 9.5% or 2.0% to 9.0% of the total volume.

[0012] In some embodiments, the first polymer has a density of at least 1x10⁻⁶. 6 Da has a high weight-average molecular weight. Such polymers are believed to have particularly high solubility in typical liquid electrolytes used to prepare gel electrodes, thus facilitating the aforementioned improvements in processability, battery performance, and lifespan.

[0013] The second polymer contains at least 75 mol% VDF as a constituent monomer. In some embodiments, the second polymer has a content of at least 1 x 10⁻⁶. 5 Da has a high weight-average molecular weight. Such polymers are considered to have low solubility in typical liquid electrolytes used to prepare gel electrodes, thus imparting good structural properties to the electrodes.

[0014] In some embodiments, the polymer blend comprises at least one additional polymer, namely a third polymer. Any third or additional polymer present differs from the first and second polymers. In some embodiments, the third polymer comprises at least 75 mol% VDF as a constituent monomer. A prudent combination of the first polymer with the second and third polymers can provide an exemplary balance between processability and durability of the battery during use. This is particularly evident in embodiments where the second polymer has particularly low solubility in the selected liquid electrolyte. For example, in some embodiments, the second polymer may have a higher weight-average molecular weight than the third polymer.

[0015] In some embodiments, the second polymer is present in an amount of at least 10% by volume of the total volume of the polymer blend. This is considered a particularly useful range of amounts for the second polymer in which a significant gelling effect can be observed.

[0016] In some embodiments, the second polymer is a polyvinylidene fluoride (PVDF) homopolymer or a PVDF copolymer. In some embodiments, the additional polymer is a polyvinylidene fluoride (PVDF) homopolymer, a polytetrafluoroethylene (PTFE) homopolymer, a polychlorotrifluoroethylene (PCTFE) homopolymer, a polymethyl methacrylate (PMMA) homopolymer, a PVDF copolymer, a PTFE copolymer, a PCTFE copolymer, or a PMMA copolymer. In some embodiments, the additional polymer is a polyvinylidene fluoride (PVDF) homopolymer or a PVDF copolymer. In some embodiments, the second and / or additional polymer contains hexafluoropropylene (HFP) as a constitutive monomer. In some embodiments, the second and / or additional polymer contains up to 2 mol% of one or more constitutive monomers other than VDF and HFP. Such polymers are considered to have exemplary solubility and achieve the gelling benefits described herein.

[0017] In some embodiments, the electrochemically active material is present in an amount of 50% to 75% by volume, for example, at least 60% by volume, of the total volume of the electrode precursor composition. Such a volumetric amount of electrochemically active material enables a useful performance electrode.

[0018] In some embodiments, the dispersed phase further comprises conductive additives. The presence of conductive additives can improve the performance of the electrode.

[0019] In some embodiments, the liquid electrolyte is present in an amount of at least 25% by volume of the total volume of the electrode precursor composition. This amount allows for particularly good electrode processability.

[0020] In some embodiments, the organic solvent comprises one or more cyclic or linear carbonate compounds. In some embodiments, the organic solvent comprises one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, butyl carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, and γ-butyrolactone. Such organic solvents are particularly suitable for balancing the solubility characteristics and safety of the aforementioned polymer blends.

[0021] In some embodiments, the alkali metal salt comprises one or more of the following: LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium 2-trifluoromethyl-4,5-dicyanimidazolium (LiTDI). Such alkali metal salts are suitable for providing electrodes for lithium-ion secondary batteries.

[0022] In some embodiments, the electrode precursor composition comprises 20 vol% to 50 vol% of a polymer-electrolyte gel matrix phase, based on the total composition volume. This proportion of the polymer-electrolyte gel matrix phase is considered to provide exemplary performance properties.

[0023] In some embodiments, the polymer-electrolyte gel matrix phase comprises 3 vol% to 30 vol% of a polymer blend, based on the total volume of the polymer-electrolyte gel matrix phase. Such a range is intended to provide compositions with exemplary processability properties without significantly affecting the structure or battery performance and lifespan properties.

[0024] In some embodiments, the electrode precursor composition is used in lithium-ion secondary electrochemical batteries. This composition is considered particularly suitable for providing electrodes that can be used in lithium-ion secondary electrochemical batteries.

[0025] This document also provides a method for preparing the electrode precursor compositions described herein. The method may include mixing an electrochemically active material with a first, second, and any optional additional polymer, as well as an electrolyte.

[0026] This document also provides the use of 0.1 vol% to 10 vol% of a first polymer in a polymer-electrolyte gel matrix phase of a composition for use in alkali metal ion secondary batteries, the composition comprising a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer and a second polymer, the first polymer having a concentration of at least 1 x 10⁻⁶. 5 The weight-average molecular weight polymethyl methacrylate (PMMA) of Da, the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and the liquid electrolyte contains an organic solvent and an alkali metal salt; and the dispersed phase contains an electrochemically active material.

[0027] In some embodiments, the use results in the electrode precursor composition described herein. Using an amount of the first polymer in the composition for use in alkali metal ion secondary batteries to form the composition described herein provides at least the advantages described above.

[0028] This article also provides an electrode for alkali metal ion secondary batteries. The electrode comprises a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer and a second polymer, the first polymer having a concentration of at least 1 x 10⁻⁶. 5The weight-average molecular weight polymethyl methacrylate (PMMA) of Da, the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and the liquid electrolyte contains an organic solvent and an alkali metal salt; the dispersed phase contains an electrochemically active material; and the first polymer accounts for 0.1 vol% to 10 vol% of the total volume of the polymer blend.

[0029] In some embodiments, the electrode comprises or is manufactured from the electrode precursor composition provided herein. The effects described above with respect to the gel electrode precursor composition herein also apply to the electrode described herein.

[0030] This document also provides a method for producing electrodes. The method includes processing the electrode precursor composition described herein to form a film or coating.

[0031] In some embodiments, the processing includes thermal processing or extrusion. Thermal processing or extrusion has been found to provide electrodes, such as those described herein, in a direct and relatively low-cost manner.

[0032] This document also provides electrochemical secondary batteries comprising the electrodes described herein or electrodes produced by the methods described herein. This document also provides electrochemical energy storage devices comprising the electrochemical secondary batteries described herein. Since both the electrochemical secondary batteries and the electrochemical energy storage devices comprise the electrodes described herein, the relevant effects described above with respect to the gel electrode precursor compositions described herein also apply. Attached Figure Description

[0033] Figure 1 shows photographic images of a gel electrode. Figure 1(a) shows an image of a gel electrode prepared from an electrode precursor composition that does not contain any of the first polymer (PMMA) as described herein. Figure 1(b) shows an image of a gel electrode prepared from an electrode precursor composition as described herein. The circles in Figure 1(a) indicate exemplary areas of the electrode with electrolyte loss. Detailed Implementation

[0034] Electrode precursor composition

[0035] The electrode precursor composition for alkali metal ion secondary batteries described herein comprises a polymer-electrolyte gel matrix phase and a dispersed phase. The electrode precursor composition can be used as a precursor material for preparing gel electrodes.

[0036] The polymer-electrolyte gel matrix phase comprises a polymer blend, which includes a first polymer, a second polymer, and optionally at least one additional polymer. The first polymer is PMMA. The second polymer differs from the first polymer and includes VDF as a constituent monomer. Any optional additional polymer differs from the first and second polymers. In some embodiments, the optional additional polymer may differ from the first and second polymers in terms of the type of constituent monomer, the amount of constituent monomer, and / or weight-average molecular weight.

[0037] The polymer-electrolyte gel matrix phase also contains liquid electrolytes.

[0038] In some embodiments, the polymer-electrolyte gel matrix phase consists of a polymer blend and a liquid electrolyte.

[0039] Typically, the first (most soluble) polymer is predominantly present to improve the processability of the electrode precursor composition. On the other hand, the second and any optional additional (less soluble) polymers are typically selected based on their ability to form a gel suitable for use as a gel electrode. That is, the first polymer is used to improve the processability of polymers (e.g., in embodiments containing only the second polymer) or polymer combinations (e.g., in embodiments containing the second polymer and at least one additional polymer, such as the second and third polymers). Therefore, the second and any optional additional polymers perform more structural functions in the finished gel electrode than the first polymer.

[0040] The first polymer has a content of at least 1x10 5 The PMMA with a weight average molecular weight of Da exhibits higher solubility in the liquid electrolyte than the second polymer, which contains at least 75 mol% VDF as a constituent monomer. Therefore, the first polymer has the highest solubility in the liquid electrolyte among all polymers in the polymer blend.

[0041] The first polymer comprises at least 0.1% and at most 10% by volume of the total volume of the first, second, and any optional additional polymers, i.e., the total volume of the polymers in the polymer blend. In other words, the first polymer is present in an additive amount.

[0042] In some embodiments, the first polymer comprises at least 0.1 vol%, at least 0.2 vol%, at least 0.5 vol%, at least 1.0 vol%, or at least 2.0 vol% of the total volume of the first, second, and any other polymers. In some embodiments, the first polymer comprises at most 9.8 vol%, at most 9.5 vol%, or at most 9.0 vol% of the total volume of the first, second, and any other polymers. Any combination of the values ​​listed above may be combined to form suitable ranges, such as 0.1 vol% to 9.5 vol%, 0.5 vol% to 9.0 vol%, or 1.0 vol% to 9.0 vol%.

[0043] Note that the sum of the volumes of the first, second, and any other polymers is the total volume of the polymer blend, and the sum is 100 volumes.

[0044] In other words, the volume ratio of the first polymer to the second polymer and any other polymer is 0.001 to 0.1. Within this range, a good balance of processability and durability can be achieved through the polymer blend. In some embodiments, the volume ratio of the first polymer to the second polymer and any other polymer is at least 0.002, at least 0.005, at least 0.01, or at least 0.02. In some embodiments, the volume ratio of the first polymer to the second polymer and any other polymer is at most 0.098, at most 0.095, or at most 0.090. Any combination of the values ​​listed above can be combined to form a suitable range, such as 0.001 to 0.095, 0.005 to 0.090, or 0.01 to 0.090.

[0045] In some embodiments, the first polymer is present in an amount of at least 0.01 vol% of the total volume of the electrode precursor composition, for example, at least 0.02 vol% or at least 0.05 vol%. In some embodiments, the first polymer is present in an amount of up to 1.0 vol% based on the total volume of the electrode precursor composition, for example, up to 0.8 vol% or up to 0.5 vol%. Any combination of the values ​​listed above can be combined to form suitable ranges, for example, from 0.01 vol% to 1.0 vol%, from 0.02 vol% to 1.0 vol%, or from 0.02 vol% to 0.8 vol% based on the total volume of the electrode precursor composition.

[0046] The first polymer has at least 1x10 5 The weight-average molecular weight of Da. In some embodiments, the first polymer is a high molecular weight polymer. In some embodiments, the first polymer is an ultra-high molecular weight polymer. In some embodiments, the first polymer has a weight-average molecular weight of at least 1 x 10⁻⁶. 6 Da, at least 2x10 6 Da or at least 3x10 6 The weight-average molecular weight of Da. No upper limit is specified.

[0047] In this study, weight-average molecular weight was measured using gel permeation chromatography (GPC). A universal calibration according to standard methods such as ASTM-D6474-99 can be used. UV-vis spectra and absorbance were recorded on a spectrophotometer. Molecular weight was calculated using appropriate analytical software such as CIRRUS® GPC software. GPC measurements were performed on a suitable HPLC system. For example, PMMA standards and organic solvent eluents are suitable for measuring polymers containing MMA or VDF.

[0048] As a further example, the weight-average molecular weight of VDF-containing polymers can be measured according to the method described in the application notes for “Polyvinylidene Fluoride Analysis on Agilent PLgel 10 µm MIXED-B and GPC / SEC” (Graham Cleaver, Agilent Technologies, Inc. 2015). Here, PMMA standard is used and DMSO is used as the eluent. The weight-average molecular weight of PMMA can be measured according to the method described in “Synthesis of ultra-high molecular weight poly(methyl methacrylate) with hydrosilane as initiator” (Yuan et al., Materials Today Communications, 2022). Here, PMMA standard is used and THF is used as the eluent.

[0049] In some embodiments, the first polymer may exhibit spontaneous dissolution in the liquid electrolyte at room temperature. This can be a very slow process, depending on the polymer, but in some embodiments, the liquid electrolyte is exposed to the first polymer at room temperature without any specific mixing leading to gel formation.

[0050] In addition to the first polymer described above, the polymer blend also includes a second polymer containing at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, such as at least 78 mol% VDF, at least 80 mol% VDF, or at least 85 mol% VDF. In embodiments where the second polymer contains 100 mol% VDF as a constituent monomer, it is a PVDF homopolymer.

[0051] As used in this article, “mol%” refers to the molar percentage of monomers present in the polymer, where the total number of moles in the polymer is 100%.

[0052] In some embodiments, the second polymer has a lower weight-average molecular weight than the first polymer. In some embodiments, the second polymer has a weight-average molecular weight of at least 1 x 10⁻⁶. 5 Da, for example, at least 2x10 5 Da or at least 5x10 5 The weight-average molecular weight of Da. No upper limit is specified.

[0053] In some embodiments, the second polymer may be a polyvinylidene fluoride (PVDF) homopolymer or a copolymer thereof. In some embodiments, the second polymer may be a copolymer containing VDF, such as poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP).

[0054] As used herein, a "polymer" refers to a polymer containing more than one monomer. Thus, for example, a PVDF copolymer contains one or more monomers in addition to VDF monomer units, and a PMMA-PEO copolymer contains at least MMA and EO monomers. The copolymer can be any suitable type of copolymer, such as random copolymers, alternating copolymers, or block copolymers. The one or more monomers other than those mentioned can be of any suitable type, provided that the effects described herein are achieved. Suitably, the copolymer may contain the mentioned monomers in an amount of at least 20% by weight (wt%), such as at least 30% by weight, at least 50% by weight, at least 70% by weight, or at least 90% by weight, based on the weight of the copolymer.

[0055] In some embodiments, the second polymer has the lowest solubility in the liquid electrolyte among the polymers constituting the polymer blend, for example, the lowest solubility in the liquid electrolyte of the first, second, and any optional additional polymers.

[0056] In some embodiments, the polymer blend consists of first and second polymers, wherein the proportion (volume %) of the second polymer is determined by the amount of the first polymer.

[0057] In some embodiments, the polymer blend includes an optional additional polymer, the second polymer being present in an amount of at least 5.0% by volume, for example at least 8.0% by volume or at least 10.0% by volume, of the total volume of the polymer blend. The upper limit of the amount of the second polymer is determined by the amount of other polymers in the polymer blend.

[0058] In some embodiments, the second polymer is present in an amount of at least 0.1 vol%, such as at least 0.2 vol% or at least 0.3 vol%, of the total volume of the electrode precursor composition. In some embodiments, the second polymer is present in an amount of up to 5.0 vol%, such as up to 4.0 vol%, up to 3.0 vol%, or up to 1.0 vol%. Any combination of the values ​​listed above may be combined to form suitable ranges, such as 0.1 vol% to 5.0 vol%, 0.1 vol% to 4.0 vol%, or 0.3 vol% to 3.0 vol%.

[0059] In some embodiments, the polymer blend comprises an additional (third) polymer. In some embodiments, the polymer blend comprises more than one additional polymer, such as a third polymer and a fourth polymer. Each of the one or more additional polymers is different from the first and second polymers. Optionally, one or more additional polymers may differ from the first and second polymers in any respect, provided the differences do not affect the effects described herein. In some embodiments, the optional additional polymer may have the same constituent monomers as the first or second polymer but differ in some other properties, such as molecular weight. In some embodiments, the optional additional polymer may differ from the first or second polymer in its constituent monomer units; for example, it may contain monomers having functional groups different from those of the first or second polymer. In some embodiments, two or more additional polymers are present, and the additional polymers may differ from the first and second polymers in the same or different ways.

[0060] In some embodiments, the polymer blend comprises a first, second, and third polymer, the third polymer having a solubility in the liquid electrolyte between that of the first and second polymers. In this way, the electrode precursor composition provides a particularly good balance between processability (through the presence of the more soluble polymer) and durability during battery use (through the presence of the less soluble polymer). In such embodiments, the second polymer is less soluble in the battery electrolyte during battery use than the first or third polymer, thus contributing to good battery life.

[0061] In some embodiments, any additional polymer, such as a third polymer, may be independently selected from: poly(ethylene glycol dimethacrylate), poly(ethylene glycol diacrylate), poly(propylene glycol dimethacrylate), poly(propylene glycol diacrylate), poly(methyl methacrylate) (PMMA), poly(acrylonitrile) (PAN), polyurethane (PU), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(ethylene oxide) (PEO), poly(ethylene glycol dimethyl ether), poly(ethylene glycol diethyl ether), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), poly[bis(methoxyethoxyethoxy)phosphazene], poly(dimethylsiloxane) (PDMS), poly(phenylene oxide), polydisulfide, polystyrene, polystyrene sulfonate, polypyrrole, polyaniline, polythiophene, polythioketone, polyvinylpyridine (PVP), polyvinyl chloride Poly(PVC), polyaniline, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene), poly(triphenylene), polyazine, polyfluorene, polynaphthalene, polyanthracene, polyfuran, polycarbazole, tetrathiofulvalene-substituted polystyrene, ferrocene-substituted polyethylene, carbazole-substituted polyethylene, polyoxyphenazine, poly(hexabenzobenzene), poly(4-styrenesulfonyl)(trifluoromethanesulfonyl)imide-co-methoxy polyethylene glycol acrylate, sulfonated poly(phenylene ether) (P The polymers include PO), N,N-dimethylacrylamide (DMAAm), lithium 2-acrylamido-2-methyl-1-propanesulfonate (LiAMPS), poly(lithium 2-acrylamido-2-methylpropanesulfonate-co-vinyltriethoxysilane), polyethylene oxide (PEO) / poly(lithium sorbate), PEO / poly(lithium mucinate), PEO / [poly(lithium sorbate)+BF3], PEO copolymers, PEO terpolymers, and NIPPON SHOKUBAI® polymers. In some embodiments, any additional polymers, such as a third polymer, are not PMMA. In some embodiments, any additional polymer, such as a third polymer, is independently selected from: polyurethane (PU), poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), poly(dimethylsiloxane) (PDMS), poly(phenylene oxide), polydisulfide, polystyrene, polystyrene sulfonate, polypyrrole, polyaniline, polythiophene, polythioketone, polyvinylpyridine (PVP), polyvinyl chloride (PVC), polyaniline, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene), poly(triphenylene), polyazine, polyfluorene, polynaphthalene, polyanthracene, polyfuran, polycarbazole, and [PSTFSI-co-MPEGA].In some embodiments, any additional polymer, such as a third polymer, is independently selected from: poly(vinylidene fluoride) (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polychlorotrifluoroethylene (PCTFE), polytetrafluoroethylene (PTFE), polyfluorene, and [PSTFSI-co-MPEGA]. In some embodiments, any additional polymer, such as a third polymer, is independently selected from: poly(vinylidene fluoride) (PVDF) or copolymers containing VDF, such as poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP).

[0062] In some embodiments, the polymer blend comprises or consists of a first polymer, a second polymer, and a third polymer. In some such embodiments, the second polymer and / or the third polymer are each independently selected from PVDF homopolymers or copolymers containing VDF monomers. In some such embodiments, the second polymer and the third polymer are each PVDF copolymers or each is a PVDF homopolymer. In some such embodiments, the PVDF copolymer is a copolymer comprising hexafluoropropylene (HFP) monomer and VFD monomer. In some such embodiments, the second polymer is selected from PVDF or copolymers thereof, and the third polymer is selected from PVDF homopolymers or copolymers thereof. In some such embodiments, the second polymer is a PVDF copolymer, and the third polymer is selected from PVDF homopolymers or PVDF copolymers. In some such embodiments, the second polymer is selected from PVDF homopolymers or PVDF copolymers, and the third polymer is a PVDF copolymer. In some such embodiments, the second polymer comprises VDF and HFP monomers as constituent monomers, and the third polymer is a PVDF copolymer.

[0063] In some embodiments, the polymer blend comprises a third polymer having a lower weight-average molecular weight than the second polymer. That is, in some embodiments, the third polymer has a lower weight-average molecular weight than either the second or third polymer. In some embodiments, the third polymer has a weight-average molecular weight of at least 1 x 10⁻⁶. 4 Da, at least 5x10 4 Da or at least 1x10 5 The weight-average molecular weight of Da. No upper limit is specified.

[0064] In some embodiments, the polymer blend comprises a third polymer, which is present in an amount of at least 50% by volume, for example, at least 60% or at least 70% by volume, of the total volume of the polymer blend. The upper limit of the amount of the third polymer will be determined by the amount of the first, second, and any other polymers in the polymer blend.

[0065] In some embodiments, the polymer blend comprises a third polymer present in an amount of at least 2.6 vol%, such as at least 2.8 vol%, at least 3.0 vol%, or at least 3.2 vol%, of the total volume of the electrode precursor composition. In some embodiments, the third polymer is present in an amount of up to 10 vol%, such as up to 9.5 vol%, up to 9.0 vol%, or up to 8.5 vol%. Any combination of the values ​​listed above may be combined to form suitable ranges, such as 2.6 vol% to 10 vol%, 2.8 vol% to 9.0 vol%, or 3.2 vol% to 8.5 vol%.

[0066] In some embodiments, the polymer blend comprises a first, second, and third polymer, wherein the first polymer has the highest solubility in the liquid electrolyte and the second polymer has the lowest solubility in the liquid electrolyte, such that the third polymer has a solubility in the liquid electrolyte intermediate between that of the first and third polymers, and the volume ratio of the second polymer to the third polymer is 1:4 to 1:10, for example, 1:5 to 1:9 or 1:6 to 1:8. Such a ratio provides a particularly stable and processable composition.

[0067] Therefore, in some embodiments, the electrode precursor composition for alkali metal ion secondary batteries comprises a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer, a second polymer, and a third polymer, the first polymer having a concentration of at least 1 x 10⁻⁶. 6 The weight-average molecular weight PMMA of Da, the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constitutive monomer and has at least 1 x 10 5 The weight-average molecular weight of Da, the third polymer contains VDF as a constituent monomer and has a lower weight-average molecular weight than the second polymer, the liquid electrolyte contains an organic solvent and an alkali metal salt; wherein the dispersed phase contains an electrochemically active material; and wherein the first polymer accounts for 0.1% to 10% of the total volume of the polymer blend.

[0068] In some embodiments, additional energy input may be applied to initiate the dissolution of a second and / or optionally additional polymer. In some embodiments, the dissolution of the second and / or third polymer in the liquid electrolyte may be carried out at elevated temperatures (e.g., at or above 30°C, at or above 50°C, or at or above 80°C).

[0069] The stability of the gel can be assessed using a variety of methods:

[0070] Visual assessment would indicate that the stable gel is a single-phase material with no obvious liquid-rich phase on the surface;

[0071] • Optical evaluation by microscopy or similar methods will not show any evidence of phase separation;

[0072] Further analysis and evaluation, such as by DSC, spectroscopic methods including FTIR, Raman (RAMAN) or EDX, or X-ray diffraction, will indicate a homogeneous single-phase mixture.

[0073] In some embodiments, the second polymer and / or any other polymer does not exhibit a tendency to swell or dissolve in the liquid electrolyte at elevated temperatures.

[0074] In some embodiments, the second polymer and / or any additional polymer, when exposed to a liquid electrolyte at high temperatures, do not exhibit significant changes in physical state, even when using high-shear mixing techniques. This can be confirmed by visual evaluation, which indicates that the polymers have not changed upon exposure to the liquid electrolyte. Furthermore, the DSC of the mixture may show an endothermic melting peak at the same temperature as the original polymer, indicating that the crystalline polymer phase in the material has not changed after exposure to the liquid electrolyte.

[0075] In some embodiments, the second polymer and / or any additional polymer exhibit a tendency to partially swell or dissolve in the liquid electrolyte at elevated temperatures. In this way, slight swelling of the second polymer in the liquid electrolyte may occur, but may be difficult to observe visually. In such cases, DSC measurements of the mixture can indicate the difference between the endothermic melting peak of the polymer in the mixture and that of the original polymer, suggesting a change in crystallinity upon exposure to the liquid electrolyte.

[0076] In some embodiments, the second polymer and / or any additional polymer may exhibit significant swelling and plasticization within the liquid electrolyte, but may not absorb all the liquid electrolyte in the desired amount. Visual evaluation will indicate the presence of free liquid around the gel to reveal this behavior.

[0077] In some embodiments, the second polymer and / or any additional polymer may swell and plasticize with the full amount of liquid electrolyte at elevated temperatures, but evaluation of the gel in this state at these temperatures may suggest a nonhomogeneous mixture. For example, rheological evaluation of the mixture may be difficult to measure or may be noisy, suggesting an inhomogeneous composition or phase separation.

[0078] In some embodiments, the second polymer and / or any additional polymer may exhibit the ability to swell or dissolve in a liquid electrolyte at elevated temperatures, but the mixture may be unstable at room temperature. Such a polymer may fully swell and plasticize with a liquid electrolyte at elevated temperatures, but when returned to room temperature, it may exhibit behavior suggesting its inhomogeneity or instability. For example, a visual assessment of the material may indicate that liquid is draining from the gel mass, such as forming droplets on the surface, or pooling around the host material.

[0079] In some embodiments, the electrode precursor composition comprises a polymer blend in an amount of 2 vol% to 10 vol%, based on the total volume of the electrode precursor composition, for example, 2 vol% to 9 vol%, 2 vol% to 8 vol%, 3 vol% to 8 vol%, or 3 vol% to 5 vol%.

[0080] In some embodiments, the polymer-electrolyte gel matrix phase comprises a polymer blend in an amount of 3 to 30 vol%, based on the total volume of the polymer-electrolyte gel matrix phase, for example, 3 to 25 vol%, 3 to 24 vol%, 5 to 24 vol%, 10 to 23 vol%, 10 to 22 vol%, or about 10 to 15 vol%.

[0081] In some embodiments, the polymer-electrolyte gel matrix phase comprises a liquid electrolyte in an amount of 70% to 97% by volume, based on the total volume of the polymer-electrolyte gel matrix phase, for example, 75% to 90% by volume, or 85% to 90% by volume.

[0082] In some embodiments, the electrode precursor composition comprises a polymer-electrolyte gel matrix phase in an amount of 20 vol% to 50 vol%, based on the total volume of the electrode precursor composition, for example 25 vol% to 45 vol%, 25 vol% to 40 vol%, or 30 vol% to 40 vol%.

[0083] In some embodiments, the electrode precursor composition comprises a liquid electrolyte in an amount of at least 25 vol%, for example, 25 vol% to 45 vol%, based on the total volume of the electrode precursor composition, for example, 26 vol% to 44 vol%, 27 vol% to 43 vol%, 28 vol% to 42 vol%, or 29 vol% to 42 vol%.

[0084] As explained above, this composition allows for an increased amount of liquid electrolyte present while maintaining good structural stability of the gel electrode. Therefore, in some embodiments, the liquid electrolyte constitutes at least 31% by volume of the electrode precursor composition, for example, greater than 31% by volume, for example, greater than 31.00% by volume, for example, from greater than 31% to 35% by volume. Compositions containing a single type of polymer to provide structural stability may not be able to incorporate such a level of electrolyte. In contrast, compositions containing a single type of polymer that can incorporate such a level of electrolyte may not provide the necessary structural stability, and the electrode may be degraded by the battery electrolyte during use, shortening battery life. In fact, compositions including only two types of polymers to provide structural stability and a high level of electrolyte may not provide a sufficiently long battery performance life; that is, the battery life may be lower compared to batteries containing the compositions described herein. This composition allows for higher levels of liquid electrolyte (and therefore higher levels of alkali metal salt) in the gel electrode while maintaining good structural stability and lifespan compared to other compositions.

[0085] The polymer-electrolyte gel matrix phase comprises a gel matrix formed by the swelling of a swellable polymer blend upon absorption of a liquid electrolyte. Therefore, the polymer-electrolyte gel matrix phase comprises a gel, which contains the polymer blend and the absorbed liquid electrolyte.

[0086] In some embodiments, the polymer-electrolyte gel matrix phase comprises the polymer blends described herein and the liquid electrolyte described herein.

[0087] Those skilled in the art will understand that the relative solubility of the first, second, and any other polymers in the liquid electrolyte depends not only on the properties of the selected first, second, and any other polymers, but also on the selection of the liquid electrolyte and / or the components of the liquid electrolyte, such as the selection of the solvent.

[0088] In some embodiments, the liquid electrolyte is present in an amount of at least 25% by volume of the total volume of the electrode precursor composition. In some embodiments, the liquid electrolyte is present in an amount of at least 28%, at least 30%, or at least 32% by volume of the total volume of the electrode precursor composition. In some embodiments, the liquid electrolyte is present in an amount of up to 50% by volume of the total volume of the electrode precursor composition, for example, up to 48%, up to 45%, up to 42%, or up to 40%. Any combination of these values ​​may be combined to form suitable ranges, such as 25% to 50% by volume, 28% to 48% by volume, or 32% to 45% by volume.

[0089] Liquid electrolytes contain organic solvents and alkali metal salts.

[0090] In some embodiments, the liquid electrolyte consists of an organic solvent and an alkali metal salt.

[0091] In some embodiments, the organic solvent comprises or is composed of one or more cyclic or linear carbonate compounds. In some embodiments, the solvent comprises one or more cyclic carbonate compounds. In some embodiments, the solvent comprises one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, butyl carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, and γ-butyrolactone.

[0092] In some embodiments, the solvent comprises one or more of the following: ethylene carbonate, propylene carbonate, vinylene carbonate, and fluoroethylene carbonate. In some embodiments, the solvent comprises or consists of a mixture of ethylene carbonate, propylene carbonate, vinylene carbonate, and fluoroethylene carbonate.

[0093] In some embodiments, the solvent comprises a blend of at least two different compounds, such as at least three or at least four different compounds. In some embodiments, the solvent comprises a blend of at least two different organic carbonate compounds, such as a blend of at least three or at least four different organic carbonate compounds. In some embodiments, the solvent is not a blend but consists of a single compound.

[0094] In some embodiments, the solvent comprises ethylene carbonate in an amount of at least 50% by weight, based on the total weight of the solvent, such as at least 55% by weight, at least 60% by weight, or at least 65% by weight. In some embodiments, the solvent comprises ethylene carbonate in an amount of up to 80% by weight, based on the total weight of the solvent, such as up to 75% by weight or up to 70% by weight. In some embodiments, the solvent comprises ethylene carbonate in an amount of 50% to 80% by weight, based on the total weight of the solvent, such as 60% to 75% by weight.

[0095] In some embodiments, the solvent comprises propylene carbonate in an amount of at least 10% by weight, based on the total weight of the solvent, such as at least 15% by weight, at least 20% by weight, or at least 22% by weight. In some embodiments, the solvent comprises propylene carbonate in an amount of up to 45% by weight, based on the total weight of the solvent, such as up to 42% by weight or up to 40% by weight. In some embodiments, the solvent comprises propylene carbonate in an amount of 10% to 45% by weight, based on the total weight of the solvent, such as 20% to 40% by weight.

[0096] In some embodiments, the liquid electrolyte further comprises one or more lithium salts. Examples of suitable lithium salts include LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium 2-trifluoromethyl-4,5-dicyanimidazolium (LiTDI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0097] In some embodiments, the liquid electrolyte comprises one or more lithium salts selected from the group consisting of LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium 2-trifluoromethyl-4,5-dicyanimidazolium (LiTDI). In some embodiments, the liquid electrolyte comprises a solvent and a lithium salt component as described above, wherein the lithium salt component comprises one or more lithium salts selected from or composed of the same as LiPF6, LiBF4, LiFSI, LiTFSI, and LiTDI. In some embodiments, the liquid electrolyte comprises a solvent and a lithium salt component as described above, wherein the lithium salt component comprises one or more lithium salts selected from or composed of the same as LiFSI and LiTDI.

[0098] In some embodiments, the liquid electrolyte comprises or is composed of an organic solvent and an alkali metal salt; wherein the organic solvent comprises one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, butyl carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, and γ-butyrolactone; and the alkali metal salt comprises one or more of the following: LiPF6, LiBF4, LiFSI, LiTFSI, and LiTDI. In some embodiments, the liquid electrolyte comprises or is composed of an organic solvent and an alkali metal salt; wherein the organic solvent comprises one or more of the following: ethylene carbonate, propylene carbonate, vinylene carbonate, and fluoroethylene carbonate; and the alkali metal salt comprises one or more of LiFSI and LiTDI.

[0099] In some embodiments, the liquid electrolyte comprises or is composed of a mixture of at least two different lithium salts. In some embodiments, the solvent comprises or is composed of a blend of at least two different organic carbonate compounds, such as at least two, at least three, or at least four different organic carbonate compounds, and the liquid electrolyte comprises or is composed of a mixture of at least two different lithium salts. In some embodiments, the liquid electrolyte is composed of an alkali metal salt and a solvent, such as a lithium salt and an organic carbonate compound. In some embodiments, the liquid electrolyte contains only one alkali metal salt and a blend of at least two different organic carbonate compounds. In some embodiments, the liquid electrolyte comprises a mixture of at least two different alkali metal salts, such as two different lithium salts, and only one organic carbonate compound as a solvent. In some embodiments, the liquid electrolyte comprises a mixture of two different alkali metal salts, such as LiFSI and LiTDI, and at least two organic carbonate compounds as solvents or is composed of them.

[0100] In some embodiments, the total concentration of the lithium salt in the organic solvent is at least 10% by weight, based on the total weight of the liquid electrolyte, such as at least 11% by weight, at least 12% by weight, at least 13% by weight, at least 14% by weight, or at least 15% by weight. In some embodiments, the total concentration of the lithium salt in the organic solvent is up to 50% by weight, based on the total weight of the liquid electrolyte, such as up to 40% by weight, up to 30% by weight, up to 25% by weight, or up to 24% by weight.

[0101] In some embodiments, the total concentration of lithium salt in the organic solvent is 10% to 30% by weight, based on the total weight of the liquid electrolyte, for example, 12% to 25% by weight or 15% to 25% by weight.

[0102] The dispersed phase contains electrochemically active materials.

[0103] In some embodiments, the electrochemically active material comprises at least 50% by volume of the total volume of the electrode precursor composition, for example, at least 52% by volume, at least 55% by volume, or at least 57% by volume. In some embodiments, the electrochemically active material comprises up to 75% by volume of the total volume of the electrode precursor composition, for example, up to 73% by volume, up to 70% by volume, or up to 68% by volume. Any combination of these values ​​may be combined to form suitable ranges, for example, 50% to 75% by volume, 50% to 73% by volume, or 52% to 73% by volume of the total volume of the electrode precursor composition.

[0104] In some embodiments, the dispersed phase is composed of electrochemically active materials.

[0105] Electrochemically active materials are granular materials, that is, materials composed of multiple discrete particles. Particles may contain primary particles and / or secondary particles formed by the aggregation of multiple primary particles.

[0106] In some embodiments, the electrochemically active material is a positive electrode active material. Such a material can be suitably used to form the cathode electrode.

[0107] In some embodiments, the positive electrode active material is a lithium transition metal oxide material. In some embodiments, the positive electrode active material is a lithium transition metal oxide material comprising a mixed metal oxide of lithium and one or more transition metals, optionally further comprising one or more additional non-transition metals. In some embodiments, the positive electrode active material is a lithium transition metal oxide material comprising lithium and one or more transition metals selected from nickel, cobalt, and manganese. In some embodiments, the positive electrode active material is selected from one or more of the following: lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel cobalt oxide (NCO), aluminum-doped lithium nickel cobalt oxide (NCA), lithium nickel manganese cobalt oxide (NMC), lithium nickel oxide (LNO), lithium nickel manganese oxide (LNMO), lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), and lithium nickel vanadate (LNV). In some embodiments, the positive electrode active material is lithium nickel manganese cobalt oxide (NMC), optionally doped with another metal such as aluminum.

[0108] In some cases, electrochemically active materials may contain carbon, preferably graphite, graphene, or a blend of carbon and silicon oxide.

[0109] Such electrochemically active materials are commercially available or can be manufactured by methods known to those skilled in the art, such as by precipitating a mixed metal hydroxide intermediate from a reaction mixture containing different precursor metal salts, followed by calcination to form a mixed metal oxide and optionally lithiation to introduce lithium into the oxide.

[0110] Electrochemically active materials may be undoped or uncoated, or may contain one or more dopants and / or coatings. For example, electrochemically active materials may be doped with small amounts of one or more metal elements. Electrochemically active materials may contain a carbon coating on the surface of the material particles.

[0111] In some embodiments, the electrochemically active material is the negative electrode active material. Such a composition can be suitably used to prepare the anode electrode.

[0112] In some embodiments, the electrochemically active material has a bimodal particle size distribution.

[0113] In some embodiments, the electrode precursor composition is used in lithium-ion secondary electrochemical batteries. In some embodiments, the electrode precursor composition is a cathode precursor composition.

[0114] electrode

[0115] This article also provides an electrode for alkali metal ion secondary batteries. The electrode comprises a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer and a second polymer, the first polymer having a concentration of at least 1 x 10⁻⁶. 5 The weight-average molecular weight polymethyl methacrylate (PMMA) of Da, the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and the liquid electrolyte contains an organic solvent and an alkali metal salt; the dispersed phase contains an electrochemically active material; and the first polymer accounts for 0.1 vol% to 10 vol% of the total volume of the polymer blend.

[0116] In some embodiments, the electrode comprises the electrode precursor composition described herein or is produced by processing the electrode precursor composition described herein to form a film.

[0117] In some embodiments, the electrode is an extruded electrode. In other embodiments, the electrode is a hot-rolled electrode. In still other embodiments, the electrode is prepared by extruding the electrode precursor composition described herein via a die to form a film.

[0118] In some embodiments, the electrode is a cathode or an anode. In some embodiments, the electrode is a cathode.

[0119] All compositional options listed for the electrode precursor compositions described herein also apply to the electrodes described herein, including specific information and relative amounts of various components of the composition that are not typically expected to be altered during the processing of the precursor compositions into electrodes.

[0120] In some implementations, the processing includes thermal processing or extrusion.

[0121] In some embodiments, thermal processing includes passing the electrode precursor composition through a roller assembly at a temperature of at least 50°C, such as at least 60°C, at least 70°C, at least 80°C, at least 90°C, or at least 100°C. In some embodiments, thermal processing includes passing the electrode precursor composition through the rollers at a temperature up to 150°C, such as up to 140°C or up to 130°C. In some embodiments, thermal processing includes passing the electrode precursor composition through the rollers at a temperature of 50°C to 150°C, such as 60°C to 150°C, 70°C to 150°C, 80°C to 150°C, 80°C to 140°C, 90°C to 140°C, 100°C to 140°C, or 110°C to 130°C.

[0122] The roller assembly may include two rollers spaced at a small distance, such that the electrode is pressed into a thin film as it passes through the rollers.

[0123] In some embodiments, thermal processing includes extruding the electrode. In some embodiments, thermal processing includes extruding the electrode using an extrusion apparatus comprising one or more screw feed sections and an extrusion die. In some embodiments, the die temperature is at least 50°C, for example at least 60°C, at least 70°C, at least 80°C, at least 90°C, or at least 100°C. In some embodiments, the die temperature is up to 150°C, for example up to 140°C or up to 130°C. In some embodiments, the die temperature is between 50°C and 150°C, for example 60°C to 150°C, 70°C to 150°C, 80°C to 150°C, 80°C to 140°C, 90°C to 140°C, 100°C to 140°C, or 110°C to 130°C.

[0124] In some embodiments, the electrode has a thickness of less than 150 µm, such as less than 100 µm, less than 90 µm, less than 80 µm, or less than 70 µm. In some embodiments, the electrode has a thickness of 40 to 150 µm, such as 40 to 100 µm, 40 to 90 µm, 40 to 80 µm, 40 to 70 µm, or 50 to 70 µm.

[0125] In some embodiments, the electrode has a thickness of 40 to 150 µm, such as 40 to 100 µm, 40 to 90 µm, 40 to 80 µm, 40 to 70 µm, or 50 to 70 µm.

[0126] In some embodiments, the electrode has a porosity of less than about 5% by volume. In some cases, the porosity of the electrode is less than 5% by volume, less than 3% by volume, or less than 2% by volume. Alternatively, the volume density of the electrode may be at least 95%, suitably at least about 97% or 98% of the density of a perfectly non-porous electrode.

[0127] In some cases, the extruded electrode can form part of an extruded monolith, which includes one or more additional layers present in the electrochemical cell. For example, the monolith may include a separator layer and / or other electrodes (i.e., the extruded monolith may include both a cathode and an anode). Different layers may be co-extruded and have different compositions from each other.

[0128] Batteries and devices

[0129] This article also provides an electrochemical secondary cell containing the electrodes described herein.

[0130] In some embodiments, the battery is an alkali metal ion secondary battery, such as a sodium ion secondary battery or a lithium ion secondary battery. In some embodiments, the battery is a lithium ion secondary battery.

[0131] In some embodiments, the electrochemical secondary cell includes one electrode as described herein. In some embodiments, the electrochemical secondary cell includes more than one, such as two or more, electrodes as described herein.

[0132] In some embodiments, the electrochemical secondary battery includes a first electrode as described herein, wherein the first electrode is a cathode, and a second electrode as described herein, wherein the second electrode is an anode, and an electrolyte between the cathode and the anode. In some embodiments, the electrochemical secondary battery includes the electrode as described herein, which is laminated together with a current collector (e.g., a metal foil).

[0133] This document also provides an electrochemical energy storage device comprising the electrochemical secondary battery described herein. In some embodiments, the electrochemical energy storage device is a battery pack. In some embodiments, the electrochemical energy storage device is a lithium-ion battery pack.

[0134] method

[0135] This document also provides a method for preparing the electrode precursor compositions listed herein. The method involves mixing an electrochemically active material with first, second, and optionally additional polymers, as well as an electrolyte. Other components, such as any conductive additives, may be mixed simultaneously or later. Mixing can be carried out by any suitable means, particularly any suitable type of mixing equipment, for any suitable time. In some embodiments, mixing is carried out at room temperature (approximately 18-25°C) and atmospheric pressure.

[0136] This document also provides the use of 0.1 vol% to 10 vol% of a first polymer in a polymer-electrolyte gel matrix phase of a composition for use in alkali metal ion secondary batteries, the composition comprising a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer and a second polymer, the first polymer having a concentration of at least 1 x 10⁻⁶. 5 The first polymer is a polymethyl methacrylate (PMMA) with a weight-average molecular weight of Da. The second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and the liquid electrolyte contains an organic solvent and an alkali metal salt; and the dispersed phase contains an electrochemically active material. Therefore, the use provides the first polymer as a processing additive for gel electrode compositions. Typically, the use results in the compositions described herein.

[0137] This document also provides a method for producing electrodes. The method includes processing the electrode precursor composition described herein to form a film or coating.

[0138] In some implementations, the process forms a film.

[0139] In some implementations, the method is a method for producing electrodes for alkali metal ion secondary batteries.

[0140] In some implementations, the processing includes thermal processing or extrusion.

[0141] In some embodiments, the method includes: mixing a polymer, an electrolyte, and an electrochemically active material to form the electrode precursor composition described herein; and thermally processing or extruding the electrode precursor composition to form an electrode film or coating. In some embodiments, the processing forms a film. In some embodiments, the processing includes thermal processing.

[0142] In some embodiments, the electrode film has a thickness of 500 to 700 µm.

[0143] In some embodiments, the method further includes cutting the electrode film to form an electrode having a predetermined size.

[0144] In some embodiments, the method further includes a second thermal processing step on the cut film to reduce the film thickness to the range of 50 to 70 µm. In some embodiments, the film is provided at the desired thickness without a second thermal processing step, i.e., a thermal processing or extrusion step produces a film of the desired thickness.

[0145] In some embodiments, the temperature during heat treatment is 100 to 140°C.

[0146] Example

[0147] Electrode precursor compositions were prepared according to the formulations shown in Table 1 below. The electrode precursor compositions were subjected to processing steps, and the resulting compounded materials were subjected to pressure at room temperature (between 20 and 25°C) to reduce the target thickness. The same pressure was applied to each example and its respective comparative example (i.e., the same pressure was applied to Example 1 and Comparative Example 1; the same pressure was applied to Example 2 and Comparative Example 2; and the same pressure was applied to Example 3 and Comparative Example 3). Visual evaluation was performed after the compounded materials were subjected to pressure.

[0148] Based on the target volume percentage and the determined component density, the mass of the component to be included in the composition is calculated using the known formula: mass = density × volume.

[0149] Typically, density can be determined from available data (in textbooks or similar) or by using suitable methods known to those skilled in the art based on first principles. For solid components—such as particulate solids, polymers, conductive carbon—density can be determined using methods such as the helium flask method, which accurately measures the volume and weight of the material (this is not powder density or tap density). For liquid components, density measurements can be performed using suitable liquid density equipment such as volumetric flasks. The density measurements used herein were performed at 25°C and atmospheric pressure.

[0150] The following components were used in the examples:

[0151] -The second polymer is an ultra-high molecular weight PVDF copolymer, which contains VDF as a constituent monomer;

[0152] -The third polymer is a high molecular weight PVDF copolymer, which contains VDF as a constituent monomer unit;

[0153] -The first polymer is PMMA;

[0154] Additive 1 is carbon black; and additive 2 is multi-walled carbon nanotubes;

[0155] Electrolytes 1 and 2 each exist at 1M.

[0156] Electrolyte 1 has the following composition, wherein the percentage values ​​provided are as a percentage of the total electrolyte, which is 100% by weight:

[0157] Electrolyte 2 is a mixture of two carbonate solvents and two lithium salts.

[0158] Table 1

[0159]

[0160] It was found that, upon application of pressure, the electrolyte was extruded from the blended materials of Comparative Examples 1, 2, and 3. No electrolyte extrusion was observed after applying the corresponding pressure to the blended material of Example 1. Upon application of pressure to the blended material of Example 2, a significant improvement in electrolyte retention was observed compared to the results of Comparative Example 2. Similarly, upon application of pressure to the blended material of Example 3, a significant improvement in electrolyte retention was observed compared to the results of Comparative Example 3.

[0161] Figure 1(a) shows the results of Comparative Example 1, i.e., the composition without the first polymer, which was subsequently processed and pressed as described above. The circled areas show regions of the blended material where electrolyte loss is visually observable. Other areas are also visible, although not indicated. Figure 1(b) shows the results of Example 1, i.e., the composition described herein containing the first polymer as an additive, used to form the material of Figure 1(a). The material shown in Figure 1(b) was processed and pressed in the same manner as the material of Figure 1(a). Figure 1(b) shows areas where no electrolyte loss is visible. Note that, for ease of comparison, these images were taken with the covering polymer film (used when pressure was applied) carefully removed.

Claims

1. An electrode precursor composition for an alkali metal ion secondary battery, comprising: a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer and a second polymer, the first polymer having a content of at least 1 x 10⁻⁶. 5 The first polymer comprises a weight-average molecular weight polymethyl methacrylate (PMMA) of Da, wherein the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and wherein the liquid electrolyte comprises an organic solvent and an alkali metal salt; wherein the dispersed phase comprises an electrochemically active material; and wherein the first polymer comprises 0.1 vol% to 10 vol% of the total volume of the polymer blend.

2. The electrode precursor composition according to claim 1, wherein the first polymer is present in an amount of at least 0.5% by volume of the total volume of the polymer blend and / or up to 9% by volume of the total volume of the polymer blend.

3. The electrode precursor composition according to any one of the preceding claims, wherein the first polymer has a content of at least 1 x 10⁻⁶. 6 The weight-average molecular weight of Da.

4. The electrode precursor composition according to any one of the preceding claims, wherein the second polymer has a content of at least 1 x 10⁻⁶. 5 The weight-average molecular weight of Da.

5. The electrode precursor composition according to any one of the preceding claims, wherein the polymer blend comprises a third polymer, which is different from the first polymer and the second polymer, and optionally comprises at least 75 mol% of vinylidene fluoride (VDF) as a constituent monomer.

6. The electrode precursor composition according to claim 5, wherein the first polymer has a weight-average molecular weight greater than that of the second polymer, and optionally wherein the third polymer has a weight-average molecular weight less than that of the second polymer.

7. The electrode precursor composition according to any one of the preceding claims, wherein at least one of the second polymer or optionally another polymer comprises hexafluoropropylene (HFP) as a constituent monomer, and optionally up to 2 mol% of one or more constituent monomers other than VDF and HFP.

8. The electrode precursor composition according to any one of the preceding claims, wherein the electrochemically active material is present in an amount of 50% to 75% by volume of the total volume of the electrode precursor composition.

9. The electrode precursor composition according to claim 8, wherein the electrochemically active material is present in an amount of at least 60% by volume of the total volume of the electrode precursor composition.

10. The electrode precursor composition according to any one of the preceding claims, wherein the dispersed phase further comprises a conductive additive.

11. The electrode precursor composition according to any one of the preceding claims, wherein the liquid electrolyte is present in an amount of at least 25% by volume of the total volume of the electrode precursor composition.

12. The electrode precursor composition according to any one of the preceding claims, wherein the organic solvent comprises one or more cyclic or linear carbonate compounds.

13. The electrode precursor composition according to any one of the preceding claims, wherein the organic solvent comprises one or more of the following: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, butyl carbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylene carbonate, and γ-butyrolactone.

14. The electrode precursor composition according to any one of the preceding claims, wherein the alkali metal salt comprises one or more of the following: LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium 2-trifluoromethyl-4,5-dicyanimidazolium (LiTDI).

15. The electrode precursor composition according to any one of the preceding claims, wherein the electrode precursor composition comprises 20 vol% to 50 vol% of the polymer-electrolyte gel matrix phase, based on the total composition volume.

16. The electrode precursor composition according to any one of the preceding claims, wherein the polymer-electrolyte gel matrix phase comprises 3 vol% to 30 vol% of the polymer blend, based on the total volume of the polymer-electrolyte gel matrix phase.

17. The electrode precursor composition according to any one of the preceding claims, used in a lithium-ion secondary electrochemical battery.

18. A method for preparing an electrode precursor composition according to any one of the preceding claims, comprising mixing the electrochemically active material with the first polymer and the second polymer, and optionally additional polymers, and the electrolyte. 19.0.1% to 10% by volume of the first polymer in a polymer-electrolyte gel matrix phase of a composition for use in an alkali metal ion secondary battery, said composition comprising: the polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising the first polymer and a second polymer, the first polymer having a concentration of at least 1 x 10⁻⁶. 5 Da is a weight-average molecular weight polymethyl methacrylate (PMMA), the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and the liquid electrolyte contains an organic solvent and an alkali metal salt; and the dispersed phase contains an electrochemically active material.

20. An electrode for an alkali metal ion secondary battery, comprising: a polymer-electrolyte gel matrix phase and a dispersed phase, wherein the polymer-electrolyte gel matrix phase comprises a polymer blend and a liquid electrolyte, the polymer blend comprising a first polymer and a second polymer, the first polymer having a density of at least 1 x 10⁻⁶. 5 The first polymer comprises a weight-average molecular weight polymethyl methacrylate (PMMA) of Da, wherein the second polymer contains at least 75 mol% vinylidene fluoride (VDF) as a constituent monomer, and wherein the liquid electrolyte comprises an organic solvent and an alkali metal salt; wherein the dispersed phase comprises an electrochemically active material; and wherein the first polymer comprises 0.1 vol% to 10 vol% of the total volume of the polymer blend.

21. The electrode of claim 20, comprising or produced from the electrode precursor composition of any one of claims 1 to 19.

22. A method of producing an electrode, comprising processing the electrode precursor composition according to any one of claims 1 to 19 to form a film or coating.

23. The method of claim 22, wherein the processing comprises thermal processing or extrusion.

24. An electrochemical secondary cell comprising an electrode according to claim 20 or 21, or an electrode produced by the method according to claim 22 or 23.

25. An electrochemical energy storage device comprising the electrochemical secondary battery according to claim 24.

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