Negative electrode including a polymer single-ion conductor coating

Abstract

Negative electrode, including: a metal substrate selected from the group consisting of lithium, sodium, and zinc; and a polymeric single-ion conductor coating formed on a surface of the metal substrate, wherein the polymeric single-ion conductor coating consists of a polymeric metal salt with an initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone, wherein the polymeric single-ion conductor coating has a comb-like structure, the polymer backbone chain extending over the surface and the attached metal salt groups extending outwards and away from the surface at predetermined positions and wherein the parts of the attached metal salt groups, which carry the associated anions, are bonded to certain atoms of the polymer backbone, wherein the initial polymeric backbone is selected from the group consisting of polyolefin, polyvinylidene fluoride, polyethylene oxide, polyimide and copolymers thereof.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a negative electrode comprising a polymeric single-ion conductor coating. BACKGROUND

[0002] Secondary or rechargeable metal-ion batteries are commonly used in many stationary and portable devices, such as those found in the electronics, automotive, medical technology, machinery, robotics, and aerospace industries. Examples of secondary or rechargeable metal-ion batteries include lithium-based, sodium-based, and zinc-based batteries. In the automotive industry, metal-ion batteries are suitable for electric vehicles such as hybrid electric vehicles (HEVs), battery electric vehicles (BEVs), plug-in HEVs, and electric range electric vehicles (EREVs).Lithium batteries are gaining popularity for several reasons, including relatively high energy density, high performance, a general storage effect compared to other types of rechargeable batteries, relatively low internal resistance, and a low self-discharge rate when not in use. The ability of lithium batteries to perform repeated power cycles throughout their lifespan makes them an attractive and reliable energy source. Such and comparable negative electrodes and electrochemical cells are described, for example, in US 2015 / 0180037A1 and CHENG, XB [et al.], A Review of Solid Electrolyte Interphases on Lithium Metal Anode, Advanced Science, Vol. 3, 2016, No. 3, pp. 1-20. SUMMARY

[0003] A negative electrode comprises a metal substrate and a polymeric single-ion conductor coating formed on the surface of the metal substrate. The metal substrate is selected from the group consisting of lithium, sodium, and zinc.The polymeric one-ion conductor coating consists of a polymeric metal salt with an initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone, wherein the polymeric one-ion conductor coating has a comb-like structure, the polymeric backbone chain extending over the surface and the attached metal salt groups extending outwards and away from the surface at predetermined positions, and wherein the parts of the attached metal salt groups carrying the associated anions are bonded to specific atoms of the polymeric backbone, wherein the initial polymeric backbone is selected from the group consisting of polyolefin, polyvinylidene fluoride, polyethylene oxide, polyimide and copolymers thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Features of examples of the present disclosure will become apparent by reference to the following detailed description and the drawings, in which the same reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features with a previously described function may or may not be described in relation to other drawings in which they appear. Fig. Figure 1 is a schematic representation of an example of the negative electrode disclosed herein; Fig. Figure 2A is a schematic representation of an example of an electrochemical cell disclosed herein; Fig. Figure 2B is a schematic representation of another example of an electrochemical cell disclosed herein; Fig. 3 is a diagram showing the specific conductivity (in mS / cm). -1 ) compared to 1000 / T (K -1) represents two exemplary polymeric single-ion conductors; and Fig. Figure 4 is a graphical representation showing the cycle performance (in terms of voltage (V) versus time in seconds (s)) of an electrochemical cell including the lithium electrodes and a polymeric one-ion conductor coating formed on a surface of one of the lithium electrodes. DETAILED DESCRIPTION

[0005] Lithium, sodium, and zinc are all suitable negative electrode materials, partly due to their respective high specific capacities (e.g., lithium has ~3860 mAh / g, sodium has 1165 mAh / g, and zinc has 820 mAh / g). However, each of these materials tends to form dendrites during the cell cycle. Dendrites are thin, conductive filaments that can short-circuit the cell, reducing its tolerance and shortening its overall lifespan.

[0006] In the examples disclosed herein, dendrite growth is suppressed by forming a substantially homogeneous distribution of lithium, sodium, or zinc cations over the surface of a lithium, sodium, or zinc metal substrate. A polymeric single-ion conductor (Li + , N / a + or Zn +The polymeric single-ion conductor is formed as a coating on the metal substrate. It is constructed from i) a metal salt of a sulfonated tetrafluoroethylene-based fluoropolymer copolymer or ii) a polymeric metal salt with an initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone. In the sulfonated tetrafluoroethylene-based fluoropolymer copolymer example, the metal salt forms at the end of each attached group. In the polymeric metal salt example, the metal salt group is attached at specific positions along the polymeric backbone. The coating of the polymeric single-ion conductor on the metal substrate positions the cation polyanions of the metal salt group relatively uniformly across the metal substrate.

[0007] The relatively / essentially uniformly distributed cations enable the current to be distributed relatively / essentially uniformly during the cell cycle. It has been found that when the current is distributed relatively / essentially uniformly using the exemplary single-ion polymeric conductors disclosed herein (Li + , N / a + or Zn + ) is distributed, which can suppress dendrite growth.

[0008] Referring to Fig. Figure 1 shows the negative electrode 10. As mentioned above, examples of the negative electrode 10 disclosed herein include a metal substrate 12 and an example of the single-ion conductor coating 14 formed on a surface of the metal substrate 12.

[0009] The metal substrate 12 can be lithium (e.g. lithium foil), sodium (e.g. sodium foil) or zinc (zinc foil).

[0010] The single-ion conductor coating 14 is formed from i) a metal salt of a sulfonated fluoropolymer copolymer based on tetrafluoroethylene or ii) a polymeric metal salt with an initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone.

[0011] The metal salt of the sulfonated tetrafluoroethylene-based fluoropolymer copolymer can be a lithium, sodium, or zinc salt of the commercially available sulfonated fluoropolymer copolymer NAFION® (available from DuPont). As an example, the metal salt of the sulfonated tetrafluoroethylene-based fluoropolymer copolymer can be synthesized by first copolymerizing tetrafluoroethylene (TFE) and a perfluoro(alkyl vinyl ether) derivative with sulfonyl fluoride (e.g., perfluoro(-3,6-dioxa-4-methyl-7-octene)sulfonyl fluoride). These monomers can be copolymerized via in-solution radical copolymerization, solventless copolymerization, or emulsion polymerization in water. An initiator may be used. The sulfonyl fluoride groups of the initial copolymer (1, see scheme below) can be converted to sulfonic acid groups by hydrolysis.The final copolymer (2) can then be reacted with lithium hydroxide (LiOH), sodium hydroxide (NaOH), or zinc hydroxide (Zn(OH)2) to form the metal salt version of the copolymer. An example of the formation of the lithium salt of the sulfonated tetrafluoroethylene-based fluoropolymer copolymer is shown below in Scheme 1.

[0012] The polymeric metal salt with the initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone. Examples of the initial polymeric backbone include (e.g., polyethylene, polypropylene, etc.) polyvinylidene fluoride, polysulfone, polyethylene oxide, polyacrylate, polysiloxane, polyvinyl acetate, polyimide, and copolymers thereof.

[0013] Examples of the attached metal salt groups can be lithium salts, sodium salts, or zinc salts, depending in part on the metal used for the metal substrate 12. The attached metal salt groups can be metal salt analogs, such as allylfluorinated metal salts. The attached metal salt groups can be considered short, depending on the length of the attached allyl group. Examples of (modified) lithium salts include lithium bis(trifluoromethane)sulfonimide (LiTFSI), lithium malonatodifluoroborate, lithium sulfonate, lithium triflate, analogs thereof, and combinations thereof. For example, lithium sulfonimide is an analog of LiTFSI and is an analog of lithium triflate. Examples of (modified) sodium salts include sodium trifluoromethanesulfonate, NaClO4, NaPF6, NaBF4, NaTFSI (sodium (I)-bis-(trifluoromethanesulfonyl)-imide), NaFSI (sodium (I)-bis(-fluorosulfonyl-)imide), analogues thereof and combinations thereof.Examples of (modified) zinc salts include zinc trifluoromethanesulfonate, Zn(ClO4)2, Zn(PF6)2, Zn(BF4)2, Zn(TFSI)2 (zinc(II) bis(-trifluoromethanesulfonyl-)imide), Zn(FSI)2 (zinc (II) bis(-fluorosulfonyl-)imide), analogues thereof and combinations thereof.

[0014] The (modified) metal salt groups may also include a linking group or chain capable of attaching to one end of the metal salt, which also acts as a linkage to the initial polymeric backbone. For example, the linking group or chain could be a hydrosilyl linking chain. Alternatively, the metal salt groups may not include a linking group or chain but may instead be linked to the initial polymeric backbone by a double bond reaction in the presence of an initiator.

[0015] The polymeric metal salt can be formed by binding the anion-bearing portion of the metal salt to the initial polymeric scaffold. A chemical reaction can attach the metal salt to the initial polymeric scaffold, and the specific chemical reaction that occurs depends on the metal salt and the initial polymeric scaffold used. For example, equal amounts of the salt and the polymer (or a prepolymer that will form the polymer) can be dissolved in a suitable solvent in the presence of a catalyst and / or a crosslinking agent. The catalyst can be used to accelerate the reaction, and a crosslinking agent can be used to crosslink the polymeric scaffold chains for improved mechanical performance. For example, the solvent could be tetrahydrofuran (TINF), and the catalyst could be platinum divinyltetramethyldisiloxane.Other suitable solvents can include toluene, diethyl ether (DEE), etc. Any platinum catalyst can be used. The solution can be heated under reflux or exposed to other suitable conditions in which the reaction can take place. A coating composition is formed as a result of the reaction.

[0016] The coating composition includes the solvent and the polymeric metal salt. Since some of the solvent may evaporate during the reaction, the coating composition can be viscous enough to be applied to the metal substrate 12 or another sacrificial substrate.

[0017] In other examples, the polymeric metal salt (as opposed to synthesis) is acquired and dissolved or dispersed in a suitable solvent to form the coating composition. The solvent can be an organic solvent such as N-methylpyrrolidone (NMP). The solvent can also be an aqueous medium (e.g., water or a mixture of water and a water-soluble solvent). In one example, a dispersion of NAFION® and water may be available. In this example, the dispersion can be neutralized with LiOH. This neutralized solution can be dried, and the dried substance (Li-NAFION®) can be dissolved (e.g., in NMP) to form the coating composition.

[0018] It is understood that the solvent selected for the coating composition is able to dissolve the polymeric metal salt and not react with the metal substrate 12.

[0019] In one example, the coating composition is applied to the surface of the metal substrate 12. The coating can be applied using any suitable technique, such as slot nozzle coating, curtain coating, brushing, roller coating, spray coating, doctor blade coating, dip coating, or centrifugal coating.

[0020] After application, the applied coating layer can be heated to evaporate any water or organic solvent to promote film coalescence, or, in the case of a thermosetting polymer, to cure the coating layer to form the single-ion conductive coating 14. Any suitable heating temperature can be used as long as the metal substrate 12 is stable at the heating temperature. Examples of suitable heating temperatures range from about 60°C to about 300°C. Alternatively, a vacuum can be applied after application to evaporate any volatile compounds.

[0021] It is understood that as long as the coating composition can be dried to remove trace water (or any other solvent), it can be applied to lithium or sodium. Zinc is stable in aqueous solutions, so the coating composition can be dried or not when using zinc.

[0022] Applying the coating composition directly to the metal substrate 12 has several advantages, including the ability to achieve thinner films (e.g., compared to freestanding membranes) and fewer manufacturing steps (e.g., no film formation and adhesion steps).

[0023] The polymeric single-ion conductive coating 14 on the surface of the metal substrate 12 can have a thickness ranging from approximately 10 nanometers to approximately 250 micrometers. In various examples, the single-ion conductive coating 14 has a thickness ranging from approximately 10 nanometers or approximately 15 nanometers to approximately 1 micrometer or to approximately 0.5 micrometers.

[0024] This thickness range is desirable because a polymeric single-ion conductor coating 14 that is too thick has a high resistance, and conversely, a coating 14 that is too thin will not conduct the current.

[0025] It is understood that the polymeric main chains can be cross-linked. In one example, cross-linking is achieved through the attached metal salt groups.

[0026] In another example, the coating composition can be applied to a sacrificial material. The coating can be applied using any suitable technique, such as slot die coating, curtain coating, brushing, roller coating, spray coating, doctor blade coating, dip coating, or centrifugal coating. After application, the applied coating layer can be heated or subjected to a vacuum to help dry the coating 14 and form a freestanding film on the sacrificial material. The freestanding film can be removed from the sacrificial material. The metal (of the desired metal substrate 12) can then be deposited onto the freestanding film under vacuum to form the metal substrate 12 with the polymeric single-ion conductor coating 14 on it.

[0027] As shown in Fig. 1, the polymeric one-ion conductor coating 14 the metal cations on (represented as M +), which are distributed essentially uniformly along the surface of the metal substrate 12. The polymeric one-ion conductor coating 14 has a comb-like structure, with the polymer backbone chain extending across the surface and the attached metal salt groups located outwards and away from the surface at predetermined positions (which depend on the polymer backbone chain and the reaction between the polymer and the attached metal salt groups). As mentioned earlier, this is due to the portions of the attached metal salt groups that carry the associated anions (shown as θ ), which are bonded to specific atoms of the polymer backbone.

[0028] The negative electrode 10 can be used in an electrochemical cell. Examples of electrochemical cells 20, 20' are shown in the Fig. 2A and Fig. 2B is shown.

[0029] In the example shown in Fig. 2A, the electrochemical cell 20 includes the negative electrode 10, a negative-side current collector 10a, a positive electrode 16 and a positive side current collector 16a.

[0030] The negative-side current collector 10a can be made of copper or any other suitable electrically conductive material. The positive-side current collectors 16a can be made of aluminum or any other suitable electrically conductive material. The selected current collectors 10a, 16a should be capable of collecting and moving free electrons to and from an associated external circuit 18.

[0031] The positive electrode 16 contains an active material, alone or in combination with a binder and / or a conductive filler. The active material depends in part on the type of cell 20.

[0032] If cell 20 is a lithium-ion cell, the active material of the positive electrode 16 can be a lithium-based active material. A common class of known lithium-based active materials suitable for the positive electrode 16 includes layered lithium transition metal oxides. Some specific examples of lithium-based active materials include spinel lithium manganese oxide (LiMn₂O₄), lithium cobalt oxide (LiCoO₂), and a manganese nickel oxide spinel (Li(Ni)₂O₆). 0,5 Mn 1,5 )O2) or a layered nickel-manganese-cobalt oxide (with a general formula xLi2MnO3 (1-x)LiMO2, where M is composed of Ni, Mn and / or Co in any ratio). A specific example of the layered nickel-manganese oxide spinel is xLi2MnO3 (1-x)Li(Ni 1 / 3 Mn 1 / 3 Co 1 / 3 )O2. Other suitable lithium-based active materials include Li(Ni) 1 / 3 Mn 1 / 3 Co 1 / 3 )O2), LiNiO2, Lix+y Mn 2-y O4 (LMO, 0 < x < 1 and 0 < y < 0.1) or a lithium iron polyanion oxide, such as lithium iron phosphate (LiFePO4) or lithium iron fluorophosphate (Li2FePO4F). Other lithium-based active materials can also be used, such as LiNi. x M 1-x O2 (M consists of any ratio of Al, Co, and / or Mg), LiNi 1-z Co 1-y M x+y O2 or LiMn 1,5-x Ni 0,5-y M x+y O4 (M consists of any ratio of Al, Ti, Cr and / or Mg), stabilized lithium manganese oxide spinel (Li x Mn 2-y M y O4, where M is composed in a ratio of Al, Ti, Cr and / or Mg), lithium nickel cobalt aluminum oxide (e.g. LiNi 0,8 Co 0,15 Al 0,05 O2 or NCA), aluminum-stabilized lithium manganese oxide spinel (Li x Mn 2-x Al yO4), lithium vanadium oxide (LiV2O5), Li2MSiO4 (where M is composed of Co, Fe, and / or Mn in any ratio), and any other high-energy nickel-manganese-cobalt material (HE-NMC, NMC, or LiNiMnCoO2). "Any ratio" means that any element can be present in any quantity. For example, M could be Al, with or without Co and / or Mg, or any other combination of the listed elements. In another example, anion substitutions can be made in the lattice of any example of the lithium transition metal-based active material to stabilize the crystal structure. For example, any O atom can be substituted by an F atom.

[0033] If cell 20 is a sodium-ion cell, the active material of the positive electrode 16 can be a sodium-based active material. Examples of suitable sodium-based active materials include sodium manganese hexacyanomanganate (Na₂Mn[Mn(CN)₆], NaVPO₄F, NaMnO₂, NaFePO₄, and Na₃V₂(PO₄)₃).

[0034] If cell 20 is a zinc ion cell, the positive electrode 16 can be alpha-manganese dioxide particles (γ-MnO2), ZnMn2O 4u and ZnMnO2.

[0035] The active material in any example of the positive electrode 16 can be mixed with the aforementioned binder and / or conductive filler. Suitable binders include polyvinylidene fluoride (PVdF), polyethylene oxide (PEO), an ethylene propylene diene monomer (EPDM) rubber, carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), styrene-butadiene rubber-carboxymethylcellulose (SBR-CMC), polyacrylic acid (PVA), cross-linked polyacrylic acid-polyethyleneimine, polyimide, or any other suitable binder material. An example of the conductive filler is a carbon with a large surface area, such as carbon black. The binder can hold the electrode materials together, and the conductive filler provides electron conduction between the positive-side current collector 16a and the active material particles of the positive electrode 16.

[0036] In the example of cell 20, shown in Fig. In Figure 2A, the polymeric single-ion conductive coating 14 of the negative electrode 10 is arranged between the metal substrate 12 and the positive electrode 16. In this example, the single-ion conductive coating 14 can, in addition to distributing current substantially uniformly across the metal substrate 12 and suppressing dendrite formation, also serve as a separator and electrolyte for the cell 20. The single-ion conductive coating 14 is able to electrically insulate the metal substrate 12 from the positive electrode 16 and is also able to serve as the electrolyte for the cell 20 with or without the addition of additional solvents.

[0037] As in Fig. As shown in Figure 2A, cell 20 also includes the interruptible external circuit 18, which connects the negative electrode 10 and the positive electrode 16 (via the current collectors 10a, 16a). Cell 20 can also carry a load device 22, which may be operationally connected to the external circuit 18. The load device 22 receives a supply of electrical energy from the electric current passing through the external circuit 18 when cell 20 is discharged. While the load device 22 can be any number of known electrically powered devices, some specific examples of an energy-consuming load device 22 include an electric motor for a hybrid or electric vehicle, a laptop computer, a mobile phone, and a cordless power tool. However, the load device 22 can also be an electrical energy-generating device that charges cell 20 for the purpose of energy storage.The tendency of wind turbines or solar power plants to generate electricity with fluctuations and / or interruptions often means, for example, that the excess energy has to be stored for later use.

[0038] As mentioned above, the single-ion conductor coating 14 is in the Fig. The example shown in Figure 2A is capable of serving as a solvation species for the ions in cell 20 and can thus function as the cell electrolyte. Additional solvents may or may not be used in this example cell 20. If used, the additional solvents can be added to at least saturate the single-ion conductive coating 14. If lithium, sodium, or zinc is used as the metal substrate 12, the additional solvent can be any solvent that increases the mobility of the Li, Na, or Zn metal cations across the single-ion conductive coating 14, such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl ether (DME), tetraethylene glycol dimethyl ether (TEGDME), etc. If zinc is used as the metal substrate 12, water can also be used as an additional solvent.Since the salt is already present in the single-ion conductor coating 14, no additional salt is added when the additional solvent is used.

[0039] Fig. Figure 2B illustrates another example of cell 20'. In the example shown in Fig. 2B, the electrochemical cell 20' includes the negative electrode 10, the negative-side current collector 10a, the positive electrode 16, the positive-side current collector 16a, the interruptible external circuit 18, the load device 22 and a separator 24 that separates the electrodes 10, 16.

[0040] The separator 24 in Fig. Separator 2B acts as both an electrical insulator and a mechanical support and is positioned between the single-ion conductor coating 14 of the negative electrode 10 and the positive electrode 16 to prevent physical contact between the two electrodes 10 and 16 and the occurrence of a short circuit. In addition to providing a physical barrier between the two electrodes 10 and 16, separator 24 allows the passage of lithium, sodium, or zinc ions and related anions through an electrolyte solution that fills its pores. This ensures that the cell 20' functions correctly.

[0041] Separator 24 is porous and can be a polyolefin membrane. The polyolefin can be a homopolymer (derived from a single monomer component) or a heteropolymer (derived from more than one monomer component) and can be either linear or branched. If a heteropolymer derived from two monomer components is used, the polyolefin can adopt any copolymer chain arrangement, including that of a block copolymer or a random copolymer. The same applies if the polyolefin is a heteropolymer derived from more than two monomer components. For example, the polyolefin can be polyethylene (PE), polypropylene (PP), a mixture of PE and PP, or a multilayered structured porous film of PE and / or PP.

[0042] In other examples, the porous separator 24 may consist of a different polymer, selected from polyethylene terephthalate (PET), polyvinylidene fluoride (PVdF), polyamides (nylon), polyurethanes, polycarbonates, polyesters, polyetheretherketones (PEEK), polyethersulfones (PES), polyimides (PI), polyamideimides, polyethers, polyoxymethylene (e.g., acetal), polybutylene terephthalate, polyethylene naphthenate, polybutene, polyolefin copolymers, acrylonitrile butadiene styrene copolymers (ABS), polystyrene copolymers, polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polysiloxane polymers (such as polydimethylsiloxane (PDMS)), polybenzimidazole (PBI), polybenzoxazole (PBO), polyphenylenes (e.g., PARMAX™ (Mississippi Polymer Technologies, Inc., Bay Saint Louis, Mississippi)). Polyaryletherketones, poly(perfluorocyclobutane), polytetrafluoroethylene (PTFE), polyvinylidene fluoride copolymers and terpolymers, polyvinylidene chloride, polyvinyl fluoride, liquid crystalline polymers (e.g.VECTRAN™ (Hoechst AG, Germany) and ZENITE® (DuPont, Wilmington, Germany) poly(p-hydroxybenzene), polyaramides, polyphenylene oxide, and / or combinations thereof. In another example, the porous separator 24 can be selected from a combination of polyolefin (such as PE and / or PP) and one or more of the other polymers listed above.

[0043] The porous separator 24 can be a single layer or a multilayer laminate produced by either a dry or wet process. For example, the entire separator 24 can consist of a single layer of polyolefin and / or another listed polymer. Alternatively, the separator 24 can be composed of several separate layers of the same or a similar polyolefin and / or polymer. In one example, the separator 24 can be formed by coating a separate layer of polyolefin with one or more layers of polymers. Furthermore, the polyolefin layer (and / or other polymers) and other optional polymer layers can also be incorporated into the separator 24 as a fibrous layer to provide the separator 24 with suitable structural and porosity characteristics.Other suitable separators 24 may contain a layer of ceramic material or a ceramic filler in the polymer matrix (i.e. an organic-inorganic composite matrix).

[0044] As mentioned above, this example cell 20' has an electrolyte that fills the pores of the separator 24.

[0045] Any suitable electrolyte solution capable of conducting lithium ions between the negative electrode 10 and the positive electrode 16 can be used for the lithium-based cell 20'. For example, the electrolyte solution could be a non-aqueous, liquid electrolyte solution containing a lithium salt dissolved in an organic solvent or a mixture of organic solvents. Examples of lithium salts that can be dissolved in the organic solvent to form the non-aqueous liquid electrolyte solution include LiClO4, LiAlCl4, LiI, LiBr, LiB(C2O4)2 (LiBOB), LiBF2(C2O4) (LiODFB), LiSCN, LiBF4, LiB(C6H5)4, LiAsF6, LiCF3SO3, LiN(FSO2)2 (LIFSI), LiN(CF3SO2)2 (LITFSI), LiPF6, LiPF4(C2O4) (LiFOP), LiNO3, LiPF3(C2F5)3 (LiFAP), LiPF4(CF3)2, LiPF3(CF3)3, and mixtures thereof.These and other similar lithium salts can be dissolved in a variety of organic solvents, such as cyclic carbonates (ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, fluoroethylene carbonate), linear carbonates (dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC)), aliphatic carboxylic acid esters (methyl formate, methyl acetate, methyl propionate), γ-lactones (γ-butyrolactone, γ-valerolactone), chain structure ethers (1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, tetraglyme), cyclic ethers (tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane) and mixtures thereof.

[0046] For the sodium-based cell 20', any suitable electrolyte solution capable of carrying sodium ions between the negative electrode 10 and the positive electrode 16 can be used. For example, the electrolyte solution could be NaPF6 dissolved in the EC and DEC.

[0047] Any suitable electrolyte solution capable of conducting zinc ions between the negative electrode 10 and the positive electrode 16 can be used for the zinc base cell 20'. For example, the electrolyte solution could be ZnSO4 dissolved in H2O.

[0048] The cells 20, 20' disclosed herein may also include a wide range of other components which, although not shown here, are known to those skilled in the art. For example, the cells 20, 20' may include a housing, seals, terminals, tabs, and any other desirable components or materials that may be located between or around the negative electrode 10 and the positive electrode 16 for power-related or other practical purposes. Furthermore, the size and shape of the cell 20, 20', as well as the design and chemical composition of its main components, may vary depending on the specific application for which it is designed. Battery-powered automobiles and handheld consumer electronics devices, for example, are two cases in which the cell 20, 20' would most likely be designed to meet different size, capacity, and power output specifications.The cell 20, 20' can also be connected in series and / or parallel to other similar cells 20, 20' to produce a larger voltage output and current (if arranged in parallel) or voltage (if arranged in series) if the load device 22 requires it.

[0049] To further illustrate the present disclosure, an example is given herein. It is understood that this example is provided for illustrative purposes and should not be interpreted as limiting the scope of the present disclosure. EXAMPLE

[0050] Two examples of the polymeric one-ion conductor were prepared. One example was a metal salt of a sulfonated tetrafluoroethylene-based fluoropolymer copolymer, and the other example was a polymeric metal salt with a polysulfone core and lithium malonatodifluoroborate salt groups bonded to the polysulfone core. Both examples were prepared according to the procedures disclosed herein. For the metal salt of the sulfonated tetrafluoroethylene-based fluoropolymer copolymer, NAFION® was purchased and reacted with LiOH as shown in the second half of Scheme 1. The lithium malonatodifluoroborate salt was bonded to the polysulfone core. The synthesis of polysulfone with attached double bonds can be found in the publication GERVAIS, M. [et al.], Ionomers with highly fluorinated side chains for use in battery and fuel cell applications, ECS Transactions, Vol. 33, 2010, No. 1, pp. 683-691.The synthesis of the allyl lithium malonatodifluoroborate salt involves: Step I. Diethyl-2-allyl-2-fluoromalonate was synthesized by reacting diethylfluoromalonate, allyl bromine, and potassium carbonate in anhydrous acetonitrile at a molar ratio of 1:1.5:3 at 70 °C for 48 hours. The crude products of the malonate formed were distilled to a purity of >99%. Step II. Lithium 2-allyl-,2-F-malonates were synthesized by hydrolysis of diethyl 2-allyl-,2-F-malonates with lithium hydroxide in H2O at 70 °C for 24 hours, followed by rinsing with a large amount of methanol to remove the residue LiOH, and vacuum drying at 120 °C. Step III. Di(trichloromethylsilyl)-2-allyl-,2-F-malonates were synthesized by reacting lithium 2-allyl-,2-F-malonates with chlorotrimethylsilane at a molar ratio of 1:2.5 in 1,2-dichloroethane at 70 °C for 3 days. The di(trichloromethylsilyl)-2-allyl-,2-F-malonates were removed by first vacuum, removing the 1,2-dichloroethane, followed by fractional distillation at 73–74 °C / 0.25 T. Step IV. Lithium 2-allyl-,2-F-malonatodifluoroborates were prepared by adding di(trichloromethylsilyl) 2-allyl-,2-F-malonates dropwise to LiBF4 acetonitrile at a molar ratio of 1:1 at ~40 °C. The final lithium 2-allyl-,2-F-malonatodifluoroborates were vacuum-dried to remove residual acetonitrile, followed by rinsing with anhydrous toluene and 1,2-dichloroethane and vacuum drying again.

[0051] The allyl lithium salt was bonded to the polysulfone by mixing equal amounts of the salt and polymer in THF in the presence of a polymerization initiator, such as azobisisobutyronitil (AIBN) or benzoyl peroxide (BPO), or in the presence of a Pt-related catalyst.

[0052] The respective coating compositions were applied to lithium foils to form SiC-coated negative electrodes, either by direct coating or by foil attachment after the coating composition had been applied to a sacrificial material and dried to form the self-supporting film. The negative electrodes were paired with lithium foil counter electrodes in coin cells and immersed in a solution of ethylene carbonate:diethyl carbonate (EC:DEC, 1:2). The specific conductivity (mS / cm) -1) was measured for each of the cells (A, including the lithium salt of NAFION® and B, including the polymeric lithium salt), and the results are in Fig. Figure 3 shows the conductivity as a function of an inverse or reciprocal temperature (1000 / T). The results show that both single-ion conductors exhibit suitable conductivity at relatively high temperatures and that the polymeric metal salt with a polysulfone backbone and lithium malonatodifluoroborate lithium salt groups (B) exhibited higher conductivity than the metal salt of a sulfonated fluoropolymer copolymer based on tetrafluoroethylene (A).

[0053] The polymeric metal salt SiC-coated negative electrode was paired with a lithium foil counter electrode in a coin cell and soaked in a solution of ethylene carbonate:diethyl carbonate (EC:DEC, 1:2).

[0054] The coin cell was continuously operated at ±100 µA for each hour and rested for 1 hour in between. The cycle power in terms of voltage (V) versus time in seconds (s) is in Fig. 4 shown. The results in Fig. Figure 4 shows that there was no lithium dendrite formation after 50 cycles. This conclusion can be drawn because there was no sudden voltage drop.

[0055] References in the description to "an example," "another example," "example," etc., mean that a specific element (e.g., feature, structure, and / or property) described in connection with the example is included in at least one example described here and may or may not be present in other examples. Furthermore, it is understood that the described elements for each example can be combined in any suitable way across the various examples, unless the context clearly dictates otherwise.

[0056] It goes without saying that the ranges provided here include the specified range and any value or subrange within that range. For example, a range of approximately 10 nanometers to approximately 250 micrometers should be interpreted to include not only the explicitly listed limits of approximately 10 nanometers to approximately 250 micrometers, but also individual values ​​such as 150 nanometers, 225 nanometers (0.225 micrometers), 10 micrometers, etc., and subranges such as from 100 nanometers to approximately 13 micrometers, from approximately 1 micrometer to approximately 5 micrometers, etc.

[0057] When "approximately" is used to describe a value, it still means that small deviations from the stated value (up to + / - 10%) are included.

[0058] When describing and claiming the examples revealed here, the singular forms “ein”, “eine”, “einer” and “der / die / das” include plural references, unless the context clearly prescribes otherwise.

[0059] Although several examples have been described in detail, it goes without saying that the disclosed examples can be modified. Therefore, the foregoing description should be considered non-restrictive.

Claims

[1] Negative electrode, comprising: a metal substrate selected from the group consisting of lithium, sodium, and zinc; and a polymeric single-ion conductor coating formed on a surface of the metal substrate, wherein the polymeric single-ion conductor coating consists of a polymeric metal salt with an initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone, wherein the polymeric single-ion conductor coating has a comb-like structure, the polymer backbone chain extending over the surface and the attached metal salt groups extending outwards and away from the surface at predetermined positions and wherein the parts of the attached metal salt groups, which carry the associated anions, are bonded to certain atoms of the polymer backbone, wherein the initial polymeric backbone is selected from the group consisting of polyolefin, polyvinylidene fluoride, polyethylene oxide, polyimide and copolymers thereof. [2] Negative electrode according to claim 1, wherein the initial polymer backbone is cross-linked. [3] Negative electrode according to claim 1, wherein the initial polymer backbone is not cross-linked. [4] Negative electrode according to claim 1, wherein the attached metal salt is one of the following: a lithium salt selected from the group consisting of lithium bis(trifluoromethane)sulfonimide, lithium malonatodifluoroborate, lithium sulfonate, lithium triflate, analogues thereof and combinations thereof; or a sodium salt selected from the group consisting of sodium trifluoromethanesulfonate, NaClO4, NaPF6, NaBF4, NaTFSI (sodium (I) bis(-trifluoromethanesulfonyl)imide), NaFSI (sodium (I) bis(-fluorosulfonyl)imide), analogues thereof and combinations thereof; or a zinc salt selected from the group consisting of zinc trifluoromethanesulfonate, Zn(ClO4)2, Zn(PF6)2, Zn(BF4)2, Zn(TFSI)2 (zinc(II) bis(-trifluoromethanesulfonyl-)imide), Zn(FSI)2 (zinc (II) bis(-fluorosulfonyl-)imide), analogues thereof and combinations thereof. [5] Negative electrode according to claim 1, wherein the metal substrate is selected from the group consisting of lithium foil, sodium foil and zinc foil. [6] Electrochemical cell, comprising: a positive electrode; a negative electrode, including: a metal substrate selected from the group consisting of lithium, sodium, and zinc; and a polymeric single-ion conductor coating formed on a surface of the metal substrate, wherein the polymeric single-ion conductor coating consists of a polymeric metal salt with an initial polymeric backbone and attached metal salt groups bonded to the initial polymeric backbone, wherein the polymeric single-ion conductor coating has a comb-like structure, wherein the polymer backbone chain extends over the surface and the attached metal salt groups extend outwards and away from the surface at predetermined positions, and , wherein the parts of the attached metal salt groups carrying the associated anions are bonded to certain atoms of the polymer backbone, wherein the initial polymer backbone is selected from the group consisting of polyolefin, polyvinylidene fluoride, polyethylene oxide, polyimide and copolymers thereof; wherein the polymeric single-ion conductor coating faces the positive electrode; and a separator that is positioned between the positive electrode and the polymeric single-ion conductor coating of the negative electrode. [7] Electrochemical cell according to claim 6, wherein the attached metal salt is one of the following: a lithium salt selected from the group consisting of lithium bis(trifluoromethane)sulfonimide, lithium malonatodifluoroborate, lithium sulfonate, lithium triflate, analogues thereof and combinations thereof; or a sodium salt selected from the group consisting of sodium trifluoromethanesulfonate, NaClO4, NaPF6, NaBF4, NaTFSI (sodium (I)-bis(-trifluoromethanesulfonyl-)imide), NaFSI (sodium (I)-bis(-fluorosulfonyl-)imide), analogues thereof and combinations thereof; or a zinc salt selected from the group consisting of zinc trifluoromethanesulfonate, Zn(ClO4)2, Zn(PF6)2, Zn(BF4)2, Zn(TFSI)2 (zinc(II) bis(-trifluoromethanesulfonyl-)imide), Zn (FSI)2 (zinc (II) bis(-fluorosulfonyl-)imide), analogues thereof and combinations thereof. [8] Electrochemical cell according to claim 6, wherein the polymeric single-lithium ion conductor coating further includes a solvent to increase the metal cation mobility.

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