US-12620618-B2 - Functionalized separator and method for preparing the same, lithium metal battery and device comprising the same

Abstract

The present application discloses a functionalized separator, a method for preparing the same, a lithium metal battery, and a device comprising the lithium metal battery. The functionalized separator comprises a porous substrate and a functional film layer provided on at least one side of the porous substrate, wherein the functional film layer comprises inorganic particles which are able to reversibly react with metal lithium to form a lithium alloy.

Inventors

• Chengyong Liu
• Yongsheng Guo
• QUAN FAN
• Tao Zhang
• Chengdu Liang
• Jun Yang

Assignees

• CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

Dates

Publication Date

20260505

Application Date

20211220

Priority Date

20190726

Claims (9)

1. 1 . A functionalized separator, comprising a porous substrate and a functional film layer provided on at least one surface of the porous substrate, wherein the functional film layer comprises inorganic particles which are able to reversibly react with metal lithium to form a lithium alloy and has a thickness of from 1 μm to 5 μm, and wherein the inorganic particles are SiO and have a volume average particle size Dv50 of from 1 μm to 2 μm, wherein at least part of surfaces of the inorganic particles is coated with a polymer coating layer, wherein the polymer coating layer comprises a group that is reversibly bonded with lithium ions, wherein the polymer coating layer has a thickness of from 5 nm to 10 nm, and wherein the coating layer comprises polyolefin acid containing an acid radical group, and the polyolefin acid comprises one or more of polyacrylic acid and polystyrene sulfonic acid, and wherein the functional film layer further comprises a polymer ionic liquid, wherein the polymer ionic liquid comprises the structural units represented by Formula IV: wherein l and m are 240.
2. 2 . The functionalized separator according to claim 1 , wherein the group that is reversibly bonded with lithium ions comprises one or more of the acid radical group, an amino group, an imino group, a sulfhydryl group, and a polysulfide group (—S b —, b≥2), and further optionally, the acid radical group comprises one or more of carboxylic acid group, sulfonic acid group, sulfinic acid group, and phosphoric acid group.
3. 3 . The functionalized separator according to claim 1 , wherein the polymer ionic liquid further comprises a structural unit represented by formula III: wherein, R 5 is C1-C10 alkylene group or C1-C10 alkylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P, and optionally is —(CH 2 ) t — or —(CH 2 ) q —O—(CH 2 ) r —, wherein t is from 1 to 8, q is from 0 to 4, r is from 0 to 4, and q and r are not 0 at the same time; R 6 is H, F, Cl, Br, I, —CN, C1-C10 hydrocarbon group, or C1-C10 hydrocarbon group containing one or more of F, Cl, Br, I, N, O, S, Si, B and P, and optionally is H, —CN, —CH 3 , —C 2 H 5 , linear —C 3 H 7 , linear —C 4 H 9 , or —(CH 2 CH 2 O) u CH 3 wherein u is from 1 to 8; n is a positive integer; optionally, 1≤n≤2500.
4. 4 . The functionalized separator according to claim 1 , wherein polymer ionic liquid has a number average molecular weight of from 40,000 to 1,000,000.
5. 5 . The functionalized separator according to claim 1 , wherein, in the functional film layer, the mass ratio of the inorganic particles to the polymer ionic liquid is (80-99):(1-20).
6. 6 . The functionalized separator according to claim 1 , wherein the substrate is a polymer substrate; and optionally, the substrate has a thickness of from 5 μm to 25 μm.
7. 7 . A lithium metal battery, comprising a positive electrode plate; a negative electrode plate comprising a lithium-based metal layer; a separator which is the functionalized separator according to claim 1 , wherein the functional film layer is arranged to contact with the lithium-based metal layer; and an electrolyte solution.
8. 8 . A device comprising the lithium metal battery according to claim 7 .
9. 9 . The functionalized separator according to claim 1 , comprising a porous substrate and a functional film layer provided on at least one surface of the porous substrate, wherein the functional film layer comprises inorganic particles which are able to reversibly react with metal lithium to form a lithium alloy and has a thickness of 5 μm, and wherein the inorganic particles are SiO and have a volume average particle size Dv50 of from 1 μm to 2 μm, wherein at least part of surfaces of the inorganic particles is coated with a polymer coating layer, wherein the polymer coating layer comprises a group that is reversibly bonded with lithium ions, wherein the polymer coating layer has a thickness of 10 nm, and wherein the coating layer comprises polyolefin acid containing an acid radical group, and the polyolefin acid comprises one or more of polyacrylic acid and polystyrene sulfonic acid, and wherein the functional film layer further comprises a polymer ionic liquid, wherein the polymer ionic liquid comprises the structural units represented by Formula IV: wherein l and m are 240.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/CN2020/101668, filed on Jul. 3, 2020, which claims priority to Chinese Patent Application No. 201910682442.1 entitled “Functionalized Separator and Lithium Metal Battery” and filed on Jul. 26, 2019, both of which are incorporated herein by reference in their entireties. TECHNICAL FIELD The application belongs to the technical field of energy storage devices, and specifically relates to a functionalized separator and a lithium metal battery. BACKGROUND Metal lithium has a theoretical specific capacity (3860 mAh/g) that is much higher than that of graphite negative materials that are widely used currently (372 mAh/g), and the metallic lithium has an electrode potential as low as −3.04V (vs. H2/H+). Therefore, lithium metal batteries using metal lithium as the negative electrode material are expected to become next generation of storage devices having high energy density. However, lithium metal batteries are prone to produce lithium dendrites during charging. This will reduce the coulombic efficiency and cycle life of the battery. Moreover, this will cause internal short circuits between the positive and negative electrodes due to the penetration of lithium dendrites through the separator, which may result in safety accidents such as the explosive or catching fire of the battery. Lithium dendrites seriously hinder the commercial application of lithium metal batteries. SUMMARY A first aspect of the present application provides a functionalized separator, comprising a porous substrate and a functional film layer provided on at least one surface of the porous substrate, wherein, the functional film layer comprises inorganic particles which are able to reversibly react with metal lithium to form a lithium alloy. The functionalized separator provided in the present application comprises a functional film layer, wherein the functional film layer comprises inorganic particles which are able to reversibly react with metal lithium to form a lithium alloy. When the functionalized separator is used in a lithium metal battery and the functional film layer contacts with lithium metal, the inorganic particles and the metal lithium, under the action of the electrolyte solution, will react reversibly to form a lithium alloy in situ; accordingly, the lithium composition on the surface of the metal lithium electrode changes. The forming of lithium alloys may adjust and control the deposition/dissolution behavior of lithium ions, may effectively inhibit the growth of dendrites on lithium metal electrodes, and may be helpful to improve the reversibility of the deposition/dissolution of lithium ions in lithium metal electrodes. Therefore, by using the functionalized separator of the present application, the initial coulombic efficiency, cycle performance, and safety performance of lithium metal batteries can be improved. In any embodiment, the inorganic particles has a volume average particle size Dv50 of from 10 nm to 20 μm, optionally from 50 nm to 10 μm, and further optionally from 200 nm to 2 μm. Under the condition that the inorganic particles have appropriate particle size, the capacity and cycle performance of the battery can be improved. In any embodiment, the inorganic particles are one or more selected from silicon, silicon oxide compound SiOa wherein 0<a<2, magnesium, aluminum, zinc, indium, antimony, silver, gold, germanium, and tin. In any embodiment, at least part of the surface of the inorganic particles is coated with a polymer coating layer, wherein the polymer coating layer comprises a group that is reversibly bonded with lithium ions. In the present application, at least part of the surface of the inorganic particles may be coated with a polymer coating layer, wherein the polymer coating layer comprises a group that is reversibly bonded with lithium ions. The group reversibly bonds with lithium ions by reacting with the lithium alloy, so that the binding tightness between the coating layer and the inorganic particles is improved. Thus, the coating layer may better inhibit the volume change of the lithium alloy during charging and discharging of the battery. Moreover, the group in the coating layer may form chemical bond in suit with lithium ions, wherein the chemical bond may serve as a channel for transmitting lithium ions, so as to promote the transmitting of lithium ions and thus improve the dynamic performance of the metal lithium electrode. Therefore, the functionalized separator can further improve the initial coulombic efficiency, cycle performance and safety performance of lithium metal batteries. Optionally, the group that is reversibly bonded with lithium ions comprises one or more of an acid radical group, an amino group, an imino group, a sulfhydryl group, and a polysulfide group (—Sb—, b≥2). Further optionally, the acid radical group comprises one or more of carboxylic acid group, sulfonic