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CN-121983514-A - Bipolar electrode and battery

CN121983514ACN 121983514 ACN121983514 ACN 121983514ACN-121983514-A

Abstract

The invention relates to the technical field of secondary batteries, and discloses a bipolar electrode, which comprises a current collector, and a first functional layer, a second functional layer and an active material layer which are sequentially laminated on the surface of the current collector, wherein the current collector is a composite current collector, the second functional layer comprises first solid electrolyte particles, and the first solid electrolyte particles comprise characteristic elements, wherein the content of the characteristic elements in the second functional layer gradually rises from inside to outside. According to the invention, the solid electrolyte particles in the second functional layer are gradually increased from inside to outside, so that a continuous transition structure from high electron conduction to high ion conduction is formed, the stress generated by asymmetric volume strain of the active material layers at two sides can be effectively buffered, the interfacial charge transmission is optimized, and the interfacial contact stability is maintained, thereby prolonging the cycle life and the rate capability of the solid battery.

Inventors

  • HUANG SHIJIE
  • XIE DONGJIU
  • ZHAO WEI

Assignees

  • 珠海冠宇电池股份有限公司

Dates

Publication Date
20260505
Application Date
20260205

Claims (10)

  1. 1. A bipolar electrode, comprising: A current collector (10) and an active material layer, wherein the active material layer comprises a first positive electrode active material layer (201) and a first negative electrode active material layer (202), the first positive electrode active material layer is arranged on a first side of the current collector, the first negative electrode active material layer is arranged on a second side of the current collector opposite to the first side, and a first functional layer and a second functional layer which are arranged in a stacked manner are arranged between the current collector and the active material layer along the thickness direction of the bipolar electrode, the first functional layer is provided with a first surface far away from the current collector, and the second functional layer is arranged on the first surface; The current collector (10) comprises a polymer substrate (101), wherein conductive layers are respectively arranged on two opposite side surfaces of the polymer substrate (101), a first conductive layer (102) is arranged on one side surface of the polymer substrate, a second conductive layer (103) is arranged on the other side surface of the polymer substrate, the first conductive layer (102) is electrically connected with the first positive electrode active material layer (201), and the second conductive layer (103) is electrically connected with the first negative electrode active material layer (202); The second functional layer (40) comprises first solid-state electrolyte particles comprising a characteristic element selected from at least one of S, Y, sc, in, la, ta, nb, zr, br, I, lu, gd, ce; The thickness of the second functional layer (40) is L, wherein, along the direction from the first surface (301) to the second functional layer (40), a region 0L to 0.16L away from the first surface (301) forms a first region (401), a region 0.16L to 0.67L away from the first surface (301) forms a second region (402), and a region 0.67L to 1L away from the first surface (301) forms a third region (403); The mass content of the characteristic element is a1 based on the total mass of the first region (401); -the mass content of the characteristic element is a2, based on the total mass of the second zone (402); the mass content of the characteristic element is a3 based on the total mass of the third region (403); Satisfies a1< a2< a3.
  2. 2. The bipolar electrode as in claim 1, wherein, The second functional layer (40) further comprises an electron conductive agent, wherein the mass content of the electron conductive agent is b1 based on the total mass of the first region (401); -the mass content of the electronically conductive agent is b2, based on the total mass of the second region (402); The mass content of the electron conducting agent is b3 based on the total mass of the third region (403); satisfies b1> b2> b3.
  3. 3. The bipolar electrode as claimed in claim 2, wherein, The second functional layer (40) further comprises a binder, wherein the mass content of the binder is c1 based on the total mass of the first region (401); -the mass content of the binder is c2, based on the total mass of the second zone (402); the mass content of the binder is c3, based on the total mass of the third zone (403); The method meets the following conditions: c1=c2 =c3.
  4. 4. The bipolar electrode as in claim 3, The first functional layer (30) is composed of an electron conductive agent and a binder; Based on the total mass of the first functional layer (30), the mass content of the electronic conductive agent is 80% -95%, and the mass content of the binder is 5% -20%.
  5. 5. The bipolar electrode according to claim 4, wherein the mass content of the binder in the second functional layer (40) is 15% -25% based on the total mass of the second functional layer (40); And/or the first solid electrolyte particles comprise at least one of a sulfide solid electrolyte and a halide solid electrolyte.
  6. 6. The bipolar electrode of claim 5, wherein at least one of the following conditions is met: A. the thickness L of the second functional layer (40) is more than or equal to 5 mu m and less than or equal to 10 mu m; B. The thickness of the first functional layer (30) is 1-5 mu m; C. The Dv50 of the first solid electrolyte particles is 0.5-3 mu m; D. The sulfide solid electrolyte comprises at least one of Li 6 PS 5 X 1 、Li 10 X 2 1 P 2 S 12 、Li 4 X 3 2 S 4 、Thio-Li 3 PS 4 、Li 7 P 3 S 11 , wherein X 1 is at least one of Cl, br and I, X 2 is at least one of Ge, sn and Si, and X 3 is at least one of Sn and Ge; E. The halide solid electrolyte comprises Li 3 MCl 6-y X 4 y , wherein X 4 is selected from at least one of Br and I, M is selected from at least one of Y, sc, in, la, lu, gd, ta, ce, nb, zr, and y is more than or equal to 0 and less than or equal to 6; F. the material of the polymer substrate (101) is at least one selected from polyimide, aramid, polyester elastomer and thermoplastic polyurethane elastomer.
  7. 7. A battery, characterized in that it comprises a bipolar electrode (1) according to any one of claims 1-6.
  8. 8. The battery according to claim 7, characterized by comprising: -a pole group body (7) comprising n of said bipolar electrodes (1), n >1, arranged in a stack, said pole group body (7) having a first outer surface (701) and a second outer surface (702) arranged in opposite spaced relation in a thickness direction; a first unipolar electrode (5) disposed opposite the first outer surface (701); a second unipolar electrode (6) disposed opposite the second outer surface (702) and having a polarity opposite the first unipolar electrode (5); A solid electrolyte layer located between two adjacent sheets of the bipolar electrodes (1) in the electrode group body, and between the first outer surface (701) and the first unipolar electrode (5), and between the second outer surface (702) and the second unipolar electrode (6); The solid electrolyte layer (80) includes second solid electrolyte particles including sulfide solid electrolyte and/or halide solid electrolyte.
  9. 9. The battery of claim 8, wherein the battery is configured to provide the battery with a battery cell, The first unipolar electrode (5) comprises an aluminum foil current collector (501) and a second positive electrode active material layer (502) arranged on one side surface of the aluminum foil current collector (501) close to the first outer surface (701); The second unipolar electrode (6) includes a copper foil current collector (601), and a second negative electrode active material layer (602) disposed on a side surface of the copper foil current collector (601) near the second outer surface (702); and/or the thickness of the solid electrolyte layer (80) is 10-40 μm, preferably the thickness of the solid electrolyte layer (80) is 20-35 μm; and/or the Dv50 of the second solid electrolyte particles is 0.5-3 μm.
  10. 10. The battery of claim 8, wherein the battery is configured to provide the battery with a battery cell, The sulfide solid electrolyte comprises at least one of Li 6 PS 5 X 1 、Li 10 X 2 1 P 2 S 12 、Li 4 X 3 2 S 4 、Thio-Li 3 PS 4 、Li 7 P 3 S 11 , wherein X 1 is at least one of Cl, br and I, X 2 is at least one of Ge, sn and Si, and X 3 is at least one of Sn and Ge; The halide solid electrolyte comprises Li 3 MCl 6-y X 4 y , wherein X 4 is selected from at least one of Br and I, M is selected from at least one of Y, sc, in, la, lu, gd, ta, ce, nb, zr, and y is more than or equal to 0 and less than or equal to 6.

Description

Bipolar electrode and battery Technical Field The invention relates to the field of secondary batteries, in particular to a bipolar electrode and a battery. Background With the increasing demands for high energy density and high safety energy storage devices, all-solid-state batteries have become an important development direction of next-generation battery technology. The internal serial battery design adopting the bipolar stacking structure can remarkably improve the output voltage of the single battery and simplify the integration of a battery system, and has great application potential. In such a structure, a composite current collector composed of a porous polymer substrate and metal conductive layers on both sides thereof is a core member for realizing efficient and lightweight design as a "shared current collector" for simultaneously connecting positive and negative electrode active materials. However, in practical applications, when the composite current collector is applied to an internal string type all-solid-state battery, a long-standing technical bottleneck is that the negative electrode material tends to undergo severe volume expansion during the lithium intercalation process, while the positive electrode material has relatively mild volume change, resulting in a phenomenon of asymmetric volume strain. This asymmetric volumetric strain poses a significant challenge for shared current collectors. Firstly, asymmetric stress on two sides in the circulation process can be rigidly transmitted through the metal conductive layer, so that the polymer substrate is subjected to uneven tensile stress circulation, fatigue cracking and desorption of the metal conductive layer are easily caused, and even plastic deformation or fracture of the substrate is caused. Secondly, the huge strain difference generates strong shearing stress at the interface of the current collector and the electrodes at two sides, so that physical contact between the electrode active layer and the current collector is invalid, an electron transmission path is interrupted, and finally, active substances are peeled off, internal resistance of the battery is increased rapidly, and capacity is reduced rapidly. Disclosure of Invention The primary objective of the present application is to provide a bipolar electrode, which is capable of alleviating the problems of mechanical damage and interface failure of a current collector caused by asymmetric volumetric strain of active materials at both sides, so as to improve the multiplying power and cycle performance of an all-solid-state battery on the premise of maintaining high energy density. It is another object of the present application to provide a battery comprising the bipolar electrode described above. The application aims at realizing the following technical scheme: According to an embodiment of the present application, there is provided a bipolar electrode including: A current collector and an active material layer, the active material layer including a first positive electrode active material layer disposed on a first side of the current collector and a first negative electrode active material layer disposed on a second side of the current collector opposite the first side; a first functional layer and a second functional layer which are arranged In a stacked manner are further arranged between the current collector and the active material layer along the thickness direction of the bipolar electrode, the first functional layer is provided with a first surface far away from the current collector, and the second functional layer is arranged on the first surface; the current collector comprises a polymer substrate, conductive layers are respectively arranged on two opposite side surfaces of the polymer substrate, a first conductive layer is arranged on one side surface of the polymer substrate, a second conductive layer is arranged on the other side surface of the polymer substrate, the first conductive layer is electrically connected with the first positive electrode active material layer, the second conductive layer is electrically connected with the first negative electrode active material layer, the second functional layer comprises first solid electrolyte particles, the first solid electrolyte particles comprise characteristic elements, the characteristic elements are at least one selected from S, Y, sc, in, la, ta, nb, zr, br, I, lu, gd and Ce, the thickness of the second functional layer is L, the area 0-0.16L away from the first surface forms a first area, the area 0.16-0.67L away from the first surface forms a second area, the total mass of the area 0.67-1L away from the first surface forms a third area based on the total mass of the first area, the mass content of the characteristic element is a1, the mass content of the characteristic element is a2 based on the total mass of the second area, the mass content of the characteristic element is a3 based on the total mass of the