Positive electrode plate, electrochemical apparatus, and apparatus
This application relates to the battery field, and specifically, to a positive electrode plate, an electrochemical apparatus, and an apparatus. The positive electrode plate in this application includes a current collector and an electrode active material layer disposed on at least one surface of the current collector, where the current collector includes a support layer and a conductive layer disposed on at least one surface of the support layer, a single-sided thickness D2 of the conductive layer satisfies 30 nm D2 3 μm, a thickness D1 of the support layer satisfies 1 μm D1 30 μm, and the support layer is made of a polymer material or a polymer composite material; and the electrode active material layer includes an electrode active material, a binder, and a conductive agent, and a total thickness D total of the electrode active material layer is not greater than 170 μm.
1. A positive electrode plate, comprising a current collector and an electrode active material layer disposed on at least one surface of the current collector, wherein
the current collector comprises a support layer and a conductive layer disposed on at least one surface of the support layer, a single-sided thickness D2 of the conductive layer along a thickness direction satisfies 30 nm≤D2≤3 μm, a thickness D1 of the support layer satisfies 1 μm≤D1≤30 μm, and the support layer along the thickness direction is made of a polymer material or a polymer composite material;
the electrode active material layer comprises an electrode active material, a binder, and a conductive agent, a total thickness D total of the electrode active material layer is not greater than 170 μm, and a sheet resistance of the electrode active material layer ranges from 0.1 ohm to 10 ohms; and
the electrode plate has a length direction, which is a main dimension direction with a larger magnitude, and a width direction, which is a secondary dimension direction with a smaller magnitude, the length direction and the width direction are perpendicular to the thickness direction of the current collector,
when viewed in the width direction of a coated surface of the electrode plate, the electrode active material layer comprises 2n+1 zones classified by compacted density, and a compacted density of a middle zone is greater than a compacted density of zones on both sides, wherein n=1, 2, or 3.
2. The positive electrode plate according to claim 1 , wherein a binder content of the electrode active material layer is not less than 1 wt %.
3. The positive electrode plate according to claim 1 , wherein the binder contained in the electrode active material layer is unevenly distributed in a thickness direction, wherein based on a total weight of the electrode active material layer, a weight percentage of the binder in an interior zone of the electrode active material layer closer to the current collector is greater than a weight percentage of the binder in an exterior zone of the electrode active material layer farther away from the current collector;
based on a total weight of the exterior zone of the electrode active material layer, a weight percentage of the binder in the exterior zone is 1 wt % to 5 wt %; and/or
based on a total weight of the interior zone of the electrode active material layer, a weight percentage of the binder in the interior zone is 1 wt % to 90 wt %.
4. The positive electrode plate according to claim 1 , wherein the conductive agent in the electrode active material layer is unevenly distributed in a thickness direction, wherein based on a total weight of the electrode active material layer, a weight percentage of the conductive agent in an interior zone of the electrode active material layer closer to the current collector is greater than a weight percentage of the conductive agent in an exterior zone of the electrode active material layer farther away from the current collector;
based on the total weight of the electrode active material layer in the exterior zone, a weight percentage of the conductive agent in the exterior zone is 0.5 wt % to 10 wt %; and
based on the total weight of the electrode active material layer in the interior zone, a weight percentage of the conductive agent in the interior zone is 10 wt % to 99 wt %.
5. The positive electrode plate according to claim 1 , wherein the conductive layer is a metal conductive layer, and the metal conductive layer is made of at least one of aluminum, nickel, titanium, silver, and aluminum-zirconium alloy; and/or
a material of the support layer is selected from at least one of an insulation polymer material, an insulation polymer composite material, a conductive polymer material, and a conductive polymer composite material; wherein
the insulation polymer material is selected from at least one of polyamide, polyterephthalate, polyimide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, aramid, polydiformylphenylenediamine, acrylonitrile-butadiene-styrene copolymer, polybutylene terephthalate, poly(p-phenylene terephthalamide), ethylene propylene rubber, polyoxymethylene, epoxy resin, phenolic resin, polytetrafluoroethylene, polyphenyl sulfide, polyvinylidene fluoride, silicone rubber, polycarbonate, cellulose and its derivatives, starch and its derivatives, protein and its derivatives, polyvinyl alcohol and its cross-linked products, and polyethylene glycol and its cross-linked products;
the insulation polymer composite material is selected from a composite material formed of an insulation polymer material and an inorganic material, wherein the inorganic material is at least one of a ceramic material, a glass material, and a ceramic composite material;
the conductive polymer material is selected from a polysulfur nitride polymer material or a doped conjugated polymer material;
the conductive polymer composite material is selected from a composite material formed of an insulation polymer material and a conductive material, wherein the conductive material is selected from at least one of a conductive carbon material, a metal material, and a composite conductive material; the conductive carbon material is selected from at least one of carbon black, carbon nanotube, graphite, acetylene black, and graphene; the metal material is selected from at least one of nickel, iron, copper, aluminum, and alloy of the foregoing metals; and the composite conductive material is selected from at least one of nickel-coated graphite powder, and nickel-coated carbon fiber; and
the material of the support layer is an insulation polymer material or an insulation polymer composite material.
6. The positive electrode plate according to claim 1 , wherein the thickness D1 of the support layer satisfies 1 μm≤D1≤15 μm; and/or
a room-temperature Young's modulus of the support layer satisfies 20 GPa≥E≥4 GPa; and/or
there are cracks in the conductive layer; and/or
an average particle size D50 of the electrode active material is 5 μm to 15 μm; and/or
the single-sided thickness D2 of the conductive layer satisfies 300 nm≤D2≤2 μm.
7. The positive electrode plate according to claim 1 , wherein a protection layer is further disposed on a surface of the conductive layer, and the protection layer is disposed only on one surface of the conductive layer of the current collector or disposed on two surfaces of the conductive layer of the current collector; and
a thickness D3 of the protection layer satisfies D3≤D2/10 and 1 nm≤D3≤200 nm.
8. The positive electrode plate according to claim 1 , wherein
the conductive agent is made of at least one of a conductive carbon material and a metal material, wherein the conductive carbon material is selected from at least one of the following: acetylene black or conductive carbon black, a carbon nanotube, conductive graphite or graphene, and reduced graphene oxide; and the metal material is selected from at least one of aluminum powder, iron powder, and silver powder;
the conductive agent contains a carbon nanotube; and
the binder is selected from at least one of styrene butadiene rubber, oily polyvinylidene fluoride (PVDF), polyvinylidene fluoride copolymer, sodium carboxy methyl cellulose, polystyrene, polyacrylic acid, polytetrafluoroethylene, polyacrylonitrile, polyimide, aqueous PVDF, polyurethane, polyvinyl alcohol, polyacrylate, polyacrylic acid-polyacrylonitrile copolymer, and polyacrylate-polyacrylonitrile copolymer.
9. An electrochemical apparatus, comprising a positive electrode plate, a negative electrode plate, a separator, and an electrolyte, wherein the positive electrode plate is the positive electrode plate according to claim 1 .
10. An apparatus, comprising the electrochemical apparatus according to claim 9 .
11. The positive electrode plate according to claim 1 , wherein the compacted density of the middle zone is greater than the compacted density of zones on both sides by 5% to 30% of the compacted density of the middle zone.
12. The positive electrode plate according to claim 1 , wherein a ratio of a width of the middle zone to a sum of a width of each one of the zones is 20% to 80%.
13. The electrode plate according to claim 12 , wherein the ratio of the width of the middle zone to the sum of the width of each one of the zones is 30% to 70%.
14. The electrode plate according to claim 13 , wherein the ratio of the width of the middle zone to the sum of the width of each one of the zones is 45% to 60%.
15. The electrode plate according to claim 14 , wherein the ratio of the width of the middle zone to the sum of the width of each one of the zones is 45% to 55%.
16. The electrode plate according to claim 11 , wherein the compacted density of the middle zone is greater than the compacted density of zones on both sides by 8% to 20% of the compacted density of the middle zone.
17. The electrode plate according to claim 1 , wherein the compacted density of the middle zone is the highest among all of the 2n+1 zones, and the compacted density of the zones on both sides gradually decreases from middle to edge along the width direction of the electrode plate.
18. The electrode plate according to claim 17 , wherein two symmetrical zones of the zones on both sides have the same compacted density.
19. The electrode plate according to claim 1 , wherein n=1, and the electrode active material layer comprises 3 zones.
20. The electrode plate according to claim 1 , wherein n=2, and the electrode active material layer comprises 5 zones.