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CN-121983638-A - Battery cell

CN121983638ACN 121983638 ACN121983638 ACN 121983638ACN-121983638-A

Abstract

The invention provides a battery, which comprises a battery core and electrolyte, wherein the battery core comprises a positive electrode plate, a diaphragm and a negative electrode plate which are sequentially stacked, the positive electrode plate comprises a positive electrode current collector, a positive electrode active layer, a positive electrode lug and a bonding piece, the positive electrode active layer is arranged on at least one side surface of the positive electrode current collector, the positive electrode active layer comprises a lug groove, the positive electrode lug is at least partially arranged in the lug groove, the positive electrode lug comprises a connecting part connected with the positive electrode current collector, the bonding piece comprises a first insulating layer and a second insulating layer, the first insulating layer covers the connecting part, the second insulating layer covers the first insulating layer, the sum of the thickness of the first insulating layer and the thickness of the second insulating layer is 8-60 mu m, the diaphragm comprises a first substrate layer, a first coating layer corresponding to the positive electrode plate and a second coating corresponding to the negative electrode plate, and the difference of the thickness of the first coating layer and the second coating layer is 0.5-8 mu m. The battery provided by the invention has the advantages of higher energy density and higher safety performance.

Inventors

  • HE ZHIJIA
  • RU YI
  • WU DEEN

Assignees

  • 珠海冠宇电池股份有限公司

Dates

Publication Date
20260505
Application Date
20251231

Claims (10)

  1. 1. The battery is characterized by comprising a battery core and electrolyte, wherein the battery core comprises a positive plate, a diaphragm and a negative plate which are sequentially stacked; the positive plate comprises a positive current collector, a positive active layer, a positive lug and a bonding piece, wherein the positive active layer is positioned on at least one side surface of the positive current collector, the positive active layer comprises a lug groove, the positive lug is at least partially positioned in the lug groove, the positive lug comprises a connecting part connected with the positive current collector, the bonding piece comprises a first insulating layer and a second insulating layer, the first insulating layer covers the connecting part, the second insulating layer covers the first insulating layer, and the sum of the thickness of the first insulating layer and the thickness of the second insulating layer is 8-60 mu m; The separator comprises a first substrate layer, and a first coating and a second coating which are respectively positioned on the two side surfaces of the first substrate layer, wherein the first coating corresponds to the positive electrode plate, the second coating corresponds to the negative electrode plate, and the difference between the thickness of the first coating and the thickness of the second coating is 0.5-8 mu m.
  2. 2. The battery of claim 1, wherein the first insulating layer and the second insulating layer are the same or different in width; and/or, the first insulating layer or the second insulating layer respectively comprises a second substrate layer and a bonding layer positioned on at least one side surface of the second substrate layer; and/or the thickness of the first insulating layer or the second insulating layer is 3 μm to 33 μm, preferably 5 μm to 25 μm; And/or the width of the first insulating layer is W 1 ,W 1 -2 mm; and/or the width of the second insulating layer is W 2 ,W 2 mm or more; and/or the end part of the first insulating layer is positioned in the tab slot or positioned outside the tab slot; And/or at least one end of the second insulating layer is positioned outside the tab slot.
  3. 3. The battery of claim 2, wherein the width W 2 of the second insulating layer and the width W 1 of the first insulating layer satisfy W 2 ＞W 1 ; and/or the first insulating layer or the second insulating layer respectively comprises a second substrate layer and a bonding layer positioned on one side surface of the second substrate layer, wherein the bonding layer is positioned on one side surface of the second substrate layer close to the positive electrode active layer; and/or the components of the second substrate layer comprise one or more of polyethylene terephthalate, polyimide and polypropylene; And/or the adhesive layer comprises one or more of an acrylic adhesive and a rubber adhesive.
  4. 4. The battery of claim 1, wherein the first coating layer comprises a heat resistant layer and a first subbing layer located on a surface of the heat resistant layer remote from the first substrate layer, the first subbing layer comprising a first polymer, the second coating layer comprising a second polymer, the components of the second polymer and the first polymer each independently comprising one or more of a fluoropolymer, an acrylate polymer, a polyimide, a modified polyimide, a poly-p-phenylene terephthalamide, a poly-m-phenylene isophthalamide; preferably, the first glue layer is a porous layer, the first glue layer comprises a first polymer and optionally first filler particles, and the components of the first filler particles comprise at least one of alumina, magnesia, boehmite, barium sulfate, barium titanate, zinc oxide, calcium oxide, silica, silicon carbide, nickel oxide; preferably, the second coating is a porous layer comprising a second polymer and optionally second filler particles, the composition of the second filler particles comprising at least one of alumina, magnesia, boehmite, barium sulfate, barium titanate, zinc oxide, calcium oxide, silica, silicon carbide, nickel oxide; preferably, the heat-resistant layer includes heat-resistant particles whose composition includes at least one of aluminum oxide, magnesium oxide, boehmite, barium sulfate, barium titanate, zinc oxide, calcium oxide, silicon dioxide, silicon carbide, and nickel oxide.
  5. 5. The battery of claim 1, the first coating comprising a heat resistant layer and a first subbing layer, the first subbing layer being located on a surface of the heat resistant layer remote from the first substrate layer, the first subbing layer comprising first polymer particles comprising at least one of first particles and second particles, the first particles being agglomerated polymer particles, the second particles being dispersed polymer particles; preferably, the heat-resistant layer includes heat-resistant particles whose composition includes at least one of aluminum oxide, magnesium oxide, boehmite, barium sulfate, barium titanate, zinc oxide, calcium oxide, silicon dioxide, silicon carbide, and nickel oxide.
  6. 6. The battery according to claim 5, wherein the primary particles of the second particles have an average particle diameter of 0.3 μm to 1.5 μm; And/or the first particles comprise secondary particles formed by agglomeration of primary particles, the primary particles of the first particles having an average particle size of 0.15 μm to 0.25 μm, the secondary particles of the first particles having an average particle size of 4 μm to 20 μm; And/or the ratio of the weight of the first particles to the weight of the second particles (10% -100%) (90% -0%); And/or the components of the first particles and the second particles each independently comprise one or more of fluoropolymers, acrylic polymers, polyimides, modified polyimides; and/or the coverage rate of the first adhesive layer on the surface of the heat-resistant layer is 8% -50%, preferably 10% -35%; And/or the heat-resistant layer comprises heat-resistant particles, and the battery satisfies the following relation of 0.3-D 5 /H 1 -0.9, wherein D 5 is Dv50 of the heat-resistant particles, the unit is mu m, H 1 is the thickness of the heat-resistant layer, and the unit is mu m.
  7. 7. The battery of claim 1, wherein the second coating comprises second polymer particles comprising at least one of third particles and fourth particles; And/or the coverage of the second coating on the surface of the first substrate layer is 8-50%, preferably 10-35%.
  8. 8. The battery of claim 7, wherein the components of the third and fourth particles each independently comprise one or more of a fluoropolymer, an acrylate polymer, a polyimide, a modified polyimide; and/or, the third particles are agglomerated polymer particles; And/or, the fourth particles are polymer particles distributed in a dispersed manner; And/or, the third particles comprise secondary particles formed by agglomeration of primary particles, the primary particles of the third particles having an average particle size of 0.15 μm to 0.25 μm, the secondary particles of the third particles having an average particle size of 4 μm to 20 μm; And/or, the primary particles of the fourth particles have an average particle diameter of 0.3 μm to 1.5 μm.
  9. 9. The battery of claim 1, wherein the tab slot comprises a first slot and a second slot, wherein a bottom wall of the first slot is the positive current collector, a thickness of the positive active layer in the second slot is smaller than a thickness of the positive active layer in a non-slot region of the positive current collector, the positive tab is at least partially positioned in the first slot, the positive tab comprises a connecting portion connected with the positive current collector, the battery satisfies the following relation O 1 ≥M 1 ≥E 1 , and/or E 1 ≥N 1 , and/or N 1 ≥C 1 , wherein O 1 is a width of the second slot in mm, M 1 is a width of the second insulating layer in mm, E 1 is a width of the first slot in mm, N 1 is a width of the first insulating layer in mm, and C 1 is a width of the positive tab in mm; Preferably, both ends of the first insulating layer are located on or in the first groove; preferably, at least one of both ends of the second insulating layer is located on the second groove.
  10. 10. The battery according to claim 1, wherein the positive electrode current collector is provided with a first edge and a second edge which are oppositely arranged along the extending direction of the positive electrode lug, a first notch is formed in the first edge and communicated with the tab groove, the width of the positive electrode lug is c and is in mm, the width of the first notch is d and is in mm, the width of the tab groove is e and is in mm, and the battery satisfies the following relation that c is less than or equal to d is less than or equal to e; The battery cell comprises a flat area and arc areas connected to two ends of the flat area, wherein the positive plate comprises a first positive straight section, a first positive arc section and a second positive straight section which are sequentially arranged along the winding starting direction of the battery cell, one end of the first positive straight section Duan Yuan, which is away from the first positive arc section, is taken as a positive winding starting end of the positive plate, the negative plate comprises a first negative straight section positioned in the flat area, the first negative straight section is positioned between the first positive straight section and the second positive straight section along the first direction, and one end of the first negative straight section, which faces the first positive arc section, is taken as a negative winding starting end of the negative plate; And/or the electrolyte comprises ethylene carbonate and propylene carbonate, wherein the total mass content of the ethylene carbonate and the propylene carbonate is 4-15% based on the total mass of the electrolyte; And/or the electrolyte comprises ethyl fluoroacetate, the content of which is 15% -70%, preferably 20% -55% based on the total mass of the electrolyte; And/or the ethyl fluoroacetate includes ethyl difluoroacetate including at least one of 2, 2-difluoroethyl acetate and 2, 2-difluoroethyl acetate; Preferably, the ethyl difluoroacetate comprises 2, 2-difluoroethyl acetate.

Description

Battery cell Technical Field The invention relates to the technical field of batteries, in particular to a battery. Background Lithium Ion Batteries (LIBS) are widely applied to consumer electronics, new energy automobiles, military and aviation fields, and people pay more and more attention to the safety performance of lithium ions while pursuing high energy density, high charging speed and long cycle life of the lithium ion batteries. In order to improve the safety of the battery, the tab glue is arranged on the tab, so that the tab glue not only can enhance the structural stability of the tab, but also can reduce the risk of short circuit inside the battery. The electrode lug generates local joule heat when charging and discharging due to current density concentration and contact impedance, a remarkable temperature rise hot spot is formed, and when the temperature of the electrode lug is raised too high, side reactions inside the battery can be accelerated, but gaps at the position of the electrode lug in the prior art are smaller, heat dissipation is poor, so that excessive heat is generated at the position of the electrode lug, the risk of thermal runaway of the battery is increased, and the safety performance of the battery is influenced. Disclosure of Invention According to the research, in the prior art, an insulating layer is arranged on a positive electrode tab, and an insulating layer is also arranged on the surface of a negative electrode plate corresponding to the positive electrode tab, so that the positive electrode insulating layer and the negative electrode insulating layer are respectively positioned on two sides of a diaphragm, and therefore the risk of short circuit between the electrode plates can be avoided, but the clearance between the diaphragm and the positive electrode plate at the position of the tab is smaller, the heat dissipation requirement of the position of the tab cannot be met, and the risk of thermal runaway of a battery is increased. Therefore, in order to solve the problems of thermal runaway risk possibly caused by poor heat dissipation of tab rubberizing parts and battery energy density loss caused by overlarge size difference of two layers of insulating adhesives in the prior art, the invention provides an improved scheme of a battery structure. According to the scheme, on one hand, the space at the positive electrode lug is increased, the electrolyte reserve is improved, so that the heat radiation capacity of the lug area is improved, the temperature rise of the lug is effectively controlled, and the thermal runaway risk is reduced. In order to achieve the above object, the present invention provides a battery comprising a battery cell and an electrolyte, wherein the battery cell comprises a positive electrode sheet, a separator and a negative electrode sheet which are sequentially stacked; the positive plate comprises a positive current collector, a positive active layer, a positive lug and a bonding piece, wherein the positive active layer is positioned on at least one side surface of the positive current collector, the positive active layer comprises a lug groove, the positive lug is at least partially positioned in the lug groove, the positive lug comprises a connecting part connected with the positive current collector, the bonding piece comprises a first insulating layer and a second insulating layer, the first insulating layer covers the connecting part, the second insulating layer covers the first insulating layer, and the sum of the thickness of the first insulating layer and the thickness of the second insulating layer is 8-60 mu m; The separator comprises a first substrate layer, and a first coating and a second coating which are respectively positioned on the two side surfaces of the first substrate layer, wherein the first coating corresponds to the positive electrode plate, the second coating corresponds to the negative electrode plate, and the difference between the thickness of the first coating and the thickness of the second coating is 0.5-8 mu m. Through the technical scheme, compared with the prior art, the invention has at least the following advantages: According to the invention, the insulating layer on the negative plate at the position corresponding to the positive electrode lug is omitted, two insulating layers, namely the first insulating layer and the second insulating layer, are arranged between the positive electrode lug and the diaphragm, wherein the first insulating layer covers the connecting part of the positive electrode lug and the positive electrode current collector, the second insulating layer covers the first insulating layer, the sum of the thickness of the first insulating layer and the thickness of the second insulating layer is controlled to be 8-60 mu m, and the difference between the thickness of the first coating corresponding to the positive electrode lug and the thickness of the second coating corresponding to the ne