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EP-4742428-A2 - ELECTRODE PLATE AND BATTERY

EP4742428A2EP 4742428 A2EP4742428 A2EP 4742428A2EP-4742428-A2

Abstract

The present invention provides an electrode piece and a battery. The electrode piece includes a current collector and a functional layer arranged on a first surface of the current collector, a tab is further arranged in middle of the first surface, and the functional layer on the first surface has a first slope area near the tab and a first normal area away from the tab, and a thickness of the first slope area gradually decreases along a direction towards the tab. The present invention can improve performances of the battery, such as rate capacity, safety and the like.

Inventors

  • ZHANG, JIAN
  • SUN, LEIMING
  • ZHANG, SHUANGHU
  • PENG, Chong

Assignees

  • Zhuhai CosMX Battery Co., Ltd.

Dates

Publication Date
20260513
Application Date
20211230

Claims (10)

  1. A positive electrode piece, comprising a current collector and a functional layer arranged on a first surface of the current collector, wherein a tab is further arranged in middle of the first surface, the functional layer on the first surface has a first slope area near the tab and a first normal area away from the tab, and a thickness of the first slope area gradually decreases along a direction towards the tab, wherein the functional layer comprises an active material layer and a bottom coating layer arranged between the active material layer and a surface of the current collector, and the active material layer has the first slope area and the first normal area; wherein a width of the first slope area is 0.25-3mm.
  2. The positive electrode piece according to claim 1, wherein in projection of the positive electrode piece parallel to a thickness direction of the positive electrode piece, an endpoint of the first slope area away from the tab is c , and an endpoint of the first slope area near the tab is d, an angle between a connecting line between c and d and a plane parallel to a surface of the positive electrode piece is an acute angle α, and α is 10-80 °.
  3. The positive electrode piece according to claim 1, wherein a minimum distance from a surface of the first slope area to the first surface of the current collector is greater than a maximum distance from a surface of the bottom coating layer to the first surface of the current collector.
  4. The positive electrode piece according to claim 1, wherein the bottom coating layer has a second slope area near the tab and a second normal area away from the tab, and a thickness of the second slope area gradually decreases along a direction towards the tab.
  5. The positive electrode piece according to claim 4, wherein, in projection of the positive electrode piece parallel to a thickness direction of the positive electrode piece, an endpoint of the second slope area away from the tab is e, and an endpoint of the second slope area near the tab is f , an angle between a connecting line between e and f and a plane parallel to a surface of the positive electrode piece is an acute angle β, and β is 10-80 °.
  6. The positive electrode piece according to claim 1, wherein a minimum distance from the active material layer to the tab is not greater than a minimum distance from the bottom coating layer to the tab.
  7. The positive electrode piece according to claim 1, wherein a minimum distance from the active material layer to the tab is m, and a minimum distance from the bottom coating layer to the tab is n, 0≤n-m≤3mm.
  8. The positive electrode piece according to claim 6, wherein the minimum distance from the active material layer to the tab is m, and the minimum distance from the bottom coating layer to the tab is n, 0≤n-m≤3mm.
  9. The positive electrode piece according to claim 1, wherein the functional layer comprises an active material layer, and raw materials of the active material layer comprise an active material, a binder and a conductive agent; and the active material comprises at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganate, lithium ferrous phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium-rich manganese-based material and lithium nickel cobalt aluminate.
  10. A battery, comprising the positive electrode piece according to any one of claims 1-9.

Description

TECHNICAL FIELD The present invention relates to an electrode piece and a battery, belonging to the field of batteries. BACKGROUND Lithium-ion battery is the most important type of battery in consumer electronic products such as smart phones and notebook computers. With the upgrading of consumer electronic products such as smart mobilephones, the requirements for energy density, charging speed and safety performance of lithium-ion batteries are becoming higher and higher. The tab of the soft-package lithium-ion battery with conventional structure is welded at one end of the electrode piece, but the lithium-ion battery with such structure has a large internal resistance, which is not conducive to rapid charging of the battery. Welding the tab in or near the middle of the electrode piece can effectively reduce the internal resistance of the battery and is conducive to improve the charging speed of the battery. Usually, after a functional coating layer is coated on a current collector, a coating at a preset tab position in the middle of the electrode piece is removed, to expose the current collector and then the tab is welded, and then an adhesive tape is applied for protection. In addition to adhering with an upper surface of the tab, the adhesive tape usually needs to be adhered with the current collector exposed around the tab and the functional coating layer around the tab (that is, an area of the functional coating layer close to the tab) to cover the tab and realize the protection of the tab. However, in a conventional structure of the electrode piece, there is a height difference between an area of the functional coating layer near the tab and the current collector. The height difference is basically consistent with the thickness of the functional coating layer, so that the adhesive tape cannot fully fit with the current collector exposed around the tab. As a result, the area of the functional coating layer near the tab is prone to enrich electrolyte, which makes the concentration of lithium ion in this area too different from the concentration of lithium ion in other areas, leading to problems such as easy lithium precipitation, thereby reducing safety and rate capability of the electrode and battery, and the like. SUMMARY The present invention provides an electrode piece, which can effectively improve protection of an area near the tab, avoid problems such as lithium precipitation, and improve, for example, safety and rate capability of the electrode piece and battery. The present invention further provides a battery, which adopts the above electrode piece and has good performances, such as safety and rate capability. In one aspect, the present invention provides an electrode piece, including a current collector and a functional layer arranged on a first surface of the current collector, where a tab is further arranged in middle of the first surface, and the functional layer on the first surface has a first slope area near the tab and a first normal area away from the tab, and a thickness of the first slope area gradually decreases along a direction towards the tab, that is, the thickness of the first slope area as a wholes tends to decrease. According to an embodiment of the present invention, in a projection of the electrode piece parallel to a thickness direction of the electrode piece, an endpoint of the first slope area away from the tab is c, and an endpoint of the first slope area near the tab is d, an angle between a connecting line between c and d and a plane parallel to a surface of the electrode piece is an acute angle α, and α is 10-80 °. According to an embodiment of the present invention, a width of the first slope area is 0.25-3mm. According to an embodiment of the present invention, the functional layer includes an active material layer and a bottom coating layer arranged between the active material layer and a surface of the current collector, and the active material layer has the first slope area and the first normal area. According to an embodiment of the present invention, the bottom coating layer has a second slope area near the tab and a second normal area away from the tab, and a thickness of the second slope area gradually decreases along a direction towards the tab. According to an embodiment of the present invention, in projection of the electrode piece parallel to the thickness direction of the electrode piece, an endpoint of the second slope area away from the tab is e, and an endpoint of the second slope area near the tab is f, an angle between a connecting line between e and f and a plane parallel to a surface of the electrode piece is an acute angle β, and β is 10-80 °. According to an embodiment of the present invention, a minimum distance from the active material layer to the tab is not greater than a minimum distance from the bottom coating layer to the tab. According to an embodiment of the present invention, a minimum distance from the active material layer to the t