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EP-4738453-A1 - ELECTRODE ASSEMBLY, ELECTROCHEMICAL DEVICE AND ELECTRIC DEVICE

EP4738453A1EP 4738453 A1EP4738453 A1EP 4738453A1EP-4738453-A1

Abstract

An electrode assembly, an electrochemical apparatus, and an electric apparatus are provided, where a positive electrode material layer of the electrode assembly includes a first positive electrode material LiMn x Fe 1-x PO 4 , a single-side thickness of the positive electrode material layer is T 1 µm, and 22 ≤ T 1 ≤ 110. A length of a positive electrode plate is L 1 mm. The electrode assembly further includes at least one positive electrode tab. When there is one positive electrode tab, the positive electrode tab is a centrally disposed tab structure; or when there are multiple positive electrode tabs, a ratio of the number of the positive electrode tabs to L 1 is B, and 0.002 ≤ B ≤ 0.01. Synergistically regulating the type of positive electrode material, the single-side thickness of the positive electrode material layer, and the structure of the positive electrode tab enables the electrochemical apparatus to achieve good discharge performance at low temperatures, thereby improving the user experience during use of electrochemical apparatus products.

Inventors

  • SHEN, Haijie

Assignees

  • Dongguan Amperex Technology Limited

Dates

Publication Date
20260506
Application Date
20240617

Claims (10)

  1. An electrode assembly, comprising at least one positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and a positive electrode material layer disposed on two surfaces of the positive electrode current collector; wherein, the positive electrode material layer comprises a first positive electrode material LiMn x Fe 1-x PO 4 , and 0 ≤ x < 0.95; a single-side thickness of the positive electrode material layer is T 1 µm, and 22 ≤ T 1 ≤ 110; a length of the positive electrode plate is L 1 mm; the electrode assembly further comprises at least one positive electrode tab; when there is one positive electrode tab, the positive electrode tab is a centrally disposed tab structure; or when there are multiple positive electrode tabs, a ratio of the number of the positive electrode tabs to L 1 is B, 0.002 ≤ B ≤ 0.01.
  2. The electrode assembly according to claim 1, wherein, when there are multiple positive electrode tabs, and a ratio of the number of the positive electrode tabs to T 1 is A, 0.05 ≤ A ≤ 0.1.
  3. The electrode assembly according to claim 1, wherein, a thickness of the positive electrode tab is T 2 mm, a width of the positive electrode tab is K 2 mm, 0.02 ≤ T 2 ≤ 1, and 1 ≤ K 2 ≤ 20.
  4. The electrode assembly according to claim 1, wherein, a width of the positive electrode plate is K 1 mm, a length of a portion of the positive electrode tab located within the positive electrode plate is L 2 mm, and 2 ≤ L 2 ≤ K 1 .
  5. The electrode assembly according to claim 4, wherein, a length of a portion of the positive electrode tab extending beyond the positive electrode plate is L 3 mm, and 2 ≤ L 3 ≤ 20.
  6. The electrode assembly according to claim 1, wherein, the first positive electrode material satisfies at least one of the following characteristics: (1) D v 50 of the first positive electrode material is 0.5 µm to 8 µm; (2) a specific surface area of the first positive electrode material is 2 m 2 /g to 40 m 2 /g; or (3) a gram capacity of the first positive electrode material is 140 mAh/g to 190 mAh/g.
  7. The electrode assembly according to claim 1, wherein, the positive electrode material layer further comprises a second positive electrode material, a conductive agent, and a binder, wherein based on a mass of the positive electrode material layer, a mass percentage of the first positive electrode material is 1% to 20%, a mass percentage of the second positive electrode material is 70% to 89%, a mass percentage of the conductive agent is 1% to 5%, and a mass percentage of the binder is 1% to 5%.
  8. The electrode assembly according to claim 7, wherein, the second positive electrode material comprises one or more selected from the group consisting of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide, lithium manganese oxide, and lithium titanate; the conductive agent comprises one or more selected from the group consisting of conductive carbon black, carbon nanotubes, and graphene; and the binder comprises at least one of polyvinylidene fluoride or lithium polyacrylate.
  9. An electrochemical apparatus, comprising the electrode assembly according to any one of claims 1 to 8.
  10. An electric apparatus, comprising the electrochemical apparatus according to claim 9.

Description

This application claims priority to Chinese Patent Application No. 202310788604.6, filed on June 29, 2023, entitled "ELECTRODE ASSEMBLY, ELECTROCHEMICAL APPARATUS, AND ELECTRIC APPARATUS", which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to the field of electrochemical technology, and in particular, to an electrode assembly, an electrochemical apparatus, and an electric apparatus. BACKGROUND With many advantages such as high specific energy density, long cycle life, high nominal voltage, low self-discharge rate, small size, and light weight, lithium-ion batteries are widely used in fields such as portable electronic devices, electric bicycles, electric vehicles, and energy storage devices. Technicians are continuously improving the use performance of lithium-ion batteries, and lithium-ion batteries will continue to hold an important position in the consumer electronics field for a long time. During the use of lithium-ion batteries, temperature is a critical factor affecting the discharge performance of lithium-ion batteries. As the temperature decreases, the discharge voltage and discharge SOC (State of Charge, State of Charge) of lithium-ion batteries both decline. Some existing products using lithium-ion batteries fail to meet the requirements for complete startup and rapid discharge in low-temperature (for example, a temperature less than or equal to 10°C) environments. Therefore, there is a need for a lithium-ion battery capable of maintaining good discharge performance at low temperatures to improve the user experience during use of lithium-ion battery products. SUMMARY This application is intended to provide an electrode assembly, an electrochemical apparatus, and an electric apparatus, which can achieve good discharge performance at low temperatures. The specific technical solution is as follows. According to a first aspect of this application, an electrode assembly is provided, including at least one positive electrode plate. The positive electrode plate includes a positive electrode current collector and positive electrode material layers disposed on two surfaces of the positive electrode current collector. The positive electrode material layer includes a first positive electrode material LiMnxFe1-xPO4, 0 ≤ x < 0.95, a single-side thickness of the positive electrode material layer is T1 µm, and 22 ≤ T1 ≤ 110. A length of the positive electrode plate is L1 mm. The electrode assembly further includes at least one positive electrode tab. When there is one positive electrode tab, the positive electrode tab is a centrally disposed tab structure; or when there are multiple positive electrode tabs, a ratio of the number of the positive electrode tabs to L1 is B, and 0.002 ≤ B ≤ 0.01. Synergistically regulating the type of positive electrode material, the single-side thickness of the positive electrode material layer, and the structure of the positive electrode tab enables the electrochemical apparatus to achieve good discharge performance at low temperatures, thereby improving the user experience during use of electrochemical apparatus products. In some embodiments of this application, when there are multiple positive electrode tabs, the ratio of the number of the positive electrode tabs to T1 is A, and 0.05 ≤ A ≤ 0.1. By regulating the value of A within the range provided in this application, the number of the positive electrode tabs matches the single-side thickness of the positive electrode material layer, which can further reduce the discharge impedance of the electrochemical apparatus, increase the initial discharge voltage, and compensate for voltage drop caused by a thick coating technology, thereby further increasing the discharge capacity of the electrochemical apparatus. In some embodiments of this application, a thickness of the positive electrode tab is T2 mm, a width of the positive electrode tab is K2 mm, 0.02 ≤ T2 ≤ 1, and 1 ≤ K2 ≤ 20. By regulating the values of T2 and K2 to be within the ranges provided in this application, the thickness and width of the tab can be maximized while matching the thickness and width of the overall electrochemical apparatus, thereby minimizing the discharge impedance of the electrochemical apparatus and increasing the initial discharge voltage. In some embodiments of this application, a width of the positive electrode plate is K1 mm, a length of a portion of the positive electrode tab located within the positive electrode plate is L2 mm, and 2 ≤ L2 ≤ K1. Preferably, 2 ≤ L2 ≤ K1/2. By regulating the relationship between the width of the positive electrode plate and the length of the portion of the positive electrode tab located within the positive electrode plate to be within the ranges provided in this application, the length of the portion of the positive electrode tab within the positive electrode plate matches the width of the positive electrode plate, which can further reduce the discharge impedance of th