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CN-121394516-B - Secondary battery and electronic device

CN121394516BCN 121394516 BCN121394516 BCN 121394516BCN-121394516-B

Abstract

The application provides a secondary battery and an electronic device, and belongs to the technical field of energy storage. The secondary battery comprises an electrolyte and a shell, wherein the electrolyte comprises a cyclic sulfate compound and a fluoro-sulfonamide compound, the mass contents of the cyclic sulfate compound and the fluoro-sulfonamide compound are respectively a% and b% based on the total mass of the electrolyte, a is more than or equal to 0.01 and less than or equal to 5, b is more than or equal to 1 and less than or equal to 15, the shell comprises a shell and a pressure relief component, the shell is made of steel shell, the pressure relief component comprises a sealing piece and a first through hole, the area of the first through hole is C mm 2 , C is more than or equal to 1 and less than or equal to 9, when the internal temperature of the shell reaches a threshold temperature, the sealing piece of the pressure relief component loses sealing effect to enable the first through hole to be communicated with the external environment so as to release the internal pressure of the battery and take out heat, and the threshold temperature is d ℃ and d is more than or equal to 100 and less than or equal to 130. The application can improve the high-temperature cycle performance and the hot box passing rate of the secondary battery through the arrangement.

Inventors

  • GONG XIANJIN
  • TANG CHAO
  • ZHANG LILAN
  • ZOU XIN

Assignees

  • 宁德新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20251224

Claims (8)

  1. 1. A secondary battery, characterized in that the secondary battery comprises an electrolyte and a case; The electrolyte comprises a cyclic sulfate compound, and the mass content of the cyclic sulfate compound is a% which is more than or equal to 0.2 and less than or equal to 4 based on the total mass of the electrolyte; the cyclic sulfate compound includes at least one of the following compounds: A formula I-1, A formula I-6, A compound of the formula I-7, Formula I-8; the electrolyte comprises a fluoro sulfonamide compound, as shown in formula II: A formula II; Wherein R 1 is selected from fluorine atoms, fully or partially fluorine substituted C1 to C5 alkyl groups, R 2 and R 3 are selected from fluorine substituted or unsubstituted C1 to C5 alkyl groups, and when R 2 and R 3 are selected from fluorine substituted or unsubstituted C1 to C5 alkyl groups, R 2 and R 3 are independent of each other; The mass content of the fluoro sulfonamide compound is b% based on the total mass of the electrolyte, and b% is more than or equal to 2 and less than or equal to 12; The shell comprises a shell body and a pressure relief assembly, wherein the shell body is made of a steel shell, the pressure relief assembly comprises a sealing piece and a first through hole, the area of the first through hole is c mm 2 , c is more than or equal to 1 and less than or equal to 9, and (a+b)/c is more than or equal to 0.7 and less than or equal to 10; the pressure relief assembly is configured such that when the temperature inside the shell reaches a threshold temperature, the sealing element of the pressure relief assembly loses sealing action to enable the first through hole to be communicated with the external environment so as to release the internal pressure of the battery and bring out heat, and the threshold temperature is d ℃ and d is more than or equal to 100 and less than or equal to 120.
  2. 2. The secondary battery according to claim 1, wherein the secondary battery satisfies at least one of the following conditions: (1)0.3≤a≤3; (2)2≤b≤8; (3)0.7≤(a+b)/c≤8; (4)105≤d≤115。
  3. 3. The secondary battery according to any one of claims 1 to 2, wherein the fluorosulfonamide compound includes at least one of the following compounds: formula II-1, Formula II-2, Formula II-3, Formula II-4, Formula II-5, Formula II-6, Formula II-7, Formula II-8, Formula II-14, Formula II-15, Formula II-16, Formula II-17, Formula II-18, Formula II-19.
  4. 4. The secondary battery according to any one of claims 1 to 2, wherein the secondary battery comprises a positive electrode sheet comprising a positive electrode active material comprising lithium cobalt oxide, and the single-sided coating weight of the positive electrode sheet is m mg/cm 2 , and 13≤m≤26.
  5. 5. The secondary battery according to any one of claims 1 to 2, wherein the secondary battery comprises a negative electrode tab comprising a negative electrode material layer containing silicon element in a mass content of h%, based on the total mass of the negative electrode material layer, of 1≤h≤25.
  6. 6. The secondary battery according to claim 5, wherein the single-sided coating weight of the negative electrode sheet is n mg/cm 2 , and n is 6.5≤n≤13.
  7. 7. The secondary battery according to any one of claims 1 to 2, wherein the volumetric energy density of the secondary battery is V Wh/L, 700≤v≤1200.
  8. 8. An electronic device comprising the secondary battery according to any one of claims 1 to 7.

Description

Secondary battery and electronic device Technical Field The application belongs to the technical field of energy storage, and particularly relates to a secondary battery and an electronic device. Background The secondary battery is used as chargeable energy storage equipment, can realize the storage and release of electric energy through electrochemical reaction, and is an indispensable key component of electronic equipment, electric automobiles and energy storage systems. With the continuous iterative upgrade of technology, lithium ion batteries are widely used due to their high energy density, long cycle life and environmental friendliness. The lithium ion battery adopting the steel shell packaging mode occupies an important position in the battery field because of the advantages of high structural strength, good sealing performance and the like. However, compared with a soft-packed battery packaged by an aluminum plastic film, the steel shell material has higher heat conductivity, so that the thermal response inside the battery cell is faster and the temperature rising gradient inside the battery cell is steeper in the process of thermal abuse test (such as needling, heating and external thermal shock). The characteristic makes the steel-shell battery trigger an internal thermal runaway chain reaction more easily in a short time under the action of an external heat source, worsens the high-temperature cycle performance and the hot box passing rate of the secondary battery, and provides systematic challenges for the flame-retardant design of the electrolyte and the collaborative design of a heat diffusion strategy of a steel-shell structure. Disclosure of Invention In view of the above, the present application provides a secondary battery and an electronic device that improve the high-temperature cycle performance and the hot box passing rate of the secondary battery by controlling the composition of an electrolyte and providing a pressure relief assembly. In a first aspect, the present application provides a secondary battery comprising an electrolyte and a case; the electrolyte comprises a cyclic sulfate compound, and the mass content of the cyclic sulfate compound is a% which is more than or equal to 0.01 and less than or equal to 5 based on the total mass of the electrolyte; the electrolyte also includes a fluorosulfonamide compound, as shown in formula II: A formula II; Wherein R 1 is selected from the group consisting of a fluorine atom, a fully or partially fluorine substituted C1 to C5 alkyl group, a fully or partially fluorine substituted C1 to C5 oxyalkyl group, a fully or partially fluorine substituted C6 to C10 aryl group, a fully or partially fluorine substituted C6 to C10 oxyaryl group, and when R 1 contains an O atom, the O atom in R 1 is not directly attached to an S atom, R 2 and R 3 are selected from the group consisting of a fluorine substituted or unsubstituted C1 to C5 alkyl group, a fluorine substituted or unsubstituted C6 to C10 aryl group, and when R 2 and R 3 are selected from the group consisting of a fluorine substituted or unsubstituted C1 to C5 alkyl group, R 2 and R 3 are independent of each other; based on the total mass of the electrolyte, the mass content of the fluoro sulfonamide compound is b%, and b is more than or equal to 1 and less than or equal to 15; The shell comprises a shell body and a pressure relief assembly, wherein the shell body is made of a steel shell, the pressure relief assembly comprises a sealing piece and a first through hole, and the area of the first through hole is c mm 2, c is more than or equal to 1 and less than or equal to 9; The pressure relief assembly is configured such that when the temperature inside the housing reaches a threshold temperature, the sealing element of the pressure relief assembly loses sealing action to enable the first through hole to communicate with an external environment so as to release the internal pressure of the battery and bring out heat, and the threshold temperature is d ℃ and d is more than or equal to 100 and less than or equal to 130. According to the application, the cyclic sulfate compound and the fluoro-sulfonamide compound with specific contents are introduced into the electrolyte, so that a stable interface film is formed on the surfaces of the positive electrode and the negative electrode, side reactions of the positive electrode interface and the negative electrode interface are effectively inhibited, heat and gas generated under high temperature or abuse conditions are reduced, meanwhile, the pressure release component with specific first through hole area is arranged, and the pressure release component can cooperate with the cyclic sulfate compound and the fluoro-sulfonamide compound, so that the first through hole is timely opened when the internal pressure reaches a threshold value, the gas is discharged and heat is taken out, the case deformation and short circuit caused by heat accumulation in t