Secondary battery and electronic device

By optimizing the combination of separator and electrolyte, the problems of high impedance and insufficient safety of secondary batteries under high temperature and high rate charge and discharge are solved, realizing a secondary battery with low impedance and high safety performance, and improving the battery's thermal test pass rate and low temperature cycle capacity retention rate.

WO2026149274A1PCT designated stage Publication Date: 2026-07-16NINGDE AMPEREX TECHNOLOGY LTD
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
NINGDE AMPEREX TECHNOLOGY LTD
Filing Date
2025-12-31
Publication Date
2026-07-16

AI Technical Summary

Technical Problem

Existing secondary batteries have problems with high impedance and insufficient safety under high temperature and high rate charge and discharge conditions. Especially under fast charging and high energy density conditions, they are prone to problems such as unqualified thermal box window, self-discharge and poor low temperature cycle performance.

Method used

By adjusting the porosity of the base membrane of the separator, the Dv99 ratio of the inorganic particles in the inorganic coating, and the mass ratio of propyl propionate and lithium bis(fluorosulfonyl)imide in the electrolyte, combined with the melting point range of the organic coating, the combination of the separator and the electrolyte is optimized, thereby improving the stability of the separator and the chemical stability of the electrolyte, and reducing the fast charging voltage drop and self-discharge of the battery.

Benefits of technology

It improves the resistance change rate and fast charging voltage drop of secondary batteries under high temperature and high rate charge and discharge conditions, enhances the pass rate of hot box test and the low temperature cycle capacity retention rate, and improves the safety and cycle performance of batteries.

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Abstract

Provided are a secondary battery and an electronic device. The secondary battery comprises a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator arranged between the positive electrode sheet and the negative electrode sheet. The separator comprises a base film and inorganic coatings on opposite surfaces of the base film. Each inorganic coating comprises multiple inorganic particles. The Dv99 of the inorganic particles is A, in units of μm; and the porosity of the base film is B%, wherein the ratio B / A of B to A satisfies: 1.25≤B / A≤40. The electrolyte comprises propyl propionate. On the basis of the total mass of the electrolyte, the mass percentage content of the propyl propionate is C%, wherein C satisfies: 20≤C≤45. By specially designing the separator and controlling the content of the propyl propionate in the electrolyte, the secondary battery has low impedance and high safety performance during high-temperature and high-rate charging and discharging, thereby effectively preventing overcharging, thus improving the cycle performance of the secondary battery.
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