Positive electrode sheet, battery, battery pack, and electric device

By using two positive electrode active materials with different shrinkage rates in the positive electrode sheet of lithium-ion batteries to form a composite material structure, the volume change problem caused by a single positive electrode active material is solved, the cycle life and capacity retention of the battery are improved, the impedance is reduced, and the mechanical structural stability and safety of the battery are improved.

CN121366869BActive Publication Date: 2026-06-05BYD CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
BYD CO LTD
Filing Date
2025-12-22
Publication Date
2026-06-05

AI Technical Summary

Technical Problem

In lithium-ion batteries, the reversible changes in the lattice structure of a single positive electrode active material during lithium-ion insertion and extraction lead to volume shrinkage and expansion, affecting the battery's electrochemical performance. This includes pulverization of active material particles, crack propagation, and deterioration of the conductive network, reducing the battery's cycle life and capacity retention.

Method used

The positive electrode sheet contains two positive electrode active materials with different shrinkage rates. By adjusting the matching relationship between their particle size and shrinkage rate, high shrinkage rate material particles are combined with low shrinkage rate material particles to form a composite material structure. The low shrinkage rate material acts as a "buffer skeleton" and "stress dispersion medium" to suppress excessive deformation of the high shrinkage rate material and protect the integrity of the conductive network.

Benefits of technology

It effectively reduces battery impedance, improves cycle life and capacity retention, reduces stress-induced particle breakage, contact loss and binder failure, and improves the mechanical structural stability and safety of the battery.

✦ Generated by Eureka AI based on patent content.

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Abstract

The application relates to the battery technical field and discloses a positive pole piece, a battery, a battery pack and a power utilization device. The positive pole piece comprises a positive pole current collector and a positive pole active material layer located on at least one side surface of the positive pole current collector. The positive pole active material layer comprises a first positive pole active material, a second positive pole active material and a positive pole conductive agent. The unit cell volume shrinkage rate of the first positive pole active material is higher than that of the second positive pole active material. The average particle size of the primary particles of the first and second positive pole active materials is Pa and Pb respectively, the unit cell volume shrinkage rate is Va and Vb respectively, and |Pa*Va-Pb*Vb|<=0.1. The positive pole piece disclosed by the application has positive pole active materials with different shrinkage rates. By adjusting the matching relationship between the particle size and the shrinkage rate, the pulverization, crack propagation and conductive network deterioration of the active material particles in the charging and discharging process are inhibited, the cycle life and capacity retention rate of the battery are improved, and the impedance is reduced.
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