A positive electrode sheet, a preparation method thereof, and a lithium ion battery

By employing a dual-layer gradient structure in the positive electrode of a lithium-ion battery, with the ascending layer and the surface layer composed of lithium iron phosphate materials of different particle sizes, the problem of uneven lithium-ion distribution is solved, thereby improving the battery's transmission efficiency and cycle stability.

CN122117809APending Publication Date: 2026-05-29BATTEROTECH CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
BATTEROTECH CO LTD
Filing Date
2026-03-25
Publication Date
2026-05-29

AI Technical Summary

Technical Problem

Traditional lithium-ion battery cathode plates suffer from lithium loss and uneven lithium-ion distribution during long-term cycling, leading to a decrease in battery life and reliability.

Method used

The positive electrode adopts a dual-layer gradient structure design, with the climbing layer and the surface layer composed of lithium iron phosphate materials of different particle sizes. The climbing layer is composed of large particles to build a stable framework, while the surface layer is composed of small particles to form a capillary network, thereby achieving uniform distribution of lithium ions.

Benefits of technology

It improves the transmission efficiency and cycle stability of lithium-ion batteries, enhances the rate performance and cycle life of batteries, reduces interfacial reaction impedance, and avoids uneven lithium intercalation problems.

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Abstract

The application provides a positive electrode sheet and a preparation method thereof and a lithium ion battery, and belongs to the technical field of lithium ion batteries. The positive electrode sheet structure comprises a current collector, at least one climbing layer and a surface layer on the current collector, and the surface layer is arranged on the outer surface of the climbing layer. The climbing layer comprises a first positive electrode active material, a lithium iron phosphate positive electrode material with a first coulomb efficiency of 95%-98%, and the particle size D50 of the lithium iron phosphate positive electrode material is 2-5 mu m, the particle size D90 is greater than 3.5 mu m, and the particle size Dmax is greater than 5.5 mu m. The surface layer comprises a second positive electrode active material, which is a lithium iron phosphate positive electrode material with a first coulomb efficiency greater than or equal to 98%, and the particle size D50 of the lithium iron phosphate positive electrode material is 0.5-2 mu m, the particle size D90 is 1-3 mu m, and the particle size Dmax is 2-5 mu m. Through the particle size gradient structure of the fine bottom layer and the coarse surface layer, the surface layer can quickly "receive" ions, and the climbing layer can uniformly distribute ions. This effectively uniformizes the lithium ion concentration in the thickness direction of the electrode sheet, thereby improving the cycle stability.
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