Cathode Active Material Surface Chemistry for Better Battery Cycling
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in improving cycle characteristics and suppressing capacity reduction due to charge and discharge, despite existing technologies extending battery life.
Innovation Solution
A positive electrode active material with a lithium-containing transition metal composite oxide having a specific surface area of 0.9 m2/g or less, with 0.3 to 2.5% lithium carbonate, 0.35% or less lithium hydroxide, and 2 to 200 ppm nitrogen compounds on the surface of primary particles, enhancing the binding force and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If existing surface coating technologies are used to extend battery life, then battery life is extended, but cycle characteristics are not sufficiently improved
Solution Approach 1:
The patent applies composite materials by combining multiple coating substances (lithium carbonate, lithium hydroxide, and nitrogen compound) to form a multi-component surface layer on the positive electrode active material. This composite coating structure simultaneously addresses both battery life extension and cycle characteristic improvement, resolving the technical contradiction where single-component coatings failed to sufficiently improve cycle characteristics while extending battery life.
Solution Approach 2:
The patent changes the surface area parameter of the positive electrode active material to 0.9 m²/g or less, and precisely controls the composition parameters of the surface coating (0.3 to 2.5% lithium carbonate, 0.35% or less lithium hydroxide, and 2 to 200 ppm nitrogen compound). These parameter changes optimize both the durability (battery life) and reliability (cycle characteristics) of the battery system.
2Duration of action of stationary object
If surface coating is applied to improve battery performance, then battery life is extended, but capacity reduction due to charge and discharge is not sufficiently suppressed
Solution Approach 1:
The patent uses a composite coating system comprising lithium carbonate, lithium hydroxide, and nitrogen compound in specific proportions. This composite structure provides synergistic effects that simultaneously extend battery life and suppress capacity reduction during charge-discharge cycles, addressing the technical contradiction where conventional single-material coatings were insufficient.
Solution Approach 2:
The patent applies surface coating with specific local quality characteristics - controlling the surface area to 0.9 m²/g or less and precisely regulating the distribution and concentration of coating materials on the particle surface. This localized optimization of surface properties effectively suppresses capacity loss while maintaining long-term battery life.
Data Source
AI summary
A lithium-containing complex transition metal oxide forming the positive electrode active material of a non-aqueous electrolyte secondary cell in one embodiment is a secondary particle obtained by aggregating primary particles and has a BET specific surface area of 0.9 m2/g or less. The surface of each primary particle comprises 0.3 to 2.5% lithium carbonate, no more than 0.35% lithium hydroxide, and 2 to 200 ppm of a nitrogen compound relative to the total mass of the lithium-containing complex transition metal oxide.