Cathode Active Material W Element Distribution for Battery Durability
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Solution Overview
Problem
Lithium ion secondary batteries face challenges in durability and performance retention during charge-discharge cycles, particularly in maintaining capacity and reducing electrode resistance, especially when the W element distribution in cathode active materials is non-uniform.
Innovation Solution
A cathode active material with a uniform distribution of the W element, represented by the formula Li(1+a)NixCoyMnzWtO2, where the W element is evenly distributed throughout the primary particles, enhancing its attraction to oxygen atoms and improving the material's durability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the W element is added to cathode active material to improve durability, then capacity retention rate increases, but the W element distribution becomes non-uniform leading to further durability limitations
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific elements (Ti, V, Cr, Al, Mg, Zr, Nb, Mo, Hf, Ta) in controlled amounts to modify the cathode active material structure. This compositional adjustment enables uniform W element distribution while maintaining high capacity retention rates, resolving the contradiction between durability improvement and distribution uniformity
Solution Approach 2:
The patent creates a composite cathode active material by combining multiple elements (Li, Ni, Co, Mn, W, and at least one of Ti, V, Cr, Al, Mg, Zr, Nb, Mo, Hf, Ta) in a specific formula Li(1+a)NixCoyMnzWtO2. This composite structure achieves both uniform W distribution and enhanced durability through synergistic effects of the combined elements
2Reliability
If charge-discharge cycles are performed to test battery performance, then capacity retention can be measured, but electrode resistance increases leading to performance deterioration
Solution Approach 1:
The patent modifies the cathode material's chemical composition by adding specific elements that alter the material's electrical and structural properties. These compositional changes reduce electrode resistance growth during cycling while maintaining high capacity retention, addressing the contradiction between measuring performance and resisting performance deterioration
Data Source
AI summary
A cathode active material with high durability and a lithium ion secondary battery. The cathode active material is a cathode active material represented by a general formula Li(1+a)NixCoyMnzWtO2 (−0.05≤a≤0.2, x=1−y−z−t, 0≤y<1, 0≤t<1, 0<t≤0.03), wherein the cathode active material satisfies the following formula (1):σ1/t1≤0.92 (1)where t1 is an element concentration average of insides and grain boundaries of primary particles of a W element, and σ1 is an element concentration standard deviation of the insides and grain boundaries of the primary particles of the W element.