High-Nickel Cathode Material for Lithium-Ion Battery
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Solution Overview
Problem
Nickel-based oxides with high nickel content face challenges in maintaining stable crystal structures during charge-discharge cycles, leading to poor charge-discharge capacity and cycle properties, while existing cathode active materials are costly and inefficient due to high cobalt content and require improved productivity.
Innovation Solution
A lithium-transition metal composite oxide with an α-NaFeO2 crystal structure, represented by the formula Li1+aNibCocMdO2+α, where M is a metal element other than Li and Ni, Co, with specific compositional ratios that enhance nickel stability and reduce cobalt content, achieving a high nickel content while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content is increased to achieve larger capacity and lower cost, then charge-discharge capacity improves and material cost decreases, but crystal structure stability deteriorates leading to poor charge-discharge cycle properties
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional ratios in the formula Li1+aNibCocMdO2+α, where a, b, c, d, and α are optimized to maintain crystal structure stability while achieving high nickel content (b≥0.80). This allows the material to achieve large charge-discharge capacity without sacrificing structural stability during cycling.
Solution Approach 2:
The patent uses composite materials by combining multiple transition metals (Ni, Co, Mn, and other metals M) in a layered structure. This composite approach allows high nickel content for capacity while Co and Mn stabilize the crystal structure, preventing the degradation that would occur with pure high-nickel materials.
2Quantity of substance
If cobalt content is reduced to lower material cost, then material cost decreases, but charge-discharge cycle properties deteriorate due to insufficient structural stabilization
Solution Approach 1:
The patent applies parameter changes by optimizing the cobalt content parameter (c≤0.10) to the minimum level required for structural stabilization. This precise parameter control allows significant cobalt reduction for cost savings while maintaining sufficient Co to stabilize the crystal structure and ensure good charge-discharge cycle properties.
Solution Approach 2:
The patent replaces expensive cobalt with cheaper alternative metals (Mn, Ni, and other metals M) that can provide similar structural stabilization functions. This substitution reduces material cost while maintaining reliability through the synergistic effects of the composite metal system.
3Quantity of substance
If nickel content is increased to replace expensive cobalt, then material cost decreases, but manufacturing complexity increases due to difficulty in maintaining compositional precision
Solution Approach 1:
The patent applies parameter changes by establishing clear, quantifiable ranges for compositional parameters (a, b, c, d, α) that define the optimal composition window. These parameter specifications provide manufacturing guidance that simplifies compositional control, allowing high nickel content to be achieved while maintaining precision through well-defined target ranges rather than vague specifications.
Data Source
AI summary
The present invention is to provide a cathode active material used for a lithium ion secondary battery which has a large charge-discharge capacity, and excels in charge-discharge cycle properties, output properties and productivity, and, a lithium ion secondary battery using the same. The cathode active material used for a lithium ion secondary battery comprises a lithium-transition metal composite oxide having an α-NaFeO2 type crystal structure and represented by the following formula (1); Li1+aNibCocMdO2+α, where, in the formula (1), M is at least one metal element other than Li, Ni and Co; and a, b, c, d and a are respectively numbers satisfying −0.04≤a≤0.04, 0.80≤b≤1.0, 0≤c≤0.06, b+c+d=1, and −0.2<α<0.2, and an a-axis lattice constant of the crystal structure is 2.878×10−10 m or more.