LiNiMn Composite Cathode Material for High-Capacity Batteries
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Solution Overview
Problem
Existing positive electrode active materials for non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, face challenges in achieving both high capacity and low cost, particularly due to the influence of Ni content and lattice strain in the crystal structure.
Innovation Solution
A positive electrode active material with a crystal structure belonging to the space group R-3m, represented by Li1+a Ni b Mn c X d O e, where a ≤ 1.15, 0.35 ≤ b ≤ 0.70, 0.30 ≤ c ≤ 0.65, and 0 ≤ d ≤ 0.07, and a product (α × β) of mixing ratio α of Ni and strain β is less than or equal to 0.090, is used to enhance discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the Ni content is increased to improve battery capacity, then the charge-discharge capacity is improved, but the material cost increases and the lattice strain increases
Solution Approach 1:
The patent changes the compositional parameters by precisely controlling the Ni content (b) within 0.35-0.70 and introducing a new parameter (a) representing Li excess, where a ≤ 1.15. This parameter optimization allows achieving high capacity without excessive Ni content, thus controlling material costs while improving battery performance.
Solution Approach 2:
The patent creates a composite material system with multiple elements (Li, Ni, Mn, and optional X elements) in specific ratios. The composite oxide structure Li1+aNibMncXdOe combines the benefits of different elements: Li for capacity, Ni for electrical conductivity, Mn for stability, and X elements for additional performance enhancement, achieving high capacity without relying solely on expensive Ni.
2Quantity of substance
If the Ni content is increased to improve battery capacity, then the charge-discharge capacity is improved, but the lattice strain increases which may affect durability
Solution Approach 1:
The patent introduces parameter (a) representing Li excess, where a ≤ 1.15, which helps balance the lattice structure and reduce strain caused by high Ni content. The precise control of compositional parameters (b and c for Ni and Mn ratios) optimizes the crystal structure to minimize lattice distortion while maintaining high capacity.
Solution Approach 2:
The patent applies local quality by introducing X elements (transition metal or main-group elements other than Li, Ni, Mn) at specific positions in the crystal structure with controlled content (d ≤ 0.07). These localized additions modify specific regions of the lattice to reduce overall strain while preserving the beneficial effects of high Ni content for capacity.
3Productivity
If the mixing ratio of Ni and strain are not controlled, then the manufacturing process is simpler, but the battery performance does not achieve desired capacity increase
Solution Approach 1:
The patent establishes specific parameter ranges (a ≤ 1.15, 0.35 ≤ b ≤ 0.70, 0.30 ≤ c ≤ 0.65, 0 ≤ d ≤ 0.07) that define the optimal composition window. By controlling parameters within these ranges rather than exact values, the patent achieves high capacity while maintaining reasonable manufacturing flexibility and precision requirements.
Data Source
Figure 1
AI summary
This positive electrode active material is a composite oxide having a crystal structure belonging to a space group R-3m and represented by a composition formula of Li1+aNibMncXdOe, in which: X is at least one type selected from the group consisting of typical elements and transition metal elements other than Li, Ni, and Mn; a≤1.15, 0.35≤b≤0.70, 0.30≤c≤0.65, and 0≤d≤0.07 are satisfied; and e is a value satisfying electrical neutrality. The positive electrode active material has a value (α×β) of 0.090 or lower, which is the product of a Ni mixing rate α determined through Rietveld analysis and a strain β determined using the Williamson-Hall method.