Lithium Transition Metal Composite Oxide Coating for Battery Stability
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Solution Overview
Problem
Nickel-cobalt-lithium manganate-based lithium transition metal composite oxides face challenges in achieving balanced cycle and output characteristics, with issues of crystal structure stability and viscosity in non-aqueous electrolyte secondary batteries, particularly due to the scarcity and high cost of cobalt and the instability of nickel-rich compositions.
Innovation Solution
A positive electrode composition comprising a lithium transition metal composite oxide represented by LiaNi1-x-yCoxMnyMzO2, where 1.00≦a≦1.50, 0<x≦0.50, 0<y≦0.50, 0.00≦z≦0.02, and M is at least one element from Zr, Ti, Mg, Ta, Nb, or Mo, combined with a boron compound containing boron and oxygen, which improves output and cycle characteristics and maintains viscosity stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If nickel content is increased to reduce cost and improve capacity, then output characteristics improve, but crystal structure stability deteriorates causing lithium compound deposition
Solution Approach 1:
A boron compound is introduced as an intermediary substance that forms a coating layer on the surface of the lithium transition metal composite oxide particles. This coating layer acts as a mediator between the nickel-rich active material and the electrolyte, preventing direct harmful interactions while maintaining the high nickel content for improved output characteristics
Solution Approach 2:
The invention changes the chemical composition parameters by incorporating a boron compound with specific boron content (0.1-5.0 wt%) in the positive electrode. This parameter change stabilizes the crystal structure of nickel-rich lithium transition metal composite oxide, preventing lithium compound deposition while maintaining high capacity
2Quantity of substance
If cobalt content is decreased to reduce cost, then resource scarcity and cost issues improve, but output characteristics deteriorate
Solution Approach 1:
The invention optimizes the compositional parameters of the lithium transition metal composite oxide, specifically controlling the ratios of nickel, cobalt, and manganese within defined ranges. This parameter optimization allows reduced cobalt content while maintaining balanced output and cycle characteristics through the synergistic effect of multiple transition metals
Solution Approach 2:
The invention uses a composite material approach by creating a multi-element lithium transition metal composite oxide (containing Ni, Co, Mn, and optionally other elements like Al, Ti, V, Cr, Fe, Zn, Ga, Ge, In, Sr, Ba, Pb, Mo, W, Hf, Ta, Nb, Zr). This composite material leverages the advantages of each element to achieve cost reduction while maintaining performance
3Power
If boron compound is added to improve output and cycle characteristics, then battery performance improves, but slurry viscosity increases
Solution Approach 1:
The invention precisely controls the boron content parameter within the range of 0.1-5.0 wt% in the positive electrode. This parameter control ensures sufficient boron is present to form a protective coating and improve battery characteristics, while preventing excessive boron that would cause slurry gelation and viscosity increase
Data Source
AI summary
A positive electrode composition for a non-aqueous electrolyte secondary battery includes a lithium transition metal composite oxide represented by a formula LiaNi1-x-yCoxMnyMzO2, wherein 1.00≦a≦1.50, 0<x≦0.50, 0<y≦0.50, 0.00≦z≦0.02, 0.40≦x+y≦0.70, M is at least one element selected from the group consisting of Zr, Ti, Mg, Ta, Nb and Mo, and a boron compound that at least contains boron and oxygen.