Lithium Transition Metal Composite Oxide with Controlled Oxygen Positional Parameter
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Solution Overview
Problem
Nonaqueous electrolyte energy storage devices, such as lithium secondary batteries, face challenges in enhancing charge-discharge cycle capacity retention ratio and high rate discharge characteristics.
Innovation Solution
A positive active material for nonaqueous electrolyte energy storage devices is developed, comprising a lithium transition metal composite oxide with an α-NaFeO2 structure, containing aluminum, nickel, cobalt, and manganese, with specific oxygen positional parameters and composition ratios optimized to improve cycle capacity retention and discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium transition metal composite oxide with high lithium content (Li/Me > 1) is used to increase discharge capacity, then the discharge capacity is improved, but the charge-discharge cycle capacity retention ratio and high rate discharge characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen positional parameter (0.267 ≤ zo1 < 0.270) and lithium to transition metal ratio (1.05 ≤ Li/Me ≤ 1.30) to optimize the balance between discharge capacity and cycle stability. This parameter optimization resolves the contradiction by finding the optimal range that provides both high capacity and good retention.
Solution Approach 2:
The patent uses composite materials by combining lithium transition metal composite oxide with specific aluminum content (0.05 ≤ Al/Me ≤ 0.50) and controlled oxygen positional parameters. The composite structure with aluminum doping and optimized oxygen positions enhances both discharge capacity and cycle stability simultaneously.
2Reliability
If the oxygen positional parameter is increased to improve cycle capacity retention, then the charge-discharge cycle capacity retention ratio is improved, but the high rate discharge characteristics deteriorate
Solution Approach 1:
The patent resolves this contradiction through parameter changes by optimizing the oxygen positional parameter to a specific range (0.267 ≤ zo1 < 0.270) that simultaneously improves cycle retention and maintains high rate discharge characteristics. This precise parameter control avoids the trade-off between stability and performance.
Solution Approach 2:
The patent applies local quality by creating a surface-modified layer with specific aluminum content and oxygen positional parameters on the lithium transition metal composite oxide particles. This local optimization at the particle surface enhances both cycle stability and rate capability without compromising bulk properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optimized positive active material enhances charge-discharge cycle capacity retention ratio and high rate discharge characteristics by controlling the oxygen positional parameter and composition ratios, leading to improved performance and efficiency in nonaqueous electrolyte energy storage devices.
Implementation Method 1
a positive active material for a nonaqueous electrolyte energy storage device containing a lithium transition metal composite oxide having an α-NaFeO2 structure
Data Source
AI summary
A positive active material for a nonaqueous electrolyte energy storage device according to one aspect of the present invention is a positive active material for a nonaqueous electrolyte energy storage device containing a lithium transition metal composite oxide having an α-NaFeO2 structure, the positive active material further containing aluminum, in which the lithium transition metal composite oxide contains at least one of nickel and cobalt, and manganese, a content of manganese in a transition metal. in the lithium transition metal composite oxide is 0.6 or less in terms of molar ratio, and in a charged state at a potential of 4.35 V vs. Li/Li+ in a state where there is no charge history in which the potential reaches 4.5 V vs. Li/Li+ or more, an oxygen positional parameter of the positive active material determined from crystal structure analysis by a Rietveld method when a space group R3-m is used. for a crystal structure model based on an X-ray diffraction pattern is 0.265 or more and 0.269 or less.