Spinel Cathode Particle Sizing for Battery Output and Durability
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Solution Overview
Problem
Conventional positive-electrode active materials for non-aqueous electrolyte secondary batteries fail to achieve both high durability and high output characteristics due to cracking under pressure treatment and expansion/contraction during charge and discharge cycles.
Innovation Solution
A method involving the production of lithium transition metal composite oxide particles with a spinel structure based on nickel and manganese, achieved by obtaining a precipitate containing nickel and manganese, heat-treating it, and then mixing with a lithium compound to form particles with specific particle size distributions and structures that enhance durability and output characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If secondary particles are formed by aggregation of a large number of small primary particles to achieve high BET ratio and high output characteristics, then output characteristics are improved, but the secondary particles crack under pressure treatment and during charge/discharge expansion and contraction, reducing durability
Solution Approach 1:
The patent changes the particle size parameters by controlling the average primary particle diameter to be 5 μm or more and the average secondary particle diameter to be 3 μm or more, with a specific ratio relationship between them. This parameter optimization resolves the contradiction by finding the optimal size range that provides both high surface area (for output) and sufficient mechanical strength (for durability).
Solution Approach 2:
The patent creates a composite particle structure where primary particles aggregate to form secondary particles with a specific morphological structure. This composite structure allows the material to simultaneously achieve high BET ratio (from the aggregated structure) and high durability (from the optimized particle size and strength of the secondary particles).
2Power
If the average primary particle diameter is reduced to increase the number of primary particles for high output characteristics, then output characteristics are improved, but the secondary particles become more prone to cracking under pressure and during charge/discharge, reducing durability
Solution Approach 1:
The patent optimizes the primary particle diameter parameter to be 5 μm or more, preventing excessive reduction that would weaken particle strength. This parameter control ensures that primary particles are small enough to provide high surface area but large enough to maintain mechanical integrity and resist cracking during processing and operation.
3Power
If the average secondary particle diameter is reduced to increase BET ratio for high output characteristics, then output characteristics are improved, but the particles become more susceptible to breakage during pressure treatment and charge/discharge, reducing durability
Solution Approach 1:
The patent sets the average secondary particle diameter to be 3 μm or more, optimizing this parameter to balance surface area requirements with mechanical strength. This parameter control ensures secondary particles are sufficiently small to provide high BET ratio for good output characteristics but large enough to withstand pressure treatment and charge/discharge cycles without breaking.
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 method produces lithium transition metal composite oxide particles with improved durability and output characteristics by reducing the number of primary particles and increasing the uniformity of particle size, leading to reduced breakage during charge and discharge cycles and enhanced lithium ion diffusion paths.
Implementation Method 1
heat-treating the resulting precipitate at a temperature of from 850° C. to less than 1100° C. to obtain a first heat-treated product
Implementation Method 2
heat-treating the resulting lithium-containing mixture at a temperature of from 550° C. to 1000° C. to obtain a second heat-treated product
Data Source
AI summary
A method of producing a positive-electrode active material for a non-aqueous electrolyte secondary battery is provided. The method includes obtaining a precipitate containing nickel and manganese from a solution containing nickel and manganese, heat-treating the resulting precipitate at a temperature of from 850° C. to less than 1100° C. to obtain a first heat-treated product, mixing the first heat-treated product and a lithium compound, and heat-treating the resulting lithium-containing mixture at a temperature of from 550° C. to 1000° C. to obtain a second heat-treated product. The second heat-treated product contains a group of lithium transition metal composite oxide particles having an average particle diameter DSEM of from 0.5 μm to less than 3 μm and D50/DSEM of 1 to 2.5. The lithium transition metal composite oxide particles have a spinel structure based on nickel and manganese.