Spinel Lithium Manganese Oxide Crystallite Control
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Solution Overview
Problem
Lithium secondary batteries experience a decrease in output characteristics and discharge capacity when repeatedly charged and discharged at high temperatures due to particle aggregation and weak sintering, leading to a rupture in the conductive network between positive electrode active substance particles.
Innovation Solution
A spinel-type lithium manganese-based composite oxide with a crystallite size of 250 nm to 350 nm, strain of 0.085 or less, and specific surface area increase rate of 10.0% or less when ultrasonically dispersed, which prevents particle disintegration and maintains discharge capacity under high-temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the battery operates at high temperature, then the initial output characteristics are improved, but the discharge capacity decreases after repeated charging and discharging
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite size (250-350 nm) and strain (≤0.085) of the spinel-type lithium manganese-based composite oxide. These parameter optimizations enable the material to maintain both high output characteristics and stable discharge capacity under high-temperature conditions, resolving the contradiction between initial power performance and long-term reliability.
2Reliability
If the crystallite size is increased to reduce specific surface area, then particle disintegration is suppressed, but the conductive network may be affected
Solution Approach 1:
The patent optimizes the crystallite size parameter to a specific range (250-350 nm) that balances two competing requirements: large enough to reduce specific surface area and suppress particle disintegration, but small enough to maintain the conductive network. This precise parameter control resolves the contradiction between particle stability and conductivity.
3Reliability
If the specific surface area is reduced to prevent particle disintegration, then high-temperature stability is improved, but the reaction activity may decrease
Solution Approach 1:
The patent controls the specific surface area indirectly through crystallite size optimization (250-350 nm). This parameter setting reduces the specific surface area to improve high-temperature stability while maintaining sufficient reaction activity by avoiding excessive size reduction that would cause particle disintegration.
Solution Approach 2:
The patent uses a composite oxide structure (Li1+XM2-XO4-δ where M includes Mn, Mg, and Al) that combines multiple elements to achieve both high-temperature stability and adequate reaction activity. The composite structure allows synergistic effects that balance stability and reactivity.
Data Source
AI summary
Regarding spinel-type lithium manganese-based composite oxide (LMO) to be used as a positive electrode active substance material for lithium battery, a novel LMO is provided, which is capable of maintaining discharge capacity even if charging and discharging are repeated under high temperatures. An LMO in which the crystallite size is 250 nm to 350 nm, the strain is 0.085 or less and the specific surface area increase rate when placed in water at 25° and pH 7 and ultrasonically dispersed at 40 W ultrasonic intensity for 600 seconds is 10.0% or less, can prevent a decrease in the output that accompanies the repetition of charging and discharging while at a high temperature.