Lithium Complex Oxide Surface Coating for Residual Lithium Reduction
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Solution Overview
Problem
Lithium secondary batteries face issues with residual lithium on the surface of positive active materials, leading to high temperature stability problems and degradation of capacity and efficiency, due to unreacted LiOH and Li2CO3, which react with the electrolyte and cause swelling and gelation, necessitating a washing process that damages the material and increases resistance.
Innovation Solution
A lithium complex oxide with different interplanar distances in primary particles on the surface and internal parts of secondary particles is formed by coating different metals on the surface, with specific interplanar distance ranges and thermal treatment processes to reduce residual lithium and enhance battery characteristics, involving a method of manufacturing precursors, thermal treatments, and surface coating to achieve a uniform Co ion concentration gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a washing process is performed to remove residual lithium, then residual lithium is reduced, but the surface of the positive active material is damaged and characteristics of capacity and efficiency are degraded
Solution Approach 1:
The patent applies preliminary action by performing a heat treatment process before the washing step to modify the surface structure of the positive active material. This pre-treatment creates a more robust surface that can withstand the subsequent washing process without damage, thereby removing residual lithium while preserving capacity and efficiency characteristics.
Solution Approach 2:
The patent changes physical parameters by controlling the heat treatment temperature and duration to optimize the surface structure. By adjusting these parameters, the material achieves a state where residual lithium can be effectively removed through washing without causing surface damage or performance degradation.
2Quantity of substance
If a washing process is performed to remove residual lithium, then residual lithium is reduced, but resistance in high temperature storage is increased
Solution Approach 1:
The patent applies preliminary action by performing a heat treatment process before the washing step to modify the surface structure of the positive active material. This pre-treatment creates a more robust surface that can withstand the subsequent washing process without damage, thereby removing residual lithium while preserving capacity and efficiency characteristics.
Solution Approach 2:
The patent changes physical parameters by controlling the heat treatment temperature and duration to optimize the surface structure. By adjusting these parameters, the material achieves a state where residual lithium can be effectively removed through washing without causing surface damage or performance degradation.
3Reliability
If different elements are coated on the surface part to improve interplanar distance characteristics, then capacity and battery lifetime are improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies local quality by coating different elements specifically on the surface part of the positive active material rather than uniformly throughout. This localized approach targets the surface region where interplanar distance characteristics most affect performance, improving capacity and battery lifetime while minimizing the overall complexity of the manufacturing process.
Solution Approach 2:
The patent changes compositional parameters by selecting specific elements to coat on the surface and controlling their concentrations. By optimizing these compositional parameters, the invention achieves improved performance characteristics without requiring overly complex manufacturing procedures.
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 approach results in improved capacity, resistance, and battery lifetime by reducing residual lithium, enhancing the structural integrity and performance of lithium secondary batteries, while maintaining high temperature stability and efficiency.
Implementation Method 1
thermal treatments
Implementation Method 2
uniform Co ion concentration gradient
Implementation Method 3
coating different elements on the surface part
Implementation Method 4
washing for removing the residual lithium
Implementation Method 5
different interplanar distances of crystalline structure
Data Source
AI summary
Disclosed is a lithium complex oxide and method of manufacturing the same, more particularly, a lithium complex oxide effective in improving the characteristics of capacity, resistance, and lifetime with reduced residual lithium and with different interplanar distances of crystalline structure between a primary particle locating in a internal part of secondary particle and a primary particle locating on the surface part of the secondary particle, and a method of preparing the same.