Lithium Complex Oxide Surface Grading for Residual Lithium Removal
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Solution Overview
Problem
Lithium complex oxides for secondary batteries face issues with residual lithium causing degradation, high temperature stability, and increased resistance due to unreacted LiOH and Li2CO3 on the surface, which negatively impact capacity, efficiency, and battery lifetime.
Innovation Solution
A lithium complex oxide with a graded Co concentration on the surface and constant Co concentration internally, achieved through a method involving the manufacturing of precursors, thermal treatment, washing, and reactive coating with metals like Co, Ti, and Al to reduce residual lithium and enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LiOH and Li2CO3 are used as lithium compounds in the preparation process, then the manufacturing process is simplified and productivity is improved, but residual lithium remains on the surface causing degradation, high temperature instability, and increased resistance
Solution Approach 1:
The patent applies the extraction principle by removing residual lithium compounds (LiOH and Li2CO3) from the surface of the positive active material through a washing process. This extraction of harmful residual substances resolves the contradiction by eliminating the cause of degradation and instability while maintaining the benefits of using LiOH and Li2CO3 as lithium sources during manufacturing.
Solution Approach 2:
The patent applies preliminary action by performing the washing process to remove residual lithium compounds before the battery assembly and operation stages. This preliminary removal prevents subsequent degradation, high temperature instability, and resistance increase, thereby ensuring battery reliability without compromising manufacturing productivity.
2Ease of manufacture
If LiOH and Li2CO3 are used as lithium compounds, then ease of manufacture is improved, but residual lithium causes gas generation, swelling, and high temperature stability deterioration
Solution Approach 1:
The patent converts the harmful effect of residual lithium compounds into a beneficial process by implementing a controlled washing step. The residual LiOH and Li2CO3, which would otherwise cause gas generation and swelling, are systematically removed through washing, transforming the manufacturing simplicity advantage into a reliable final product without high temperature stability issues.
Solution Approach 2:
The washing process acts as an intermediary step between manufacturing and battery operation. This intermediate treatment removes residual lithium compounds that would otherwise mediate harmful effects during battery operation, such as gas generation and high temperature degradation, while preserving the ease of manufacture from using LiOH and Li2CO3.
3Ease of manufacture
If LiOH is present on the surface, then manufacturing is easier, but gelation occurs during slurry mixing due to high viscosity
Solution Approach 1:
The patent applies extraction by removing residual LiOH from the surface of the positive active material through washing before slurry preparation. This removal eliminates the source of high viscosity that would otherwise cause gelation during slurry mixing, ensuring ease of operation in electrode manufacturing while maintaining the manufacturing convenience of using LiOH as a lithium source.
4Reliability
If washing process is executed to remove residual lithium, then reliability is improved, but surface damage occurs and capacity characteristics degrade
Solution Approach 1:
The patent applies parameter changes by optimizing the washing process parameters (such as washing solution composition, temperature, and duration) to achieve effective removal of residual lithium compounds while minimizing surface damage. This controlled parameter adjustment resolves the contradiction by maintaining surface integrity necessary for capacity characteristics while ensuring reliability through residual lithium removal.
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 solution improves battery capacity, resistance, and lifetime by reducing residual lithium and maintaining structural stability, resulting in enhanced performance and reduced impedance, especially at high temperatures.
Implementation Method 1
A lithium complex oxide secondary particle formed by coagulation of a plurality of primary particles
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.