Coated LiCoO2 Cathode for Cycling Stability
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Solution Overview
Problem
Lithium ion batteries experience capacity loss and poor cycling life due to irreversible changes in cathode active materials during charging and discharging cycles, primarily caused by reactions with organic solvents, which current surface treatments do not adequately address.
Innovation Solution
A cathode composite material is developed with a coating layer of lithium metal oxide, specifically Co doped Li2TiO3, applied to lithium transition metal oxides like LiCoO2, enhancing stability and preventing unwanted reactions by forming a core-shell structure that allows lithium ion mobility while suppressing electron migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer of lithium metal oxide is applied to the cathode active material, then cycling stability and capacity retention are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where a coating layer of lithium metal oxide (specifically Co doped Li2TiO3) is applied to the cathode active material particle (LiCoO2). This composite structure combines the high capacity properties of LiCoO2 with the stability and protective properties of the Li2TiO3 coating layer, resolving the contradiction between maintaining reliability through coating while managing the complexity through a well-defined composite architecture.
Solution Approach 2:
The patent applies local quality by doping cobalt specifically in the Li2TiO3 coating layer while keeping the core LiCoO2 material unchanged. This localized modification of the coating layer's composition (adding Co dopant) provides enhanced stability and electronic properties at the critical interface region without altering the bulk properties of the cathode material, thus improving cycling stability while maintaining a relatively simple overall structure.
2Object-affected harmful factors
If a coating layer is applied to improve stability, then unwanted reactions with organic solvent are suppressed, but manufacturing precision and process difficulty increase
Solution Approach 1:
The patent applies parameter changes by carefully controlling the doping concentration of cobalt in the Li2TiO3 coating layer and optimizing the coating thickness. By adjusting these parameters (Co doping level, coating layer thickness), the material achieves optimal protection against side reactions with organic solvents during cycling, while maintaining manufacturability through well-defined parameter ranges that ensure uniform coating formation.
3Productivity
If the coating layer allows lithium ion mobility, then capacity retention is improved, but electron migration control becomes more difficult
Solution Approach 1:
The patent applies the intermediary principle by using the Li2TiO3 coating layer as a mediator between the LiCoO2 cathode material and the electrolyte. This intermediate layer selectively facilitates lithium ion transport (improving capacity retention) while simultaneously blocking electron migration and preventing direct contact between the cathode material and organic solvent (enhancing electronic stability and reducing side reactions). The coating layer acts as a selective barrier that mediates the interactions at the electrode-electrolyte interface.
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 cathode composite material significantly improves cycling stability and capacity retention, maintaining high discharge specific capacity even at high current rates, outperforming batteries without the coating layer by reducing side reactions and enhancing chemical and thermal stability.
Implementation Method 1
forming a core-shell structure that allows lithium ion mobility while suppressing electron migration
Implementation Method 2
stability improving problem during the cycling of the lithium ion battery has not been properly solved... reducing side reactions and enhancing chemical and thermal stability
Data Source
AI summary
A cathode composite material includes a cathode active material and a coating layer coated on a surface of the cathode active material. The cathode active material includes a lithium cobalt oxide. The coating layer includes a lithium metal oxide having a crystal structure belonging to C2/c space group of the monoclinic crystal system. The present disclosure also relates to a lithium ion battery including the cathode composite material.