Rock Salt Coated LiCoO2 Cathode for High-Voltage Stability
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Solution Overview
Problem
Lithium cobalt oxide (LiCoO2) based positive electrode materials in lithium rechargeable batteries face instability and metal elution at high charge voltages, leading to reduced battery performance and lifespan when charged beyond 4.2 V.
Innovation Solution
A surface-modified lithium cobalt oxide with a rock salt crystal structure is developed, incorporating a cobalt-based compound coating layer on a core particle doped with aluminum, stabilizing the crystal structure and reducing metal elution at higher voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If charge voltage is increased above 4.2V to achieve higher capacity, then battery capacity is improved, but crystal structure becomes unstable and cobalt elution occurs
Solution Approach 1:
The patent applies aluminum doping to modify the crystal structure parameters of LiCoO2, substituting aluminum ions for lithium ions in the layered structure. This parameter change stabilizes the crystal lattice at high voltages above 4.2V, preventing structural collapse and cobalt elution while maintaining high capacity
Solution Approach 2:
The patent creates a composite material system by doping aluminum into LiCoO2 to form a modified layered structure with enhanced stability. This composite approach combines the high capacity characteristics of LiCoO2 with the structural stability provided by aluminum doping, enabling operation at voltages above 4.2V without degradation
2Quantity of substance
If charge voltage is increased above 4.2V to achieve higher capacity, then battery capacity is improved, but cobalt elution occurs leading to side reactions
Solution Approach 1:
Aluminum doping modifies the electrochemical parameters of LiCoO2 by stabilizing the crystal structure and adjusting the electronic properties. This parameter change suppresses cobalt elution at high voltages, preventing harmful side reactions with the electrolyte while maintaining high capacity performance
3Power
If charge voltage is increased above 4.2V to achieve higher power, then battery power is improved, but battery lifespan deteriorates
Solution Approach 1:
Aluminum doping changes the structural and electrochemical parameters of LiCoO2 to enhance high-voltage stability. This parameter modification allows the material to withstand repeated charging cycles at high voltages (4.2-4.5V) without structural degradation, thereby extending battery lifespan while maintaining high power output
Data Source
AI summary
A surface of a LiCoO2-based positive electrode active material to have a rock salt crystal structure is provided. Specifically, a positive electrode active material for a lithium rechargeable battery is provided, including: a core particle containing lithium cobalt oxide doped with aluminum (Al); and a coating layer positioned on a surface of the core particle and containing a cobalt (Co)-based compound having a rock salt crystal structure. A method of producing the positive electrode active material is also provided using a solid-phase method. The positive electrode active material can be applied to a positive electrode, lithium rechargeable battery, battery module, battery pack, and the like.