LCO Cathode Composition for High-Voltage Cycle and Thermal Stability
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Solution Overview
Problem
Conventional lithium cobalt composite oxides used in non-aqueous electrolyte secondary batteries face issues with crystal structure collapse and degraded thermal stability when the end-of-charge voltage is increased to enhance capacity, leading to shorter charge-discharge cycle life.
Innovation Solution
A positive electrode active material comprising a lithium cobalt composite oxide with specific compositions LiCo(1-w-x-y-z)AlwMgxTiyMnzO2, where 0.010≤w≤0.013, 0.003≤x≤0.006, 0.0004≤y≤0.0006, and 0≤z≤0.0015, is used to stabilize the crystal structure and improve cycle and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the end-of-charge voltage is increased to enhance capacity, then the battery capacity increases, but the crystal structure of LCO becomes collapsed leading to shorter charge-discharge cycle life and degraded thermal stability
Solution Approach 1:
The patent modifies the chemical composition parameters of LCO by incorporating multiple metal elements (Al, Mg, Ti, Mn, Zr) in specific proportions. This changes the material's fundamental properties to achieve both high capacity and structural stability, resolving the contradiction between capacity enhancement and cycle life maintenance
Solution Approach 2:
The patent creates a composite oxide material by combining LCO with multiple metal elements forming a complex composite structure. This composite approach allows the material to simultaneously achieve high capacity and maintain crystal structure stability during charging-discharging cycles, preventing structure collapse
2Quantity of substance
If the end-of-charge voltage is increased to enhance capacity, then the battery capacity increases, but thermal stability is degraded
Solution Approach 1:
The patent adjusts the compositional parameters of LCO by adding specific amounts of metal elements (Al: 0.01-0.05, Mg: 0.003-0.01, Ti: 0.0004-0.0006, Mn: 0-0.002, Zr: 0-0.003). These parameter changes enhance the material's thermal stability while maintaining high capacity, preventing thermal degradation at elevated charging voltages
Solution Approach 2:
The patent develops a composite oxide with multiple metal elements that work synergistically to improve thermal stability. The composite structure provides enhanced thermal resistance while maintaining electrochemical performance, allowing high capacity operation with improved thermal safety
Data Source
AI summary
A positive electrode active material for a non-aqueous electrolyte secondary battery according to one example of the present embodiment contains, as a main component, a lithium-cobalt composite oxide having a layered crystalline structure. The lithium-cobalt composite oxide is represented by general formula LiCo(1-w-x-y-z)AlwMgxTiyMnzO2 (in the formula, 0.010≤w≤0.013, 0.003≤x≤0.006, 0.0004≤y≤0.0006, and 0≤z≤0.0015), and preferably contains Mn.