Alkali-Modified Lithium Cobalt Oxide for Battery Stability
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Solution Overview
Problem
Lithium cobalt oxide-based positive active materials in lithium secondary batteries suffer from high costs and instability due to cobalt usage, leading to reduced cycle characteristics and capacity retention.
Innovation Solution
A positive active material represented by the formula Li1-aAaNixCoyMn1-x-yO2, where A is an alkali metal (such as sodium, potassium, or cesium) partially substitutes for lithium, enhancing structural stability and cyclic performance by distorting the crystalline structure, thereby improving initial efficiency, rate capability, and lifetime characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium cobalt oxide is used as positive active material, then high energy density per volume is achieved, but high cost and poor stability are incurred
Solution Approach 1:
The patent changes the compositional parameters of the positive active material by introducing alkali metal elements (Na, K, or Cs) at specific concentrations (0.001≤a≤0.05) into the lithium cobalt oxide structure (Li1-aAaNi0.8Co0.1Mn0.1O2). This parameter modification allows the material to maintain high energy density while improving structural stability and reducing cost by partially replacing lithium with alkali metals.
Solution Approach 2:
The patent creates a composite material system by combining lithium cobalt oxide with alkali metal elements (Na, K, or Cs) to form a new compound Li1-aAaNi0.8Co0.1Mn0.1O2. This composite approach leverages the high energy density of lithium cobalt oxide while incorporating alkali metals to enhance stability and reduce cobalt dependency, thereby resolving the contradiction between energy density and stability.
2Use of energy by moving object
If lithium cobalt oxide is used as positive active material, then high energy density per volume is achieved, but high cost is incurred
Solution Approach 1:
The patent modifies the compositional parameters by introducing alkali metals at controlled concentrations (0.001≤a≤0.05) into the lithium cobalt oxide structure. This parameter change reduces cobalt content requirements while maintaining energy density, thereby lowering material costs without sacrificing performance.
Solution Approach 2:
The patent develops a composite material Li1-aAaNi0.8Co0.1Mn0.1O2 that combines lithium cobalt oxide with alkali metals. This composite reduces dependence on expensive cobalt while preserving high energy density, making the battery more cost-effective without compromising energy performance.
3Use of energy by moving object
If traditional lithium cobalt oxide is used, then high energy density is achieved, but poor cycle characteristics and capacity retention are incurred
Solution Approach 1:
The patent optimizes compositional parameters by incorporating alkali metals (Na, K, or Cs) at specific concentrations (0.001≤a≤0.05) into the lithium cobalt oxide structure. This parameter adjustment enhances structural stability during charge-discharge cycles, improving cycle life and capacity retention while maintaining high energy density.
Solution Approach 2:
The patent creates a composite material system Li1-aAaNi0.8Co0.1Mn0.1O2 that combines lithium cobalt oxide with alkali metals. This composite structure provides enhanced stability during cycling, resolving the contradiction between high energy density and long cycle life by leveraging the synergistic effects of the combined materials.
Data Source
AI summary
A positive active material represented by Formula 1 and a lithium secondary battery having a positive electrode that includes the positive active material are provided:Li1-aAaNixCoyMn1-x-yO2 Formula 1wherein, in Formula 1, A is an alkali metal; 0.0025≤a≤0.02; 0.0<x≤1.0; and 0.0≤y≤1.0.