Composite Cathode Active Material for Lithium Battery
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Solution Overview
Problem
Lithium batteries with high-capacity cathode active materials suffer from performance deterioration and require high voltages, leading to reduced lifespan and inefficient charge/discharge characteristics due to residual lithium and side reactions with electrolytes.
Innovation Solution
A composite cathode active material is developed, comprising a core of first lithium transition metal oxide with a R-3m space group and a coating layer of second lithium transition metal oxide having multiple layered crystalline phases, reducing residual lithium and suppressing side reactions through heat-treatment in an oxidation atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high-capacity cathode active material is used to achieve high energy density, then the battery capacity increases, but the battery lifespan deteriorates due to performance degradation
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where the core is LiNi0.8Co0.1Mn0.1O2 and the shell is Li2MnO3. This composite structure allows the high-capacity core material to function while the protective shell prevents degradation, thus maintaining both high capacity and extended lifespan. The shell acts as a barrier that stabilizes the core material during charge-discharge cycles.
Solution Approach 2:
The patent implements local quality by applying the Li2MnO3 coating specifically on the surface of the LiNi0.8Co0.1Mn0.1O2 particles. The core maintains its high-capacity properties while the shell provides protective characteristics. This localized modification allows different regions of the material to have different functions: the core for high capacity and the shell for stability and protection.
2Quantity of substance
If a high-capacity cathode active material is used to achieve high energy density, then the battery capacity increases, but the operating voltage increases leading to inefficient charge/discharge characteristics
Solution Approach 1:
The patent changes the electrochemical parameters of the cathode material by combining LiNi0.8Co0.1Mn0.1O2 with Li2MnO3 coating. This composite structure modifies the voltage profile and charge/discharge characteristics, allowing the battery to operate at lower average voltages while maintaining high capacity, thus improving energy efficiency during charge and discharge cycles.
3Quantity of substance
If a high-capacity cathode active material is used, then residual lithium remains causing side reactions with electrolytes, but the battery performance deteriorates
Solution Approach 1:
The Li2MnO3 coating serves as an intermediary layer between the LiNi0.8Co0.1Mn0.1O2 core and the electrolyte. This intermediate shell prevents direct contact and harmful side reactions between the residual lithium in the core material and the electrolyte, while still allowing lithium ion transport. This mediator protects the system from degradation reactions.
Solution Approach 2:
The patent applies preliminary anti-action by pre-coating the LiNi0.8Co0.1Mn0.1O2 particles with Li2MnO3 before battery assembly. This preventive coating stops side reactions with the electrolyte before they can occur, protecting the high-capacity core material from degradation and maintaining battery performance over time.
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 composite cathode active material enhances charge/discharge characteristics, maintains high capacity, and extends battery lifespan by minimizing residual lithium and side reactions, thereby improving the overall performance and efficiency of lithium batteries.
Implementation Method 1
heat-treating the mixture in an oxidation atmosphere to obtain a composite cathode active material
Implementation Method 2
heat-treating the mixture in an oxidation atmosphere
Data Source
AI summary
A composite cathode active material includes a first cathode active material including a core including a first lithium transition metal oxide represented by Formula 1 and having a first layered crystalline phase that belongs to a R-3m space group; and a coating layer disposed on the core and including a second lithium transition metal oxide having a plurality of layered crystalline phases, wherein each layered crystalline phase of the plurality of layered crystalline phases has a different composition:LiaMO2 Formula 1wherein, in Formula 1, 1.0≤a≤1.03; andM includes nickel and an element including a Group 4 element to a Group 13 element other than nickel.