Composite Cathode Core-Shell Structure for Lithium Battery
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Solution Overview
Problem
Lithium batteries with nickel-based cathode active materials face performance deterioration due to side reactions caused by residual surface lithium and poor thermal stability, limiting their capacity and cycle life.
Innovation Solution
A composite cathode active material is developed, comprising a core with a layered lithium transition metal oxide and a shell with a spinel crystal structure and dopant, formed by mixing a metal-organic framework with the lithium transition metal oxide and thermally treating it under an oxidizing atmosphere, which inhibits side reactions and enhances lithium ion transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a high nickel content cathode active material is used to achieve high capacity, then the battery capacity increases, but side reactions occur due to residual surface lithium and cation mixing, leading to poor lifetime characteristics and poor thermal stability
Solution Approach 1:
The patent applies composite materials by creating a core-shell structure where the core is a high-nickel lithium transition metal oxide (providing high capacity) and the shell is a spinel-structured lithium transition metal oxide (providing stability). This composite structure allows the high-nickel core to deliver high capacity while the stable spinel shell prevents side reactions, suppresses cation mixing, and improves both lifetime characteristics and thermal stability, thus resolving the contradiction between high capacity and reliability.
2Quantity of substance
If a high nickel content cathode active material is used to achieve high capacity, then the battery capacity increases, but thermal stability deteriorates due to side reactions
Solution Approach 1:
The patent uses a composite core-shell structure where the high-nickel layered core provides high capacity while the spinel-structured shell provides thermal stability. The spinel shell acts as a protective barrier that suppresses side reactions between the high-nickel material and the electrolyte, thereby maintaining thermal stability even when high nickel content is used to achieve high capacity.
3Quantity of substance
If a high nickel content cathode active material is used to achieve high capacity, then the battery capacity increases, but lifetime characteristics deteriorate due to side reactions
Solution Approach 1:
The patent employs a composite core-shell structure where the high-nickel layered core delivers high capacity and the spinel-structured shell protects against side reactions. The spinel shell suppresses cation mixing and prevents degradation reactions with the electrolyte, thereby improving lifetime characteristics while maintaining the high capacity provided by the high-nickel core.
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 improves charge-discharge characteristics, reduces residual surface lithium, and enhances thermal stability and cycle life of lithium batteries by suppressing side reactions and providing a 3D lithium ion transfer path.
Implementation Method 1
thermally treating the mixture under an oxidizing atmosphere at about 650° C. to about 800° C. for about 3 hours to about 20 hours
Implementation Method 2
thermally treating the mixture under an oxidizing atmosphere
Implementation Method 3
providing a 3D lithium ion transfer path
Data Source
AI summary
A composite cathode active material, and a cathode and a lithium battery each including the composite cathode active material. The composite cathode active material includes: a core including a first lithium transition metal oxide represented by Formula 1,LiaMO2 wherein, in Formula 1, M includes Ni and at least one non-nickel Group 4 to Group 13 element, a content of Ni is about 70 mol % or greater, based on a total content of M, 0.9≤a≤1.1, and wherein the first lithium transition metal oxide has a layered crystal structure belonging to an R<o ostyle="single">3</o>m space group; and a shell on a surface of the core, the shell having a spinel crystal structure and including a dopant.