Composite Cathode Material With Grain-Boundary Doping for Cycle Stability
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Solution Overview
Problem
Lithium batteries with nickel-based cathode active materials face performance deterioration due to side reactions, thermal instability, and poor lifetime characteristics, primarily caused by residual surface lithium and cation mixing.
Innovation Solution
A composite cathode active material is developed, featuring a core of nickel-containing lithium transition metal oxide doped with a first metal, where the grain boundaries between primary particles include a specific composition that suppresses side reactions and enhances lithium ion conduction, thereby improving cycle characteristics and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If nickel-based cathode active material is used to achieve high capacity, then battery capacity is improved, but side reactions occur causing poor lifetime characteristics and thermal stability
Solution Approach 1:
A coating layer comprising a spinel structure and a layered structure is introduced as an intermediary between the nickel-based cathode active material and the electrolyte. This coating layer suppresses side reactions and prevents performance deterioration while maintaining high capacity, thereby resolving the contradiction between battery capacity and lifetime characteristics
Solution Approach 2:
The cathode active material is designed as a composite structure with a core-shell configuration, where the core contains nickel-based lithium transition metal oxide and the shell contains a coating layer with dual spinel and layered structures. This composite structure enables both high capacity and improved lifetime characteristics by combining the advantages of different material phases
2Quantity of substance
If nickel-based cathode active material is used to achieve high capacity, then battery capacity is improved, but thermal stability deteriorates due to residual surface lithium and cation mixing
Solution Approach 1:
The coating layer acts as a protective intermediary that suppresses residual lithium on the surface of the nickel-based cathode active material, thereby improving thermal stability while preserving high capacity performance
Solution Approach 2:
The coating layer is selectively formed on the surface of the cathode active material particles, providing localized protection against thermal degradation and side reactions only where needed, without altering the bulk properties of the high-capacity nickel-based material
3Reliability
If coating layer is formed on cathode active material to suppress side reactions, then lifetime characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The coating layer is formed by combining multiple metal precursors in a single aqueous solution, allowing simultaneous deposition of spinel and layered structure components in one coating step, thereby reducing manufacturing complexity while achieving the desired protective function
Solution Approach 2:
The coating process utilizes controlled precipitation reactions by adjusting solution parameters such as pH and temperature during thermal treatment, enabling precise control of coating layer formation without requiring complex multi-step manufacturing processes
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 effectively prevents performance deterioration, reduces residual surface lithium, and enhances the thermal stability and cycle life of lithium batteries by facilitating lithium ion conduction and suppressing nickel ion release and gas generation.
Implementation Method 1
the grain boundaries between the plurality of primary particles include a first composition including the first metal
Implementation Method 2
thermally treating the mixture to thereby prepare the composite cathode active material
Data Source
AI summary
A composite cathode active material includes: a secondary including a core including a plurality of primary particles; and a shell on the core, wherein the plurality of primary particles include a nickel-containing lithium transition metal oxide doped with a first metal, and wherein at least one grain boundary between the plurality of primary particles includes a first composition including the first metal.