Lithium Battery Cathode with Concentration Gradient and Single Particle Structure
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Solution Overview
Problem
Lithium secondary batteries face challenges in achieving high capacity, power, life-span, stability, and resistance to penetration-induced failures such as short-circuit and ignition, particularly with existing cathode active materials that lack sufficient stability and longevity.
Innovation Solution
A lithium secondary battery design incorporating a cathode active material comprising a first particle with a concentration gradient region and a second particle with a single particle structure, specifically a lithium metal oxide represented by Chemical Formula LixM1′aM2′bM3′cOy, where M1′, M2′, and M3′ are selected metals, and a blending weight ratio of the first and second particles optimized for improved electrical and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a cathode active material with high capacity and power is used, then the battery achieves high performance, but the life-span and stability deteriorate
Solution Approach 1:
The cathode active material employs a concentration gradient structure where the composition varies from the central portion to the surface portion. The central portion has a first concentration of metal elements optimized for high capacity and power, while the surface portion has a second concentration optimized for stability and life-span. This local variation in composition allows different regions to perform different functions simultaneously.
Solution Approach 2:
The cathode active material is designed as a composite structure combining two different concentration regions within a single particle. This composite approach integrates the benefits of high-capacity materials in the core with stable materials at the surface, achieving both high power and long life-span without requiring separate particles or complex multi-layer structures.
2Quantity of substance
If a cathode active material with high capacity is used, then the battery achieves high energy density, but the resistance to penetration-induced failures deteriorates
Solution Approach 1:
The surface portion of the cathode active material particles has a modified concentration of metal elements that provides enhanced structural integrity and resistance to penetration. This surface modification does not significantly reduce the overall lithium content and capacity while providing the necessary protection against penetration-induced failures such as short-circuit and ignition.
3Productivity
If a cathode active material with improved electrical performance is used, then the battery charging rate increases, but the mechanical stability deteriorates
Solution Approach 1:
The concentration gradient structure allows the central portion to be optimized for electrical performance and fast charging, while the surface portion maintains mechanical stability. The surface region's composition is tailored to provide structural support and resistance to mechanical degradation during charge-discharge cycles, enabling fast charging without sacrificing mechanical integrity.
Data Source
AI summary
A lithium secondary battery comprises a cathode active material including a first cathode active material particle having a concentration gradient region and a second cathode active material particle having a single particle structure, to obtain improved electrical performance and mechanical stability.