Dual-Layer Battery Cathode Layout for Longer Cycle Life
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Solution Overview
Problem
Secondary batteries, particularly lithium secondary batteries, face issues with stability and reliability due to precipitation of internal cathode materials during repeated charging and discharging, which affects long-term durability and cycle life.
Innovation Solution
A cathode design with a specific loading amount ratio and gap between two cathode active material layers, positioned differently around a winding center, to prevent material precipitation and enhance operational reliability and capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single cathode active material layer is used, then the structure is simple, but material precipitation occurs during repeated charging and discharging reducing durability
Solution Approach 1:
The cathode active material layer is divided into two distinct layers: a first cathode active material layer and a second cathode active material layer. This segmentation prevents material precipitation during repeated charging and discharging by distributing electrochemical reactions across multiple layers, thereby improving cycle life and durability without excessive complexity
Solution Approach 2:
Each cathode active material layer is positioned at different locations relative to the winding center (first layer at a first location, second layer at a second location), creating local quality differences. This spatial distribution optimizes electrochemical performance at different radial positions, preventing precipitation while maintaining structural manageability
2Reliability
If cathode active material layers are positioned asymmetrically around the winding center, then capacity distribution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The cathode active material layers are positioned asymmetrically around the winding center, with the first layer at a first location and the second layer at a second location. This asymmetric positioning creates optimized capacity distribution during winding, improving capacity retention rates while the patent provides guidance on managing the associated positioning requirements
Data Source
AI summary
A cathode for a lithium secondary battery according to embodiments of the present disclosure includes: a cathode current collector including a first surface and a second surface that face each other, a first cathode active material layer disposed on the first surface; and a second cathode active material layer disposed on the second surface, wherein a loading amount ratio of the second cathode active material layer to the loading amount of the first cathode active material layer is 102% to 104%.