Lithium Ion Battery Cathode Inactive Coating for Tolerance Control
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Solution Overview
Problem
Conventional lithium ion battery manufacturing processes result in reduced energy density due to increased tolerance between the anode and cathode, exposure of the metal layer of the cathode current collector, and damage to the punching die, leading to material wastage and reliability issues.
Innovation Solution
Coating specific regions of the cathode current collector with an inactive electrochemical stable material layer during the electrode manufacturing process to prevent metal exposure and minimize tolerance, thereby enhancing energy density and physical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode coating portion is cut by a punching process, then the battery cell can be assembled, but the metal layer of the cathode current collector may be exposed and tolerance between anode and cathode increases
Solution Approach 1:
An inactive coating layer is formed on the cathode current collector at specific regions before the punching process. This preliminary coating prevents metal layer exposure during subsequent punching operations, eliminating the need for excessive coating material extensions and reducing tolerance issues during assembly.
Solution Approach 2:
The inactive coating layer is applied selectively to specific regions of the cathode current collector where exposure risks occur during punching, rather than coating the entire surface. This localized approach maintains manufacturing precision while preventing metal layer exposure at critical areas.
2Reliability
If the cathode coating portion is extended to prevent metal exposure, then reliability improves, but energy density decreases due to increased tolerance
Solution Approach 1:
The inactive coating layer is formed in advance at precise locations on the cathode current collector before assembly. This allows the cathode coating portion to be cut to the exact required size without extending beyond necessary boundaries, maximizing the active material area and maintaining high energy density while ensuring metal layer protection.
Solution Approach 2:
The coating method changes from extending the cathode coating portion (increasing non-active material area) to applying a targeted inactive coating layer (maintaining compact dimensions). This parameter change preserves the active material area and maintains energy density while achieving the same protective function.
3Reliability
If the cathode active material is used extensively, then cathode performance improves, but material cost increases and punching die damage occurs
Solution Approach 1:
The inactive coating layer is applied only at specific regions where metal layer exposure risks exist during punching, rather than throughout the entire cathode structure. This localized application minimizes the use of inactive materials and preserves maximum active material area, reducing material costs while maintaining cathode performance and protecting the punching die.
Data Source
AI summary
A lithium ion secondary battery includes: an anode including an anode current collector and an anode coating layer coating a region of the anode current collector; a cathode including a cathode current collector, a cathode coating layer coating a region of the cathode current collector, and an inactive coating layer disposed on a surface of a region of the cathode current collector on which the cathode coating layer is not disposed, the inactive coating layer extending from one or more of both end portions of the cathode coating layer toward an end portion of the anode; and a separation membrane arranged between the cathode and the anode.