Wound Li-Ion Electrode Groove Layout to Prevent Lithium Plating
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Solution Overview
Problem
The existing lithium-ion batteries in wound structure face issues with lithium precipitation at the negative electrode area due to the absence of effective negative electrode active material, affecting electrical and safety performance, particularly around the adhesive tape used for isolation protection.
Innovation Solution
Incorporating grooves on the positive electrode piece to isolate the insulating adhesive tape from the active material, preventing excessive lithium ion migration to the negative electrode area, and optimizing the size and placement of adhesive tapes and grooves to enhance electrical and safety performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive tape is used for isolation protection at the negative electrode area, then the positive electrode active material is isolated from the negative electrode, but lithium precipitation occurs in the negative electrode area around the adhesive tape
Solution Approach 1:
The patent divides the positive electrode active material layer into two regions: a covered region under the adhesive tape and an uncovered region. The groove separates these regions, allowing the covered region to provide isolation protection while the uncovered region prevents lithium precipitation by maintaining proper lithium ion distribution.
Solution Approach 2:
The patent applies different properties to different parts of the positive electrode active material layer. The covered region provides isolation functionality, while the uncovered region prevents lithium precipitation. This local differentiation resolves the contradiction between isolation protection and lithium precipitation prevention.
2Ease of manufacture
If positive electrode active material is removed at the position corresponding to the negative electrode tab, then the tab can be welded to the current collector, but the negative electrode area cannot receive lithium ions from the corresponding positive electrode area
Solution Approach 1:
The positive electrode active material layer is segmented into covered and uncovered regions. The uncovered region ensures that lithium ions can reach the negative electrode tab area, while the covered region provides isolation protection.
Solution Approach 2:
The groove acts as an intermediary structure that allows the adhesive tape to provide isolation protection while preventing it from blocking lithium ion transport to the negative electrode tab area.
3Reliability
If the positive electrode active material layer is completely covered by adhesive tape for isolation, then isolation protection is maximized, but lithium ion transport to the negative electrode is blocked
Solution Approach 1:
The patent segments the positive electrode active material layer into covered and uncovered regions, allowing simultaneous achievement of isolation protection and lithium ion transport functionality.
Solution Approach 2:
Different regions of the positive electrode active material layer are assigned different functions: the covered region provides isolation protection while the uncovered region enables lithium ion transport.
Data Source
AI summary
A lithium-ion battery includes a positive electrode piece, a negative electrode piece, a separator arranged between the positive electrode piece and the negative electrode piece, and an electrolyte. The positive electrode piece includes a positive electrode current collector, a positive diaphragm and a positive electrode tab which are attached to a surface of the positive electrode current collector. The negative electrode piece includes a negative electrode current collector, a negative electrode diaphragm and a negative electrode tab which are attached to a surface of the negative electrode current collector. The negative electrode diaphragm is provided with a first groove in which the negative electrode tab is arranged. The positive electrode piece opposite to the first groove is provided with a first insulating adhesive tape thereon, and the positive electrode diaphragm around an edge of the first insulating adhesive tape is provided with a first adhesive tape groove.