Battery Electrode Peel Strength Tuning to Prevent Winding Cracks
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Solution Overview
Problem
Secondary batteries with wound electrode structures often experience cracking at inner sections due to stress, leading to reduced battery capacity and potential short circuits, as the stiff electrode material can cause the electrode to break at the innermost bent sections during winding.
Innovation Solution
An electrode with a composite material layer containing titanium-containing oxide particles and carbon nanotubes, where the peel strength between the active material-containing layer and the current collector is controlled within a range of 0.2 kN/m to 0.7 kN/m to prevent cracking, allowing the active material-containing layer to partially peel away and reduce stress at the bent portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the electrode is made stiff to maintain structural integrity, then the electrode strength is improved, but the electrode cracks at innermost bent sections during winding
Solution Approach 1:
The invention changes the mechanical parameter of the electrode by controlling the peel strength between the active material-containing layer and current collector to be within 0.2 kN/m to 0.7 kN/m. This parameter optimization allows the electrode to have sufficient strength while preventing crack formation at bent sections during winding.
Solution Approach 2:
The invention uses a composite structure consisting of an active material-containing layer and a current collector with controlled interfacial bonding. This composite design allows the electrode to exhibit both strength and flexibility, preventing cracking while maintaining structural integrity during the winding process.
2Stability of the object's composition
If the active material-containing layer is tightly bound to the current collector, then the electrode structural integrity is improved, but stress concentrates at bent portions causing cracking
Solution Approach 1:
The invention optimizes the peel strength parameter to a specific range (0.2 kN/m to 0.7 kN/m) that balances structural integrity and stress distribution. This controlled bonding strength prevents stress concentration at bent portions while maintaining overall electrode stability.
Solution Approach 2:
The invention applies partial peeling of the active material-containing layer from the current collector at controlled locations. This partial separation allows stress relief at bent portions without completely compromising the electrode's structural integrity or electrical functionality.
Data Source
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AI summary
Provided is an electrode (3) including a current collector (3a) and an active material-containing layer (3b) in contact with the current collector (3a). The active material-containing layer (3b) contains a carbon nanotube and particles of titanium-containing oxide having an average particle size or 0.1 µm to 3 µm. A peel strength between the current collector (3a) and the active material-containing layer (3b) is within a range of 0.2 kN/m to 0.7 kN/m.