Spirally-Wound Lithium Battery Anode Conductor Attachment
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Solution Overview
Problem
In spirally-wound lithium batteries, the lithium anode can crack or break during discharge, leading to increased internal resistance and reduced battery capacity, as existing solutions either result in high initial internal resistance or significant voltage drops at the discharge ending stage.
Innovation Solution
A conductor is attached to the outer circumferential surface of the lithium anode, specifically in the region where breakage occurs, to maintain electrical connection and reduce internal resistance, with the conductor's width varying between 5% and 100% of the anode's width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductor is attached to the entire outer surface of the lithium anode, then electrical connection is maintained, but initial internal resistance increases
Solution Approach 1:
The conductor is attached only to the winding end region of the lithium anode (from the end of the winding end to an area opposed to the inner surface of the cathode on its winding end side), not the entire surface. This localized attachment maintains electrical connection where breakage occurs most frequently while minimizing impact on initial internal resistance.
Solution Approach 2:
The anode surface is segmented into different functional zones: the winding end region where conductor attachment occurs to prevent breakage, and the rest of the surface that remains exposed for optimal electrochemical performance. This segmentation allows each zone to fulfill its specific function without compromising the other.
2Loss of energy
If no conductor is attached to the lithium anode, then initial internal resistance remains low, but voltage drops significantly at discharge ending stage due to anode breakage
Solution Approach 1:
The conductor is attached in advance to the winding end region of the lithium anode before discharge begins. This preliminary protective measure ensures that when the anode undergoes breakage during discharge (particularly at the ending stage), the conductor maintains electrical continuity and prevents the voltage drops that would otherwise occur.
3Reliability
If the conductor width is increased to fully cover the anode, then electrical connection is improved, but device complexity and material usage increase
Solution Approach 1:
Instead of using a wide conductor covering the entire anode surface, the invention uses a conductor with optimized width (5-100% of anode width) positioned specifically at the winding end region. This localized approach provides sufficient electrical connection for reliability while minimizing conductor material usage and device complexity.
Data Source
AI summary
A spirally-wound lithium battery includes: a bottomed cylindrical cell can doubling as an anode current collector; and a strip-shaped electrode body including an anode and a cathode arranged faced each other via a separator, the anode including an anode active material of lithium metal or alloy, the cell can being sealed, with a non-aqueous organic electrolyte, containing the electrode body wound in a longitudinal direction, the electrode body being wound from a winding axis side around the axis in a vertical direction, an extending direction of a cell can cylindrical axis, such that the anode is arranged at an outermost circumference, the electrode body is attached with a conductor, continuously extending in the longitudinal direction thereof, on an outer circumferential surface of the anode, from a winding end of the anode to an area thereof opposed to an inner surface of the cathode on its winding end side.