Cylindrical Li-Ion Electrode Layout for High Capacity Cycle Life
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Solution Overview
Problem
Existing non-aqueous electrolyte secondary batteries face challenges in increasing battery capacity per unit volume while maintaining improved cycle characteristics, as previous technologies do not effectively address the issue of heat accumulation and side reactions that degrade performance.
Innovation Solution
The battery design incorporates a band-shaped positive and negative electrode assembly with a phosphorus compound in the positive electrode mixture layer, a layered rock-salt structured lithium-containing composite oxide, and a cylindrical exterior with a specific sealing assembly, which enhances the positive electrode current collector connection and reduces connecting resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery size is increased to increase battery capacity per unit volume, then the battery capacity per unit volume is improved, but the cycle characteristics deteriorate due to heat accumulation and side reactions
Solution Approach 1:
A phosphorus compound is introduced as an intermediary substance in the positive electrode mixture layer. This phosphorus compound acts as a mediator that suppresses side reactions between the positive electrode active material and the non-aqueous electrolyte, thereby improving cycle characteristics while maintaining high battery capacity per unit volume.
Solution Approach 2:
The invention changes the chemical composition parameters of the positive electrode by incorporating a phosphorus compound into the positive electrode mixture layer. This parameter change modifies the electrode's chemical properties to reduce harmful side reactions and improve thermal stability, enabling both high capacity density and good cycle life.
2Loss of energy
If multiple positive electrode leads are drawn out to reduce connecting resistance, then the connecting resistance is improved, but the device complexity increases
Solution Approach 1:
The positive electrode is divided into multiple segments with multiple positive electrode leads drawn out from different locations. This segmentation approach reduces the current density on each individual lead, thereby reducing connecting resistance and energy loss, while the modular structure makes the complexity manageable.
Data Source
AI summary
This non-aqueous electrolyte secondary battery comprises: an electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator interposed therebetween; a bottomed cylindrical exterior body having an outer diameter of 25 mm or more, that is connected to the negative electrode; and a sealing body that seals an opening at the upper end of the exterior body and is connected to the positive electrode. The positive electrode includes a positive-electrode current collector, and a positive-electrode mixture layer formed on the surface of the positive-electrode current collector, the positive-electrode mixture layer containing a positive-electrode active material and a phosphorus compound. The positive-electrode active material includes a lithium-containing composite oxide having a layered rock-salt structure. The weight per unit area of the positive-electrode mixture layer is 250 g/m2 or more. In the electrode body, three or more positive-electrode leads are led out.