Negative Electrode Sheet Layout for Edge Lithium Plating Control
Solution Overview
Problem
Lithium precipitation occurs at the edge of the negative electrode in lithium-ion batteries due to a lower state of charge (SOC) at the edge compared to the middle, leading to inefficiencies during charging and discharging.
Innovation Solution
A negative electrode sheet design with a first region having a higher surface density of active material and a surrounding second region with a lower surface density, reducing the SOC difference between the edge and middle, thereby minimizing lithium precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode sheet has a higher surface density of active material at the edge to increase SOC, then lithium precipitation is reduced, but the manufacturing complexity increases due to the need for non-uniform density distribution
Solution Approach 1:
The patent applies local quality by creating a non-uniform surface density distribution of active material across the negative electrode sheet. The edge regions have a lower surface density (50-80 g/m²) compared to the center region (80-100 g/m²), which locally optimizes the SOC distribution to prevent lithium precipitation at the edges while maintaining high capacity in the center region.
2Quantity of substance
If the negative electrode sheet has a larger area to increase capacity, then more lithium can be stored, but the SOC difference between edge and middle increases leading to more lithium precipitation
Solution Approach 1:
The patent divides the negative electrode sheet into different regions with different active material surface densities. The center region has higher density (80-100 g/m²) for maximum lithium storage, while the edge regions have lower density (50-80 g/m²) to maintain better SOC uniformity and prevent lithium precipitation, thus resolving the contradiction between total capacity and SOC uniformity.
Data Source
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AI summary
Provided are a negative electrode sheet, a battery core, and an electric device. The electric device includes the battery core. The battery core includes the negative electrode sheet. The negative electrode sheet includes a first region and a second region. The second region surrounds the first region. A surface density of an active material in at least part of the second region is less than a surface density of an active material in the first region. The present disclosure reduces a probability of lithium precipitation at an edge of an electrode sheet.