Electrode Assembly Non-Coating Offset for Battery Safety
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Solution Overview
Problem
Secondary batteries are prone to short-circuiting and accidents due to separator shrinkage or deformation, which can lead to burning or explosions, as the positive and negative electrodes may come into physical contact when heated.
Innovation Solution
The electrode assembly design includes a positive electrode plate with a non-coating portion offset from its ends and a wider negative electrode non-coating portion that overlaps the positive non-coating portion, along with a copper positive electrode tab and negative electrode tabs, which are wound together in a jelly-roll shape with a center pin, to reduce the risk of short-circuiting and enhance safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the separator is used to insulate the positive and negative electrodes, then the electrodes are protected from short-circuiting, but the separator may shrink or deform when heated, causing the electrodes to come into contact and short-circuit
Solution Approach 1:
The patent applies preliminary action by pre-positioning the positive electrode non-coating portion offset from the ends of the positive electrode plate before assembly. This offset positioning is established in advance during manufacturing, creating a safety margin that prevents short-circuiting even if the separator deforms or shrinks during operation, thereby addressing the instability of the separator.
2Ease of manufacture
If the positive electrode non-coating portion is positioned at the ends of the positive electrode plate, then the assembly is simplified, but the risk of short-circuiting increases when the separator deforms
Solution Approach 1:
The patent applies asymmetry by deliberately offsetting the positive electrode non-coating portion from the ends of the positive electrode plate along the length direction. This asymmetric positioning creates an uneven distribution of coating material that establishes a safety buffer zone, preventing the positive and negative electrodes from coming into contact even when the separator deforms, thus improving reliability while maintaining manufacturing feasibility.
3Reliability
If the negative electrode non-coating portion is made wider to overlap the positive non-coating portion, then safety is improved, but the amount of active material is reduced
Solution Approach 1:
The patent applies segmentation by dividing the electrode plate into distinct coating and non-coating portions. The negative electrode non-coating portion is segmented to be wider than the positive electrode non-coating portion, creating an overlapping safety zone. This segmentation strategy localizes the reduction of active material to specific non-coating areas while maintaining adequate capacity in the coating portions, thus balancing safety improvements with energy storage requirements.
Data Source
AI summary
An electrode assembly includes: a positive electrode plate including a positive electrode collector having, on its first side, a positive electrode coating portion having a positive electrode active material thereon and a first positive electrode non-coating portion; a positive electrode tab on the first positive electrode non-coating portion; a negative electrode plate including a negative electrode collector having, on its first side facing the first side of the positive electrode collector, a negative electrode coating portion having a negative electrode active material thereon and a first negative electrode non-coating portion; and a separator between the positive and negative electrode plates. The first positive electrode non-coating portion is between ends of the positive electrode plate, and the first negative electrode non-coating portion overlaps the first positive electrode non-coating portion.