Negative Electrode Current Collector Slits for Battery Cycle Stability
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Solution Overview
Problem
In non-aqueous electrolyte secondary batteries, the expansion and contraction of the negative electrode during charge and discharge can cause the negative electrode current collector to rupture, leading to a break in the electrical connection and deterioration of cycle characteristics.
Innovation Solution
A negative electrode current collector with a belt-like shape and slit groups extending in a dashed line form, including a hole on one end side with a width larger than the slits, allowing controlled rupture and maintaining electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode current collector is made rigid to maintain electrical connection, then electrical connection is improved, but the current collector cannot accommodate electrode expansion and may rupture
Solution Approach 1:
The current collector is divided into multiple segments by forming slits that extend from one end toward the other end. These slits create discrete segments that can independently expand and contract, allowing the current collector to accommodate electrode volume changes while maintaining overall electrical connectivity through the segmented structure.
Solution Approach 2:
The invention introduces a longitudinal dimension of flexibility by forming slits that extend along the length of the current collector. This creates a one-dimensional flexible structure that can expand and contract along the slit direction, accommodating electrode expansion without requiring complete structural redesign.
2Adaptability or versatility
If slits are formed in the current collector to allow expansion, then adaptability to electrode expansion is improved, but the current collector may rupture and break electrical connection
Solution Approach 1:
The hole is positioned specifically at or near the end of the slits, creating a localized stress relief zone. This local structural modification prevents rupture propagation along the entire current collector by concentrating the expansion accommodation function at the slit termination point, while the rest of the structure maintains its integrity.
3Reliability
If the current collector structure is modified to prevent rupture, then cycle characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The slits and hole are pre-formed in the current collector during manufacturing, creating a built-in rupture prevention mechanism. This preliminary structural preparation ensures that when electrode expansion occurs during battery operation, the current collector is already configured to accommodate the stress without rupturing, eliminating the need for additional protective components.
Data Source
AI summary
A non-aqueous electrolyte secondary battery includes an electrode group, and a non-aqueous electrolyte. The electrode group includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The negative electrode includes a negative electrode current collector having a belt-like shape and having a first end and a second end in a short-side direction of the negative electrode current collector. The negative electrode current collector includes at least one slit group constituted of a plurality of slits extending in a form of a dashed line along the short-side direction from one end of the first end and the second end toward the other end, and a hole formed on the other end side of the plurality of slits and having a width larger than an average width of the plurality of slits.