Asymmetric Battery Case Volume for Heat Suppression
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Solution Overview
Problem
Existing nonaqueous electrolyte secondary batteries face challenges in suppressing local heat generation during overcharging and maintaining high performance under high-rate charging and discharging cycles, leading to increased resistance and potential safety issues.
Innovation Solution
The design includes a wound electrode body with a larger spatial volume on the negative electrode side compared to the positive electrode side within the battery case, utilizing a copper negative electrode current collector with higher thermal conductivity, and a positioning member to manage heat distribution, along with an offset configuration in pack batteries to enhance heat dissipation and maintain capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the spatial volume on the negative electrode side is increased relative to the positive electrode side, then local heat generation during overcharging is suppressed, but the battery case design becomes more complex
Solution Approach 1:
The battery case is designed with an asymmetric spatial volume distribution where the negative electrode side has a larger volume than the positive electrode side. This asymmetric design allows heat generated during overcharging to be distributed to the larger negative electrode side volume, suppressing local heat generation while maintaining a relatively simple overall case structure.
Solution Approach 2:
The battery case provides different spatial volumes for different electrodes based on their specific heat generation characteristics. The negative electrode side, which generates more heat during overcharging, is provided with a larger spatial volume to accommodate and dissipate this heat, while the positive electrode side requires less volume.
2Temperature
If the copper negative electrode current collector with higher thermal conductivity is used, then heat dissipation is improved, but the manufacturing cost increases
Solution Approach 1:
The material parameter of the negative electrode current collector is changed from conventional materials to copper, which has higher thermal conductivity. This parameter change improves heat dissipation capability, allowing the battery to better manage heat generation during high-rate charging and discharging cycles.
3Temperature
If the wound electrode body is offset positioned in the battery case, then heat distribution is improved, but the positioning precision requirements increase
Solution Approach 1:
The wound electrode body is intentionally positioned asymmetrically (offset) within the battery case, with the negative electrode side having more space than the positive electrode side. This offset positioning improves heat distribution by allowing better thermal management on the heat-generating negative electrode side, while the positioning member ensures the offset is controlled within acceptable tolerances.
4Temperature
If the first spatial volume to second spatial volume ratio is maintained between 2.1 and 5.7, then local heat generation is suppressed and battery performance is maintained, but the design flexibility is reduced
Solution Approach 1:
The design specifies a parameter range for the spatial volume ratio (2.1 to 5.7) between the negative electrode side and positive electrode side. This parameter optimization ensures sufficient space for heat dissipation on the negative electrode side while maintaining acceptable battery performance. The range provides some design flexibility while ensuring the heat suppression effect is achieved.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses local heat generation during overcharging, reduces resistance increase after high-rate cycles, and maintains high battery performance and safety, particularly in applications like electric vehicles.
Implementation Method 1
a copper negative electrode current collector with higher thermal conductivity
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a wound electrode body housed in a battery case. The wound electrode body is positioned to the battery case with a positioning member. Among a spatial volume excluding the wound electrode body in the battery case, in a direction of a winding axis of the wound electrode body, a spatial volume X on a negative electrode side of the battery case is larger than a spatial volume Y on a positive electrode side of the battery case. Here, the spatial volume X and the spatial volume Y satisfy 2.1≤(X/Y)≤5.7.