Nonaqueous Electrolyte Battery Separator Design for Heat Management
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Solution Overview
Problem
Nonaqueous electrolyte batteries experience performance deterioration during large-current cycles due to heat generation and resistance issues, which existing methods fail to adequately address without impairing output performance.
Innovation Solution
A nonaqueous electrolyte battery design featuring an electrode group with a laminated structure where positive and negative electrodes are alternately interposed between a separator folded in a zigzag form, with a Gurley value of the outermost layer being larger than the inner layer, satisfying the equation 3×10−5≦(X/Y)≦1.5×10−3, where X is the rated resistance and Y is the rated capacity, to manage heat accumulation and resistance effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If current is increased to improve power output, then power increases, but heat generation increases and cycle performance deteriorates
Solution Approach 1:
The separator is divided into multiple layers with different air permeability characteristics. The first separator (outer layer) has higher air permeability to facilitate heat dissipation, while the second separator (inner layer) has lower air permeability to maintain structural integrity and prevent thermal runaway. This segmentation allows the battery to handle high currents effectively by managing heat at different levels of the separator structure.
2Loss of energy
If resistance is reduced to suppress heat generation, then heat generation decreases, but output performance may be compromised
Solution Approach 1:
Different regions of the separator structure are assigned different properties: the outer separator layer has higher air permeability optimized for heat dissipation, while the inner separator layer has lower air permeability optimized for safety and structural support. This local differentiation allows each layer to perform its specific function optimally without compromising overall battery performance.
3Temperature
If separator air permeability is increased to improve heat dissipation, then heat dissipation improves, but safety against thermal runaway may be reduced
Solution Approach 1:
The separator is constructed as a composite structure with two different separator materials having distinct air permeability characteristics. The first separator (higher air permeability) provides heat dissipation pathways, while the second separator (lower air permeability) acts as a safety barrier to prevent thermal runaway. The composite structure synergistically combines the advantages of both separator types to achieve both heat management and safety.
Data Source
AI summary
A nonaqueous electrolyte battery includes an electrode group and a nonaqueous electrolyte. The electrode group has a laminated structure in which positive electrodes and negative electrodes are alternately interposed between overlapped parts of a separator folded in a zigzag form. A Gurley value of an outermost layer of the separator is larger than that of an inner layer. The battery satisfyies the following equation (1):3×10−5≦(X/Y)≦1.5×10−3 (1)wherein X is a rated resistance [mΩ] of the nonaqueous electrolyte battery and Y is a rated capacity [mAh] of the nonaqueous electrolyte battery.