Bipolar Electrode Stack With Crushing-Time Discharge Path
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Solution Overview
Problem
Existing power storage devices face excessive temperature rises due to short circuits caused by external forces breaking separators in stacked electrode assemblies.
Innovation Solution
Incorporation of uncoated portions on termination electrodes and bipolar electrodes with thinner separators in specific regions, forming crushing-time discharging portions that prioritize external discharge over internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a stacked electrode assembly with bipolar electrodes is used to increase energy density, then the power storage capacity is improved, but the risk of internal short circuit and excessive temperature rise increases when external force is applied
Solution Approach 1:
The electrode assembly is segmented into multiple independent pouches, each containing bipolar electrodes stacked in series. This segmentation allows individual pouches to be isolated if damaged, preventing cascade failures while maintaining high energy density through the bipolar configuration.
Solution Approach 2:
External terminals are preliminarily provided on the outer surfaces of the pouches, enabling the battery to discharge externally before an internal short circuit can occur. This preliminary discharge path prevents excessive temperature rise by allowing controlled energy release prior to failure.
2Volume of stationary object
If separators are made thinner to reduce space and increase energy density, then the volume efficiency is improved, but the separator becomes more susceptible to breaking under external force
Solution Approach 1:
The separator thickness is optimized locally - thinner in regions where space efficiency is critical and maintained at adequate thickness in areas more susceptible to mechanical stress. This local differentiation maintains volume efficiency while preserving separator durability where needed.
Solution Approach 2:
External terminals are preliminarily positioned to enable discharge before separator failure occurs. This preliminary discharge mechanism compensates for the reduced separator strength by providing an alternative energy release path before the thinner separator can break under external force.
3Power
If bipolar electrodes are stacked in series to increase voltage and energy density, then the power output is improved, but the complexity of preventing short circuits between adjacent electrodes increases
Solution Approach 1:
The bipolar electrode stack is segmented into multiple pouches, with each pouch containing a specific number of stacked bipolar electrodes. This segmentation simplifies short circuit prevention by isolating potential failure points, while the series connection within each pouch maintains high voltage and power output.
Solution Approach 2:
Separators and pouches serve as intermediary protective layers between adjacent bipolar electrodes. These intermediaries prevent direct contact between positive and negative electrodes of adjacent cells, simplifying the overall short circuit prevention strategy while enabling high-power series stacking.
4Reliability
If external terminals are provided on outer surfaces to enable pre-discharge, then the safety under external force is improved, but the device structure becomes more complex
Solution Approach 1:
The external terminals serve multiple functions: they enable pre-discharge for safety, provide electrical connection for normal operation, and facilitate heat dissipation. This multi-functionality improves safety under external force without proportionally increasing structural complexity.
Solution Approach 2:
The external terminal structure is merged with the pouch packaging and electrode assembly design. The terminals are integrated into the outer surface structure, combining the protective housing and electrical connection functions, thereby improving safety without adding separate complex components.
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
Suppresses excessive temperature rises by allowing external discharge before internal short circuits occur, ensuring safer operation under external forces.
Implementation Method 1
a separator being interposed between the bipolar electrode and each of the positive-electrode termination electrode and the negative-electrode termination electrode
Implementation Method 2
The uncoated portion of one of the positive-electrode termination electrode and the negative-electrode termination electrode extends in a stacking direction of the stacked electrode assembly together with the separator adjacent to the uncoated portion
Data Source
AI summary
A power storage device includes a stacked electrode assembly and a seal member. An electrode plate (bipolar electrode) having a positive electrode layer and a negative electrode layer is stacked between a positive-electrode termination electrode and a negative-electrode termination electrode with a separator being interposed between the electrode plate and each of the positive-electrode termination electrode and the negative-electrode termination electrode so as to form a stacked electrode assembly. An uncoated portion of the negative-electrode termination electrode (current collector) and an uncoated portion of the electrode plate (current collector) extend in a stacking direction of the stacked electrode assembly together with the separator adjacent to each of the uncoated portions, and are folded so as to be stacked on the positive-electrode termination electrode with the separator being interposed between each of the uncoated portions and the positive-electrode termination electrode, thereby forming a crushing-time discharging portion.