Sheet-Cell Battery Pack Layout for Lightweight Cold-Weather Power Tools
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Solution Overview
Problem
Cylindrical lithium battery packs for power tools are heavy due to rigid metal housings, making them cumbersome to use and affecting user experience, and their performance is reduced in low-temperature environments.
Innovation Solution
A battery pack design featuring a sheet-shaped cell assembly with an elastic cell support member that encapsulates tabs, allowing for high discharge rates and gravimetric energy density, along with temperature and leakage sensors for enhanced performance and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If cylindrical lithium cells with rigid metal housings are used, then structural strength is improved, but weight increases making the battery pack cumbersome
Solution Approach 1:
The patent replaces rigid metal housings with flexible polymer encapsulation members that wrap around individual cells and cell assemblies. This flexible packaging approach significantly reduces weight while maintaining adequate protection through the polymer's inherent strength and elasticity, directly resolving the contradiction between structural strength and weight.
2Power
If multiple cylindrical lithium cells are connected in series and parallel to improve electrical energy output, then power is improved, but weight and complexity increase
Solution Approach 1:
The patent transitions from the traditional cylindrical cell geometry to flat sheet-shaped cells arranged in stacked configurations. This dimensional change allows for more efficient space utilization and higher energy density, achieving improved electrical energy output with reduced weight by optimizing the spatial arrangement of cells in three-dimensional stacked layers rather than linear cylindrical configurations.
3Ease of manufacture
If cylindrical lithium cells are used, then manufacturing maturity is improved, but performance in low-temperature environments deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the battery system by using sheet-shaped cells with different electrode configurations and electrolyte compositions optimized for low-temperature operation. These parameter changes enable the battery to maintain adequate ionic conductivity and electrochemical performance in cold environments, resolving the low-temperature performance issue while the standardized manufacturing processes for sheet cells address the manufacturing maturity requirement.
Data Source
AI summary
A battery pack includes a housing, a cell assembly, a cell support member, a first sensor, and a second sensor. The cell assembly is disposed in the housing; and the cell support member is at least configured to support the cell assembly. The cell assembly includes a plurality of cells which are sheet-shaped, the plurality of cells are stacked, and a cell among the plurality of cells includes an encapsulation member configured to encapsulate the cell and a tab disposed at at least one end of the cell assembly and protruding from the cell. The first sensor is configured to detect a temperature of the cell and is disposed on a side of the tab facing towards the cell support member. The second sensor is configured to detect a parameter related to leakage of the cell and is disposed in the cell assembly.