Cellulose Spacer for Lithium Metal Deposition in Batteries
Solution Overview
Problem
Current nonaqueous electrolyte secondary batteries require further improvement in initial and cycle characteristics, particularly in managing the deposition and dissolution of metals like lithium during charging and discharging, which can lead to electrode expansion and internal short circuits.
Innovation Solution
Incorporating a spacer with a resin containing a cellulose-based compound and a filler between the positive and negative electrodes to create a space for metal deposition, suppressing electrode expansion and enhancing cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spacer is provided between the positive electrode and separator to store lithium metal during charging, then the battery can accommodate metal deposition, but the device complexity increases
Solution Approach 1:
The spacer is integrated into the separator structure, with the spacer forming an integral part of the separator assembly. This nesting approach allows the spacer to be incorporated without adding separate components, thus accommodating lithium metal storage while minimizing structural complexity
Solution Approach 2:
The spacer and separator are combined into a single integrated component rather than separate parts. The spacer is formed as part of the separator structure, merging the functions of separation and lithium storage accommodation into one element, thereby reducing device complexity while maintaining reliability
2Reliability
If the positive electrode current collector is made shorter in the first direction to accommodate spacers, then metal deposition space is created, but the battery capacity decreases
Solution Approach 1:
Instead of reducing the length in the first direction, the spacer is positioned to extend in the second direction (width direction). This dimensional shift allows the active material layer to maintain its length in the first direction, preserving battery capacity while still creating the necessary space for metal deposition through the spacer structure in the perpendicular dimension
3Stability of the object's composition
If a thermoplastic polymer coating layer is applied to the separator substrate, then thermal stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The separator is constructed as a composite structure combining a porous substrate with a thermoplastic polymer coating layer. This composite approach provides enhanced thermal stability through the coating while using a standardized multi-layer manufacturing process that balances performance requirements with production feasibility
Data Source
Figure 1
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AI summary
A disclosed nonaqueous electrolyte secondary battery includes a positive electrode (11), a negative electrode (12), a separator (50) provided between the positive electrode (11) and the negative electrode (12), and a spacer (53) provided in at least one region selected from the group consisting of a region between the positive electrode (11) and the separator (50) and a region between the negative electrode (12) and the separator (50). The negative electrode (12) is a negative electrode in which a metal used as a negative electrode active material deposits during charging and the metal dissolves during discharging. The spacer (53) contains a resin and a filler. The resin contains a cellulose-based compound.