Lithium Secondary Battery Electrolyte for Isolated Lithium Recovery
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Solution Overview
Problem
Existing lithium secondary batteries face challenges in controlling the morphology of deposited lithium metal, leading to dendrite formation and capacity retention issues due to lithium metal isolation from the negative electrode.
Innovation Solution
Incorporating an organic compound with a redox potential of 0 V or more and 4 V or less vs Li/Li+ into the non-aqueous electrolyte, which facilitates the recovery of isolated lithium metal by converting it back into lithium ions, thereby enhancing capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as negative electrode active material to improve capacity, then battery capacity is improved, but lithium metal deposits in dendritic form causing negative electrode expansion and capacity retention drop
Solution Approach 1:
The patent changes the physical-chemical parameters of the negative electrode current collector by controlling its surface roughness (ten-point average roughness Rz of 10 μm or less) and applying specific surface treatments. This parameter control prevents dendritic lithium deposition by ensuring uniform current distribution during charging, thereby maintaining high capacity retention ratios while utilizing lithium metal's high capacity.
Solution Approach 2:
The patent introduces a protective layer or coating on the negative electrode current collector surface that acts as an intermediary between the lithium metal and the current collector. This intermediary layer suppresses dendrite formation and prevents isolation of lithium metal during discharge, ensuring stable capacity retention while maintaining high battery capacity.
2Reliability
If negative electrode current collector surface is smoothed to suppress dendrite growth, then dendrite formation is suppressed, but lithium metal deposition control becomes difficult
Solution Approach 1:
The patent optimizes the surface roughness parameter of the negative electrode current collector to a specific range (Rz ≤ 10 μm) that balances dendrite suppression with controlled lithium deposition. This precise parameter control enables both reliable dendrite suppression and manufacturable lithium metal deposition control.
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
The use of the organic compound in the non-aqueous electrolyte effectively suppresses the drop in capacity retention ratio by making isolated lithium metal available for charge-discharge reactions, thereby improving the battery's overall performance.
Implementation Method 1
the non-aqueous electrolyte including an organic compound having a redox potential of 0 V or more and 4 V or less vs Li/Li+
Implementation Method 2
lithium metal deposits on the negative electrode during charge, and the lithium metal dissolves during discharge and are released as lithium ions into the non-aqueous electrolyte
Data Source
AI summary
A lithium secondary battery including a positive electrode, a negative electrode having a negative electrode current collector that faces the positive electrode, and a non-aqueous electrolyte, wherein lithium metal deposits on the negative electrode during charge, and the lithium metal dissolves from the negative electrode into the non-aqueous electrolyte during discharge. The non-aqueous electrolyte includes an organic compound having a redox potential of 0 V or more and 4 V or less vs Li/Li+.