Lithium Metal Battery Separator Coating for Uniform Li Deposition
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Solution Overview
Problem
Lithium metal negative electrode secondary batteries face challenges in cycle endurance due to non-uniform lithium metal deposition, leading to rapid capacity retention degradation.
Innovation Solution
Incorporating a separator with a covering layer containing a lithium-ion conductor of specific conductivity (1.0×10^-13 to 2.0×10^-9 S/cm) to facilitate uniform lithium ion supply, reducing congestion and enhancing deposition uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in a lithium metal negative electrode secondary battery, then the structure is simple, but lithium metal deposits non-uniformly during charging, leading to rapid capacity retention degradation
Solution Approach 1:
The separator is divided into multiple functional layers: a base separator layer and a covering layer with lithium-ion conductor particles. This segmentation allows each layer to perform its specific function - the base separator provides structural support and ion transport, while the covering layer regulates lithium ion supply to achieve uniform deposition and improve cycle endurance
Solution Approach 2:
Lithium-ion conductor particles (such as Li3PO4, Li2SiO3, or Li4SiO4) are introduced as intermediary substances in the covering layer. These particles act as mediators that control lithium ion transport from the electrolyte to the negative electrode, preventing direct contact between the electrolyte and electrode while ensuring uniform ion supply for improved deposition uniformity
2Manufacturing precision
If lithium metal deposition is allowed without control, then energy density is high, but non-uniformity increases with repeated cycles, causing capacity retention to degrade rapidly
Solution Approach 1:
The lithium-ion conductivity of the covering layer is precisely controlled by selecting specific materials (Li3PO4 with conductivity of 10^-13 to 10^-9 S/cm) and adjusting particle size (1-10 μm) and concentration (1-50 wt%). This parameter optimization ensures uniform lithium ion supply while maintaining adequate charge-discharge rates, achieving both deposition uniformity and productivity
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 solution improves cycle endurance and energy density by ensuring uniform lithium metal deposition, as evidenced by enhanced capacity retention and power output performance.
Implementation Method 1
The covering layer includes a lithium-ion conductor. The lithium-ion conductor has a lithium-ion conductivity from 1.0×10^-13 to 2.0×10^-9 S/cm
Implementation Method 2
At a negative electrode of a Li metal negative electrode secondary battery, a dissolution/deposition reaction takes place. More specifically, during charging, Li metal becomes deposited from the electrolyte solution. During discharging, Li metal dissolves into the electrolyte solution
Data Source
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AI summary
A lithium metal negative electrode secondary battery (100) comprises a positive electrode (10), a separator (30), a negative electrode (20), and an electrolyte solution. The electrolyte solution includes Li ions. The separator (30) is interposed between the positive electrode (10) and the negative electrode (20). The separator (30) includes a porous base material (31) and a covering layer (32). The porous base material (31) has a first main face (31a) and a second main face (31b). The first main face (31a) faces the positive electrode (10). The second main face (31b) faces the negative electrode (20). The covering layer (32) covers the second main face (31b). The covering layer (32) includes a Li-ion conductor. The Li-ion conductor has a Li-ion conductivity from 10×10-13 to 2.0×10-9 S/cm.