Lithium Metal Anode Layer Structure for Longer Cycle Endurance
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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 and capacity degradation, particularly when a protective layer with high lithium-ion conductivity is used, leading to insufficient electrolyte impregnation and reduced peel strength between the lithium metal layer and the negative electrode base material.
Innovation Solution
A lithium metal negative electrode secondary battery configuration is introduced, featuring a lithium-ion conductor with a lower lithium-ion conductivity of 2.0×10−9 S/cm or less, where the lithium-ion conductor is trapped within the lithium metal layer, enhancing lithium-ion mobility and reducing side reactions, and a binder volume fraction of less than 0.2 to facilitate improved lithium-ion supply and maintain interface integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a protective layer with high lithium-ion conductivity is used, then lithium metal deposition becomes uniform, but electrolyte impregnation becomes insufficient and peel strength decreases
Solution Approach 1:
The patent changes the lithium-ion conductivity parameter of the protective layer from high (conventional) to low (1.0×10^-13 to 2.0×10^-9 S/cm). This parameter change allows the protective layer to maintain uniform lithium metal deposition while permitting sufficient electrolyte impregnation and maintaining peel strength, thereby resolving the contradiction between deposition uniformity and interface strength.
2Manufacturing precision
If a protective layer is formed on the negative electrode base material, then lithium metal deposition becomes uniform, but capacity degradation increases
Solution Approach 1:
The patent applies parameter change by optimizing the lithium-ion conductivity of the protective layer to a specific low range (1.0×10^-13 to 2.0×10^-9 S/cm). This optimized parameter allows the protective layer to promote uniform lithium metal deposition while preventing excessive capacity degradation, thus improving cycle endurance despite the presence of the protective layer.
3Shape
If the lithium metal layer grows and pushes up the protective layer, then a three-layer structure is formed, but lithium-ion supply to the interface becomes insufficient
Solution Approach 1:
The patent changes the lithium-ion conductivity parameter of the protective layer to a low range (1.0×10^-13 to 2.0×10^-9 S/cm), which prevents the protective layer from becoming too dense or impermeable. This parameter change ensures that even when the lithium metal layer grows and forms a three-layer structure, lithium ions can still be supplied adequately to the interface between the lithium metal layer and the negative electrode base material.
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
This configuration improves cycle endurance by maintaining lithium-ion conductivity within the optimal range (1.0×10−13 to 2.0×10−9 S/cm) and reduces capacity degradation, while ensuring sufficient lithium-ion supply to the interface, thereby enhancing the battery's overall performance.
Implementation Method 1
The lithium-ion conductor has a lithium-ion conductivity from 1.0×10−13 to 2.0×10−9 S/cm
Implementation Method 2
During charging, Li metal becomes deposited from the electrolyte solution. During discharging, Li metal dissolves into the electrolyte solution.
Implementation Method 3
The separator is interposed between the positive electrode and the negative electrode
Data Source
AI summary
A lithium metal negative electrode secondary battery comprises a positive electrode, a separator, a negative electrode, and an electrolyte solution. The electrolyte solution includes Li ions. The separator is interposed between the positive electrode and the negative electrode. The negative electrode includes a negative electrode base material and a Li metal layer. The Li metal layer includes a continuous phase and a dispersed phase. The continuous phase includes Li metal. The dispersed phase includes a Li-ion conductor. The Li-ion conductor has a Li-ion conductivity from 1.0×10−13 to 2.0×10−9 S/cm.