Lithium Metal Battery Phase Transformation Layer Reduces Interfacial Resistance
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Solution Overview
Problem
Lithium secondary batteries with solid electrolytes face issues such as increased resistance and dendrite growth due to dead spaces at the electrode-solid electrolyte interface, leading to safety concerns and reduced cycle life, especially when using lithium metal as the negative electrode.
Innovation Solution
A lithium metal battery design incorporating a composite solid electrolyte membrane with a phase transformation layer containing a plasticizer and lithium salt, a porous polymer sheet layer, and a solid polymer electrolyte layer, where the phase transformation layer is liquefied to reduce interfacial resistance and fill dead spaces, enhancing ion conductivity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte membrane is used to ensure safety and prevent leakage, then reliability is improved, but dead spaces are generated at the electrode interface leading to increased resistance
Solution Approach 1:
The patent employs a composite solid electrolyte membrane consisting of a porous polymer sheet layer and a solid polymer electrolyte layer. The porous polymer sheet provides mechanical strength and fills dead spaces at the electrode interface, while the solid polymer electrolyte provides ion conductivity. This composite structure simultaneously improves reliability and reduces interfacial resistance.
2Productivity
If lithium metal is used as negative electrode to improve energy density, then productivity is improved, but dendrite formation occurs leading to safety concerns
Solution Approach 1:
The porous polymer sheet layer with controlled porosity (30-80%) serves as a physical barrier that prevents dendrite growth while allowing ion transport. The porous structure provides pathways for uniform ion distribution, preventing localized dendrite formation on the lithium metal surface, thus maintaining high energy density while improving safety.
3Ease of manufacture
If the surface of electrode is non-uniform due to active material shape, then manufacturing flexibility is improved, but dead spaces are generated increasing resistance
Solution Approach 1:
The porous polymer sheet layer adapts locally to the non-uniform electrode surface, filling dead spaces and voids wherever they occur. The porous structure provides local contact improvement without requiring uniform electrode fabrication, thus maintaining manufacturing flexibility while reducing dead space volume and interfacial resistance.
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 composite solid electrolyte membrane reduces interfacial resistance, prevents dendrite growth, and improves the battery's cycle life and safety by ensuring uniform electric current flow and maintaining mechanical properties.
Implementation Method 1
a phase transformation layer which is liquefied by heating, thereby reducing the interfacial resistance between the lithium metal negative electrode and the composite solid electrolyte membrane
Implementation Method 2
The phase transformation layer is liquefied by heating, such as an increase in internal temperature of a battery
Data Source
AI summary
Provided is provided a lithium metal battery which includes a composite solid electrolyte membrane interposed between a lithium metal negative electrode and a positive electrode, wherein the composite solid electrolyte membrane includes: a phase transformation layer containing a plasticizer and a lithium salt; a porous polymer sheet layer; and a solid polymer electrolyte layer, the phase transformation layer, the porous polymer sheet layer and the solid polymer electrolyte layer stacked successively, and the phase transformation layer is disposed in such a manner that it faces the lithium metal negative electrode. The lithium metal battery shows reduced resistance at the interface with an electrode and increased ion conductivity, has improved safety, and provides improved energy density of an electrode.