Negative Electrode Layer Structure for Stable Lithium Deposition
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Solution Overview
Problem
All-solid-state batteries using lithium metal as a negative electrode face issues with lithium volume expansion and irreversible dendrite growth during charge and discharge, leading to low power characteristics and short-circuit phenomena.
Innovation Solution
A negative electrode for all-solid-state batteries comprising a current collector, an ion transport layer, and a negative coating layer with specific thickness ratios and compositions, including amorphous carbon and a binder, to facilitate lithium ion transport and prevent dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal is used as a negative electrode to increase energy density, then energy density is improved, but lithium volume expansion and irreversible dendrite growth occur during charge and discharge
Solution Approach 1:
The patent introduces a solid electrolyte layer as an intermediary between the lithium metal negative electrode and the positive electrode. This solid electrolyte acts as a mediator that physically blocks dendrite growth while still allowing lithium ion transport, thus resolving the contradiction between achieving high energy density with lithium metal and preventing dendrite-induced short circuits.
Solution Approach 2:
The patent changes the physical state parameter of the electrolyte from liquid to solid, and optimizes specific parameters such as the solid electrolyte layer thickness (5-50 μm) and composition (sulfide-based solid electrolyte). This parameter change enables the electrolyte to mechanically suppress dendrite growth while maintaining ionic conductivity, thereby resolving the reliability issue while preserving high energy density.
2Reliability
If a lithium deposition layer is formed on the negative electrode current collector to avoid using lithium metal, then dendrite growth is reduced, but power characteristics deteriorate and short-circuit phenomena occur
Solution Approach 1:
The patent employs a composite structure consisting of a current collector, a lithium deposition layer, and a solid electrolyte layer. This composite material approach allows the system to benefit from the dendrite-suppressing effect of the solid electrolyte while maintaining the electrical conductivity and power characteristics provided by the current collector and lithium deposition layer, thus resolving the contradiction between reliability and power performance.
3Reliability
If the ion transport layer thickness is increased to improve lithium ion transport, then electrochemical performance is improved, but the thickness ratio with the negative coating layer deviates from the optimal 1:0.1 to 1:0.5 range
Solution Approach 1:
The patent optimizes the thickness parameters of both the negative coating layer (5-50 μm) and the ion transport layer (0.5-5 μm) to achieve the optimal thickness ratio range of 1:0.1 to 1:0.5. This parameter optimization ensures that the ion transport layer is sufficiently thick to provide effective dendrite suppression and lithium ion transport pathways, while the negative coating layer maintains appropriate thickness for electrical conductivity and lithium deposition, thus resolving the contradiction between electrochemical performance and structural proportion.
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 enhances electrochemical properties by suppressing overvoltage and dendrite growth, improving charge/discharge efficiency and cycle-life characteristics of the battery.
Implementation Method 1
an ion transport layer; and a negative coating layer located between the current collector and the ion transport layer
Implementation Method 2
including first amorphous carbon, a metal, and a first binder... The first amorphous carbon may have a BET surface area of greater than 50 m2/g and less than 1500 m2/g
Data Source
AI summary
The present invention relates to a negative electrode for an all-solid-state battery and an all-solid-state battery comprising same, and the negative electrode for an all-solid-state battery comprises: a current collector, an ion transport layer, and a negative coating layer positioned between the current collector and the ion transport layer and comprising first amorphous carbon, metal, and a first binder, wherein a thickness ratio of the negative coating layer and the ion transport layer is 1:0.1 to 1:0.5.