Multilayer Sulfide Solid Electrolyte for Uniform Lithium Plating
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Solution Overview
Problem
Lithium secondary batteries face issues with non-uniform lithium-ion plating on the lithium metal negative electrode, leading to dendrite formation and short-circuits due to varying resistance in the solid electrolyte layer during charging and discharging cycles.
Innovation Solution
A solid-state battery design with a multilayer solid electrolyte structure, where the first electrolyte layer facing the positive electrode has a higher resistance and the second electrolyte layer facing the negative electrode has a lower resistance, using sulfide-based solid electrolytes with different average particle diameters and contents to control lithium-ion plating uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a solid electrolyte layer with uniform resistance is used, then the battery structure is simple, but lithium ions cannot be plated uniformly on the lithium metal negative electrode during charging/discharging cycles
Solution Approach 1:
The solid electrolyte layer is divided into multiple layers with different resistance values. The first solid electrolyte layer (facing the positive electrode) has a first resistance value, while the second solid electrolyte layer (facing the negative electrode) has a second resistance value that is different from the first. This segmentation allows different regions of the electrolyte to perform different functions in controlling lithium-ion transport, thereby achieving uniform plating on the lithium metal negative electrode.
Solution Approach 2:
Different portions of the solid electrolyte are given different electrical resistance properties. The first solid electrolyte layer has a specific resistance characteristic optimized for its position near the positive electrode, while the second solid electrolyte layer has a different resistance characteristic optimized for its position near the negative electrode. This local differentiation of properties enables precise control over lithium-ion flux distribution, resulting in uniform plating.
2Reliability
If a single-layer solid electrolyte is used, then the device complexity is low, but lithium dendrite forms on the lithium metal negative electrode causing short-circuit
Solution Approach 1:
The solid electrolyte is segmented into multiple layers with different resistance values to prevent dendrite formation. The first solid electrolyte layer and second solid electrolyte layer work together to create a more controlled environment for lithium-ion transport, preventing the formation of dendrites that would otherwise cause short-circuits during charging/discharging cycles.
Solution Approach 2:
The multi-layer solid electrolyte structure acts as a preventive measure against dendrite formation. By having different resistance values in different layers, the system creates a buffer that prevents the concentration gradients and stress conditions that lead to dendrite growth, thereby cushioning against the harmful effect of short-circuits before they can occur.
3Manufacturing precision
If the solid electrolyte resistance varies during cycling, then the battery can operate, but lithium ions cannot be plated uniformly leading to dendrite formation
Solution Approach 1:
By dividing the solid electrolyte into multiple layers with different resistance values, the system can accommodate resistance variations during cycling. Each layer responds differently to changes in operating conditions, and their combined effect maintains more stable and uniform lithium-ion plating on the negative electrode compared to a single-layer structure.
Solution Approach 2:
Different layers of the solid electrolyte have different resistance properties that are optimized for their specific positions and functions. This local quality differentiation allows the system to maintain uniform lithium deposition even when overall resistance varies during charging/discharging cycles, as each layer compensates for resistance changes in a way that promotes uniform plating.
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 controlled lithium-ion plating rate reduces dendrite formation, delaying the occurrence of short-circuits and improving the cycle characteristics of the battery by ensuring uniform lithium deposition on the negative electrode.
Implementation Method 1
the second solid electrolyte layer shows a lower electrical resistance than the electrical resistance of the first solid electrolyte layer
Data Source
AI summary
Disclosed is a solid-state battery which includes a positive electrode, a negative electrode and a solid electrolyte membrane interposed between the positive electrode and the negative electrode, wherein the solid electrolyte membrane includes a first solid electrolyte layer and a second solid electrolyte layer, the first solid electrolyte layer faces the positive electrode, the first solid electrolyte layer includes a first sulfide-based solid electrolyte, the second solid electrolyte layer includes a second sulfide-based solid electrolyte, and the second sulfide-based solid electrolyte has an average particle diameter (D50) larger than the average particle diameter (D50) of the first sulfide-based solid electrolyte. In the solid-state battery, it is possible to control the lithium-ion plating rate on a lithium metal negative electrode uniformly so that lithium-ion may be plated uniformly, and thus to reduce dendrite formation.