Solid-State Battery Anode Layering to Protect the Electrolyte
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Solution Overview
Problem
Conventional solid-state batteries face low capacity retention rates due to reductive decomposition of the solid electrolyte layer during charging and discharging, leading to increased interfacial resistance.
Innovation Solution
The solid-state battery is structured with a negative electrode active material layer comprising Li, Li-Mg, Li-Mg-X, or Li-X layers in specific orders, with Li-X layers formed on the surface of the solid electrolyte layer, preventing direct contact and reducing reductive decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metallic lithium is deposited directly between the coating layer and solid electrolyte layer during charging, then the battery can achieve high capacity, but the capacity retention rate decreases due to reductive decomposition of the solid electrolyte layer
Solution Approach 1:
An Li-X layer (where X is Sn, Zn, or Al) is introduced as an intermediary layer between the Li-Mg layer and the solid electrolyte layer. This intermediary layer prevents direct contact between metallic lithium and the solid electrolyte, thereby suppressing reductive decomposition reactions while still allowing lithium ion diffusion. The Li-X layer acts as a protective mediator that maintains both high capacity and good capacity retention.
Solution Approach 2:
The negative electrode active material layer is designed as a composite structure comprising multiple layers: Li-Mg layer (or Li-Mg-X layer) and Li-X layer. This composite structure combines the high capacity benefits of metallic lithium deposition with the protective effects of the Li-X layer, achieving both high capacity and high capacity retention rate simultaneously.
2Device complexity
If a zinc layer is formed by sputtering on the negative electrode current collector, then the battery structure can be simplified, but interfacial resistance increases leading to poor capacity retention
Solution Approach 1:
The patent employs a composite negative electrode active material layer structure consisting of Li-Mg layer (or Li-Mg-X layer) and Li-X layer. This composite structure provides both electrical conductivity and protection against solid electrolyte decomposition, achieving good capacity retention without excessive structural complexity.
Solution Approach 2:
The invention changes the compositional parameters of the negative electrode active material layer by incorporating specific elements (Mg, Sn, Zn, or Al) to form Li-Mg and Li-X layers. This parameter change transforms the layer's properties to simultaneously provide conductivity and protection, improving capacity retention while maintaining reasonable structural complexity.
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 enhances the capacity retention rate by minimizing interfacial resistance and facilitating easier lithium ion diffusion, resulting in improved battery performance.
Implementation Method 1
the Li-X layer is formed on a surface of the solid electrolyte layer... preventing direct contact and reducing reductive decomposition
Implementation Method 2
facilitating easier lithium ion diffusion
Data Source
AI summary
A solid-state battery of the present disclosure includes a positive electrode layer, a solid electrolyte layer, and a negative electrode layer in this order. The negative electrode layer has a negative electrode current collector and a negative electrode active material layer in this order, in a direction from the negative electrode layer toward a side of the solid electrolyte layer. When the solid-state battery is at full charge, the negative electrode active material layer has an Li layer, an Li-Mg layer, or an Li-Mg-X layer and an Li-X layer in this order, in the direction from the negative electrode layer toward the side of the solid electrolyte layer. X is at least one selected from the group consisting of Sn, Zn, and Al. The Li-X layer is formed on a surface of the solid electrolyte layer.