Solid-State Battery V-Gradient Electrolyte for Leakage and Cycle
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Solution Overview
Problem
Solid-state batteries with oxide-based negative electrodes and LISICON-type solid electrolytes face challenges in achieving both high energy density and storage characteristics due to low cycle retention rates and excessive leakage currents, which hinder their performance.
Innovation Solution
A solid-state battery design incorporating a negative electrode layer with a molar ratio of Li to V of 2.0 or more, combined with a solid electrolyte layer having a LISICON-type structure and a varying ratio of V, specifically in the vicinity of the negative electrode, to enhance cycle characteristics and leakage resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative electrode layer containing V and a solid electrolyte layer containing V are combined, then bondability is improved and side reactions are suppressed, but cycle characteristics deteriorate with low capacity retention rate
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of V ratio within the solid electrolyte layer. The V ratio varies from 0.1 to 0.9 in the thickness direction, with higher V content near the negative electrode to suppress side reactions and improve bondability, and lower V content toward the positive electrode to maintain capacity retention and cycle characteristics.
Solution Approach 2:
The patent changes the chemical composition parameter (V ratio) spatially within the solid electrolyte layer. By controlling the V ratio to vary in the thickness direction with a change amount of 0.20 or more, the patent optimizes both bondability (high V near negative electrode) and cycle characteristics (lower V toward positive electrode) simultaneously.
2Reliability
If a negative electrode layer containing V and a solid electrolyte layer containing V are combined, then leakage resistance is improved, but storage characteristics deteriorate with excessive leakage current
Solution Approach 1:
The patent applies local quality by concentrating higher V content (ratio of 0.5 to 0.9) in the region adjacent to the negative electrode, where leakage reactions occur. This localized high V content suppresses leakage current and improves leakage resistance, while the lower V content elsewhere in the layer prevents excessive energy loss during storage.
Solution Approach 2:
The patent changes the V ratio parameter throughout the solid electrolyte layer thickness, with a change amount of 0.20 or more. This parameter gradient allows the system to achieve low leakage current (improved leakage resistance) while maintaining acceptable storage characteristics by not having uniformly high V content throughout the layer.
3Quantity of substance
If V ratio in solid electrolyte is increased to suppress side reactions, then energy density improves, but capacity retention rate decreases
Solution Approach 1:
The patent applies local quality by spatially differentiating the V ratio within the solid electrolyte layer. Higher V content (0.5 to 0.9) near the negative electrode increases energy density and suppresses side reactions, while lower V content toward the positive electrode preserves capacity retention rate, achieving both goals simultaneously through localized composition optimization.
Solution Approach 2:
The patent changes the V ratio parameter in the thickness direction of the solid electrolyte layer with a change amount of 0.20 or more. This gradient allows the system to achieve high energy density (through high V content regions) while maintaining good capacity retention (through lower V content regions), resolving the contradiction between these two parameters.
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 proposed design significantly improves cycle characteristics and leakage resistance, leading to better energy density and storage performance by optimizing the bondability and reducing side reactions during co-sintering.
Implementation Method 1
suppress a side reaction during co-sintering
Implementation Method 2
a solid electrolyte having a lithium super ionic conductor (LISICON)-type structure
Data Source
AI summary
A solid-state battery including: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer. The negative electrode layer contains a negative electrode active material in which a molar ratio of Li to V is 2.0 or more, the solid electrolyte layer contains a solid electrolyte having a lithium super ionic conductor structure and containing at least V, and a ratio y of V in the solid electrolyte changes by a change amount of 0.20 or more in a thickness direction of the solid electrolyte layer.