Sulfide All-Solid Battery Sulfur Compound Layer
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Solution Overview
Problem
In all-solid batteries with sulfide solid electrolytes, the reaction between metals used in negative electrode current collectors and sulfide solid electrolytes increases electronic conduction resistance, affecting battery performance.
Innovation Solution
Incorporating a sulfur compound layer formed by the reaction between the sulfide solid electrolyte and metal in the negative electrode current collector, with specific metals like Cu, Fe, Ni, or Ti, and optimizing the sulfur compound generation to improve output, particularly in the low SOC region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a metal current collector (Cu, Fe, Ni, Ti) is used in the negative electrode, then electrical conductivity and ease of manufacture are improved, but electronic conduction resistance increases due to reaction with sulfide solid electrolyte
Solution Approach 1:
An aluminum oxide layer is formed on the surface of the metal current collector to act as an intermediary barrier between the metal and the sulfide solid electrolyte. This oxide layer prevents direct contact and reaction between the metal current collector and sulfide solid electrolyte, thereby maintaining low electronic conduction resistance while preserving the electrical conductivity of the metal current collector
Solution Approach 2:
The current collector structure is designed as a composite material system consisting of a metal base layer (Cu, Fe, Ni, or Ti) coated with an aluminum oxide layer. This composite structure combines the high electrical conductivity of the metal with the protective and insulating properties of the aluminum oxide coating, resolving the contradiction between conductivity and resistance
2Productivity
If sulfide solid electrolyte is used in the negative electrode layer, then battery output and energy density are improved, but reaction with metal current collector increases internal resistance
Solution Approach 1:
The aluminum oxide layer serves as a protective intermediary that allows the sulfide solid electrolyte to maintain its high output performance while preventing harmful reactions with the metal current collector. This enables the system to achieve high battery output without the penalty of increased internal resistance from metal-sulfide reactions
3Ease of operation
If metal current collector reacts with sulfide solid electrolyte, then interface formation occurs, but electronic conduction resistance increases and performance deteriorates
Solution Approach 1:
The aluminum oxide layer is introduced as a controlled interface intermediary that replaces the uncontrolled metal-sulfide reaction interface. This oxide layer interface maintains ease of manufacturing and assembly while preventing the chemical reactions that would otherwise degrade battery performance through increased electronic conduction 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
Enhances the output of all-solid batteries by optimizing the reaction between the sulfide solid electrolyte and metal current collector, improving charge capacity and reducing internal resistance.
Implementation Method 1
a sulfur compound layer that contains a sulfur compound generated by a reaction of the sulfide solid electrolyte contained in the negative electrode layer and the metal contained in the negative electrode current collector
Data Source
AI summary
An all-solid battery that includes a negative electrode layer, a positive electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, a negative electrode current collector connected to the negative electrode layer, and a positive electrode current collector connected to the positive electrode layer, wherein the negative electrode layer contains a sulfide solid electrolyte, the negative electrode current collector contains a metal that reacts with the sulfide solid electrolyte, a sulfur compound layer that contains a sulfur compound generated by a reaction of the sulfide solid electrolyte and the metal is present between the negative electrode layer and the negative electrode current collector, charge capacity when constant current charge was conducted up to 3.6 V at 0.3 C or more and 3.6 C or less in an initial charge after preparation of the all-solid battery is 50 mAh/g or more and 90 mAh/g or less.