Fluorinated Sulfide Electrolyte with Oxide Coating for All-Solid Batteries
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Solution Overview
Problem
Existing all-solid batteries face challenges in reducing interface resistance between electrode active materials and solid electrolytes, leading to decreased battery performance due to reactions that form high-resistance portions, particularly when using sulfide-based solid electrolytes.
Innovation Solution
Incorporating a sulfide-based solid electrolyte material with fluorine, ranging from 0.1 to 20 mole percent, that is partially fluorinated and contains phosphorus, along with an oxide coating on the electrode active material to suppress reaction-induced resistance and enhance electrochemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a sulfide-based solid electrolyte material is used to increase lithium ion conductivity, then battery power is improved, but interface resistance increases due to reaction between the positive electrode active material and the solid electrolyte material
Solution Approach 1:
An oxide coating layer is introduced as an intermediary between the positive electrode active material and the sulfide-based solid electrolyte material. This coating layer prevents direct contact and reaction between the two materials, thereby reducing interface resistance while allowing lithium ion transport to continue through the sulfide-based electrolyte, maintaining high battery power.
Solution Approach 2:
The invention creates a composite structure consisting of the positive electrode active material, the oxide coating layer, and the sulfide-based solid electrolyte material. This composite approach combines the high lithium ion conductivity of sulfide-based electrolytes with the reaction-blocking properties of oxide coatings, achieving both high power and low interface resistance.
2Ease of manufacture
If the positive electrode layer is formed by powder molding using only positive electrode active material, then manufacturing is simplified, but the electrolyte cannot permeate into the positive electrode layer, reducing interface area and deteriorating battery performance
Solution Approach 1:
Instead of uniformly mixing the solid electrolyte material throughout the positive electrode active material, the invention applies the solid electrolyte material and oxide coating locally on the surface of the positive electrode active material particles. This localized application increases the interface area between electrode and electrolyte, improving battery performance while maintaining a relatively simple manufacturing process.
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 approach effectively reduces interface resistance and improves the durability and performance of all-solid batteries by preventing the formation of high-resistance portions, thereby maintaining output and extending battery life.
Implementation Method 1
A sulfide-based solid electrolyte material has a high lithium ion conductivity
Implementation Method 2
the surface of LiCoO2 is coated with LiNbO3 to suppress reaction between LiCoO2 and the solid electrolyte material
Data Source
Figure 1~2
Figure 3~4B
Figure 5~6
AI summary
A solid electrolyte material that can react with an electrode active material to forms a high-resistance portion includes fluorine.