Fluoride-Coated Electrode Material for Stable Sulfide Interfaces
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Solution Overview
Problem
Sulfide solid electrolytes in all-solid-state batteries degrade when in direct contact with active materials, leading to impaired ion-conductive properties and increased post-endurance resistance due to inadequate interface formation between oxide and sulfide solid electrolytes during the manufacturing process.
Innovation Solution
A method involving a fluoride solid electrolyte coating on active materials, followed by adherence of sulfide solid electrolyte, using a wet process with high-shear mixing and controlled solvent addition to ensure stable interface formation and prevent fluoride electrolyte detachment, resulting in an electrode material with a solid concentration of 72% or more, which reduces post-endurance resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide SE is used to cover composite particles in dry process, then mechanical load is applied to the surface, but oxide SE comes off and active material contacts sulfide SE directly
Solution Approach 1:
A fluoride solid electrolyte is introduced as an intermediate layer between the oxide SE and sulfide SE. This fluoride SE layer prevents direct contact between oxide SE and sulfide SE, eliminating the degradation reaction, while also preventing oxide SE from coming off during dry process mixing by providing a stable intermediate interface.
2Strength
If wet process is used to cover composite particles with sulfide SE, then mechanical load is reduced, but interface formation between oxide SE and sulfide SE is insufficient
Solution Approach 1:
The fluoride SE serves as a mediator that facilitates interface formation between oxide SE and sulfide SE in the wet process. The fluoride SE has compatibility with both oxide SE and sulfide SE, enabling stable interface formation even in the presence of solvent, thus achieving both good adhesion and reliable interface quality.
3Reliability
If fluoride SE is used to cover active material, then interface formation with sulfide SE is facilitated, but fluoride SE may detach during mixing
Solution Approach 1:
The fluoride SE is pre-coated on the active material surface before sulfide SE addition, creating a stable foundation layer. This preliminary action ensures that when sulfide SE is added later, the interface formation occurs on a stable fluoride SE surface, preventing detachment during subsequent mixing operations.
4Productivity
If solid concentration is increased to 72% or more, then stable high-shear mixing is achieved, but dense coverage of sulfide SE on composite particle surface is required
Solution Approach 1:
The solid concentration is optimized to 72% or more, which provides stable high-shear mixing conditions. Combined with the fluoride SE intermediate layer that ensures uniform distribution and adhesion, this parameter change enables both mixing stability and dense sulfide SE coverage on composite particle surfaces.
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 approach enables stable high-shear mixing and dense sulfide solid electrolyte coverage, effectively reducing post-endurance resistance increments in all-solid-state batteries by facilitating robust interface formation between fluoride and sulfide solid electrolytes.
Implementation Method 1
The composite particle includes an active material and a fluoride solid electrolyte. The fluoride solid electrolyte covers at least part of a surface of the active material.
Implementation Method 2
The sulfide solid electrolyte is adhered to the composite particle. In wet process, interface formation between oxide SE and sulfide SE tends not to proceed. However, interface formation between fluoride SE and sulfide SE may relatively readily proceed even in a wet process.
Implementation Method 3
Stable high-shear mixing of the electrode material tends to be achieved. Stable high-shear mixing allows for dense covering of the surface of the composite particle with the sulfide SE.
Implementation Method 4
In wet process, the presence of solvent (liquid) may reduce the mechanical load applied to the surface of the composite particles.
Data Source
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AI summary
An electrode material has a solid concentration of 72% or more. It includes a composite particle, a sulfide solid electrolyte, and a solvent. The composite particle includes an active material and a fluoride solid electrolyte. The fluoride solid electrolyte covers at least part of a surface of the active material. The sulfide solid electrolyte is adhered to the composite particle.