Core-Shell Cathode Coating for Moisture-Stable Solid-State Batteries
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Solution Overview
Problem
High-nickel cathode materials and halide solid electrolytes in solid-state batteries are sensitive to moisture, and there is a need to enhance the electrochemical performance of Li3InCl6 in halide solid electrolytes.
Innovation Solution
A cathode material with a lithium metal oxide core layer and a solid electrolyte coating layer, where the core layer has a composition of Li[NiaCobMncAld]O2 and the coating layer has a composition of Li3InClxFy, with controlled chlorine and fluorine ratios, is developed using a wet mixing method with an organic solvent to form a uniform core-shell structure, improving moisture resistance and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-nickel cathode materials are used to increase energy density, then the energy density is improved, but the moisture sensitivity increases
Solution Approach 1:
The patent uses composite materials by combining high-nickel cathode material (Li[Ni0.83Co0.05Mn0.12]O2) with solid electrolyte coating (Li3InCl5.5F0.5) to create a core-shell structure. The solid electrolyte coating layer protects the moisture-sensitive high-nickel cathode material while maintaining high energy density, resolving the contradiction between energy density improvement and moisture sensitivity increase.
2Reliability
If halide solid electrolytes are used to improve ion conductivity, then the ion conductivity is improved, but the moisture sensitivity increases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the inner core is the high-nickel cathode material and the outer shell is the solid electrolyte coating. The shell layer provides moisture protection specifically at the interface with the cathode material, allowing the halide solid electrolyte to maintain high ion conductivity while being protected from moisture degradation.
3Reliability
If the thickness of solid electrolyte is reduced to improve battery performance, then the electrochemical performance is improved, but the mechanical strength decreases
Solution Approach 1:
The patent employs a thin film approach by coating the solid electrolyte (Li3InCl5.5F0.5) as a thin shell layer on the cathode material surface. This thin coating provides sufficient electrochemical performance and moisture protection while maintaining mechanical integrity of the overall cathode structure, resolving the contradiction between improved electrochemical performance and reduced mechanical strength.
4Manufacturing precision
If wet mixing method with organic solvent is used to improve dispersion, then the dispersion uniformity is improved, but the processing complexity increases
Solution Approach 1:
The patent uses an organic solvent as an intermediary medium in the wet mixing process. The solvent facilitates uniform dispersion of the solid electrolyte coating material on the cathode material surface, creating a homogeneous core-shell structure. After coating, the solvent is evaporated, leaving the desired uniform coating without requiring complex processing equipment.
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 cathode material achieves high discharge capacity and retention, and the method is cost-effective, energy-efficient, and environmentally friendly, enhancing the electrochemical performance while eliminating moisture sensitivity.
Implementation Method 1
A lithium metal oxide material, a first material and an organic solvent are mixed and heat-treated to form the cathode material. Compared to dry mixing, wet mixing using the organic solvent offers cost efficiency and easy controllability.
Implementation Method 2
The heat treatment has a temperature ranged from 100° C. to 250° C., ensuring that the preparation method of the cathode material is energy-efficient, cost-effective and environmentally friendly.
Implementation Method 3
The cathode material and a preparation method thereof for obtaining a solid electrolyte coating layer through an organic solvent thereby eliminating the adverse effects of moisture on the cathode material
Data Source
AI summary
A cathode material including a plurality of particles. Each of the plurality of particles includes a core layer and a coating layer coated thereon. The core layer includes a lithium metal oxide material having a composition of Li[NiaCobMncAld]O2, wherein a+b+c+d=1, 0<a<1, 0<b<1, 0≤c<1, and 0≤d<1. The coating layer includes a solid electrolyte formed by a reaction of a first material on the core layer. The solid electrolyte has a composition of Li3InClxFy, wherein x+y=6, 0<x<6, and 0<y<6. The lithium metal oxide material, the first material, and a solvent are mixed to form a precursor, and the precursor is heat-treated to form the cathode material. The first material includes lithium, indium, chlorine, and fluorine. The lithium metal oxide material and the solid electrolyte have a weight ratio ranged from 1:0.3 to 1:0.6.