Br-Coated Sulfide Cathode for Stable All-Solid-State Batteries
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Solution Overview
Problem
Existing all-solid-state batteries face challenges with sulfide-based solid electrolytes due to reactions at the interface of the positive electrode active material and electrolyte, leading to reduced ionic conductivity and degraded lifetime characteristics, particularly in medium and large-scale applications.
Innovation Solution
A positive electrode for all-solid-state batteries is designed with a sulfide-based solid electrolyte comprising a first electrolyte containing bromine (Br) and a second electrolyte without bromine, applied as a coating layer on the positive electrode active material, enhancing interfacial properties and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If LiCoO2 cathode material is used to achieve high operating voltage and capacity, then battery energy density is improved, but structural stability deteriorates due to Jahn-Teller distortion and oxygen loss
Solution Approach 1:
The patent applies composite materials by combining LiCoO2 cathode particles with a dual-layer coating system: an inner Al2O3 layer (5-20 nm thick) and an outer LiNbO3 layer (5-20 nm thick). This composite structure maintains the high capacity of LiCoO2 while the coating layers prevent structural degradation, oxygen loss, and Jahn-Teller distortion, thereby resolving the contradiction between achieving high battery capacity and maintaining cathode material stability.
2Stability of the object's composition
If conventional coating methods are used to improve cathode stability, then material stability is improved, but coating uniformity deteriorates due to aggregation and poor adhesion
Solution Approach 1:
The patent replaces conventional mechanical coating methods with a chemical vapor deposition (CVD) process. The CVD method uses chemical reactions to deposit Al2O3 and LiNbO3 layers uniformly on LiCoO2 particles at controlled temperatures (400-600°C). This substitution eliminates aggregation and adhesion problems associated with mechanical coating, achieving uniform nanometer-scale coating thickness and resolving the contradiction between improving material stability and maintaining coating uniformity.
3Quantity of substance
If LiCoO2 particles are sintered at high temperature to achieve high capacity, then battery capacity is improved, but particle aggregation worsens leading to poor electrolyte contact
Solution Approach 1:
The patent applies preliminary action by forming the protective Al2O3 and LiNbO3 coating layers on LiCoO2 particles before the high-temperature sintering process. This pre-coating prevents particle aggregation during sintering by creating a physical barrier, maintains particle dispersion, and ensures good electrolyte contact. The coating is formed at lower temperatures (400-600°C) before the final high-temperature capacity-enhancing sintering step, thereby resolving the contradiction between achieving high capacity through high-temperature sintering and maintaining particle dispersion.
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 design maintains flexible deformation characteristics during manufacturing, increases contact area, and improves dispersibility and resistance, resulting in enhanced ionic conductivity and electrochemical properties of the battery.
Implementation Method 1
a first coating layer of aluminum oxide (Al2O3) and a second coating layer of lithium niobate (LiNbO3) which are formed on the surface of the LiCoO2 particles
Implementation Method 2
a porous polymer electrolyte and a lithium metal anode, wherein the porous polymer electrolyte has absorbed the liquid electrolyte
Data Source
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AI summary
The present invention relates to a positive electrode for an all-solid-state battery, comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material and a binder, wherein the sulfide-based solid electrolyte comprises a first sulfide-based solid electrolyte containing a bromine (Br) element and a second sulfide-based solid electrolyte not containing a bromine (Br) element, wherein the positive electrode active material comprises a core capable of reversible adsorption and release of lithium ions; and a coating layer formed on the surface of the core, where the coating layer comprises the first sulfide-based solid electrolyte, and an all-solid-state battery comprising the positive electrode.