Coated Cathode Materials for Stable Sulfide Solid-State Batteries
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Solution Overview
Problem
Sulfide-based solid electrolytes in all-solid-state batteries are highly reactive with oxide cathode active materials, leading to side reactions and deterioration of electrochemical characteristics, and current coating materials like Li2ZrO3 and LiNbO3 are expensive, making them unsuitable for mass production.
Innovation Solution
A cathode for all-solid-state batteries is developed using a composite particle with a core cathode active material coated with a thin shell layer composed of inexpensive lithium and boron/phosphorus-based materials (Li2+xBxO3 and Li2+yPyO4), which suppresses side reactions and improves battery performance by preventing direct contact with sulfide-based solid electrolytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to prevent side reactions between cathode active material and sulfide-based solid electrolyte, then electrochemical characteristics are improved, but manufacturing cost increases due to expensive coating materials
Solution Approach 1:
The patent replaces expensive coating materials (Li2ZrO3, LiNbO3, LiTaO3) with inexpensive alternatives (Li2SiO3, Li2TiO3, Li2VO3, Li2CrO3, Li2MnO3, Li2FeO3, Li2CoO3, Li2NiO3, Li2CuO3, Li2ZnO3, Li2AlO3, Li2GaO3, Li2InO3). This substitution maintains the protective function of preventing side reactions between the cathode active material and sulfide-based solid electrolyte while dramatically reducing manufacturing costs, making the all-solid-state batteries economically viable for mass production
Solution Approach 2:
The patent changes the chemical composition parameters of the coating material from traditional expensive oxides (zirconium, niobium, tantalum-based) to inexpensive oxide alternatives (silicon, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, aluminum, gallium, indium-based). This parameter change in material composition achieves the same protective function at lower cost, resolving the contradiction between reliability improvement and manufacturing cost reduction
2Manufacturing precision
If alkoxide-based precursor materials are used to coat cathode active material thinly and uniformly, then coating quality is improved, but manufacturing cost increases and mass production becomes difficult
Solution Approach 1:
The patent replaces expensive alkoxide-based precursor materials with inexpensive oxide-based precursor materials for the coating process. This substitution maintains the ability to form thin and uniform coating layers (0.5-50 nm thickness) while reducing material costs and improving suitability for mass production, as the inexpensive precursors can be processed using conventional manufacturing techniques
3Stability of the object's composition
If electron conductivity of coating material is reduced to prevent decomposition of sulfide-based solid electrolyte, then stability is improved, but lithium ion conductivity may be affected
Solution Approach 1:
The patent applies the local quality principle by designing a coating layer with specific dual properties: low electron conductivity to prevent decomposition of the sulfide-based solid electrolyte, while maintaining sufficient lithium ion conductivity to allow ion transport. The selected inexpensive oxide materials (Li2SiO3, Li2TiO3, Li2VO3, etc.) inherently possess this dual characteristic, creating a localized functional barrier that protects the interface while permitting necessary ion transport
Solution Approach 2:
The patent utilizes composite material characteristics of the coating layer, combining the protective function (low electron conductivity) with the transport function (lithium ion conductivity). The oxide-based coating materials form a composite structure at the interface between the cathode active material and sulfide-based solid electrolyte, achieving both stability and ion conductivity requirements simultaneously
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 use of inexpensive precursor materials allows for a thin and uniform coating that reduces internal resistance and enhances battery performance by preventing side reactions, thereby improving charge/discharge capacity and efficiency.
Implementation Method 1
the shell portion may include a first material represented by Chemical Formula 1 below and a second material represented by Chemical Formula 2 below... suppresses side reactions and improves battery performance by preventing direct contact with sulfide-based solid electrolytes
Implementation Method 2
a cathode for all-solid-state batteries is developed using a composite particle with a core cathode active material coated with a thin shell layer... In order to coat the cathode active material thinly and uniformly
Data Source
AI summary
Disclosed are a cathode for an all-solid-state battery including a composite-coated or double-coated cathode active material and a method of manufacturing the same.