Coated Conversion Cathodes for High Energy Density
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Solution Overview
Problem
Conventional lithium-ion batteries have high costs and low energy density, failing to meet market demands for many applications, while conversion material batteries offer lower costs and higher energy density but require performance improvements.
Innovation Solution
The development of an energy storage device with a cathode comprising coated electrochemically active material particles, where the coating selectively isolates the conversion material from the electrolyte, enhancing ion conductivity and capacity, and includes a sulfide, oxide, halide, or phosphide conversion material with a lithium compound and metal component, such as ferric fluoride, coated with aluminum oxide or fluoride using methods like atomic layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conversion material is used in cathodes, then energy density and cost are improved, but performance stability and cycle life deteriorate due to metal loss and electrolyte interaction
Solution Approach 1:
A protective coating layer is introduced as an intermediary between the conversion material and the electrolyte. This coating prevents direct contact and harmful interactions while allowing ionic conduction, thereby maintaining the high energy density benefits of conversion materials while improving cycle life and performance stability.
Solution Approach 2:
A thin film coating is applied to the surface of the conversion material particles. This flexible shell provides protection against metal loss and electrolyte degradation without significantly increasing particle size or compromising the electrochemical performance, enabling both high energy density and improved reliability.
2Reliability
If conversion material particles are coated with protective layers, then cycle life and performance stability are improved, but ion conductivity may deteriorate due to coating barriers
Solution Approach 1:
The protective coating is designed with a porous structure that allows lithium ions to diffuse through while providing mechanical protection and preventing metal loss. The porosity ensures that ion conductivity is maintained despite the presence of the protective layer, resolving the contradiction between reliability improvement and ion transport.
Solution Approach 2:
The coating parameters such as thickness, porosity, and material composition are optimized to balance protection and ion conductivity. By adjusting these parameters, the coating provides sufficient protection for improved cycle life while maintaining adequate ion transport pathways for high conductivity.
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 coated cathode materials exhibit increased capacity and ion conductivity, achieving energy densities of up to 2500 Wh/kg and maintaining high performance over multiple cycles, with improved efficiency and cycle life due to the protective coating preventing metal loss and electrolyte interaction.
Implementation Method 1
the coating selectively isolates the conversion material from the electrolyte
Implementation Method 2
the coating selectively isolates the conversion material from the electrolyte... exhibiting increased capacity and ion conductivity
Data Source
AI summary
Battery systems using coated conversion materials as the active material in battery cathodes are provided herein. Protective coatings may be an oxide, phosphate, or fluoride, and may be lithiated. The coating may selectively isolate the conversion material from the electrolyte. Methods for fabricating batteries and battery systems with coated conversion material are also provided herein.