Solid-Liquid Alloy Electrodes for High-Current Lithium Metal Anodes
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Solution Overview
Problem
Lithium-ion batteries face limitations in energy density and charging time due to low critical current density and mechanical instability at the electrode-electrolyte interface, leading to dendrite formation and reduced cycle life.
Innovation Solution
The use of an electrochemical device with an electrode comprising an alloy that has both a solid and liquid phase, specifically designed to operate at room temperature, which includes alkali metals like lithium, sodium, and potassium, allowing for increased mechanical softness and higher critical current densities by adjusting the composition and phase ratio of the solid and liquid phases during charge and discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal based anodes are used to improve energy density, then energy density is improved, but plating current density is limited below 1 mA/cm2
Solution Approach 1:
The patent changes the physical state parameter of the electrode material from purely solid to a composite solid-liquid system. By incorporating a eutectic alloy composition that melts at or below room temperature, the electrode achieves a liquid phase that enables higher ion transport kinetics and current density while maintaining the high capacity benefits of lithium metal.
Solution Approach 2:
The patent creates a composite electrode structure combining solid lithium metal or alloy particles with a eutectic liquid phase. This composite approach allows the solid phase to provide high capacity while the liquid phase provides enhanced ion conductivity and accommodation of volume changes, enabling current densities above 1 mA/cm2 without sacrificing energy density.
2Use of energy by moving object
If high areal capacity cathodes are used to increase energy density, then energy density is improved, but charging time increases due to limited current density
Solution Approach 1:
By changing the electrode from solid to solid-liquid composite, the patent enables faster charging kinetics. The liquid phase reduces resistance and facilitates rapid ion transport, allowing high areal capacity cathodes to be charged at higher current densities without excessive time loss.
3Stability of the object's composition
If solid phase alloys are used to maintain structural stability, then mechanical stability is improved, but ion mobility and current density are reduced
Solution Approach 1:
The patent exploits the phase transition parameter by using a eutectic composition that is solid at lower temperatures but becomes liquid at operating temperatures. This temperature-dependent phase change allows the material to provide structural stability when needed while enabling high ion mobility during electrochemical operation.
Solution Approach 2:
The composite solid-liquid structure allows the solid phase to provide mechanical framework and structural stability while the liquid phase provides channels for rapid ion transport. The two phases work synergistically to simultaneously achieve mechanical stability and high ion mobility.
4Use of energy by moving object
If pure lithium metal is used to maximize energy density, then energy density is improved, but dendrite formation and interface instability increase
Solution Approach 1:
The patent uses a composite structure where lithium metal or alloy particles are dispersed in a eutectic liquid phase. This composite approach maintains the high capacity of lithium while the liquid matrix prevents dendrite formation by accommodating volume changes and providing uniform ion distribution, thereby improving interface stability and reliability.
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
This approach enhances energy density and current density while reducing the risk of dendrite-induced short circuits, enabling high areal capacities and extended cycle life, with the alloy's mechanical properties facilitating a stable interface and improved ion mobility.
Implementation Method 1
the alloy has a solid phase and a liquid phase at a temperature between or equal to 15° C. and 30° C.
Implementation Method 2
a method of operating an electrochemical device comprises charging and/or discharging an electrochemical device
Data Source
AI summary
Electrochemical devices, and associated materials and methods, are generally described. In some embodiments, an electrochemical device comprises an electroactive material. The electroactive material may comprise an alloy having a solid phase and a liquid phase that co-exist with each other. As a result, such a composite electrode may have, in some cases, the mechanical softness to permit both high energy densities and an improved current density as compared to, for example, a substantially pure metal electrode.