Composite Alkali Metal Anode for Open-Air Battery Assembly
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Solution Overview
Problem
The high ambient reactivity of alkali metals, such as sodium and lithium, during battery cell assembly has prevented the widespread use of metallic anodes in rechargeable batteries, despite their high theoretical capacity and low cost, due to impractical electrolyte compositions, complex substrate preparation, and irreproducible Coulombic efficiency.
Innovation Solution
A composite anode material comprising a matrix material and a distributed material, where the matrix material has a lower melting point than the distributed material, is used to create a stable anode for electrochemical cells, allowing assembly in a dry room or open air environment, with optional halogenated electrolyte additives for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metallic sodium anodes are used to achieve high theoretical capacity and low cost, then energy density and manufacturing cost are improved, but ambient reactivity during assembly prevents reliable manufacturing
Solution Approach 1:
A liquid metal alloy intermediate layer is introduced between the sodium anode and electrolyte. This intermediate layer acts as a mediator that reduces the reactivity of metallic sodium with the electrolyte and atmosphere during assembly, while still allowing efficient sodium ion transfer during operation. The intermediate layer protects the highly reactive sodium from direct exposure to harmful environments.
Solution Approach 2:
The invention changes the physical and chemical parameters of the anode system by using liquid metal alloys with specific compositions and melting points. By selecting alloys with appropriate melting points below operating temperature, the system achieves a liquid state that enhances ion conductivity and reduces interfacial resistance, while the specific alloy composition controls reactivity with the electrolyte.
2Ease of manufacture
If discharged state assembly with electro-deposition is used to reduce reactivity issues, then manufacturing safety is improved, but impractical electrolyte composition and complicated substrate preparation increase device complexity
Solution Approach 1:
The liquid metal alloy anode performs multiple functions simultaneously: it serves as the active sodium source, provides a self-forming protective interface with the electrolyte, and eliminates the need for separate substrate preparation steps. The alloy self-organizes at the interface, creating a stable, reactive intermediate layer without requiring additional processing or specialized substrates.
Solution Approach 2:
The liquid metal alloy layer serves multiple functions: (1) as the active sodium source for ion transfer, (2) as a protective barrier reducing reactivity with electrolyte and atmosphere, (3) as a self-healing interface that maintains contact during cycling, and (4) as a simplifying element that eliminates complex substrate preparation requirements.
3Use of energy by moving object
If conventional metallic anodes are used to achieve high capacity, then energy density is improved, but irreproducible Coulombic efficiency data indicates poor manufacturing precision
Solution Approach 1:
The invention uses a composite liquid metal alloy system combining sodium with other metals (such as potassium, lithium, or alkaline earth metals). This composite structure provides consistent electrochemical behavior, stable interface formation with the electrolyte, and reproducible Coulombic efficiency. The composite nature ensures uniform properties across different manufacturing batches.
Solution Approach 2:
By changing the composition parameters of the liquid metal alloy and controlling the melting point parameter below operating temperature, the invention achieves consistent phase state and interfacial properties. These controlled parameter changes lead to reproducible electrochemical performance and Coulombic efficiency across different manufacturing runs.
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 composite anode material enables efficient electro-deposition and stripping of metallic alkali metals, providing improved Coulombic efficiency, reduced electrode-electrolyte interface resistance, and stable cycling performance, suitable for both discharged and charged state assembled battery cells.
Implementation Method 1
The matrix material may have a lower melting point than the distributed material
Implementation Method 2
Successful development of such an anode is beneficial to commerce and industry. The disclosed anode material, anode and anode production method allows electrochemical cell assembly to be carried out in a dry room or even open air environment.
Implementation Method 3
metallic anodes do not require solid-state diffusion of ions to transfer material from the charged to the discharged state, but merely the successful deposition/dissolution of the ions to/from the surface of the metal
Data Source
AI summary
An anode material for an electrochemical cell comprises a matrix material:distributed material composite, which comprises one or more alkali metals and/or alkali earth metals. The distributed material may comprise a metal other than that of the matrix material, such as a transition and/or post transition metal. The anode material may be all or part of an anode for an electrochemical cell, which may further comprises a current collector and/or an SEI layer. The electrolyte may comprises an alkali metal and/or alkali earth metal and/or a transition metal and/or post transition metal containing electrolyte salt. The matrix material and/or the distributed material may comprise one or more of the metals of the electrolyte salt. All or part of the anode may be used as a substrate for electro-deposition of one or more matrix materials during charging and/or all or part of the anode may be used as a source of matrix material during discharging. The electrolyte may further comprise one or more electrolyte additives. The anode material may be produced by mixing a matrix material and distributed material and heating the mixture to selectively melt the matrix material to produce a matrix material:distributed material composite. The composite may be further chemically or mechanically processed to reduce the size of the distributed material and/or to increase the homogeneity of the matrix material:distributed material composite. The anode material, the anode or the electrochemical cell may be used in a device.