Li-Si-Sn Alloy Anode for Thermal Battery Conductivity
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Solution Overview
Problem
There is a need for anode materials in thermal batteries that improve conductivity, voltage, and lifetime without increasing volume or sacrificing density, as existing lithium-aluminum and lithium-silicon alloys do not effectively contribute to performance.
Innovation Solution
The use of an alloy comprising at least 40 wt% lithium, 25 wt% silicon, and 10 wt% tin, which can be formed into pellets for use as an anode material, providing enhanced conductivity and maintaining a solid state at temperatures up to 600°C, and optionally combined with free lithium as a composite material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If iron powder is added to lithium-aluminum or lithium-silicon alloy powder to increase density and reduce volume, then the density increases, but the iron does not contribute to anode performance and may harm conductivity
Solution Approach 1:
The invention changes the chemical composition parameters of the anode alloy by replacing inert iron powder with reactive tin metal. This substitution transforms the alloying strategy from physical filling (iron) to chemical integration (tin), where tin actively participates in electrochemical reactions while maintaining high density (7.3 g/cm³). The parameter change resolves the contradiction by achieving volume reduction through atomic-level alloying rather than inert filler addition.
Solution Approach 2:
The invention creates a composite anode material system consisting of lithium-silicon-tin alloy with specific weight ratios (Li: 30-70%, Si: 10-40%, Sn: 5-20%). This composite structure combines the high capacity of lithium-silicon alloys with the density and stability contributions of tin, achieving synergistic effects that simultaneously improve density, conductivity, and overall anode performance while reducing volume.
2Quantity of substance
If lithium-silicon alloy is used to increase lithium content, then the capacity increases, but the conductivity and lifetime are insufficient
Solution Approach 1:
The invention applies local quality by introducing tin specifically to address the conductivity deficiency in lithium-silicon alloys. Rather than uniformly modifying all properties, the tin addition locally targets electron transport pathways and interfacial properties, creating regions of enhanced conductivity within the alloy matrix while preserving the high lithium content and capacity characteristics of the lithium-silicon base alloy.
Solution Approach 2:
The invention modifies the alloy composition parameters by adding tin within specific ranges (5-20 wt%) to optimize both conductivity and lifetime. This parameter change transforms the electrochemical properties of the alloy, enhancing electron transport and structural stability during cycling, thereby improving lifetime performance while maintaining high lithium content for capacity.
3Volume of stationary object
If the anode material is designed for high density, then the volume is reduced, but the conductivity may be compromised
Solution Approach 1:
The invention changes the material composition parameters by selecting tin with its high density (7.3 g/cm³) to replace lower-density components. This parameter change achieves volume reduction through increased density while simultaneously improving conductivity, as tin's electronic structure and metallic bonding characteristics enhance electron transport throughout the alloy matrix, resolving the apparent trade-off between density and conductivity.
Data Source
AI summary
An alloy includes lithium, silicon and tin. An anode may be formed of an anode material containing the alloy of lithium, silicon and tin. The anode material may include an electrolyte. The anode material may be a pressed powder pellet that is solid at ambient temperature. A battery, for example, a thermal battery, can contain an electrolyte-separator, a cathode, and/or an anode with the alloy of lithium, tin and silicon. The anode formed of the alloy consisting of lithium, tin and silicon can have a melting point from about 500° C. to about 600° C. or higher making it suitable for use in a thermal battery.