Core-Shell Lithium Alloy Anode for Tin Volume Expansion
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Solution Overview
Problem
Lithium-tin batteries face issues with poor cycle life and tin utilization due to volume expansion and breaking of tin agglomerates during charging, leading to decreased battery capacity.
Innovation Solution
A composite particle with a lithium alloying material core and an outer shell having an inner volume that includes solid material and void space, allowing for alloying and de-alloying without damaging the shell, and produced using a method involving precursor powders and a plasma torch to achieve a core that occupies between 5 and 99% of the inner volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If tin-based anode is used to increase capacity, then battery energy capability is improved, but cycle life deteriorates due to volume expansion and particle separation
Solution Approach 1:
The tin core is nested within a protective outer shell, creating a core-shell structure where the core contains the lithium alloying material and the shell provides mechanical protection. This nested configuration allows the high-capacity tin core to expand and contract during cycling while the outer shell maintains structural integrity and prevents particle separation, thus preserving both capacity and cycle life
Solution Approach 2:
The outer shell is designed with sufficient thickness and appropriate material properties to accommodate the volume expansion of the tin core during lithium alloying while maintaining structural integrity. The shell acts as a flexible container that expands and contracts with the core, preventing particle separation and maintaining electrical contact throughout cycling, thereby improving cycle life without sacrificing the high capacity benefit
2Quantity of substance
If tin alloying material is used to achieve high capacity, then energy capability is improved, but structural stability deteriorates due to volume expansion breaking agglomerates
Solution Approach 1:
The tin core is nested within a protective outer shell that constrains the volume expansion during lithium alloying. This nested structure prevents the breaking apart of tin agglomerates by containing the expansion forces within the shell, maintaining structural stability while preserving the high energy capability of the tin-based material
Solution Approach 2:
The outer shell parameters (thickness, material composition, mechanical properties) are specifically designed to match and accommodate the volume expansion characteristics of the tin core during lithium alloying. By tuning these parameters, the structure maintains stability throughout cycling while allowing the core to achieve its full capacity potential
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 solution enhances the cycle life and utilization of tin, maintaining contact between the core and shell during charging and discharging cycles, thereby improving battery capacity and performance.
Implementation Method 1
a method involving precursor powders and a plasma torch
Implementation Method 2
Passing the precursor powder through a plasma torch produces a shell-core precursor
Data Source
AI summary
Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.