A recent study published in Advanced Functional Materials introduces a method for stabilizing eutectic gallium indium (EGaIn) nanoparticles using a graft copolymer, creating self-healing anodes with improved electrochemical performance.
The approach involves grafting a fluorinated polymer with ionic channels onto EGaIn, producing a stable interface that supports lithium-ion transport and prevents particle re-aggregation.
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Background
EGaIn is a liquid metal with properties favorable for battery electrodes, including high conductivity, deformability, and self-healing behavior. However, in bulk form, it suffers from shape instability and volume expansion during cycling. Reducing EGaIn to the nanoscale helps accommodate these changes and increases surface area, but nanoparticle stabilization remains a challenge.
Previous efforts to stabilize EGaIn nanoparticles have involved coating or embedding them within various polymers. However, many of these polymers lack ionic functionality or do not promote effective interaction with lithium ions, leading to issues like particle aggregation, poor ionic conductivity, and limited electrochemical stability.
To improve these limitations, the concept of grafting polymers with ionic channels—ionomers—onto nanoparticle surfaces has been introduced.
Synthesis Approach
The team synthesized a graft copolymer composed of a PVDF-TrFE backbone, chosen for its mechanical durability and chemical resistance, with grafted sulfonated polystyrene (SPS) segments to enable ionic conductivity.
PVDF-TrFE was dissolved in DMSO and mixed with SPS in NMP. Graft polymerization was initiated with CuCl and HMTETA at 120°C and continued for five days. The resulting material was washed, purified, and dried to yield an ionically conductive polymer with rubber-like mechanical properties.
EGaIn nanoparticles were created via sonication in DMSO containing the graft copolymer. The polymer adsorbed onto the nanoparticle surfaces, forming a stabilizing shell that prevented aggregation. This process produced uniformly sized particles ( approximately 200 nm) with improved stability and electrochemical responsiveness.
Results and Discussion
The stabilized EGaIn nanoparticles retained their morphology over 200 electrochemical cycles. SEM imaging showed minimal aggregation, while energy-dispersive X-ray spectroscopy confirmed the persistent presence of gallium, indium, sulfur, and fluorine, indicating a stable interface throughout cycling.
Electrochemical tests demonstrated enhanced performance. The ionic channels in the copolymer promoted lithium-ion transport, supporting high capacity and long cycle life. Lithium half-cells retained 85 % of their initial capacity after 500 cycles at 0.5 A g-1.
The capacity reached over 800 mAh g-1 at a low current density, comparable to or exceeding traditional anode materials. The rate capability was also prominent, with a capacity retention of around 45 % at a high current density of 2.0 A g-1, indicating efficient ionic transport and robust structural stability.
The self-healing nature of EGaIn helped mitigate mechanical degradation and accommodate volume changes during cycling. The copolymer’s ionic functionality prevented particle re-aggregation, contributing to stable long-term operation. Together, these features produced a flexible and resilient anode structure.
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Conclusion
This study presents a promising route to durable, high-capacity LIB anodes by combining the flowability of EGaIn with an ionically conductive, stabilizing copolymer. The materials demonstrated stable cycling, strong rate capability, and self-healing behavior.
Future work may focus on tuning the copolymer’s ionic composition, exploring alternative ionomers, and integrating the materials into full-cell systems for practical applications.
Journal Reference
Seo Y., Kim H., et al. (2025). Graft copolymer-stabilized liquid metal nanoparticles for lithium-ion battery self-healing anodes. Advanced Functional Materials, 2508062. DOI: 10.1002/adfm.202508062, https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202508062