Electrolyte solvents as architects: How solvents guide the spontaneous formation of 3D porous nanostructures in Alloy- and Conversion-type battery anodes

During battery cycling, fragmented anode materials following alloying, conversion, and conversion-alloying reactions spontaneously form three-dimensional (3D) porous nanostructures, influenced by the electrolyte solvent. While it is known that various solvents can enhance anode energy capacity, rate performance, and cycling stability by promoting this 3D structure, the specific solvent property responsible for this transformation was unclear. Our study investigates the role of 48 commercial solvents in Sn nanoparticle self-assembly, using both experimental and simulation methods. We discovered that solvent electrophilicity is crucial in initiating a solvation layer, guiding the development of the 3D nanostructure. This finding is significant in addressing anode fragmentation issues in alloying, conversion, and conversion-alloying processes. The resulting 3D nanostructures show enhanced mechanical and chemical resilience, offering a cost-effective and robust method to improve battery performance. Our research provides new insights into nanostructured anode design, paving the way for advanced battery technologies and enhancing our understanding of nanostructure formation in batteries.