Voltage-Modulated Structure Stress for Enhanced Electrochemcial Performances: The Case of μ-Sn in Sodium-Ion Batteries

Alloy-type anodes in alkaline ion batteries have to face the challenges of huge volume change and giant structure strain/stress upon cycling. Here, reducing the structure stress for advanced performances by voltage regulation is demonstrated by using microsized Sn (mu-Sn) for sodium ion batteries as a model. Density functional theory and finite element analysis indicate that Sn/NaSn3 is the crucial phase transition highly responsible for inducing surface cracks, particle aggregations, and cell failures. Eliminating this phase transition by the control of cutoff voltages successfully extends the cycle life of mu-Sn to 2500 cycles at 2 A g(-1), much longer than similar to 40 cycles in a regular voltage window. The specific capacity is still retained at similar to 455 mAh g(-1), leading to a capacity decay of only similar to 0.0088% per cycle. The results provide a simple way to achieve the outstanding performances without complicated preparation, expensive reagents, and laborious processing.

Automated summary

By controlling the cutoff voltages to eliminate the Sn/NaSn3 phase transition, the cycle life of microsized Sn in sodium ion batteries has been significantly extended, while maintaining a high specific capacity. This simple and effective approach allows for outstanding performance without the need for complicated preparation, expensive reagents, or laborious processing.