Stress Self‐Adaptive Engineering Advances the Low‐Temperature Na Storage Cycling Stability of Microsized Sn

The cycling performance of μ-Sn is enhanced by using a temperature-reduced polarization strategy. As the temperature decreases, the polarization of μ-Sn increases, leading to a lower sodiation degree and reduced volume expansion. This effect, coupled with the high mechanical strength of the SEI, mitigates structural degradation, thereby ensuring superior cycling stability at low temperatures.

Abstract

Microsized Sn (μ-Sn) is a promising anode material for sodium-ion batteries that has a high theoretical capacity of 847 mAh g⁻¹ and demonstrates a phase transition from β-Sn to α-Sn below 13 °C, enabling faster ion transport at low-temperatures. However, it faces challenges such as considerable volume expansion during cycling, unstable solid electrolyte interphase (SEI) formation, and an absence of effective regulation methods. Herein, a “killing three birds with one stone” strategy leveraging stress self-adaptive engineering is proposed to achieve low-temperature cycling stability in μ-Sn. At the expense of a partially reversible capacity, lowering the temperature increases the polarization voltage of μ-Sn during sodiation, resulting in a lower sodiation degree and the formation of dispersed amorphous products, thereby reducing the volume change. This relatively small volume expansion, compared to that at room temperature, is mitigated by the high-mechanical-strength SEI formed by the preferred low-temperature-resistant electrolyte, suppressing chemomechanical degradation and enhancing low-temperature cycling stability. The μ-Sn exhibits a high specific capacity of 680.9 mAh g⁻¹ after 150 cycles at −30 °C, which is 6.6 times higher than that at 25 °C. This work demonstrates a simple and effective approach for obtaining safe and high-performance sodium-ion batteries across broad temperature ranges.