Among the tin-based composites, stannous sulfide (SnS) is a prospective material to serve as an anode for lithium-ion batteries (LiBs) owing to its high theoretical-capacity, layer-structure for fast Li+ diffusion paths, and low toxicity. However, severe volume expansion/shrinkage exfoliates the electrode coating, leading to the severe loss of active materials. Herein, free volume was introduced into SnS to relieve the sequelae of volume expansion/shrinkage creatively, which effectively improved the cyclability of the SnS-based anode. The as-synthesized SnS/G-15% exhibited overall optimal electrochemical performances, i.e., the highest reversible capacity and best cyclability over pure SnS, SnS/G-5% and SnS/G-25%. Ex situ scanning electron microscopy images also illustrated that no cracks were generated in the cycled SnS/G-15% electrode. This work highlights an efficient and cost effective approach for the synthesis of long-cycle life and high-cyclability anodes.
Hao Sun,Qinghua Yang,Detao Kong,Yanrui Li,Yaolong He,NengHui Zhang,Hongjiu Hu
Polyethylene oxide (PEO)-based solid polymer electrolytes are regarded as promising electrolyte materials because of their safety and flexibility. However, low ionic conductivity at ambient temperature and poor mechanical properties have been a hindrance to its development. In this work, we thermally compressed the PEO-based electrolytes and explored the ionic conductivity, mechanical performance, free volume, and thermal properties of the electrolyte under different thermal pre-compressing strains (TPC-strains). The results show that TPC-strain can significantly improve the ionic conductivity, in-plane strength, stiffness, and cell specific capacity as well as the mechanical integrity of solid polymer electrolytes within the battery environment. However, it also results in a reduction in the modulus and stiffness of the SPEs in the through-plane. In particular, applying a TPC-strain of 10%–20% to the SPEs by thermal compressing may be a suitable option, which can increase the ionic conductivity of the through-plane to a factor of 3.4 compared with the uncompressed electrolyte, and increase the in-plane strength by up to 141%, resulting in better mechanical integrity during charging/discharging processes. At the same time, the compression modulus can be maintained at 80% or higher.
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