Graphite-nanoplate-coated Bi2S3 composite with high-volume energy density and excellent cycle life for room-temperature sodium-sulfide batteries

Graphite-nanoplate-coated Bi2S3 composite (Bi2S3@C) has been prepared by a simple, scalable, and energy-efficient precipitation method combined with ball milling. The Bi2S3@C composite was used as the cathode material for sodium-sulfide batteries. It delivered an initial capacity of 550 mAh g−1 and high stable specific energy in the range of 275-300 Wh kg−1 at 0.1 C, with an enhanced capacity retention of 69 % over 100 cycles. The unique structure demonstrates superior cycling stability, with a capacity drop of 0.3 % per cycle over 100 cycles, compared with that of bare Bi2S3. The sodium storage mechanism of Bi2S3 was investigated based on ex situ X-ray diffraction and scanning transmission electron microscopy.