Sb2S3 embedded in amorphous P/C composite matrix as high-performance anode material for sodium ion batteries

Sodium-ion battery is being regraded as an alternative to lithium-ion batteries in view of low-cost and high energy density. However, poor cycle life accompanying huge electrode swelling of existing metal based anode are the main issues to be solved. Sb2S3 embedded in amorphous phosphorus/carbon matrix is synthesized from P2S5, Sb, and carbon by using a facile mechano-chemical method and subsequent heat treatment, which is investigated on its potential as anode material for rechargeable sodium ion batteries. Several analytical tools including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron spectroscopy (TEM) reveal that as-synthesized composite is composed of Sb2S3 nano-crystallites (less than 10 nm) dispersed in robust phosphorus/carbon (P/C) composite matrix. Although Sb2S3 nano-domain converts to the Sb and S during sodiation, the recombination of Sb and S to form the original Sb2S3 phase is also confirmed by HR-TEM image of the subsequently desodiated electrode. This composite electrode exhibits superior electrochemical performances including a high reversible capacity of 654 mAh g−1 with well controlled electrode swelling of 62% at fully charged state, an excellent cycle stability with a capacity retention of 93.4% after 100th cycle at 50 mA g−1 for sodium ion batteries. Furthermore, even at a high current density of 2000 mA g−1 (3C rate), a desodiation capacity of 390 mAh g−1 is achieved. These outstanding electrochemical performances are attributed to the effective mechanical-buffering and electrical-conduction properties of the amorphous P/C composite matrix, which also prevent the aggregation of electroactive particles reacting with Na.