Pulsed Laser Deposited Sns-Snse Composite Thin Film As a New Anode Material for Lithium Storage

In recent years tin-based materials has been subjected as promising anode materials due to a high theoretical capacity of Li_4.4Sn (994mAh g^-1). However, tin-based materials is still far away from practical use since it suffers from significant volume change. It has been demonstrated that nano-thin film have its unique characteristics than bulk materials.

In this work, SnS-SnSe composite thin films are synthesized by plused laser deposition. Its first discharge capacity was 1225.8 mAh g^-1 and capacity after three cycles maintained about 650 mAh g^-1. SnS-SnSe composite thin film firstly reacted with Li during discharge to form Li₂SALi₂Se and Sn, then Sn reacted with Li to form Li_xSn alloy. During the charge, Li_xSn firstly decomposed to form elementary Sn, then Sn catalyzed Li₂S and Li₂Se to decompose to rebuild SnS-SnSe composite thin film. Li₂S and Li₂Se produced during discharge can suffer a certain amount of volume change which enhanced the cycle performance. SnS-SnSe composite thin film had more grain boundary than SnS or SnSe thin film which could effectively enhance electrochemical activity and increase capacity.

Fig.1 The first three CVs of SnS-SnSe composite thin film

Fig.2 Galvanostatic charge-discharge curve of SnS-SnSe composite thin film electrodes

Fig.3 Cycling performance of SnS-SnSe, SnS and SnSe thin films with 20 cycles

Acknowledgements

The authors appreciate the financial support of LPMT, CAEP (ZZ13007), Project 2013A030214 supported by CAEP.