High-rate performance of SnS2 nanoplates without carbon-coating as anode material for lithium ion batteries

Abstract

Two-dimensional (2D) SnS2 nanoplates were synthesized through a facile hydrothermal method. The influences of reaction conditions such as temperature and pH on the size, crystallinity and the forming process of SnS2 were investigated in detail. At low temperature (160°C), the SnS2 nanoplates showed poor crystallinity; while at higher temperatures above 200°C, the crystallinity and thickness of the SnS2 nanoplates tended to increase. In addition, pH had notable impact on the nucleation velocity of SnO2 and the conversion speed from SnO2 to SnS2 in further as well. When used as anode materials in rechargeable lithium ion batteries, the SnS2 nanoplates synthesized at 200°C and pH=10.5 (SnS2-200-10.5) showed the best lithium storage capacity, good cycling stability and excellent rate capability. It retained a high reversible capacity of 521mAhg−1 over 50 cycles at a current of 100mAg−1, equal to 90.0% of the initial reversible capacity. In addition, the coulombic efficiency increased from 36% in the first cycle to over 97% in the subsequent cycles. Even at high current densities of 1, 2 and 3Ag−1, the electrodes could still delivery as high as 472, 397 and 340mAhg−1, respectively. The enhanced electrochemical performance of the SnS2-200-10.5 can be attributed to the compact and regular crystal structure with a moderate thickness and crystallinity, which is beneficial for maintaining the stability of the structure and fast ion transport during lithiation/delithiation processes.