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

Two-dimensional (2D) SnS 2 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 SnS 2 were investigated in detail. At low temperature (160   °C), the SnS 2 nanoplates showed poor crystallinity; while at higher temperatures above 200   °C, the crystallinity and thickness of the SnS 2 nanoplates tended to increase. In addition, pH had notable impact on the nucleation velocity of SnO 2 and the conversion speed from SnO 2 to SnS 2 in further as well. When used as anode materials in rechargeable lithium ion batteries , the SnS 2 nanoplates synthesized at 200   °C and pH   =   10.5 (SnS 2 -200-10.5) showed the best lithium storage capacity, good cycling stability and excellent rate capability. It retained a high reversible capacity of 521   mA   h   g −1 over 50 cycles at a current of 100   mA   g −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 3   A   g −1 , the electrodes could still delivery as high as 472, 397 and 340   mA   h   g −1 , respectively. The enhanced electrochemical performance of the SnS 2 -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.