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

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 degrees C), the SnS2 nanoplates showed poor crystallinity; while at higher temperatures above 200 degrees C, the crystallinity and thickness of the SnS2 nanoplates tended to increase. In addition, pH had notable impact on the nucleation velocity of Sn02 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 degrees 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 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 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. (C) 2013 Elsevier Ltd. All rights reserved.