ABSTRACT
High-capacity germanium-based anode materials are alternative materials for outstanding electrochemical performance lithium-ion batteries (LIBs), but severe volume variation and pulverization problems during charging-discharging processes can seriously affect their electrochemical performance. In addressing this challenge, a simple strategy was used to prepare the self-assembled GeOX/Ti3C2TX composite in which the GeOX nanoparticles can grow directly on Ti3C2TX layers. Nanoscale GeOX uniformly renucleates on the surface and interlayers of Ti3C2TX, forming the stable multiphase structure, which guarantees its excellent electrochemical performance. Electrochemical evaluation has shown that the rate capability and reversibility of GeOX/Ti3C2TX are both greatly improved, which delivers a reversible discharge specific capacity of above 1400 mAh g-1 (at 100 mA g-1) and a reversible specific capacity of 900 mAh g-1 after 50 cycles while it still maintains a stable specific capacity of 725 mAh g-1 at 5000 mA g-1. Furthermore, the composite exhibits an exceptionally superior rate capability, making it a good electrochemical performance anode for LIBs.
ABSTRACT
Transition-metal sulfides have been considered as promising anode materials for lithium-ion batteries (LIBs) due to their high theoretical specific capacity and superior electrochemical performance. However, the large volume change during the discharge/charge process causes structural pulverization, resulting in rapid capacity decline and the loss of active materials. Herein, we report Co1-xS hollow spheres formed by in situ growth on reduced graphene oxide layers. When evaluated as an anode material for LIBs, it delivers a specific capacity of 969.8 mAh·g-1 with a high Coulombic efficiency of 96.49% after 90 cycles. Furthermore, a high reversible capacity of 527.2 mAh·g-1 after the 107th cycle at a current density of 2.5 A g-1 is still achieved. The results illustrate that in situ growth on the graphene layers can enhance conductivity and restrain volume expansion of cobalt sulfide compared with ex situ growth.
ABSTRACT
A dynamic monitoring on the rainfall-runoff process and the surface runoff and sediment yield in a sloping farmland was conducted at a natural rainfall runoff plot in the watershed of Jianshan River, the first tributary of Fuxian Lake, Chengjiang, aimed to study the regulation effects of reverse-slope level terrace on the runoff and sediment yield in red soil sloping farmlands of Yunnan. The regulation rates of runoff and sediment yield by the reverse-slope level terrace were 49.5%-87.7% and 56.7%-96.1%, averagely 65.3% and 80.7%, respectively, showing that the regulation effects of reverse-slope level terrace on the runoff and sediment yield, especially the latter in sloping farmland were prominent. The variation coefficients of the test parameters for undisturbed sloping farmland and reverse-slope level terrace were in the order of sediment yield > runoff > rainfall. Comparing with undisturbed sloping farmland, reverse-slope level terrace had smaller surface runoff and smaller relative deviation degree of sediment yield, demonstrating its remarkable effect in controlling runoff and sediment yield in sloping farmland.
