Performance of carbon-coated nano-ZnO prepared by carbonizing gel precursor as anodic material for secondary alkaline Zn batteries

Although carbon coating can improve the cycle life of anode for alkaline Zn batteries, the specific capacity reported is still lower compared with nanosized ZnO. Herein, carbon-coated nanosized ZnO(nano-ZnO@C) was synthesized by one-step heat treatment from a gel precursor in N2. Commercial ZnO and homemade ZnO prepared similarly in air atmosphere were studied for comparison. Structure analysis displayed that both nano-ZnO@C and homemade ZnO had a porous hierarchical agglomerated architecture produced from primary nanoparticles with a diameter of approximately 100 nm as building blocks. Electrochemical performance measurements showed that nano-ZnO@C displayed the highest electrochemical activity, the lowest electrode resistance, the highest discharge capacity(622 m A·h/g), and the best cyclic stability. These properties were due to the combination of nanosized ZnO and the physical capping of carbon, which maintained the high utilization efficiency of nano-ZnO, and simultaneously prevented dendrite growth and densification of the anode.

Intimately coupled WS_(2) nanosheets in hierarchical hollow carbon nanospheres as the high-performance anode material for lithium-ion storage

Lithium-ion hybrid capacitors(LIHCs)have drawn extensive attention in fleld of energy storage.However,the absence of appropriate electrode materials with rapid kinetics restricted the overall performance of the capacitors.Herein,hierarchical N,P-codoped hollow car-bon nanospheres coupling with WS_(2) nanosheets(N,P-codoped HCNS/WS_(2)NSs)were fabricated for boosting lithium storage materials.Specially,the WS_(2) nanosheets with several layers embedded in the N,P-codoped hollow carbon nanospheres could not only enhance the conduc-tivity of composites,but also provide abundant channels for the rapid transfer of ions.As a result,as-prepared N,P-codoped HCNS/WS_(2) NSs demonstrated superior rate performance and long-term cycling stability.The reversible discharge capacity of 725.2 mAh·g^(-1) could be preserved after 1000 cycles at a current density of 1.0 A·g^(-1).Fur-thermore,LIHCs devices were assembled by using N,P-codoped HCNS/WS_(2) NSs and activated carbon(AC)as the cathode and anode,which exhibited high energy density of 166.7 Wh·kg^(-1) and power density of 5312.4 W·kg^(-1).Last but not least,the capacity almost had no obvious deterioration after 6000 cycles at a high current density of 10.0 A·g^(-1).