科研之友
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摘要
It is a great challenge to engineer thick or bulk electrodes with well maintained rate performance, since their charge-transport kinetics are severely worsened at large current densities. Here, high-power thick cathode of Li-ion batteries has been built based on mesoporous lithium vanadium phosphate interweaved with carbon nanotube nest. A facile yet effective synthesis method based on aerosol-assisted spray process followed with high-temperature calcination has been developed to synthesize such nanocomposite. During spraying process, high-aspect-ratio carbon nanotubes are interweaved into lithium vanadium phosphate and form long-range conductive nest. This structure provides efficient charge transport for the active material, even in their thick electrodes. To verify this, 30 and 160 pm binder-free electrodes have been fabricated. The results show that the 160 ktm electrode can reach comparable rate performance to that of 30 pm from the rate of 0.2-10 C. The discharge capacities at 10 C for 30 and 160 mu m electrodes are 130 and 122 mAh g(-1), respectively, which are 98% and 92% of theoretical capacity of lithium vanadium phosphate. Also, a capacity retention over 96% is still retained after 1000 cycles at 20 C, exhibiting good cycling stability. Hence, the designed nanocomposite is promising for fast charging/discharging of batteries. The synthetic method is scalable, and can be used for synthesis of other electrochemical active materials.
