The Research of Synthesis and Performance of Nano-sized Energy Storage Materials

Author:Tian Ye

Supervisor:zhong jian xin

Database:Doctor

Degree Year:2017

Download:143

Pages:79

Size:4916K

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The thesis is focused on synthesis of advanced electrodes materials for lithium-ion battery and sodium-ion battery by novel methods.Nanotechnology was employed to obtain titanium-based and vanadium-based electrodes.The energy storage performance of the as-prepared electrode materials was excellent,revealed by a variety of measurements.This thesis includes three aspects:(1)synthesis of LTO/MWCNTs nanosheets and their energy storage performance.(2)synthesis of self-supporting LTO-AT/rGO and their energy storage performance.(3)synthesis of vanadium pentaoxide nanospheres and their the energy storage performance.The main achievements are listed in the following:(1)Convenient hetero-assemble method was employed to obtain LTO/MWCNTs nanosheets.The as-prepared nanosheets were tested in lithium-ion batteries and sodium-ion batteries,displaying excellent performance better than the LTO nanosheets.At 1C charging/discharging rate,after 500 times cycling,the lithium-ion batteries with LTO/MWCNTs electrodes had 90% specific capacity of the starting time maintained.And as the electrodes of sodium-ion batteries,75% specific capacity of the first cycle was maintained by the LTO/MWCNTs nanosheets after 200 times cycling at 2C charging/discharging rate.Even at 5C charging/discharging rate,the LTO/MWCNTs nanosheets can achieve relatively ideal specific capacity of 80mAh/g.(2)Graphene oxide was introduced to improve the mechanical behavior and the conductivity of the LTO-AT to achieve advanced energy storgy performance.In experiment,hetero-assemble method was employed to help the combination,and the frozen drying togather with machanical pressing were employed to obtain self-supporting electrodes.This kind of electrodes can be directly deployed into batteries without adhesives and conductive additives.As the sodium-ion batteries’ performance was measured,the specific capacity reached 208mAh/g at 0.1C rate,141mAh/g at 6C and 117 mAh/g at 10 C.After 1000 cycles charging/discharging,the battery remained a high specific capacity of 154mAh/g.(3)Vanadium pentaoxide nanoshperes were obtained by solvant-thermal method,and Sn-doping was simply introduced by modifying the compositon ratio of the precursor.The performance of different doping ratio samples was measured,and the 5% Sn doped vanadium pentaoxide performed better than the other samples.At 0.1C charging/discharging rate,the doped nanospheres maitained the specific capacity of 240mAh/g,at 2C charging/discharging rate the doped nanospheres held the specific capacity of 200mAh/g.When setting the charging/discharging rate back to 1C after tested at 2C,the specific capacity of 240mAh/g can be maintained.