Fabrication Of Phosphorus And Germanium Nanomaterials And Their Application In Energy Storage

The theoretical specific capacity of phosphorus materials is higher(2600 mA h g',)when used as anode in lithium and sodium ion batteries,but it also has problems such as low electronic conductivity and large volume change during charge and discharge processes,which lead to electrode fraction and poor cycling performance.In addition,the germanium-based material has a capacity of 1600 mA h g-1 when used as anode in lithium ion batteries,and possesses a high electrical conductivity.But the germanium-based material is mainly obtained by the reduction of germanium oxide,and generally requires high temperature.In addition,when the germanium-based material is used as anode material,it also suffers a large volume change during charge/discharge processes.In this paper,We have prepared germanium and phosphorus material through molten salt reaction,and explored the application of phosphorus material as anode in lithium-ion batteries and sodium-ion batteries.And we also tested the electrochemical performance of germanium in lithium-ion batteries.The main research contents are listed as follows:1.Amorphous phosphorus nanoparticles were prepared in the molten aluminum trichloride.The amorphous phosphorus material has been obtained by the reduction of phosphorus pentachloride with zinc in molten aluminum trichloride at 50 ?.The prepared phosphorus material has abundant pore structure,which benefits for the fast ionic/electronic diffusion,provides more active sites,and buffers the volume change during discharge/charge cycling.When used as anode material in lithium ion battery,it exhibits a capacity of 1605 mA h g-1 at 520 mA g-1 after 100 cycles,and it still has a capacity of 1283 mA h g-1 at 26 A g-1.And it exhibits a capacity of 1082 mA h g-1 at 2.6 A g-1 after 200 cycles.Further,we have tested its sodium storage performance.It exhibits a capacity of 873.2 mA h g-1 at 520 mA g-1 after 100 cycles when used as anode in sodium ion batteries.In addition,the method can be extended to the preparation of transition metal phosphides.The metal phosphides can be prepared by the addition of the corresponding transition metal chloride into the system at 50 ?.2.Germanium with different morphologies has been prepared in different molten salts.Monodisperse germanium particles have been prepared by magnesium and GeO2 in molten aluminum trichloride at 250?.When the monodispersed Ge particles were used as anode in lithium ion batteries,the anode has a capacity of 1329 mA h g-1 at 320 mA g-1 after 150 cycles,with a capacity retention of 86.3%.And the anode has a capacity of 1124mA h g-1 at 1280 mA g-1 after 400 cycles,with a capacity retention of only 76.7%.And mesoporous hollow germ anium microspheres were prepared by magnesium and germanium oxide in molten ZnCl2 at 350?.when the mesoporous hollow Ge microspheres were used as anode in lithium ion batteries,the anode has a capacity of 1291 mA h g-1 at 320 mA g-1 after 150 cycles,with a capacity retention of 97.3%.And it has a capacity of 1217 mA h g-1 at 1280 mA g-1 after 400 cycles,with a capacity of retention of 91.9%.And it has a capacity of 673 mA h g-1even at 16 A g-1 The mesoporous hollow Ge microspheres deliver a better cycle performance and rate performance,which are attributed to the smaller primary particle size,high-specific surface area and the porous structure.They would provide more active reaction sites and fast diffusion path,and accommodate the volume change,and make the mesoporous hollow Ge microspheres have better electrochemical performance.