Preparation Of Biomass Carbonaceous Materials And Their Performance As Anode For Lithium Ion Batteries

Lithium-ion batteries?LIBs?have been widely used in various electronic devices due to their high energy density,long cycle life and negligible memory effect.Graphite-based anodes appear largely restricted for their relatively low specific capacity,which can not meet the increasing demands for LIBs.Recently,biomass-derived carbon materials receive much attention because of their rich abundance,low expenditure,adjustable pore structure and phase state,which makes them as promising candidate for LIBs.In this thesis,a series of biomass-derived carbon and its derivatives were prepared by simple pyrolysis method using palm tree bark hair and palm leaf stem as raw materials.The relationship between the morphology,structure and the lithium storage performance of these as-prepared materials was studied.The conclusions are as follows:?1?Biomass-derived carbon was produced by direct pyrolysis of palm tree bark hair.The pyrolysis temperature has great influence on the structure and electrochemical properties of biomass-derived carbon.The related electrochemical testing results show that specimen produced from pyrolization at 700 ^oC exhibits better lithium storage performance due to its maximum specific surface area,pore volume and average pore diameter when compared to other counterparts synthesized under different temperatures.?2?The phosphorus-doped biomass-derived carbon materials were obtained by mixing palm leaf stem with NaH₂PO₄ followed by pyrolysis.Comparative study shows that doping phosphorus into biomass-derived carbon can not only improve the specific surface area of the obtained carbon material,but also optimize its pore structure,interlayer spacing and phase structure.Besides,a large number of introduced defects provide more lithium storage sites,thus significantly improving the lithium storage performance of P-PTT.?3?The palm tree bark hair?PTBH?was used as initial carbon source,and prepared activated tube-like carbon?ATC?by pre-carbonization followed by alkali etching method.Then ultrafine CuO nanoparticles decorated ATC?ATC/CuO?was successfully fabricated by a phase-transfer approach.The results show that ATC/CuO hybrid possesses rich C-O-Cu bond and unique ultrafine CuO structure.ATC/CuO electrode exhibits remarkable cycling stability(the initial discharge capacity at 100 mA g^-1 was 1116.6 mAh g^-1,and remained as 545.1 mAh g^-1 even after500 cycles)and excellent rate capability(the discharge capacity reached 420 mAh g^-1 at a high current density of 2 A g^-1)as LIBs anode.