| Since the 21st century,with the rapid development of portable electronic devices and power vehicles,the development of lithium-ion batteries with higher energy and functional density,smaller size,light weight,cost and long cycle life has become a challenging issue.As an important component of lithium-ion batteries,commercial graphite has been unable to meet the requirements of high energy and high power density due to its low theoretical specific capacity of 372 mAh g-1.Therefore,the development of high performance and low cost anode materials has become one of the urgent problems to be solved.Recently,natural biomass resources with the advantages of renewability,sustainability and wide sources have been widely used to prepare biomass-derived carbon and its composites with high specific capacity,excellent cycle and rate performance.However,the biomass-derived carbons have lower flexibility and ability to be composited with other diverse functional active materials for further improvement of LIBs performance.The preapration of biomass derived carbon-based materials is of great significance in promoting the development of lithium battery anode materials with low cost and high performance.In this paper,the construction of biomass carbon-based materials and lithium storage performance as the research topic,mainly carried out the following three work:(1)In this work,an interwove carbon fiber anchored with well dispersed FeS nanoparticles(C/FeS)was in situ fabricated via "Adsorption-Carbonization" approach,taking use of bio-waste eggshell membrane as an as an intrinsic source of carbon and sulfur.When used as a anode material,the conductive carbon fiber and interwove structure could promote electrical conductivity,and suppress the aggregation and volume expansion of FeS nanoparticles during cycling.C/FeS composite displays a reversible capacity of 503.5 mAh g-1 after 100 cycles at 200 mA g-1 and good rate performance.Interestingly,this work offers an environmentally friendly approach to fabricate C/FeS structures,and can be extended to synthesize a variety of carbon/metal sulfide composites for energy application.(2)Hierarchical porous carbon(HPC)materials have been synthesized via a combined freeze drying and carbonization process,that using egg white protein(EW-protein)as a precursor,NaCl as a template.Two competitive effects,salting out and salting in of EW-protein,were conveniently tuned by changing the NaCl concentrations,resulting in controllable hierarchical structures,surface areas and pore size distributions of HPC.The optimal product of HPC-4 displays a 3D honeycomb-like network(100-200 nm),inner cubic mesopores(20-50 nm)and high large surface area of 1745.64 m2 g-1.As an anode material of Li-ion battery,HPC-4 presents reversible capacity of 1131 mAh g-1 after 100 cycles at 0.2 A g-1,good rate capability,and a reversible capacity of 553 mA h g-1 after 1000 cycles at high current density of 10 A g-1.This work provides an environmentally friendly and low cost route to fabricate HPC with excellent electrochemical performances.(3)On the basis of the research in chapter 4,Fe3+source was introduced into the precursor of freeze-drying.In high-temperature carbonization,nitrogen-containing amino acids in egg white protein were decomposed to produce NH3,and reacted with Fe3+in the system to form Fe3N phase.At the same time,carbon source in the protein was transformed into carbon material after high temperature.C/Fe3N composite material embedded in graded porous carbon was obtained after removing NaCl template with simple water washing.As a lithium ion battery anode,the C/Fe3N composite exhibited excellent electrochemical performance,with a reversible capacity of 1007 mAh g-1 at 0.2 A g-1 after 150 cycles.It also delivered a excellent long cycle stability even at high current density of 5 A g-1,which exhibited a high reversible capacity of 444.8 mAh g-1 after 1500 cyles.This approach provides a new idea for the low cost and green synthesis of lithium ion battery anode materials. |
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