Preparation And Lithium Storage Performance Of Corn Straw-Based Hard Carbon And Its Composite Materials

In recent years,an"energy revolution"has been launched in response to environmental pollution,the greenhouse effect and resource depletion and other ecological crises.Lithium-ion batteries have made technological breakthroughs in energy storage and conversion,opening up markets for electric vehicles and electronic devices.As a highly promising energy storage device,lithium-ion batteries enable the effective use of sustainable energy sources such as wind and solar power.Currently,graphite anode material is no longer able to provide sufficient energy supply for advanced electronic devices.At the same time,it is a non-renewable resource and cannot guarantee the sustainability of its supply chain.In view of this,various advanced high-performance anode materials are valued,such as SnO₂,which has a high theoretical specific capacity of 782 m Ah g^-1and is widely available.However,the stress caused by the process of lithium de-embedding in the SnO₂anode material can cause the electrode structure to be pulverized and detached,ultimately leading to deterioration of the electrical properties.Therefore,it is crucial to effectively solve the current SnO₂problem.Biomass as a renewable energy source with huge reserves,the related derived carbon and composite materials have a broad prospect in developing high-level lithium-ion anode materials.Among them,corn straw,a biomass material,has a huge annual output but is not effectively utilized.In this paper,SnO₂and corn straw cellulose composites,corn straw-based carbon nanospheres,SnO₂and corn straw-based carbon nanosphere composites were prepared using corn straw as the carbon source,and related characterization and testing were done.(1)After treatment by sodium hydroxide and dilute sulfuric acid solution,corn straw cellulose(CLDC)was obtained.CLDC and SnO₂nanoparticles were hydrothermally carbonized and high temperature calcined to prepare SnO₂@CLDC composites.The integrative effects of hydrothermal time and the percentage of SnO₂on the composites were investigated.The analysis reveals that at a hydrothermal time of 36 h and a SnO₂content of 55%,the SnO₂@CLDC composite has a stable structure and a large specific surface area,and possesses a discharge specific capacity of 1248m Ah g^-1at 0.2 C(100 cycles).Meanwhile,to verify the excellent performance of the SnO₂@CLDC composite,a comparison was made with the carbonized cellulose CLDCC and the pure phase SnO₂electrode.The results suggest that SnO₂appears very severe capacity decay,CLDCC has good cycling stability,and the specific capacity of the SnO₂@CLDC composite is significantly higher than that of the pure phase SnO₂.(2)Corn straw-based carbon nanospheres(CSHC)were prepared by hydrothermal method using corn straw as raw material,and different additives(ammonium persulphate,hydrogen peroxide,concentrated sulfuric acid)were added during the hydrothermal process to modify the hydrolysis and aromatization processes of corn straw.The results indicate that the carbon nanospheres(CSHC-(NH₄)₂S₂O₈)assembled with the assistance of ammonium persulphate have a specific surface area of 277 m~2g^-1and a small degree of cross-linking of the carbon spheres.The specific capacities of 787 m Ah g^-1and 581 m Ah g^-1can be retrieved at 0.2 C(100 cycles)and2 C(1000 cycles),respectively.Under the optimum sphere-forming conditions,the composite SnO₂@CSHC_(N)was prepared by combining CSHC-(NH₄)₂S₂O₈with SnO₂to explore its structure characteristics and lithium storage properties.The data demonstrate that the specific capacity of the SnO₂@CSHC_(N)electrode at 0.2 C is further enhanced and can be kept at 1145 m Ah g^-1after 100 cycles.