Research On The Preparation Of Biomass-based Hard Carbon And Its Application In Sodium Ion Batteries

With the development of society,the era of energy Internet is coming,and large-scale energy storage power stations will play a pivotal role.Although the commercial development of lithium-ion batteries is very mature,due to its resource and price issues,it is difficult to become the choice of large-scale energy storage power stations.Sodium is similar in physical and chemical properties to lithium,rich in resources and low in price,making it the preferred option for energy storage power stations.Hard carbon,especially biomass-based hard carbon,is considered to be the most likely commercial anode material for sodium ion batteries.However,the preparation process of biomass-based hard carbon is still insufficient.In this paper,two problems are innovated that we not only successfully prepared two kinds of hard carbon materials by simple technology,but also explored their sodium storage performances.First,biomass waste reed straw(RS)was prepared as biomass-based hard carbon anode materials for sodium ion battery.In view of the problem of more impurities in the precursor of natural biomass,we removed the impurity elements in the biomass precursor by simple hydrothermal treatment,instead of the pickling and washing process after carbonization.After hydrothermal treatment,the relationship between the microstructure and sodium storage performance was investigated by adjusting the carbonization temperature of the reed straw and changing the internal structure of the material.RS-1300 provides the highest reversible capacity of 372.0 mAh g-1 at a small current density of 0.1 C.and the remaining ca pacuy of 283.8 mAh g-1 after cycling for 200 cycles at a current density of 0.4 C,thecapacity retention rate is 84%,showing excellent sodium storage performance.At the same time,through the analysis of microscopic characterization and electrochemical data,we have summarized the sodium storage mechanism of reed straw-based hard carbon.Then,for the carbonization foaming problem of starch,sucrose and other materials,the starch(ST)was combined with the graphene oxide(GO)by a simple spray drying method.The obtained composite microspheres were disposed by one-step carbonization to obtain monodisperse and well-formed carbon microspheres,which were applied to anode for sodium ion battery.We investigated the inhibition of foaming behavior during the carbonization of starch/GO composite microspheres by adjusting GO contents.The experimental results show that when the mass fraction of GO is 10%,the morphology and dispersibility of the composite carbon microspheres are the best.We further explored the effects of GO composite content and carbonization temperature on the structure and sodium storage properties of composite carbon microspheres.Through characterization and testing,ST10G-900 shows the best sodium storage performance,and its reversible specific capacity can reach 343.1 mAh g-1 at a current density of 0.1 C.