The Preparation And Sodium Storage Performance Of Hard Carbon From Heavy Organic Matters Of Coal

Due to the good performance of sodium ion battery in the field of large-scale energy storage,the research on the system of sodium ion battery has attracted more and more attention in recent years.High energy density,low cost and good safety are the important goals of its research and development.One of the important factors affecting these properties is the appropriate anode materials.Hard carbon is considered to be the best choice for sodium storage.There are many raw materials for the preparation of hard carbon,among which heavy organic matter of coal series has a wide range of sources and high carbon residue rate,and it is a kind of high-quality carbon source precursor.In this paper,coal liquefaction extract was used as raw material,under the catalysis of Lewis acid,the raw material was chemically crosslinked by Friedel-Crafts?F-C?reaction.The crosslinked product was carbonized to obtain hard carbon material.Hard carbon materials were prepared by the same method with coal tar pitch?CTP?,wash oil?WO?and anthracene oil?AO?as raw materials,which proved the universality of this method.The specific work and results are as follows.The hard carbon anode materials for sodium ion batteries were successfully prepared by using coal liquefaction residue?CLR?as raw material through chemical crosslinking and carbonization treatment.The results show that chemical cross-linking treatment can introduce a large number of oxygen-containing functional groups?methoxy groups?.The three-dimensional structure produced effectively hinders the graphitization tendency of CLR in high temperature carbonization,the resulting carbon display the random oriented carbon layers with more defects.Electrochemical test results show that compared with the CLR-1600that direct carbonized at 1600?,the specific capacity is increased by about 2.5 times(up to309.7 mAhg^-1)and the initial coulomb efficiency increased by 25%?up to 68.36%?.The specific charge capacity of hc-CLR-1600 after 100 cycles reaches 261.6 mAh g^-1,and the capacity retention rate is 86.4%,indicating a good cycle stability.The hc-CLR-1100 sample shows the best rate capability,delivering the specific capacities of 100.4 mAh g^-1 at the current density of 1.5 A g^-1.The hard carbon anode materials for sodium ion batteries were successfully prepared by using CTP,WO and AO as raw material through the same treatment method.The results show that no matter CTP or WO AO,a large number of methoxy groups are introduced into the chemical crosslinking treatment,forming a three-dimensional structure of the crosslinking products.The steric effect hinders the graphitization tendency in the high-temperature carbonization,obtaining the hard carbon with disordered structure,which proves the universality of this method.Electrochemical test results show that compared with the CTP-1500 that direct carbonized at 1500?,at the current density of 0.05 A g^-1 the specific capacity is increased by about 2.5 times(up to 348.2 mAhg^-1)and the initial coulomb efficiency increased by 22%?up to 64.59%?.The specific charge capacity of hc-CTP-1500after 100 cycles reaches 261.6 mAhg^-1,and the capacity retention rate is 86.2%,indicating a good cycle stability.The specific capacity of hc-WO-1500 and hc-AO-1500 were 264.6mAhg^-1 and 284.8 mAhg^-1 at the current density of 0.05 A g^-1,initial coulomb efficiency were42.53%and 64.43%,respectively.It shows excellent electrochemical sodium storage performance.