Preparation And Performance Study On Carbonaceous And MoS₂ Based Anode Materials For Lithium-ion Batteries

Lithium-ion batteries（LIBs）are regarded as one of the most promising large-scale energy storage device due to their high energy density,high operating voltage,and good safety performance.However,commercial graphite negative electrodes（372 m Ah/g）are no longer able to meet the growing performance requirements.In this work,based on the functional application orientation,we designed and synthesized N doped porous carbon（NPC）and N,P doped porous carbon（NPPC）,Co doped MoS₂ composite with NPPC.The effects of their morphology,structure,composition,and other factors on their lithium storage performance and mechanism were studied and discussed in depth.1.A series of N-doped porous carbons（NPC-Ts,T=600,750,and 900℃）were prepared in batches through one-step pyrolysis at different temperatures using biomass agar and urea as precursors,KOH as activator.The electrochemical test results indicate that the lithium storage performance of NPC-Ts is related to factors such as material disorder,doped N configuration and pore structure.Among them,NPC-750 exhibits excellent lithium storage performance,with a reversible capacity of 1019 m Ah/g after100 cycles at 0.1 A/g,281 m Ah/g at a current density of 10 A/g,and a capacity retention rate of 87%after 5000 cycles,which far superior to commercial graphite and reported carbon materials.Assembled with LiFePO₄ positive electrode material,the full battery has a capacity of 125 m Ah/g and a capacity retention rate of 95%after 220 cycles.Considering cost,process,and performance,NPC-750 is expected to replace graphite as a new negative electrode for lithium-ion batteries.2.In order to improve the reversibility of the conversion reaction of MoS₂ during the initial lithium storage process,a series of Co doped MoS₂ based carbon composites（Co MoS-x,x=1,2,3,4）were synthesized using the hydrothermal one pot method in the presence of N,P doped porous carbon（NPPC）by adjusting the ratio of Co and Mo.The electrochemical test results showed that the introduction of Co into the Monanoparticles generated by the MoS₂ conversion reaction resulted in the construction of Co Monanoalloys,which improved the reaction activity of Moelemental with Li S₂and suppressed the production of Li₂S_x.The conversion reaction exhibited the best reversibility in Co MoS-2,with a reversible capacity of 1103 m Ah/g（0.1 A/g）and a capacity retention rate of 132.2%after 200 cycles.