Synthesis Of Phosphorus (Carbon)-Based Electrode Materials For Lithium Ions Storage

The electrochemical performance of lithium-ion batteries can be further improved by exploring high-performance electrode materials.Transition metal phosphates（TMPs）are regarded as promising anode materials owing to their high specific capacity and abundant resources.However,their further application is severely restricted by the irreversible capacity fading and low conductivity,which is caused by the volume expansion of the material during the lithium-ion intercalation process.Ti₃C₂materials present high electrical conductivity and excellent mechanical strength,which can promote electrical conductivity and suppress the volume change of TMPs.In addition,biomass-derived carbon materials also display the advantage of low cost and excellent rate performance,when they serve as anode materials for lithium-ion batteries.Meanwhile,heteroatom doping and constructing composite can further improve their lithium-ion storage properties.Therefore,in this work,we prepared phosphorus-based TMPs@Ti₃C₂composites via hydrothermal method associated with a low-temperature phosphating process.And the N-doped biomass-derived carbon and phosphorus/biomass-derived carbon composite were also synthesized via a high-temperature carbonization method.The above-mentioned phosphorus-based and carbon-based materials were served as the anode materials for the lithium-ion batteries and displayed an enhanced electrochemical performance.The detailed research contents are as follows:Firstly,the urchin-like CoP and Ti₃C₂nanosheets（CoP@Ti₃C₂）composite were prepared by hydrothermal method associated with low-temperature phosphating method.The Co P@Ti₃C₂composite presented an enhanced electrochemical performance by optimizing the content of Ti₃C₂in the composite.Co P@Ti₃C₂composite showed the specific capacity of 429 mAh g^-1after 900 cycles at a current density of 1000 mA g^-1.Meanwhile,the morphology of the material kept well after the cycling,indicating good structural stability of Co P@Ti₃C₂.Secondly,FeP₂nanoparticles and Ti₃C₂nanosheets composite（Fe P₂@Ti₃C₂）were synthesized by hydrothermal method associated with low-temperature phosphating method.Meanwhile,the effect of Ti₃C₂addition on the electrochemical performance of composite was investigated.The optimized Fe P₂@Ti₃C₂composite displayed a specific capacity of 1194 mAh g^-1after 1000 cycles at a current density of1000 mA g^-1.In addition,the rate performance and cycle stability of Fe P₂@Ti₃C₂are better than that of pure Fe P₂.Then,cotton-derived carbon was prepared via a traditional carbonization process.Adding KOH and urea could effectively introduce the porous structure and N doping,respectively.As-prepared cotton-derived carbon showed improved rate ability and lithium-ion storage behavior.It should be noticed that the N-PCC 800 material showed better electrochemical performance than other cotton-derived carbon with different amounts of N.The N-PCC 800 presented specific capacities of 810 and 577mAh g^-1at the current densities of 100 and 1000 mA g^-1,respectively.In addition,it exhibited capable cycling stability.Finally,the phosphorus embedded biomass carbon composite was prepared using KOH as a pore-forming agent and red phosphorus as a phosphorus source.By adjusting the mass content of phosphorus,the optimized P-PCC 800 material showed the best electrochemical performance.The P-PCC 800 showed specific capacities of547 and 326 mAh g^-1at the current densities of 100 and 1000 mA g^-1,respectively.Meanwhile,the rate performance of the P-PCC 800 was also improved due to the addition of phosphorus...