Preparation Of Red Phosphorus/hollow Carbon Sphere Composites And Their Lithium/sodium Storage Properties

Lithium-ion batteries have attracted widespread attention due to their long cycle life,low self-discharge,no memory effect and environmental friendliness.The operation principle of sodium-ion batteries and lithium-ion batteries is similar,so it has also been studied extensively.One of the most important obstacles in the development of lithium/sodium ion batteries is the lack of suitable anode materials.The theoretical capacity of red phosphorus(RP)as the negative electrode of lithium/sodium ion battery is 2595 mAh/g.and the red phosphorus is abundant in nature and cheap so it is one of the ideal materials for the negative electrode of lithium/sodium ion battery.However,the violent volume expansion caused by red phosphorus during charging and discharging will seriously affect the cycle stability of the battery,and the red phosphorus itself has very poor conductivity(about 10-12 S/m),so red phosphorus cannot be used alone.Sodium ion battery anode material.In this paper,the red phosphorus is combined with single-shell hollow carbon spheres(HCS)and double-shell hollow carbon spheres(m-DSHCS)with microporous/mesoporous shells by evaporative condensation method to improve the conductivity of red phosphorus.And it can alleviate the volume expansion caused by lithium/sodium intercalation during charge and discharge,so that the electrochemical performance of red phosphorus is improved.The main research contents are as follows:(1)First,HCS was prepared by one-step method using dopamine hydrochloride and ethyl orthosilicate as raw material,and the red phosphorus particles were ground by a ball milling method,and the size of the red phosphorus particles after ball milling was about 1-2 ?m.Then,the ball-milled red phosphorus was combined with HCS by evaporation condensation method.The composite of RP/HCS composites was characterized by X-ray diffraction analysis and energy dispersive X-ray spectroscopy analysis to determine the synthesis process.The RP/HCS composite was then applied to a lithium/sodium ion battery to test its electrochemical performance.The capacity is 550 mAh/g after circulating for 200 cycles at 1 A/g current density in lithium battery,and the capacity can still be maintained at 330 mAh/g at 10 A/g high current density.The capacity remains at 167 mAh/g after 200 cycles at 1 A/g current density in sodium,and the capacity can still reach 155 mAh/g at 10 A/g at high current density.Compared with pure red phosphorus,the cycle performance and rate performance are greatly improved.(2)The red phosphorus after ball milling was combined with the prepared m-DSHCS by evaporation condensation method.The composite of RP/m-DSHCS composite was characterized by XRD analysis and EDS analysis,and the process conditions of evaporation condensation were determined.The RP/m-DSHCS composite was then applied to a lithium/sodium ion battery to test its electrochemical performance.After circulating 1000 cycles at a current density of 1 A/g in a lithium ion battery,the capacity remains at 200 mAh/g,and the reversible capacity at 10 A/g at a high current density can reach 80 mAh/g.After circulating for 1000 cycles at a current density of 1 A/g in a sodium ion battery,the capacity remains at 100 mAh/g,and at a high current density of 10 A/g,the reversible capacity can also be maintained at 50 mAh/g.Compared with pure red phosphorus as the negative electrode of lithium/sodium ion battery,the cycle performance and rate performance are greatly improved.