Study On Phosphorus Based Materials As Anode For Lithium Ion Batteries

Rechargeable Li-ion batteries(LIB)are among the most promising power resources for electric vehicle,while higher requirements for energy storage density and safety are put forward in recently.Phosphorus is considered to be one of the most attractive anode for LIB due to it's high theoretical capacity(2596 mAh g-1)and low work potential(?0.8V).Unfortunately,the main drawback of phosphorus anode is its low conductivity and large volume changed upon cycling,leading to poor electrochemical performance.Therefore,reducing the negative effect of volume change on electrochemical performance becomes the key issue.Carbon materials have been wildly studied as performance fitter component in phosphorus based composite due to their excellent electrical conductivity and mechanical properties.We develop red phosphorus@fluffy hard carbon(RPFC)with 80wt%phosphorus loading through a simple vacuum ball-milling process.Working as LIB anode,it displays a reversible capacity of 1655.9 mAh g-1 at first place and a capacity of 1300 mAh g-1 after 300 cycles at current density of 130mA g-1,capacity retention almost 80%;Additionally,the capacity retention as high as 93.2%after 1000 cycles under current density 2.6A g-1(1C)with initial capacity 1291.7 mAh g-1.The excellent electrochemical performance of RPFC is attributed to the diatinctive structure,thin and uniform cladding carbon layer make a synerfistic effect for performance.by the mean time,a serials RPFC with different P ratio,discover the related connection between structure and P ratio.Since we synthesis by ball-milling with high energy process,the analysis and characterization result prove P-O-C bonding is another reason for excellent performance.We hope that MXene with excellent electric conductivity could be great help to improve rate performance of the composites.First,a three-dimensional cross-linked MXene/CNT conductive network was accomplished by ultrasonic,and a phosphorus @MXene/CNT composite(BRP@MXene/CNT)was prepared by argon ball milling to establish a stable conductive network structure.It do deliver outstanding cycle and rate performance,the initial reversible capacity 2718.05 mAh g-1 under current density 260 mA g-1 was achieved,with 77%initial efficiency,and 2357.2 mAh g-1 after 510 cycles,the capacity retention as high as 87%.As for rate perpormance,it deliver exceed 350 mAh g-1 at current density 40C(104A g-1).We design BRP@MXene to prove that introducing CNT is crucial for build stable three-dimensional conductive network structure,which improved the electrochemical performance.At the seam time,we confirm the formation of C-Ti-Ox-P bonds between MXene and P during the synthesis can enhanced mechanical strength of the interface.Three factors are central for phosphorus composites as LIB anode:structure,amount of phosphorus loading,and chemical bonding enhancement interface.We studied RPFC and BRP@MXene/CNT materials and the comparative samples to illustrate the important influence of these three factors,and successfully improved performance of Phosphorus-based materials.