Preparation Of Manganese Monoxide-Carbon Based Flexible Composite Film And Its Application In Li-ion Battery

The development of flexible thin film lithium-ion batteries（LIBs）is very significance for portable electronic devices,including smart communication,wearable devices and so forth.However,it is still a great challenge for fabrication of flexible electrodes with long cycle life and high specific capacity in the commercial applications.manganese monoxide（MnO）have received extensive research interest due to their high theoretical capacities(e.g.,756 m Ah g^-1 for MnO),relatively low electrochemical motivation force（emf）（1.032 V vs.Li/Li⁺）,small voltage hysteresis,low cost,environmental friendliness and natural abundance.However,its low electronic conductivity and large volume change during charge-discharge process have limited its commercial applications.Especially,the biggest issue of MnO materials towards LIBs is that they can react with lithium to form metal Mn（dispersed in the Li₂O matrix）,resulting in severe agglomeration and repeated volume change during cycling.This could also give rise to drastic pulverization of the entire MnO electrodes and leads to shedding and dissolution of Mn into the electrolyte,leading rapid capacity fading upon cycling.To overcome these problems,electrospinning and electrospray techniques were used in this work to prepare manganese oxide/carbon nanofibers@reduced graphene oxide composite membrane electrodes（MnO/CNFs@rGO）,MnO/C@rGO composite membranes and Core-shell MnO/C nanofiber composite films,and the application of these membrane electrodes in lithium ion batteries were studied.The Mn O particles,nanofibers,and graphene sheets in the composite membrane material construct a conductive network through point-to-surface line interactions,showing good electrochemical performance and certain application.The specific findings are as follows:1,we combine electrospinning with electrospray in a simultaneous process to achieve the Mn O/CNFs@rGO composite film electrodes for Li-ion batteries.For as-obtained thin film electrode,we study found the 2D reduced graphene sheets are dispersed on each of the 1D Mn O/CNFs composite filaments.Lithium-ion battery was assembled by using lithium metal as the counter electrode,the study found that the composite electrode exhibits a high discharge capacity of 1118 mAh g^-1 at 0.1A g^-1,and then back to 0.1A g^-11 after 80 cycles,the capacity retention is still up to 98%;although at high rates(e.g.5 A g^-1),the composite is still able to maintain a high reversible capacity of 574 mAh g^-11 after 3000 cycles with a significant coulombic efficiency of 99%.2,we combine electrospinning with electrospray in a simultaneous process to achieve the MnO/CNFs@rGO composite film electrodes for Li-ion batteries.We study found that the as-prepared CNFs/MnO nanowires dispersed on the 2D reduced graphene oxide（rGO）sheets to build a 3D composite flexible film,formatting a specially stable,freestanding,and free-binder structure.The electrode material also showed good electrochemical performance by assembling a simulated battery,it exhibited a reversible capacity of 1,148 mAh g^-1 at a current density of 0.1 A g^-1 and retained a capacity of 332 mAh g^-1 at a current density of 5 A g^-1 even after 4,500cycles.More significant,the recovery MnO₂ products from the spent batteries have been directly used as the Mn source.This work also demonstrates a great potential approach to utilize the MnO₂ from the spent Zn/MnO₂ batteries into high value anode materials for Li-ion batteries applications.3,A double carbon layer MnO composite flexible thin film electrode（Mn/PAN/β-CD）was prepared by high-voltage electrospinning technique and using host-guest molecular interaction and self-assembly.The study found thatβ-CD’s inner cavity can well contain manganese ions,and spontaneously coated on nanowires with PAN as the backbone.Theβ-CD in the prepared double-layer carbon structure well inhibited the reunion of manganese ions.And finally,MnO particles having a uniform dispersion and a small particle size are obtained.Its simulated battery test shows:a high reversible capacity(1025 mAh g^-1 at 0.1 A g^-1),excellent rate capability(376mAh g^-1 at 5 A g^-1),and superior cyclability(844 mAh g^-1 at the current density of 1 A g^-1 after 800 cycles).Such outstanding electrochemical performance endows the composites thin film with great potential and important commercial value as anode material for LIBs.