Li Storage Performance for the Composite Structure Of Graphene and Boron Fullerene

We study the stability and performance of Li absorption on the composite structure （B80 C72） of boron fullerene and graphene by first-principles calculations. Our results show that the Li storage capacity of the composite structure is estimated to be at least Li54B80C72, which is steady with improved dispersibility and electronic conductivity. The composite structure could have the potential application as the anode material of Li-ion batteries with high Li storage capacity and great mechanical property.

Freestanding MoSe_(2)nanoflowers for superior Li/Na storage properties

MoSe_(2),with high theoretical specific capacity,has attracted a lot of attention.There remains an open challenge to effectively suppress the irreversible selenium dissolution and rapid capacity decrease induced by severe volume change during cycling.Herein,we synthesize MoSe_(2)nanoflowers dispersed on one-dimensional(1D)N-doped carbon nanofibers(MoSe_(2)@NCNFs)for use as a freestanding electrode.In this unique structure,the 1D N-doped carbon nanofibers are found to not only enhance the conductivity but also ensure the structural integrity during the Li^(+)/Na^(+)insertion/destraction processes.As expected,at 2 A·g^(-1),the specific capacity of the MoSe_(2)@NCNFs is maintained at 180 mAh·g^(-1)after 500 cycles when used in lithium storage applications.Furthermore,in the case of sodium storage,at 1 A·g^(-1),the MoSe_(2)@NCNFs shows a capacity of 122mAh·g^(-1)after 500 cycles.These findings suggest that the MoSe_(2)@NCNF electrodes may be a promising candidate for use in reversible Li/Na storage applications.

Lithium storage properties of Ti3C_(2)Tx(Tx= F,Cl,Br) MXenes

In this work, Ti3C_(2)TxMXene with-F,-Cl and-Br surface terminations are synthesized and the effect of these halogen terminations on the lithium storage properties is investigated. A maximum Li+storage capacity of 189 m Ah/g is achieved with Ti3C_(2)BrxMXene much higher than Ti3C_(2)Clxand Ti3C_(2)Fxwith 138 m Ah/g and 123 m Ah/g, respectively. Density functional theory(DFT) calculation shows that the adsorption formation energy of halogen atoms on Ti atoms follows the trend of Ti-F > Ti-Cl > Ti-Br, leading to the same trend in the content of terminations on corresponding MXenes. In addition, inevitable exposure of MXene to oxygen causes competition between halogen and oxygen. Theoretical results show Ti3C_(2)BrxMXene has the highest Ti to O ratio and the lowest Ti to Br ratio, the high lithium affinity of O explains the maximum Li-ion storage capacity with Ti3C_(2)BrxMXene. This work shed light on the opportunity for achieving improved lithium storage properties of MXene electrodes by regulating the surface chemistry.

Reduced graphene oxide decorated with Bi2O2.33 nanodots for superior lithium storage

Bismuth oxides are important battery materials owing to their ability to electrochemically react and alloy with Li,which results in a high capacity level,which substantially exceeds that of graphite anodes.However,this high Li-storage capability is often compromised by the poor electrochemical cyclability and rate capability of bismuth oxides.To address these challenges,in this study,we design a hybrid architecture composed of reduced graphene oxide （rGO） nanosheets decorated with ultrafine Bi2O2.33 nanodots （denoted as Bi2O2.33/rGO）,based on the selective and controlled hydrolysis of a Bi precursor on graphene oxide and subsequent crystallization via solvothermal treatment.Because of its high conductivity,large accessible area,and inherent flexibility,the Bi2O2.33/rGO hybrid exhibits stable and robust Li storage （346 mA＆#183;h＆#183;g-1 over 600 cycles at 10 C）,significantly outperforming previously reported Bi-based materials.This superb performance indicates that decorating rGO nanosheets with ultrafine nanodots may introduce new possibilities for the development of stable and robust metal-oxide electrodes.

PVA-assisted hydrated vanadium pentoxide/reduced graphene oxide films for excellent Li^(+)and Zn^(2+)storage properties

Low-cost,high safety and environment-friendly aqueous energy storage systems(ESSs)are huge potential for grid-level energy storage,but the(de)intercalation of metal ions in the electrode materials(e.g.vanadium oxides)to obtain superior long-term cycling stability is a significant challenge.Herein,we demonstrate that polyvinyl alcohol(PVA)-assisted hydrated vanadium pentoxide/reduced graphene oxide(V_(2)O_(5)·n H_(2)O/r GO/PVA,denoted as the VGP)films enable long cycle stability and high capacity for the Li^(+)and Zn^(2+)storages in both the VGP//Li Cl(aq)//VGP and the VGP//Zn SO4(aq)//Zn cells.The binderfree VGP films are synthesized by a one-step hydrothermal method combination with the filtration.The extensive hydrogen bonds are formed among PVA,GO and H_(2)O,and they act as structural pillars and connect the adjacent layers as glue,which contributes to the ultrahigh specific capacitance and ultralong cyclic performance of Li^(+)and Zn^(2+)storage properties.As for Li^(+)storage,the binder-free VGP4 film(4mg PVA)electrode achieves the highest specific capacitance up to 1381 F g^(-1)at 1.0 A g^(-1)in the three-electrode system and 962 F g^(-1)at 1.0 A g^(-1)in the symmetric two-electrode system.It also behaves the outstanding cyclic performance with the capacitance retention of 96.5%after 15000 cycles in the three-electrode system and 99.7%after 25000 cycles in the symmetric two-electrode system.As for Zn^(2+)storage,the binder-free VGP4 film electrode exhibits the high specific capacity of 184 m A h g^(-1)at 0.5A g^(-1)in the VGP4//Zn SO4(aq)//Zn cell and the superb cycle performance of 98.5%after 25000 cycles.This work not only provides a new strategy for the construction of vanadium oxides composites and demonstrates the potential application of PVA-assisted binder-free film with excellent electrochemical properties,but also extends to construct other potential electrode materials for metal ion storage cells.