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Abstract: In this paper, monodispersed LiFePO4 nanopillows have been successfully synthesized via solvothermal route with ethylene glycol (EG) as reaction medium. Subsequently, with the basis of the solvothermally synthesized monodispersed LiFePO4 nanopillows, monodispersed LiFePO4@C core–shell nanostructures are facilely prepared in high yield. Based on the experimental results, the formation mechanism of the monodispersed LiFePO4 nanopillows has been discussed simply. The monodispersed LiFePO4@C core–shell nanostructures exhibit nice capacity retention and high rate capacity due to the full carbon-coating and the well-crystallized nanosized particles. [Copyright &y& Elsevier]

Tin (Sn)-based materials are potential alternatives to the commercial graphite anode for next-generation Li-ion batteries (LIBs) due to their high theoretical capacity. However, the poor cyclic stability, originating from the large volumetric changes during charge/discharge process, hinder their practical utilization. Herein, we have successfully prepared a Sn-based metal-organic framework (MOF, Sn-PMA), and explored as potential anode materials in LIBs. Benefiting from its layered structure and efficient electron transport channels, Sn-PMA electrodes deliver a high initial capacity of 1567 mAh g−1, at 100 mA g−1, and maintained a reversible capacity of 707 mAh g−1, at 800 mA g−1, after 400 cycles. Furthermore, the detailed post-electrochemical structural, morphological and compositional analysis is carried out to unveil the structural changes and Li-ion storage mechanism of electrodes. Ex-situ XRD and XPS results revealed that, in Sn-PMA electrode, O atom, coordinated to the Sn atom, exhibited higher electronegativity, served as major Li-ion storage site and rendered excellent cyclic stability due to a stable structure. Kinetic analyses reveal that the excellent performance of the Sn-PMA is typical attributed to the pseudocapacitive contribution induced by the special porous structure. A Sn-based MOF has successfully prepared by hydrothermal reaction, which shows outstanding lithium storage properties. Image 1 • Sn-based MOF was fabricated through a simple hydrothermal reaction. • Sn-PMA exhibits excellent electrochemical performance with typical pseudocapacitive contribution. • Ex-situ XRD and XPS reveal the lithium storage mechanism of Sn-PMA. [ABSTRACT FROM AUTHOR]

Abstract: We report a simple strategy to prepare a hybrid of lithium titanate (Li4Ti5O12, LTO) nanoparticles well-dispersed on electrical conductive graphene nanosheets as an anode material for high rate lithium ion batteries. Lithium ion transport is facilitated by making pure phase Li4Ti5O12 particles in a nanosize to shorten the ion transport path. Electron transport is improved by forming a conductive graphene network throughout the insulating Li4Ti5O12 nanoparticles. The charge transfer resistance at the particle/electrolyte interface is reduced from 53.9Ω to 36.2Ω and the peak currents measured by a cyclic voltammogram are increased at each scan rate. The difference between charge and discharge plateau potentials becomes much smaller at all discharge rates because of lowered polarization. With 5wt.% graphene, the hybrid materials deliver a specific capacity of 122mAhg−1 even at a very high charge/discharge rate of 30C and exhibit an excellent cycling performance, with the first discharge capacity of 132.2mAhg−1 and less than 6% discharge capacity loss over 300 cycles at 20C. The outstanding electrochemical performance and acceptable initial columbic efficiency of the nano-Li4Ti5O12/graphene hybrid with 5wt.% graphene make it a promising anode material for high rate lithium ion batteries. [Copyright &y& Elsevier]

Abstract: One of the most attractive research areas in lithium-ion batteries (LIBs) is to design elaborate nanostructure of the electrode, which has been considered as keys to solve the problems such as the low energy density, slow lithium ion and electron transport, and the large volume change of electrode materials during cycling processes. Here, mesoporous Co3O4 with controllable structures was directly grown on a graphene membrane by hydrothermal reaction followed by annealing treatment, and used as an integrated anode in LIBs without using metallic current collector, binder and conductive additive. The light graphene membrane as current collector with high electrical conductivity and stability contributes to the high energy density of LIBs. A mesoporous structure with enough space is beneficial to lithium ion diffusion and strain buffer of Co3O4 during discharge/charge processes, rendering the electrodes high performance. The integrated electrode shows good rate capability and impressive cycling stability without capacity loss over 500 cycles under a high current density of 500 mA g−1. [Copyright &y& Elsevier]

Abstract: Nanoporous copper (NPC), as a new kind of porous metal prepared by dealloying, is introduced into the lithium-ion battery as both the current collector and substrate of active material. The nanoporous copper has three-dimensional structure composed of large channels (hundreds of nanometers) and small pores (tens of nanometers) on the channel walls. Anodes were prepared by electroless depositing of a thin layer of tin on NPC and copper foil. By comparing the electrochemical performance of both electrodes, the nanostructured electrode exhibits much higher areal capacity and better Coulombic efficiency than planar electrode. [Copyright &y& Elsevier]

Inspired by the successful application of spinel LiMn 2 O 4 cathode in Li-ion batteries, analogous spinel ZnMn 2 O 4 (ZMO) is regarded as a promising cathode for rechargeable aqueous Zn-ion batteries (ZIBs). Nevertheless, clear Zn2+ storage mechanism and phase transition of spinel ZMO is still scarce. Herein, in the first time, we report an in-situ Raman study in dynamically probing the phase and structure evolution of a spinel ZMO-based cathode during charging-discharging process, in which spinel ZMO nanoparticles are anchored on porous carbon polyhedrons (PCPs). By in-situ investigation, it is demonstrated that the electrochemical mechanism can be attributed to the highly reversible phase transformation between spinel ZMO and λ-type MnO 2 upon Zn2+ insertion/extraction, which is driven by stepwise oxidation and reduction reactions of Mn3+/Mn4+ along with efficient charge carriers. Furthermore, the resultant ZMO@PCPs composite as cathode delivers a large reversible capacity of 125.6 mAh g−1 at a high current density of 1 A g−1 after 2000 cycles, representing superior long-term cyclic stability (capacity retention of 90.3%) and remarkable rate capability in aqueous ZIBs. As a proof of concept, high-performance flexible aqueous ZIBs are fabricated and represent stable electrochemical performance under various deformation states, indicating their potential applications in portable and wearable electronics. • A 3D-confined spinel ZnMn 2 O 4 cathode is proposed for aqueous Zn-ion batteries (ZIBs). • Zn2+ storage mechanism is explored by in-situ Raman investigation in the first time. • Reversible phase change between ZnMn 2 O 4 and λ-MnO 2 upon Zn2+ insertion/extraction. • The resultant cathode represents superior electrochemical behaviors in aqueous ZIBs. • Flexible aqueous ZIBs show stable electrochemical performance at deformation states. [ABSTRACT FROM AUTHOR]