Rechargeable lithium-sulfur battery is considered to be one of the most promising candidates for the next-generation energy storage applications due to its high energy density, large theoretical specific capacity, low cost, and abundant sources. However, low conductivity of sulfur, shuttle effect, and volume expansion hindered its practical application. In this study, N,P co-doped hierarchical porous carbon has been fabricated from biomass fallen leaves through novel simple carbonization process with mild H 3 PO 4 as an activator. By adjusting the mass ratio of H 3 PO 4 and leaves, the porous carbon can be optimized to be tube-like morphology with a neatly arranged or monodispersed layout way. When serving as a sulfur host, the as-produced N,P dual-heteroatom doped porous carbon is favorable for advanced conductivity and binding polysulfides through physi-/chemisorption, so as to endow excellent electrochemical performance. An initial specific capacity of 1320 mAh·g −1 can be achieved and maintained above 1000 mAh·g −1 after 300 cycles at 0.1C.

A novel composite, consisting of bimetal oxide Co3V2O8 with high Li+ accommodation capacity and metal-organic framework derived conductive carbon skeleton (Co3V2O8@HCB), is designed and fabricated through a facile process. Co3V2O8 nanorods are implanted on 3D holey carbon boxes to suppress aggregation and volume expansion during cycling, as well as take advantage of the superior conductivity of carbon support. Pseudocapacitance behavior of the unique nano-architecture furtherly promotes the lithium storage capacity and rate capability. As hybrid anode material, the synergistic effects endow the Co3V2O8@HCB with distinguished electrochemical performance, which delivers a reversible capacity of around 1000 mAh.g(-1) after 500 cycles at 1 A.g(-1), together with an excellent rate capability of 648 mAh.g(-1) at 5 A.g(-1).

Transition metal oxides have been intensively studied as potential anode materials for the next generation lithium-ion batteries due to their high theoretical capacity, low cost and higher safety. Herein, the nano-cubic Cu2O was fabricated through simple liquid-phase method followed by the self assembly of ZIF-67/ZIF-8 bi-metal organic framework(MOF), then the hierarchical porous Cu2O/Co3O4@C heterostructured composite material with Co3O4 and N-doped carbon as double shell was successfully constructed. XRD, SEM, TGA, BET, Raman spectra and XPS characterization proved the successful engineering of the heterostructured Cu2O/Co3O4@C composite material. Benefiting from the double-shell and hierarchical porous construction, the volume expansion of the composite material during cycling was effectively restrained. The SEM images after even 100 cycles proved the maintaining of the original morphology and structure of the composite material. The sufficient electrolyte infiltration owing to the porous surface structure, the built-in electric field at the heterostructure interface and the coating of defective N-doped carbon mutually enhance the electronic and ionic conductivity and facilitate the reaction kinetics. The synergistic effects of heterostructure design, morphology regulation, porous properties and N-doped carbons coating endow the Cu2O/Co3O4@C composite material with excellent electrochemical performance. An as high initial discharge capacity as 2065 mA.h/g at 0.1 A/g and reversible discharge capacity of 360 mA.h/g at 2 A/g are delivered, and the stable discharge capacity of 550 mA.h/g maintains after 350 cycles at 1 A/g.