Lithium Storage Performances Of ZnO-based Anode Materials And Li-rich Mn-based Cathode Materials

ZnO has attracted enormous research interest as anode material in lithium ion batteries due to its large theoretical capacity.Unfortunately,the development of ZnO-based anode materials is greatly bottlenecked by their poor capacity retention and limited cyclic life.Herein,ingeniously designed 3D graphene encapsulated ZnO-NiO-CuO double-shelled hollow microspheres?DSHM@RGO?have been prepared by a facile surfactant-assisted assembly method.Benefiting from their unique features including the large specific surface area,the double-shelled hollow architecture,the modification of graphene and the nanoscale building blocks,the DSHM@RGO anode exhibits better electrochemical performances.Commercialized cathode materials serious hinder the development of Lithium ion batteries due to lower operating voltage and higher cost.The Mn/Ni/Co carbonate were synthesized by hydrothermal method.We discover that the increase of Lithium source in heat treatment lead to increasing specific capacity and reducing cycling stability of Li-rich Mn-based materials.The main contents and results are as follows:?1?In a typical procedure,zinc citrate solid microspheres were pre-synthesized through an one-step route based on our previous report.After that,zinc citrate solid microspheres were dispersed into copper sulfate solution with the aid of ultrasonication,and subsequently aged for 1 h at room temperature.Then,the resulting mixtures were dispersed into nickel nitrate solution and aged for another 1 h at room temperature to produce zinc-nickel-copper double-shelled hollow microspheres.Subsequently,the above precipitate was annealed at 500? for 2 h in air to achieve ZnO-NiO-CuO double-shelled hollow microspheres.A high reversible capacity of 350 mA h g^-1 is delivered after 170 cycles at a current density of 0.1 A g^-1,?2?ZnO-NiO-CuO double-shelled hollow microspheres was dispersed into graphene oxide solution under vigorously stirring condition.After that,CTAB solution was added dropwise to the above suspension to form GO sheets encapsulated ZnO-NiO-CuO double-shelled hollow microspheres.Finally,DSHM@RGO was obtained after the thermal reduction of DSHM@GO at 500 ? for 2 h in argon atmosphere.Benefiting for the encapsulated RGO,a high reversible capacity of 560 mA h g^-1 is delivered after 100 cycles at a current density of 1 A g^-1.Even at a current density of 3 A g^-1,a high reversible discharge capacity of 366 mA h g^-1 can be retained.?3?The firstly synthesis of ternary carbonate by hydrothermal method,following by mixing with lithium carbonate and then annealing in air to obtain Li-rich ternary cathode materials was carried out.The morphology,phase,microstructure and electrochemical properties of the obtained Li-rich ternary cathode materials were measured and summarized.The increasing content of lithium source will lead to the improvement of reversible capacity and the decline of cycling stability of Li-rich ternary cathode materials.