Electrochemical Fabrication Of Core/Shell Sandwiched Structures For High Performance Energy Storage Devices

With the rapid development of battery technologies,consumer electronics of high performance are used more and more extensively.It is urgent to develop energy storage devices with high specific capacity,high power density,low price and rapid charge/discharge capabilities.Due to the high specific capacity,high-efficiency,and high energy density,lithium ion batteries are widely used among various energy storage devices.Supercapacitors which have high power density,rapid charge/discharge capabilities,and long circle lives have great study value in energy storage technology.Transition metal oxides/oxyhydroxides(TMOs)are promising high capacity materials for electrochemical energy storage.However,their low rate and poor cyclability hinder the practical applications.In this work,we developed a general electrochemical route to fabricate monolithic core/shell sandwiched structures,which are able to significantly improve the electrochemical properties of TMO electrodes by electrically wiring the insulating active materials and alleviating the adverse effects caused by volume changes using engineered porous structures.As an example,a lithium ion battery anode of porous MnO sandwiched between CNT and carbon demonstrates a high capacity of 554 mAh g-1 even after 1000 cycles at 2 A g-1.A all-solid-state symmetric pseudocapacitor consisting of CNT@MnOOH@polypyrrole exhibits a high specific capacitance of 148 F g-1 and excellent capacitance retention(92%after 10000 cycles at 2 A g-1).Several other examples and applications have further confirmed the effectiveness of improving the electrochemical properties by core/shell sandwiched structures.