All-solid-state flexible asymmetric supercapacitors with high energy and power densities based on NiCo_2S_4@MnS and active carbon

Electrode material based on a novel core–shell structure consisting of NiCoS（NCS） solid fiber core and Mn S（MS） sheet shell（NCS@MS） in situ grown on carbon cloth（CC） has been successfully prepared by a simple sulfurization-assisted hydrothermal method for high performance supercapacitor. The synthesized NiCoS@Mn S/CC electrode shows high capacitance of 1908.3 F gat a current density of 0.5 A gwhich is higher than those of NiCoSand Mn S at the same current density. A flexible all-solid-state asymmetric supercapacitor（ASC） is constructed by using NiCoS@Mn S/CC as positive electrode, active carbon/CC as negative electrode and KOH/poly（vinyl alcohol）(PVA) as electrolyte. The optimized ASC shows a maximum energy density of 23.3 Wh kgat 1 A g, a maximum power density of about7.5 kw kgat 10 A gand remarkable cycling stability. After 9000 cycles, the ASC still exhibited67.8% retention rate and largely unchanged charge/discharge curves. The excellent electrochemical properties are resulted from the novel core–shell structure of the NiCoS@Mn S/CC electrode, which possesses both high surface area for Faraday redox reaction and superior kinetics of charge transport. The NiCoS@Mn S/CC electrode shows a promising potential for energy storage applications in the future.

Flexible fiber-shaped supercapacitors based on hierarchically nanostructured composite electrodes

A novel all-solid-state, coaxial, fiber-shaped asymmetric supercapacitor has been fabricated by wrapping a conducting carbon paper on a MnO2-modified nanoporous gold wire. This energy wire exhibits high capacitance of 12 mF.cm^-2 and energy density of 5.4 μW.h.cm^-2 with excellent cycling stability. Hierarchical nanostructures and coaxial architectural design facilitate effective contacts between the two core@sheath electrodes and active layers with high flexibility and high performance. This work provides the first example of coaxial fiber- shaped asymmetric supercapacitors with an operation voltage of 1.8 V, and holds great potential for future flexible electronic devices.

Flexible asymmetric supercapacitor with high energy density based on optimized MnO_2 cathode and Fe_2O_3 anode

All-so lid-state flexible supercapacitors have shown great potential in wearable and portable electronics.In this work, a flexible asymmetric pseudocapacitor(FAPC) is fabricated by using MnO_2 nanosheetscarbon fabric as cathode and Fe_2O_3 nanowire-carbon fabric as anode in the presence of PVA-LiCl as gel electrolyte. With high area capacitances of MnO_2 and Fe_2O_3 based electrodes by optimizing the reaction conditions, the device shows high working potential of 1.8 V, high area capacitance of 83.3 mF/cm^2(119 F/g), stable cycling performance with 82.3% of capacitance retention after 5000 cycles, and a competitive energy density of 53.55 Wh/kg in the broader context of MnO_2-based supercapacitors. In addition, the FAPC demonstrates excellent mechanical stability and flexibility with negligible degradation of electrochemical performance after numerous bending tests, establishing it as a promising candidate for portable and wearable energy storage.

NiCoO2/NiCoP@Ni nanowire arrays:tunable composition and unique structure design for high-performance winding asymmetric hybrid supercapacitors

Transition metal phosphides(TMPs)are recognized as such promising supercapacitor materials for the practical application,due to their superior electrical conductivity and excellent redox activity.Here,self-supported three-dimensional NiCoP nanoparticles embedded in NiCoO2 nano wires(NiCoO2/NiCoP)electrode consisting of nickel cobalt phosphides(NiCoP)with high activity and nickel cobalt oxides(NiCoO2)with good stability were fabricated by a hydrothermal and phosphorization method.The electrode integrates the advantages of nanowire arrays for fast ion transport and foam Ni for effective charge transport and flexibility.Benefitting the proper composition control of the nanohybrid and unique structure design,the optimized NiCoO2/NiCoP-20 exhibits a high specific capacitance of 3204 F·g-1 at 1 A·g-1 in 3 mol·L-1 KOH aqueous electrolyte in a three-electrode system.Moreover,the asymmetric supercapacitor assembled with the prepared NiCoO2/NiCoP-20 and activated carbon achieves a specific capacitance of 116 F·g-1 with a high energy density of 40.32 Wh·kg-1 at the power density of 800.18 W·kg-1.The practical application is further demonstrated with all-solid-state winding supercapacitor devices,with decent flexibility,in series to light the Central South University(CSU)logo consisting of 21 red LED indicators.

基于石墨烯和氮化硼的高性能电容器

柔性全固态超级电容器(FASS)是可穿戴电子设备以及电力设备的能源供应,石墨烯纳米片具有独特的二维结构,较强的机械性能和优异的导电性,在纸片状柔性电极中应用广泛.基于简单石墨烯纳米片的FASS的双层电容性能的基本特征限制了其性能的提高和实际应用.研究了一种基于超大型石墨烯纳米片和超薄氮化硼(BN)纳米片的FASS,通过真空辅助过滤组装独立式超大型石墨烯纳米片/BN纳米片复合纸电极.新型超大型石墨烯纳米片/BN纳米片纸的特有结构可以有效整合假电容BN纳米片和导电石墨烯的优点,从而在FASS中表现出出色的电化学性能.5000次充放电后,FASS的最高面积比电容达到325.4 mF/cm^(2),并具有约86.2%的高容量保持率,且在85.7 W/kg的功率密度下具有22.8 W·h/kg(1 W·h=3.6 kJ)的高能量密度.