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This study proposes MnO 2 thin nanosheets assembled microspheres with oxygen vacancies and preinsertion of Na ions (NaMnO 2−x ) as highly capable supercapacitor electrodes. The NaMnO 2−x electrode can reach a stable potential window of 1.2 V without oxygen evolution reactions in threeelectrode configuration. The voltage window of the assembled aqueous ASC device can be expanded to 2.4 V (1 M Na 2 SO 4 ) by using NaMnO 2−x electrode and activated carbon electrode as positive and negative electrodes, respectively. The NaMnO 2−x electrode delivers a good specific capacitance of 215 F·g −1 at current density of 1 A·g −1 . It displays high-rate capability and an excellent cycling stability, maintaining 95.5% of its initial specific capacitance at 2 A·g −1 after 2500 cycles. The ASC device shows a high energy density and power density of 28.56 W·h·kg −1 and 1246 W·kg −1 , respectively, at a current density of 1 A·g −1 . OPEN ACCESS RECEIVED

In this work, a three dimensional (3D) conductive material of activated carbon coating Copper-Cobalt Prussian Blue (PB) is synthesized and applied on sodium ion supercapacitors. The activated carbon is proved able to enhance the conductivity, prevent structural collapse during sodium ion deintercalation, reduce interstitial water in PB crystals as well as special hindrance, and improve electrochemical performance of super capacitors dramatically. It is demonstrated that a specific capacity of 90.4 F g−1 and and power density of 4.3 kW kg−1 as well as energy density of 65.1 Wh kg−1 are achieved for CuCoHCF@ AC//AC device. In addition, 90% % starting value are retained for the specific capacity after 2000 cycles operation.

Pure Al coating, AlSi alloy coating, NiAl alloy coating and 316L stainless steel coating were prepared on the Q235 steel by arc spraying technology. The corrosion of the four sprayed alloy coatings in the 220kV transformer substation soil and soil solution was studied by buried specimens and electrochemical test in Hunan. The corrosion behaviors of the coating steel samples in transformer substation soil solution were investigated by line polarization, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. The results show that the best corrosion resistance of the four sprayed alloy coatings was AlSi coating, sequentially in the order of NiA1 and stainless steel coating, and the Al coating was easy bouffant at long time in the underground, so that the corrosion resistance is not good.