We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g−1 at 0.5 A g−1 and 1181 F g−1 even at current density as high as 10 A g−1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg−1 (at power density of 551 W kg−1) with a 1.5 V operating voltage.

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Novel sulfonated diamines bearing aromatic pendant groups, namely, 3,5diamino-3 0 -sulfo-4 0 -(4-sulfophenoxy) benzophenone (DASSPB) and 3,5-diamino-3 0 -sulfo-4 0 -(2,4-disulfophenoxy) benzophenone (DASDSPB), were successfully synthesized. Novel side-chain-type sulfonated (co)polyimides (SPIs) were synthesized from these two diamines, 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA) and nonsulfonated diamines such as 4,4 0 -bis(3-aminophenoxy) phenyl sulfone (BAPPS). Tough and transparent membranes of SPIs with ion exchange capacity of 1.5-2.9 meq g À1 were prepared. They showed good solubility and high thermal stability up to 300 8C. They showed isotropic membrane swelling in water, which was different from the mainchain-type and sulfoalkoxy-based side-chain-type SPIs. The relative humidity (RH) and temperature dependence of proton conductivity were examined. At low RH, the novel SPI membranes showed much higher conductivity than the sulfoalkoxy-based SPIs. They showed comparable or even higher proton conductivity than Nafion 112 in water at 60 8C (>0.10 S cm À1 ). The membrane of NTDA-DASDSPB/BAPPS (1/1)-s displayed reasonably high proton conductivities of 0.05 and 0.30 S cm À1 at 50 and 100% RH, respectively, at 120 8C.

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