Among numerous active electrode materials, nickel hydroxide is a promising electrode in electrochemical capacitors. Nickel hydroxide research has thus far focused on the crystalline rather than the amorphous phase, despite the impressive electrochemical properties of the latter, which includes an improved electrochemical efficiency due to disorder. Here we demonstrate high-performance electrochemical supercapacitors prepared from amorphous nickel hydroxide nanospheres synthesized via simple, green electrochemistry. The amorphous nickel hydroxide electrode exhibits high capacitance (2,188 F g−1), and the asymmetric pseudocapacitors of the amorphous nickel hydroxide exhibit high capacitance (153 F g−1), high energy density (35.7 W h kg−1 at a power density of 490 W kg−1) and super-long cycle life (97% and 81% charge retentions after 5,000 and 10,000 cycles, respectively). The integrated electrochemical performance of the amorphous nickel hydroxide is commensurate with crystalline materials in supercapacitors. These findings promote the application of amorphous nanostructures as advanced electrochemical pseudocapacitor materials.

Cobalt hydroxide (Co(OH)2) has received extensive attention for its exceptional splendid electrical properties as a promising supercapacitor electrode material. Co(OH)2 study so far prefers to crystal instead of amorphous, in spite of amorphous impressive electrochemical properties including the ability to improve the electrochemical efficiency based on the disorder structure. The amorphous Co(OH)2 nanostructures with excellent electrochemical behaviors were successfully synthesized by a simple and green electrochemistry. Our as-prepared Co(OH)2 electrode exhibited ultrahigh capacitance of 1094 F g(-1) and super long cycle life of 95% retention over 8000 cycle numbers at a nominal 100 mV s(-1) scan rate. The united pseudo-capacitive performances of the amorphous Co(OH)2 nanostructures in electrochemical capacitors are totally comparable to those of the crystalline Co(OH)2 nanomaterials. These findings actually open a door to applications of amorphous nanomaterials in the field of energy storage as superior electrochemical pseudocapacitors materials.

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The serious limitations of MnO2 are poor electrical conductivity and low utilization rate of electrochemical active area. These problems have seriously limited the application of MnO2 aqueous zinc‐ion batteries (AZIBs). Herein, preparing MnO2 uniformly loaded on carbon nanotubes with good electrical conductivity can greatly improve the poor electrical conductivity of MnO2. Moreover, by introducing oxygen vacancy, the surface capacitance, the reaction kinetics, and the electrochemical performance of MnO2 is increased. The specific capacity of the Vo‐MnO2/CNT material is 314 mAh g−1, at 0.2 A g−1, and capacity retention of 81% is achieved after 1000 cycles. In particular, the prepared device presents a distinct energy density of 416.2 Wh kg−1. As a result, the capacity as well as the cycle stability is effectively improved compared with the original MnO2.

Amorphous cobalt hydroxide nanostructures have been synthesized by a simple and green electrochemistry technique. Magnetism measurements showed that the as-synthesized amorphous cobalt hydroxide nanoparticles are ferromagnetic under the Curie temperature of 10 K with high magnetization of 30 emu g À1 and an exchange bias field of 100 Oe at 5 K. These findings may lead to novel applications of the amorphous cobalt hydroxide nanostructures as magnetic materials.