10.1021/acsami.7b05384.s001 Shude Liu Shude Liu Kalimuthu Vijaya Sankar Kalimuthu Vijaya Sankar Aniruddha Kundu Aniruddha Kundu Ming Ma Ming Ma Jang-Yeon Kwon Jang-Yeon Kwon Seong Chan Jun Seong Chan Jun Honeycomb-Like Interconnected Network of Nickel Phosphide Heteronanoparticles with Superior Electrochemical Performance for Supercapacitors American Chemical Society 2017 surface area Ni x P y electrode exhibits surface-to-volume ratios electrode material design Nickel Phosphide Heteronanoparticles Supercapacitors Transition-metal-based heteronanoparticles supercapacitor electrode rate capability Superior Electrochemical Performance electrochemical activity electrode materials as-synthesized Ni x P y cycling stability optimized Ni x P y novel nanostructured Ni x P y Honeycomb-Like Interconnected Network kg 2017-06-08 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Honeycomb-Like_Interconnected_Network_of_Nickel_Phosphide_Heteronanoparticles_with_Superior_Electrochemical_Performance_for_Supercapacitors/5139166 Transition-metal-based heteronanoparticles are attracting extensive attention in electrode material design for supercapacitors owing to their large surface-to-volume ratios and inherent synergies of individual components; however, they still suffer from limited interior capacity and cycling stability due to simple geometric configurations, low electrochemical activity of the surface, and poor structural integrity. Developing an elaborate architecture that endows a larger surface area, high conductivity, and mechanically robust structure is a pressing need to tackle the existing challenges of electrode materials. This work presents a supercapacitor electrode consisting of honeycomb-like biphasic Ni<sub>5</sub>P<sub>4</sub>–Ni<sub>2</sub>P (Ni<sub><i>x</i></sub>P<sub><i>y</i></sub>) nanosheets, which are interleaved by large quantities of nanoparticles. The optimized Ni<sub><i>x</i></sub>P<sub><i>y</i></sub> delivers an ultrahigh specific capacity of 1272 C g<sup>–1</sup> at a current density of 2 A g<sup>–1</sup>, high rate capability, and stability. An asymmetric supercapacitor employing as-synthesized Ni<sub><i>x</i></sub>P<sub><i>y</i></sub> as the positive electrode and activated carbon as the negative electrode exhibits significantly high power and energy densities (67.2 W h kg<sup>–1</sup> at 0.75 kW kg<sup>–1</sup>; 20.4 W h kg<sup>–1</sup> at 15 kW kg<sup>–1</sup>). These results demonstrate that the novel nanostructured Ni<sub><i>x</i></sub>P<sub><i>y</i></sub> can be potentially applied in high-performance supercapacitors.