Facile synthesis of Mn3[Co(CN)6]2·nH2O nanocrystals for high-performance electrochemical energy storage devicesElectronic supplementary information (ESI) available. See DOI: 10.1039/c6qi00595k

Recently, although great efforts have been committed to enhance the electrochemical performance of supercapacitors (SCs), these devices are still unable to meet our expectations on account of limited working voltage, insufficient cycle life, low mechanical flexibility, and high cost. In this work, we have successfully synthesized several Mn 3 [Co(CN) 6 ] 2 · n H 2 O nanocrystals by a mild precipitation method at room temperature. These Mn 3 [Co(CN) 6 ] 2 · n H 2 O nanocrystals, as a novel kind of positive electrode materials, are firstly applied in flexible solid-state electrochemical energy storage devices. The best one of the as-assembled devices based on the as-prepared Mn 3 [Co(CN) 6 ] 2 · n H 2 O nanocrystals shows high electrochemical performance activity, which offers the highest volumetric energy density of 4.69 mW h cm −3 at 1.0 mA cm −2 and exhibits the largest power density of 177.1 mW cm −3 at 20.0 mA cm −2 . Remarkably, the device displayed wonderful mechanical flexibility as the bending angle range from 0° to 180°. Moreover, the device demonstrated little capacitance change over 7000 cycles at 1.0 mA cm −2 , and exhibited a great cycling stability with 96.1% capacitance retention. Mn 3 [Co(CN) 6 ] 2 · n H 2 O nanocrystals are firstly applied in flexible solid-state electrochemical energy storage devices.