A new carbon modification strategy aimed to fully address the issues of NiO as an electrode material for supercapacitors

In this work, we choose NiO as an example of battery-type materials. We reveal that the electrochemical destabilization of NiO is attributed to the particle merging caused by electrochemical Ostwald ripening. Based on this understanding, we construct a particulate NiO-composed 2D structure coated by a thin carbon layer. Due to the prevention of particle merging by carbon coating and the increase of electrical and ionic conductivities by oxygen vacancies, this structure presents high electrochemical performance and an ultra-long cycling life. This carbon-coated 2D structure of NiO has a high specific capacity of 437.8 C g −1 at low current density and presents excellent high-rate performance (capacity retention of 66% at high current density). It exhibits ultra-high electrochemical stability (capacity retention of 93.5% after an ultra-long cycling of 100,000 cycles). This work demonstrates the success of carbon modification strategy for NiO, also may provide a significant outlet for transforming low-performance battery-type materials into high-performance materials.