Application of hard ceramic materials B4C in energy storage: Design B4C@C core-shell nanoparticles as electrodes for flexible all-solid-state micro-supercapacitors with ultrahigh cyclability

B 4 C is widely known by a series of unique advantages, such as low density, high hardness, good chemical stability and excellent environmental stability, as a hard ceramic material. However, the study of B 4 C as the electrode material on micro-electrochemical energy storage devices has not yet been reported. To some extent, the poor conductivity of B 4 C is an important reason to limit its extensive application in energy storage field. Here, we first report an elaborated design B 4 C@C of core-shell structure by simple vacuum heating synthesis strategy as electrodes for flexible all-solid-state micro-supercapacitors (MSCs) with the method of mask assisted-vacuum filtration. Notably, the B 4 C@C-MSCs exhibit outstanding electrochemical performances, such as high areal capacitance of 7.33 mF cm −2 , remarkable cycling stability with 100.94% capacitance retention after 50000 cycles, wide operating temperature range (−25 to 75 °C), excellent mechanical flexibility without obviously performance degradation under different bending states, distinguished environmental stability and superior integration. These results suggest that the hard ceramic materials B 4 C have a promising prospect in micro-electrochemical energy storage devices.