Energy storage is now well recognised in both industry and academia as one of the key technologies to enable safe, secured, and sustainable supply of energy in the post-fossil era. Whilst there are many options for storage of various forms of energy, electricity storage is perhaps most important for at least two interdependent reasons. Firstly, many renewable harvesting technologies output electricity as the commercial product. Secondly, there should be as few as possible conversion steps in the storage and release processes to minimise energy loss. This presentation will focus on a newly proposed and demonstrated electricity storage device, supercapattery, that combines the performance characteristics of rechargeable batteries (high energy capacity, low power capability) and supercapacitors (high power capability, low energy capacity, also known as ultra-capacitor or electrochemical capacitor). In particular, the performance of supercapattery (cf. the Ragone plot) is correlated to the nanostructured electrode materials (hybrid materials of carbon nanotubes with electronically conducting polymer or transition metal oxides), and device designs developed by the author’s research team in the past decade (cf. Refs.1-5). Examples are provided to demonstrate the principle, practice and prospect of this new device.