Intrinsically stretchable hetero-nanostructures for wearable energy storage devices

Abstract

Stretchable energy storage devices that can accommodate large strain while retaining their electrochemical functions are the key components to power elastomeric electronics and make them truly autonomous systems. Many efforts have been made to improve the electrochemical energy performance using various morphologies of nanomaterials as the electrodes. However, a single-component electrode material can hardly obtain the characteristics of high electronic/ionic conductivity, high electrochemical and mechanical stability, simultaneously. Therefore, designing well-arranged hetero-nanostructures that overcome the limitations of different electrochemically active materials and combine the advantages of them is of great significance and still remains a challenge.1 Herein, we extend hetero-nanostructure strategy to the emerging battery technologies for wearables. It contributes to the development and breakthroughs of advanced electrodes, enabling wearable batteries to be high performance as well as multifunctional – transparent1, electrochromic2, integrated3, or self-healing. Firstly, Ag– Ni and Ag– Fe core– shell nanowire networks embedded in an elastomer are suggested as stretchable transparent electrodes for asymmetric supercapacitors1. The unique Ag– bimetallic hetero-structured core-shell nanowires guarantee a high electrochemical stability and stable conductivity up to 100% tensile strain, as well as providing high specific capacitances (~ 3 mF cm− 2) with 50% transparency. Secondly, by inkjet-printing single layer of WO3 nanoparticles on an elastomeric transparent conductor, we demonstrate a stretchable transmissive electrochromic energy storage device2. The devices consisting of WO3-based hybrid electrode and polyaniline/carbon nanotubes composite electrode maintain excellent electrochromic and energy storage performance up to 50% strain. Lastly, reduced-graphene oxide/Au heterostruct