A Sodium Hybrid Capacitor with High Energy Retention and Ultra-High Stability

Abstract

Sodium ion batteries have been recently proved to be a cost-effective and promising alternative to lithium-ion batteries for next generation high-energy applications. However, the sluggish intercalation kinetics in batteries greatly forbid the efficient high power operation.[1] Recently, sodium hybrid capacitors (NHCs) emerged as a promising energy storage system to retain high specific energy at high power conditions. Benefiting from the simultaneous sodium intercalation/deintercalation in battery type electrode and anionic adsorption/desorption in capacitor type electrode, a fast kinetics in NHCs have been achieved. However, the poor sodium ion storage in battery electrode along with limited anionic adsorption in commercial electrode diminish the output performance of NHCs. The research on NHCs is still in a nascent stage and requires deep investigation to improve energy retention and cycle stability at high power. The kinetics in both battery and capacitor type electrodes must be synergistically improved to achieve a high energy.[2] In this work, we developed a high performing NHC with metal oxide nanoparticles embedded in graphene network as a battery electrode along with a highly mesoporous carbon derived from bio-mass precursor as a capacitor electrode. The highly favorable architecture in both the electrodes showed an enhanced capability towards ion storage (Shown in Ragone plot). A high energy retention at high power condition along with ultra-high stability have been achieved. The detailed results will be presented and discussed in detail.