Pushing the Energy Output and Cyclability of Sodium Hybrid Capacitors at High Power to New Limits

4 years ago

Pushing the Energy Output and Cyclability of Sodium Hybrid Capacitors at High Power to New Limits

Do Kyung Kim, Ranjith Thangavel, Yun-Sung Lee, Brindha Moorthy

Hybrid capacitors, especially sodium hybrid capacitors (NHCs), have continued to gain importance and are extensively studied based on their excellent potential to serve as advanced devices for fulfilling high energy and high power requirements at a low cost. To achieve remarkable performance in hybrid capacitors, the two electrodes employed must be superior with enhanced charge storage capability and fast kinetics. In this study, a new sodium hybrid capacitor system with a sodium super ionic conductor NaTi2(PO4)3 grown on graphene nanosheets as an intercalation electrode and 2D graphene nanosheets as an adsorption electrode is reported for the first time. This new system delivers a high energy density of ≈80 W h kg−1 and a high specific power of 8 kW kg−1. An ultralow performance fading of ≈0.13% per 1000 cycles (90%–75 000 cycles) outperforms previously reported sodium ion capacitors. The enhanced charge transfer kinetics and reduced interfacial resistance at high current rates deliver a high specific energy without compromising the high specific power along with high durability, and thereby bridge batteries and capacitors. This new research on kinetically enhanced NHCs can be a trendsetter for the development of advanced energy storage devices requiring high energy—high power. A high performing sodium hybrid capacitor is fabricated utilizing graphene nanosheets as high power adsorption electrode and graphene/NaTi2(PO4)3 as a high energy intercalation electrode. High energy retention at high power along with excellent stability of 90% after 75 000 cycles with a lowest ever energy loss of ≈0.13% per 1000 cycles is documented.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/aenm.201602654