Fabrication of Mo-Doped Strontium Cobaltite Perovskite Hybrid Supercapacitor Cell with High Energy Density and Excellent Cycling Life.

Enriched with oxygen vacancies Mo-doped strontium cobaltite (SrCo0.9Mo0.1O3-δ, SCM) is synthesized as an oxygen anion-intercalated type charge storage material through sol-gel method. Thanks to the supplemented oxygen vacancies, good electrical conductivity and high ion diffusion coefficient that bestow SCM electrode with excellent specific capacitance (1223.34 F g-1) and specific capacity (168.88 mAh g-1) at 1 A g-1. The decisive constant (b-value) deduced for charge storage mechanism (low scan rate region) is nearly 0.8 indicating highly capacitive process. Under high scan rate region, however, b-value is almost 0.5 and a linear pattern of charge (q) vs. inverse of square root of the scan rate (v-1/2) is obtained. The results reveal O2- diffusion as the rate limiting factor for charge storage. Furthermore, a hybrid cell SCM║LRGONR is fabricated using lacey reduced graphene oxide nanoribbon (LRGONR) as negative electrode which exhibits high energy density (74.8 Wh kg-1 at a power density of 734.5 W kg-1). With charging time only 20.7 s, the cell sustains very high energy density (33 Wh kg-1) with high power delivery rate (6600 W kg-1). The excellent cycling stability (165.1% activated specific capacitance retention and 97.6% from the maximum value attained) after 10,000 charging/discharging cycles, signifies SCM as a potential electrode material for supercapacitors.