A rational combination of metal cations is necessary to obtain a synergistic effect leading to improved electrochemical energy storage performance of bimetal compounds. So, the effect of concentration variation of reactants (nickel and cobalt ratio) in nickel cobalt phosphate material and their influence on physicochemical properties and electrochemical capacitive performances are investigated. The morphological evolution from microflowers (nickel phosphate) to microsheets (cobalt phosphate) is observed with increasing cobalt content in nickel cobalt phosphate thin films. The optimum nickel and cobalt composition (∼1:1) in nickel cobalt phosphate (Ni1.38Co1.62(PO4)2·8H2O) thin film electrode demonstrate maximum specific capacitance (capacity) of 1116 F g−1 (446 C g−1) at 0.5 A g−1 current density. Also, a fabricated hybrid asymmetric aqueous device consists of nickel cobalt phosphate thin film as cathode and rGO as an anode in 1 M KOH electrolyte delivers a higher specific capacitance of 120 F g−1 with a high energy density of 42.3 Wh kg−1 at a power density of 1 kW kg−1. Moreover, a hybrid asymmetric solid-state device fabricated using PVA-KOH gel electrolyte exhibits a maximum specific capacitance of 102 F g−1 with an energy density of 36.2 Wh kg−1 at 160 W kg−1 power density and 83.7 % initial capacitance retention after 4000 GCD cycles. Such excellent electrochemical capacitive performance of hybrid asymmetric devices is attributed to the synergy between nickel and cobalt species in nickel cobalt phosphate thin film electrodes, suggesting its potential application as a cathode in hybrid energy storage devices.
|Journal||Chemical Engineering Journal|
|Publication status||Published - 2022 Feb 1|
Bibliographical noteFunding Information:
We are thankful to the Ministry of Science and Technology India, Department of Science and Technology-Innovation in Science Pursuit for Inspired (DST-INSPIRE), for financial support through research project sanction no. DST/INSPIRE/04/2016/000260. HHP and VGP announce that this work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (No. 2020R1A5A1019131). Also, authors are thankful to the Science and Engineering Research Board (DST-SERB), New Delhi, India for financial support through research project sanction no. CRG/2019/005730.
© 2021 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering