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Mn 3 O 4 thick film electrodes have been synthesized by spray pyrolysis method. Effect of its two important synthesis parameters viz. solution feed rate and substrate temperature has been studied. Solution feed rate was studied in the range of 150 to 250 cc.min −1 while substrate temperature was varied from 325 to 400 °C. X-ray diffraction studies confirms Hausmannite crystal structure and SEM studies show spherical grains, uniformly distributed porous microstructure obtained for deposited Mn 3 O 4 thick films. The contact angle measurements show these electrodes have very low contact angle in the range of 2−8° and high surface energy. Cyclic voltammetry study showed specific and interfacial capacitance of Mn 3 O 4 electrodes increased with increase in solution feed rate, due to increased thickness of films. On the other hand, substrate temperature shows effect on film morphology, grain size and porosity, however, does not show any explicit effect on specific and interfacial capacitance. Highest values of specific and interfacial capacitance exhibited by Mn 3 O 4 are 187.79 F.g −1 and 0.82 F.cm −2 respectively for sample prepared at 250 cc.min −1 solution feed rate and 325 °C substrate temperature. The calculated energy density and power density for the same sample was 26.08 Wh.kg −1 and 1.01 kW.kg −1 respectively. [ABSTRACT FROM AUTHOR]

Abstract: High energy density Li-ion hybrid electrochemical capacitors (Li-HEC) are fabricated with 3 D architectured high surface area porous carbon (HSPC) derived from the poly(acrylamide-co-acrylic acid) potassium salt in a single step without any activating agent. The obtained HSPC exhibits high specific surface area of 1490 m2 g−1 and characterized with several analytical techniques. Li-HEC is fabricated with insertion type Li4Ti5O12 anode by adjusting the mass balance based on the single electrode performance with Li. The Li-HEC delivered the maximum energy density of ∼55 Wh kg−1, which is much higher than commercially available activated carbon (∼36 Wh kg−1). Further HSPC based Li-HEC delivered excellent cycleability and rendered ∼87% of initial value after 2000 cycles. [Copyright &y& Elsevier]