Sputtered (Fe,Mn)₃O₄ Spinel Oxide Thin Films for Micro-Supercapacitor

Abstract

The scaling up of wireless operating microelectronics for upcoming Internet of Things (IoT) applications demands high-performance micro-supercapacitors (MSCs) with corresponding high-energy and power capabilities. Indeed, this necessitates the quest for MSC’s electrode materials capable of delivering high energy density at high charge/discharge rates. Many multicationic oxides, such as spinel manganese-iron compounds, demonstrate good pseudocapacitive properties as positive electrodes in conventional supercapacitors. However, fulfilling the required fabrication techniques is a challenge for their applications in MSCs. Hence, this study, for the first time, demonstrates the successful deposition of spinel Mn-Fe thin films on a functional platinum-based current collector. The deposition is achieved in a reactive oxygen environment via reactive DC magnetron sputtering techniques and subsequently annealed ex-situ at 600°C in a nitrogen environment. The electrochemical signature in neutral 1 M Na2SO4 aqueous electrolyte is comparable to those reported for spinel type Mn-Fe bulk counterparts. The areal capacitance at 10.0 mV.s-1 is 15.5 mF.cm-2 for 1 µm thick film, exhibiting excellent coulombic efficiency (close to 100%) and long-term cycle stability after 10,000 cycles. Thus, the synthesis of the multicationic pseudocapacitive oxides via compatible microelectronic deposition methods has set a prospective path to achieve very high-performance MSCs for future IoT applications.

Advances on Microsupercapacitors: Real Fast Miniaturized Devices toward Technological Dreams for Powering Embedded Electronics?

“…96 Recent research has shown that Mn-based spinels, particularly MnFe 2 O 4 , demonstrate a wide working potential range in an aqueous medium and a pseudocapacitance mechanism close to that of MnO 2 , suggesting favorable properties for both highenergy and power applications. 51,93,94 Sputtered TiVN ternary films were also investigated as an electrode for MSC and exhibit a surface capacitance value of 15 mF cm −2 in KOH aqueous electrolyte. 97 MXenes, 36,98,99 the family of early transition metal carbides, nitrides, or carbonitrides, have also been widely investigated as efficient electrodes, due to the high rate/high capacitance properties issued from their two-dimensional properties.…”

“…Recent research has shown that Mn-based spinels, particularly MnFe 2 O 4 , demonstrate a wide working potential range in an aqueous medium and a pseudocapacitance mechanism close to that of MnO 2 , suggesting favorable properties for both high-energy and power applications. ,, Sputtered TiVN ternary films were also investigated as an electrode for MSC and exhibit a surface capacitance value of 15 mF cm –2 in KOH aqueous electrolyte …”

“…49 Depending on electrode material, Coulombic efficiency can vary from 97% for the amorphous TiO 2 Electrode 50 to 100% (Fe,Mn) 3 O 4 for spinel oxide. 51 Recently, alternate current (AC) line-filtering has been one of the new important aspects to consider in the performance of MSCs, opening new avenues for commercializing applications. The fundamental mechanism relies on the frequency response, particularly at 120 Hz, characterized by Nyquist and Bode plots of MSCs.…”

“…Coulombic efficiency, which is the ratio of discharge to charge capacity, can give an idea about the cycle life and rate capabilities of MSCs . Depending on electrode material, Coulombic efficiency can vary from 97% for the amorphous TiO 2 Electrode to 100% (Fe,Mn) 3 O 4 for spinel oxide …”

Wafer-Scale Performance Mapping of Magnetron-Sputtered Ternary Vanadium Tungsten Nitride for Microsupercapacitors

“…Their film exhibited 15.5 mF• cm −2 (155 F•cm −3 ) of capacitance and stability after 10,000 cycles. 20 Besides the trial-and-error method, the predictive approach using DFT (density-functional theory) theoretical calculations is nowadays a very interesting approach to discovering new materials. In that context, since our group had some experience in the synthesis of metal nitrides compounds, 11,12 we decided to follow the extensive work of Sun et al 21 who have systematically mapped predicted inorganic ternary nitrides (i.e., multicationic compounds).…”