Advanced Hybrid Supercapacitor Based on a Mesoporous Niobium Pentoxide/Carbon as High-Performance Anode

Abstract

Recently, hybrid supercapacitors (HSCs), which combine the use of battery and supercapacitor, have been extensively studied in order to satisfy increasing demands for large energy density and high power capability in energy-storage devices. For this purpose, the requirement for anode materials that provide enhanced charge storage sites (high capacity) and accommodate fast charge transport (high rate capability) has increased. Herein, therefore, a preparation of nanocomposite as anode material is presented and an advanced HSC using it is thoroughly analyzed. The HSC comprises a mesoporous Nb2O5/carbon (m-Nb2O5-C) nanocomposite anode synthesized by a simple one-pot method using a block copolymer assisted self-assembly and commercial activated carbon (MSP-20) cathode under organic electrolyte. The m-Nb2O5-C anode provides high specific capacity with outstanding rate performance and cyclability, mainly stemming from its enhanced pseudocapacitive behavior through introduction of a carbon-coated mesostructure within a voltage range from 3.0 to 1.1 V (vs Li/Li(+)). The HSC using the m-Nb2O5-C anode and MSP-20 cathode exhibits excellent energy and power densities (74 W h kg(-1) and 18,510 W kg(-1)), with advanced cycle life (capacity retention: ∼90% at 1000 mA g(-1) after 1000 cycles) within potential range from 1.0 to 3.5 V. In particular, we note that the highest power density (18,510 W kg(-1)) of HSC is achieved at 15 W h kg(-1), which is the highest level among similar HSC systems previously reported. With further study, the HSCs developed in this work could be a next-generation energy-storage device, bridging the performance gap between conventional batteries and supercapacitors.

Electrochemical Transport Phenomena in Hybrid Pseudocapacitors under Galvanostatic Cycling

“…Indeed, several pseudocapacitor studies, featuring Figure 1a indicates that, for hybrid pseudocapacitors with Nb 2 O 5 , the cell potential ψ s (t) increased rapidly at the beginning of the charging step. 9,12,21 Then, the rate of change |dψ s /dt| abruptly decreased, resulting in a distinct "kink" in the potential evolution. The slope |dψ s /dt| also increased toward the end of the cycle, although it was not as large as at the beginning of the cycle.…”

“…The cell potential ψ s varied approximately linearly for the rest of the cycle, except for a very brief period of large slope |dψ s /dt| immediately after the charging/discharging transition. 9,12,21 Figure 1a also shows experimentally measured potential drops between each electrode and a reference electrode, denoted as ψ P (t) and ψ C (t) for the pseudocapacitive and carbon electrodes, respectively, and such that ψ s (t) = ψ C (t) − ψ P (t). It indicates that ψ C (t) for the carbon electrode varied linearly and that the variation of |dψ s /dt| was associated with the pseudocapacitive electrode.…”

Facile synthesis of T-Nb2O5 nanosheets/nitrogen and sulfur co-doped graphene for high performance lithium-ion hybrid supercapacitors

“…The CV curves (Fig. 5a) [2,15]. Generally, in CV tests the currents (i) are proportional to the scan rates (v):…”

“…The obtained b values can classify electrochemical reaction kinetics mechanism: b = 0.5 symbolizes a diffusion-controlled insertion process and b = 1 represents a surface capacitive behavior [2,30].…”

“…Supercapacitors (SCs) and Li-ion batteries (LIBs) have been the focus of research and discussion during past decades [1,2]. However, SCs often suffer from the relatively limited energy density despite providing high power density and long cycling stability through fast accumulation of electric charges on the electrode/electrolyte interface [3][4][5][6].…”