Nb₂O₅/graphene nanocomposites for electrochemical energy storage

Abstract

Development of electrode materials for energy storage, with high energy and power densities along with good cyclic stability, still remains a big challenge. Here we report synthesis of Nb2O5/graphene nanocomposites through simple hydrothermal method, with Nb2O5 nanoparticles anchored on reduced graphene oxide (RGO) sheets. The fabricated Nb2O5/graphene electrodes exhibited excellent electrochemical performance when studied as anodes for Lithium-ion battery, with superior reversible capacity and high power capability (192 mAhg -1 under 0.1C rate over 50 cycles). Signature curve' studies showed high power capability of Nb2O5/graphene electrode with ~80% of the total capacity retained at 16C rate compared to ~30% retention for pristine Nb2O5 nanoparticles. To achieve further improvement in energy density and power capability, Li-ion hybrid electrochemical capacitors (Li-HEC) are fabricated with Nb2O5/graphene nanocomposite as anode and rice husk-derived activated porous carbon as cathode, in non-aqueous electrolyte. The Li-HEC showed enhanced electrochemical performances with high energy density of 30 WhKg -1 , at specific power density of 500 WKg -1 . The Nb2O5/graphene nanocomposites show promising results and hence have great potential for application in efficient electrochemical energy storage devices.

Facile fabrication of interconnected-mesoporous T-Nb2O5 nanofibers as anodes for lithium-ion batteries

“…Among these, niobium pentoxide (Nb 2 O 5 ) has been widely studied because of its slight volume changes upon cycling and high lithiation potential (1.0-2.0 V vs. Li/Li + ). The unique lithiation potential which is higher than that of the formation voltage of solid electrolyte interface (SEI) can suppress lithium dendrite deposition on the electrode surface, thereby relieving electrode pulverization and improving safety and cycling capability [15,16]. As reported, Nb 2 O 5 has a class of polymorphic forms, including amorphous (a-Nb 2 O 5 ), orthorhombic (T-Nb 2 O 5 ), pseudo hexagonal (TT-Nb 2 O 5 ) and monoclinic (M-Nb 2 O 5 ) [17][18][19].…”

Formation of a Surficial Bifunctional Nanolayer on Nb2O5 for Ultrastable Electrodes for Lithium‐Ion Battery

“…[1,2] However, constant demands for highly stable, safe LIBs are present, where safety issues and stable cycling as well as rate capability of LIBs are required for rechargeable (2 of 9) 1603610 However, two major issues hinder the usage of Nb 2 O 5 as viable electrode materials for LIBs, which are (i) capacity decay resulting from subsequent pulverization and (ii) poor intrinsic electrical conductivity (6.3 × 10 6 ). [12] Different approaches have been attempted to resolve the above issues by involving nanoengineering, such as synthesis of Nb 2 O 5 nanostructures, [12,[14][15][16][17][18][19] Nb 2 O 5 with electrically conductive layers, [20,21] and Nb 2 O 5 -composite nanomaterials, [22][23][24] or synthesizing metastable phase of Nb 2 O 5 [25] with some fundamental research on the ion intercalation in Nb 2 O 5 [26] and its application as sodium ion capacitors. [27] Although previous studies have demonstrated that nanostructured Nb 2 O 5 can be used to enhance the electrochemical performance, most of the studies so far required additional synthetic processes and sometimes expensive procedures to synthesize such nanostructured materials.…”

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

“…[ 326 ] Nevertheless, some new hybrids were introduced in the LIB anode fi eld too. Indeed, graphene-containing glassy metal alloy nanofi ber, [ 327 ] selenides, [328][329][330][331][332] silicates, [ 333,334 ] molybdates, [335][336][337] oxides, [338][339][340][341] intermetallic compounds, [ 342,343 ] intermetallic oxides, [ 344,345 ] oxalate, [ 346 ] sulfi de, [ 347 ] nitride, [ 348 ] carbide [ 349 ] and phosphide [ 350 ] hybrids were reported (see Table 2 ). Despite the usual sloping delithiation voltage and the generally low content of graphene (i.e., ≤30 wt%), few of these hybrids [ 329,331,335 ] showed a low 1 st cycle irreversible capacity (i.e., <20%).…”

“…Despite the usual sloping delithiation voltage and the generally low content of graphene (i.e., ≤30 wt%), few of these hybrids [ 329,331,335 ] showed a low 1 st cycle irreversible capacity (i.e., <20%). Interestingly, the RGO/ Nb 2 O 5 hybrid, [ 339 ] displayed one of the lowest 1 st cycle irreversible capacities (i.e., about 2%) and one of the best capacity retentions in the category of high-voltage anodes (i.e., approaching 100% after 50 cycles). Following the trend begun in 2014, this year was mainly characterized by a large number of works focused on long-term cyclability tests (e.g., ≥1000 cycles), generally performed at medium/high currents (e.g., ≥1 A g −1 ).…”