Superior Cathode of Sodium-Ion Batteries: Orthorhombic V₂O₅ Nanoparticles Generated in Nanoporous Carbon by Ambient Hydrolysis Deposition

Abstract

For the first time, we demonstrate that orthorhombic V2O5 can exhibit superior electrochemical performance in sodium ion batteries when uniformly coated inside nanoporous carbon. The encapsulated V2O5 shows a specific capacity as high as 276 mAh/g, while the whole nanocomposite exhibits a capacity of 170 mAh/g. The V2O5/C composite was fabricated by a novel ambient hydrolysis deposition that features sequential water vapor adsorption in nanoporous carbon, followed by a hydrolysis reaction, exclusively inside the nanopores. The unique structure of the nanocomposite significantly enhances the capacity as well as the rate performance of orthorhombic V2O5 where the composite retains a capacity of over 90 mAh/g at a current rate of 640 mA/g. Furthermore, by calculating, we also revealed that a large portion of the sodium-ion storage, particularly at high current rates, is due to the V2O5 pseudocapacitance.

Na+ intercalation pseudocapacitance in graphene-coupled titanium oxide enabling ultra-fast sodium storage and long-term cycling

“…After a slow capacity fading in the initial dozens of cycles, a reversible capacity of 120 mA h g -1 keeps unchanged during the subsequent cycles, indicating a superior long-term cyclability. As far as we know, this is the longest cycle life up to date for both anode and cathode materials for SIBs using nonaqueous electrolytes [32][33][34]47,48 . We should also note that the Coulombic efficiency increased gradually up to 91.8% during the initial cycles.…”

“…Cyclic voltammetry (CV) has been proven to be a powerful technique to evaluate the electrochemical kinetics of electrode materials towards Li þ or Na þ (refs [30][31][32][33]. Here, kinetic analysis based on CV analysis was carried out to gain further insight into the electrochemistry of the G-TiO 2 /Na cell.…”

“…Recently, pseudocapacitive charge storage that is not a diffusion-controlled process demonstrates superior high-rate performance and reversibility [30][31][32][33] . Previous works by Dunn and co-workers 30 show great promise towards high-rate electrodes in LIBs driven by an intercalation pseudocapacitive mechanism.…”

Insertion of Mono- vs. Bi- vs. Trivalent Atoms in Prospective Active Electrode Materials for Electrochemical Batteries: An ab Initio Perspective

“…Although investigations on their use in LIBs are still predominant, increasing attention is paid to the incorporation of other metal ions, such as Na, Mg and Al. Appreciable voltages and capacities could be reached with these elements with different vanadium oxide phases and stoichiometries [121][122][123][124][125][126][127][128][129][130]. A systematic experimental rationalization and conclusive statement about the performance of vanadium oxides as electrode materials with regard to capacity, potential or rate is, however, complicated by the large number of stoichiometric and non-stoichiometric phases at different conditions and their close proximity in the phase space.…”

Atomic layer deposition of vanadium oxide thin films from tetrakis(dimethylamino)vanadium precursor

“…5 V 2 O 5 also has a fairly wide scope of applications. Examples include cathode materials for lithium-ion batteries 6 and sodiumion batteries, 7 active materials for supercapacitors, 8,9 charge-injection-layer materials for field-effect transistors, 10 and catalysts for organic synthesis.…”