Interfacial Engineered Vanadium Oxide Nanoheterostructures Synchronizing High-Energy and Long-Term Potassium-Ion Storage

Abstract

Potassium ion hybrid capacitors (KICs) have drawn tremendous attention for large-scale energy storage applications because of their high energy and power densities and the abundance of potassium sources. However, achieving KICs with high capacity and long lifespan remains challenging because the large size of potassium ions causes sluggish kinetics and fast structural pulverization of electrodes. Here, we report a composite anode of VO2–V2O5 nanoheterostructures captured by a 3D N-doped carbon network (VO2–V2O5/NC) that exhibits a reversible capacity of 252 mAh g–1 at 1 A g–1 over 1600 cycles and a rate performance with 108 mAh g–1 at 10 A g–1. Quantitative kinetics analyses demonstrate that such great rate capability and cyclability are enabled by the capacitive-dominated potassium storage mechanism in the interfacial engineered VO2–V2O5 nanoheterostructures. The further fabricated full KIC cell consisting of a VO2–V2O5/NC anode and an active carbon cathode delivers a high operating voltage window of 4.0 V and energy and power densities up to 154 Wh kg–1 and 10 000 W kg–1, respectively, surpassing most state-of-the-art KICs.

Conductive Co-based metal organic framework nanostructures for excellent potassium- and lithium-ion storage: kinetics and mechanism studies

“…[1][2][3][4] One main drawback of LIBs is the limited resources and the unbalanced distribution of lithium metal all over the world. 5,6 It is of great importance to develop other energy storage devices based on earth abundant elements. As an alternative, potassium ion batteries (PIBs) have attracted much attention in recent years.…”

“…The potassiumion radius (0.138 nm) is larger than that of lithium-ion (0.076 nm), resulting in a limited capacity, sluggish kinetics, and irreversible structural collapse of the electrode during potassiation/depotassiation. 5,[14][15][16][17][18] It is signicant to develop advanced electrodes for PIBs with high specic capacity, excellent rate performance and stability.…”

Surface Redox Pseudocapacitance Boosting Vanadium Nitride for High‐Power and Ultra‐Stable Potassium‐Ion Capacitors

“…The irreversible reduction peak around 1.3 V in the 1st cycle could be attributed to the irreversible reaction between K + and the surface vanadium oxides. [ 39,40 ] The coincidence between the 2nd and 3rd CV curves indicates the ideal reversibility of VN@CFs‐550 during the potassiation/depotassiation process. The two reversible peaks located at 0.88 and 0.34 V are observed in the cathodic sweep of VN@CFs‐550, which may belong to the redox reactions related to the two V species bonding with the N 3– and O 2– , respectively.…”

“…Based on the oxidation states of vanadium and the inflection point positions by the first derivative of pre‐edge peaks in XANES spectra of the standards (Figure 2f), the chemical valence of vanadium species in VN@CFs‐550 determined by the linear regressions is derived to be +2.75. [ 39 ]…”

“…Based on the oxidation states of vanadium and the inflection point positions by the first derivative of pre-edge peaks in XANES spectra of the standards (Figure 2f), the chemical valence of vanadium species in VN@CFs-550 determined by the linear regressions is derived to be +2.75. [39] The current versus voltage curves of VN@CFs were tested (Figure S10, Supporting Information). The VN@CFs-550 exhibits a linear current-voltage characteristic with an electrical conductivity of 17.9 S cm -1 , higher than those of VN@CFs-400 (5.8 S cm -1 ) and VN@CFs-700 (15.5 S cm -1 ).…”