Lithium Storage in Carbon Cloth–Supported KNb₃O₈ Nanorods Toward a High‐Performance Lithium‐Ion Capacitor

Abstract

Exploration of novel anodes with a high capacity and fast charge rate is crucial for developing high‐energy‐density lithium‐ion capacitors. Herein, high‐rate Li+ insertion into KNb3O8 nanorods grown on conductive carbon cloth (CC) by a facile electrodeposition technique is reported. The hierarchically porous network and the enhanced conductivity enable the CC‐KNb3O8 electrode to deliver a high discharge capacity of 271 mA h g−1 at 0.01 A g−1 with a low yet safe voltage (1.2 V versus Li/Li+) while exhibiting outstanding cycling stability (225 mA h g−1 after 100 cycles) and superior rate capability (159 mA h g−1 at 0.5 A g−1). Electrochemical results and X‐ray photoelectron spectroscopy (XPS) analysis show that accompanying mutielectron transfers involving the Nb5+/Nb4+ and Nb4+/Nb3+ redox reactions, KNb3O8 remains in the stable orthorhombic phase without notable volume expansion during the whole charging and discharging process. A lithium‐ion capacitor built with a CC‐KNb3O8 anode and active carbon cathode delivers a maximum energy density of 69 W h kg−1 at a power output of 346 W kg−1 and retains 88% capacity after 1000 cycles at 2.0 A g−1. This work opens up a new avenue for designing high‐capacity niobium‐based electrodes toward a high‐performance charge storage device.

Polarization Sensitive Solar‐Blind Ultraviolet Photodetectors Based on Ultrawide Bandgap KNb3O8 Nanobelt with Fringe‐Like Atomic Lattice

“…In the past reports, low-dimensional KNb 3 O 8 materials synthesized via sol-gel or hydrothermal methods were widely applied in photocatalysis and lithium ion battery. [39][40][41][42][43] However, the disordered morphology of thick KNb 3 O 8 nanoflakes synthesized by the above methods cannot be used in micro-nano devices due to incompatibility with semiconductor processing technology. The low crystallinity, numerous oxygen defects, and unavoidable surface contamination of the liquidphase synthesized KNb 3 O 8 nanoflakes also hinder its development in optoelectronic devices.…”

Improved Performance of Li-Added Mo–Nb Oxide as the Anode for Li-Ion Batteries with N-Carbon Coating

“…The high-resolution XPS of Nb 3d orbital in Figure a shows two asymmetric peaks. The peaks at binding energies of 206.8 and 209.6 eV correspond to the Nb 4+ 3d 5/2 and Nb 4+ 3d 3/2 orbitals, respectively, while the other two weak and broad peaks at 207.6 and 210.4 eV confirm the presence of Nb 5+ 3d 5/2 and Nb 5+ 3d 3/2 , respectively Figure b shows the high-resolution XPS of the Mo 3d orbital.…”

“…The peaks at binding energies of 206.8 and 209.6 eV correspond to the Nb 4+ 3d 5/2 and Nb 4+ 3d 3/2 orbitals, respectively, 30 while the other two weak and broad peaks at 207.6 and 210.4 eV confirm the presence of Nb 5+ 3d 5/2 and Nb 5+ 3d 3/2 , respectively. 31 Figure 3b shows the high-resolution XPS of the Mo 3d orbital. The peaks at 231.9 and 235.0 eV correspond to the hexavalent molybdenum for Mo 6+ 3d 5/2 and Mo 6+ 3d 3/2 orbitals, respectively.…”

Nb-Based Mixed Oxides As Anodes for Metal-Ion Capacitors: Progress, Challenge, and Perspective

“…It has been reported that TNO wrapped by carbon (TNO@C) matched with a carbon fibers (CFs) cathode to assemble CFs//TNO@C LICs, and LICs exhibited a high ED of 110.4 Wh kg –1 at 99.58 W kg –1 , and even at a PD of 5464 W kg –1 , the ED also remained 20 Wh kg –1 . Besides, Sun et al synthesized KNb 3 O 8 NRs grown on the surface of carbon cloth (CC) (CC-KNb 3 O 8 ) by electrodeposition . The CC-KNb 3 O 8 and AC-constructed LICs (i.e., AC-3//CC-KNb 3 O 8 -2.8) exhibited a maximum ED of 69 Wh kg –1 at a PD of 346 W kg –1 , and the capacity retained 88% for 1000 cycles at 2 A g –1 .…”