Understanding the Effect of Interplanar Space and Preintercalated Cations of Vanadate Cathode Materials on Potassium-Ion Battery Performance

Abstract

Nonaqueous potassium-ion batteries (KIBs) have been regarded as a promising alternative energy system to lithium-ion batteries, due to the abundance of the K resource and unique electrochemical properties. However, exploring suitable KIB cathode materials remains a great challenge, owing to the much larger size of the K ion than that of the Li ion. Here, a series of layered vanadates have been developed as cathodes for KIBs to elucidate the key factors that determine the electrochemical performance of KIBs, including the interlayer distance between adjacent (100) planes (d 100) and preintercalated cations. Compared to NH4V3O8 nanowires with a d 100 of 7.80 Å, (NH4)0.5V2O5 nanowires with a wider d 100 of 9.52 Å show a faster K+ diffusion and much higher reversible capacity. The preintercalation of potassium ions into V-O slabs is also crucial to the stability of the structure of vanadates, which leads to better electrochemical cycling stability in K0.5V2O5 than that in (NH4)0.5V2O5 and NH4V3O8 nanowires. These findings reveal the great potential of the vanadate cathode in future KIBs and provide a new direction to rationally design a stable layered intercalation compound for practical KIBs.

Synergetic Effect of Alkali‐Site Substitution and Oxygen Vacancy Boosting Vanadate Cathode for Super‐Stable Potassium and Zinc Storage

“…As depicted in Figure S24, Supporting Information, the excess charge capacity of NVO cathode in the first cycle originates from the deintercalation of 0.1 NH 4 + at the high voltage region, which usually leads to structural instability. [ 37e,43 ] To demonstrate the stable presence of NH 4 + in KNVO, ex situ FTIR spectra have been conducted (Figure 4e). For the powder samples, both KNVO and NVO have the characteristic peaks of NH, indicating the existence of NH 4 + .…”

Aqueous Zn‐based rechargeable batteries: Recent progress and future perspectives

“…For instance, ammonium vanadates with the intercalated NH 4 + show enhanced cycling stability compared to other vanadates, due to the pillar effect. 175,176 In addition, Zhang et al reported an aqueous Zn-V 2 O 5 battery employing 3 M Zn(CF 3 SO 3 ) 2 as electrolyte (Figure 9B). 127 The co-intercalated H 2 O molecules can shield the electrostatic interactions between Zn 2+ and the V 2 O 5 framework, thus enhancing the kinetics of cation transfer.…”

“…In addition, the enlarged crystal tunnel caused by guest species insertion contributes to more ion occupation, thus leading to improved battery performance. For instance, ammonium vanadates with the intercalated NH 4 + show enhanced cycling stability compared to other vanadates, due to the pillar effect 175,176 . In addition, Zhang et al reported an aqueous Zn–V 2 O 5 battery employing 3 M Zn(CF 3 SO 3 ) 2 as electrolyte (Figure 9B).…”

Structure Engineering of BiSbSx Nanocrystals Embedded within Sulfurized Polyacrylonitrile Fibers for High Performance of Potassium‐Ion Batteries

“…Owing to the natural abundance of potassium (K, 2.09 wt% on earth), a lower standard redox voltage (−2.93 V) for K + /K and smaller Stokes radius for K + ions (3.6 Å in polycarbonate), it should be possible to ultimately obtain preferable mobility and reaction kinetics between charge/electron transfer, and, thus improved electrochemical performance. However, the challenge for developing high‐performance PIBs is to probe into a suitable electrode materials, especially anode materials, which can accommodate K + with an ion radius of 1.38 Å, significantly larger than that of Li + (0.76 Å) and Na + (1.02 Å) [6–9] . Therefore, the difficulty of repeated insertion/extraction of K + ions leads to sluggish kinetics and large volume variation for electrodes during charge/discharge relative to Li and Na ions.…”

“…However, the challenge for developing high-performance PIBs is to probe into a suitable electrode materials, especially anode materials, which can accommodate K + with an ion radius of 1.38 Å, significantly larger than that of Li + (0.76 Å) and Na + (1.02 Å). [6][7][8][9] Therefore, the difficulty of repeated insertion/extraction of K + ions leads to sluggish kinetics and large volume variation for electrodes during charge/discharge relative to Li and Na ions.…”