Investigation of Alkali‐Ion (Li, Na, and K) Intercalation in K_xVPO₄F (x ∼ 0) Cathode

Abstract

This work compares the intercalation of K, Na, and Li in K x VPO 4 F (x ∼ 0). The K x VPO 4 F (x ∼ 0) cathode delivers reversible capacities of ≈90-100 mAh g −1 in K, Na, and Li cells, at an average voltage of ≈4.33 V for K, ≈3.98 V for Na, and ≈3.96 V for Li. This is so far the highest average voltage known for a K-intercalation cathode. The lower voltage of Li insertion compared to Na is attributable to undercoordinated Li ions in the K x VPO 4 F (x ∼ 0) framework. While the material shows high rate capability for all the alkali ions, Li migration in K x VPO 4 F (x ∼ 0) is more difficult than with Na and K. This work suggests that a large cavity is not always good for insertion of alkali ions and cathode materials need to be suitably tailored to each intercalating ion species.

Reaching the Energy Density Limit of Layered O3‐NaNi0.5Mn0.5O2 Electrodes via Dual Cu and Ti Substitution

“…[1][2][3][4][5][6][7] Most of the Na-ion systems demonstrated till now use hard carbon (HC) as common negative electrode and either sodium layered oxides (Na x TMO 2 , 0 < x ≤ 1, TM = transition metals) or polyanionic compounds (Na 3 V 2 (PO 4 ) 2 F 3 ) as positive electrodes. [1][2][3][4][5][6][7] Most of the Na-ion systems demonstrated till now use hard carbon (HC) as common negative electrode and either sodium layered oxides (Na x TMO 2 , 0 < x ≤ 1, TM = transition metals) or polyanionic compounds (Na 3 V 2 (PO 4 ) 2 F 3 ) as positive electrodes.…”

Multiscale factors in designing alkali-ion (Li, Na, and K) transition metal inorganic compounds for next-generation rechargeable batteries

“…For example, Kim and his colleagues show that the migration of a relatively small Li ion in K x VPO 4 F (x ~ 0) is more difficult than large Na and K ions by both experiments and theoretical calculations. 55 56,57 One can find a similar behavior in K x FeSO 4 F: Li insertion shows larger polarization than Na insertion. 58 In addition, Komaba et al claimed that, in the layered oxide frameworks, the diffusion of Na ions would be faster than that of Li because longer alkali-oxygen bonding results in reduced electrostatic interaction.…”

“…In polyanion, K x VPO 4 F (x~0) for example, a large K ion insertion exhibits similar capacity retention with Li and Na insertion. 55 In fact, there are many other parameters affecting cycle life, including anode stability, electrolyte stability, and electrode composition. For example, in many cases, the choice of electrolytes improves the cyclability considerably.…”

A High‐Power Aqueous Zinc–Organic Radical Battery with Tunable Operating Voltage Triggered by Selected Anions

“…[1] Traditional rechargeable rock-chairm etal-ion batteries are fabricatedb yc ation-insertion electrode materials, in which cation chargec arriers shuttle between anode and cathode and predominate the electrochemical behavior of batteries whereas anion chargec arriers work as coordinating counterpart for ionicc onduction in the electrolyte. [2] In contrastt or ock-chairm etal-ion batteries, dual-ion batteries (DIBs) involve redox reactions with anions rathert han cations in p-type cathodes. [3] They usually present high redox potentialo wing to the low electron energy level of p-type cathodes.…”

“…[10] In addition, powerd ensitieso ft hese zinc-ion insertion cathodes are limited to 1000-8000 Wkg À1 owing to sluggish diffusion kinetics of divalent Zn 2 + .T od ate, only af ew zinc-based dual-ion batteries using p-typeo rganic cathodes have been reported with high operating voltage and rate capability, which are formidable competitors for ZIBs. [11] Among them, poly (2,2,6,,ap-typen itroxyl radical polymer,d isplays ah igh discharge plateau of 1.7 Vv s. Zn 2 + /Zn and fast kinetics enabling 60 C-rate operation. [11c] Although the aqueous Zn-organic radical battery (Zn-ORB)c omposisting of an itroxylr adical polymer cathode and aZ na node is ap romising DIB, it attracted limited attention and the understanding of its underlying reaction mechanism is insufficient.…”