Electrochemical potassium-ion intercalation in Na_xCoO₂: a novel cathode material for potassium-ion batteries

Abstract

Reversible electrochemical potassium-ion intercalation in P2-type NaCoO was examined for the first time. Hexagonal NaCoO platelets prepared by a solution combustion synthesis technique were found to work as an efficient host for K intercalation. They deliver a high reversible capacity of 82 mA h g, good rate capability and excellent cycling performance up to 50 cycles.

Recent Progress in Rechargeable Potassium Batteries

“…Barpanda and co‐workers examined the insertion of K + into P2‐type Na 0.84 CoO 2 . In this case, electrochemical desodiation resulted in the oxidation of Co 3+ to Co 4+ with a concomitant charge capacity of ≈110 mAh g −1 .…”

“…In effect, prismatic layers offer a larger interlayer distance in P′3 structures compared with that in O3‐type structures such that the P′3 structure is more likely to facilitate the intercalation of large potassium ions. As with the P2‐type Na 0.84 CoO 2 material prepared by Barpanda and co‐workers, Naveen et al tested the O3‐type layered NaCrO 2 in K cells using 1 m KFSI as the electrolyte. The first desodiation voltage was observed to increase to ≈3.25 V, which is higher than that for desodiation in Na cells, which occurs at ≈3 V .…”

Review on Recent Advances of Cathode Materials for Potassium‐ion Batteries

“…The unusual ligand field in an octahedral composition with the preference of Cr 3+ will compensate for the energy loss caused by K + -K + repulsion, which endows the stable electrochemical performance for the KCrO 2 . On the other hand, KCrO 2 with an octahedral structure retains stable structure in the electrolyte with high K concentration, in stark contrast to the severe structural deformation for those Co 3+/4+ P2-type K 0.41 CoO 2 2.0-3.9 57 95% 96% at C/10 66% at 40 C [58] Co 3+/4+ P3-type K 2/3 CoO 2 2.0-3.9 60 95% 91% at C/10 - [58] Co 3+/4+ P2-type K 0.6 CoO 2 1.7-4.0 62 98% 65% at C/40 56% at 1.8 C [105] Co 3+/4+ P2-type Na 0.84Àx K x CoO 2 2.0-4.2 81 81% 85% at C/10 65% at 1 C [122] Mn 3+/4+ P 0 2-type K 0.3 MnO 2 1.5-3.5 74 99% 68% at C/10 54% at 5 C [62] Mn 3+/4+ P 0 2-type K 0.3 MnO 2 2.0-4.0 105 --28% at 5 C [62] Mn 3+/4+ P 0 2-type K 0.3 MnO 2 1.5-4.0 136 --11% at 5 C [62] Mn 3+/4+ P3-type K 0.5 MnO 2 1.5-4.2 140 87% 35% at C/20 - [106] Mn 3+/4+ P3-type K 0.5 MnO 2 1.5-3.9 110 98% 78% at C/20 - [106] Ni 2+/4+ Mn 3+/4+ K 0.67 Ni 0.17 Co 0.17 Mn 0.66 O 2 2.0-4.3 80 97% 90% at C/10 71% at C/2 [61] Mn 3+/4+ Fe 3+/4+ K 0.7 Fe 0.5 Mn 0.5 O 2 1.5-4.0 178 82% 70% at C/10 38% at 5 C [63] Cr 3+/4+ P 0 3-type Na 0.52 CrO 2 2.0-3.4 89 75% 73% at 2 C 56% at 5 C [56] Cr 3+/4+ O3-type KCrO 2 0-4.0 92 68.10% 76.08%(100 cycles) - [59] Co 3+/4+ P3-type K 2/3 CoO 2 2.0-3.9 57 95% 96% (30 cycles) 41.3% at 500 mA g À1 [56] Co 3+/4+ P2-type K 0.41 CoO 2 2.0-3.9 60 95% 96% (30 cycles) - [56] Fe 2+/3+ FeSO 4 F 2.0-5.0 98% -- [73] Fe 2+/3+ FePO 4 1.5-3.5 156 99% 86% at C/50 - of the conventional layered frameworks at the same condition. The layered KCrO 2 structure exhibits intact structure during the charge/discharge process, thus leading to good cyclic stability in PIBs.…”

P2‐K0.75[Ni1/3Mn2/3]O2 Cathode Material for High Power and Long Life Potassium‐Ion Batteries

“…One of the interesting approaches is electrochemical ion‐exchange of sodiated transition metal oxides in potassium cells, which enables exploration of new compounds. Sada et al, introduced that P2‐Na 0.84 CoO 2 was first charged for desodiation in K‐based electrolytes, which yielded a new P2‐K 0.5 CoO 2 compound. Hwang et al, used a similar approach to produce P3‐K x CrO 2 from O3‐NaCrO 2 .…”

“…Improvement of the rate capability is necessary through a rational design of cathode materials composed of cost-effective elements.One of the interesting approaches is electrochemical ionexchange of sodiated transition metal oxides in potassium cells, which enables exploration of new compounds. Sada et al, [42] introduced that P2-Na 0.84 CoO 2 was first charged for desodiation Rationally designed P2-K 0.75 [Ni 1/3 Mn 2/3 ]O 2 is introduced as a novel cathode material for potassium-ion batteries (KIBs). P2-K 0.75 [Ni 1/3 Mn 2/3 ] O 2 cathode material designed through electrochemical ion-exchange from P2-Na 2/3 [Ni 1/3 Mn 2/3 ]O 2 exhibits satisfactory electrode performances; 110 mAh g −1 (20 mA g −1 ) retaining 86% of capacity for 300 cycles and unexpectedly high reversible capacity of about 91 mAh g −1 (1400 mA g −1 ) with excellent capacity retention of 83% over 500 cycles.…”