A Low‐Strain Phosphate Cathode for High‐Rate and Ultralong Cycle‐Life Potassium‐Ion Batteries

Abstract

Most potassium-ion battery (PIB) cathode materials have deficient structural stability because of the huge radius of potassium ion, leading to inferior cycling performance.W e report the controllable synthesis of an ovel low-strain phosphate material K 3 (VO)(HV 2 O 3 )(PO 4 ) 2 (HPO 4 )(denoted KVP) nanorulers as an efficient cathode for PIBs.The as-synthesized KVP nanoruler cathode exhibits an initial reversible capacity of 80.6 mAh g À1 under 20 mA g À1 ,with alarge average working potential of 4.11 V. It also manifests an excellent rate property of 54.4 mAh g À1 under 5Ag À1 ,w ith ah igh capacity preservation of 92.1 %o ver2 500 cycles.T he outstanding potassium storage capability of KVP nanoruler cathode originates from al ow-strain K + uptake/removal mechanism, inherent semiconductor characteristic,a nd small K + migration energy barrier.The high energy density and prolonged cyclic stability of KVP nanorulers//polyaniline-intercalated layered titanate full battery verifies the superiority of KVP nanoruler cathode in PIBs.

Stabilizing V2O3 in carbon nanofiber flexible films for ultrastable potassium storage

“…[10][11][12][13][14] However, the practical application of potassium-ion batteries is restricted due to the larger ion radius of K + , which leads to poor kinetics and terrible cycle life. [15][16][17][18] Therefore, it is significant and urgent to design high-performance electrode materials with high conductivity and structural stability to promote the development of potassium-ion batteries.…”

Advancements in cathode materials for potassium-ion batteries: current landscape, obstacles, and prospects

“…6 showcases the average voltages achieved by various polyanion-based cathode compounds reported thus far for KIBs. Vanadiumbased orthophosphates (e.g., K 3 V 3 (PO 4 ) 4 , 168 K 3 V 3 (PO 4 ) 4 H 2 O, 169 K 3 V 2 (PO 4 ) 3 162,170 ), fluorophosphates (KV 0.5 Ti 0.5 PO 4 F, 171 KVPO 4 F, 18,159 174 oxyphosphates (KVOPO 4 ), 18,175 and pyrophosphates (KVP 2 O 7 ) 176,177 exhibit high voltages, reaching 4 V and even beyond, whilst maintaining fast rate capabilities and good cyclability. Mixed polyanion compounds, such as K 6 (VO) 2 (V 2 O 3 ) 2 (PO 4 ) 4 -(P 2 O 7 ), 178,179 also exhibit high voltages surpassing 4 V. Titanium-based fluorophosphates like KTiPO 4 F exhibit voltages of 3.6-3.7 V (Fig.…”

“…Vanadium-based orthophosphates ( e.g. , K 3 V 3 (PO 4 ) 4 , 168 K 3 V 3 (PO 4 ) 4 H 2 O, 169 K 3 V 2 (PO 4 ) 3 162,170 ), fluorophosphates (KV 0.5 Ti 0.5 PO 4 F, 171 KVPO 4 F, 18,159 K 1.5 VOPO 4 F 0.5 , 172 K 3 V 2 O 2 (PO 4 ) 2 F, 163 KVPO 4 F 0.5 O 0.5 173 ), K 3 (VO)(HV 2 O 3 )(PO 4 ) 2 (HPO 4 ), 174 oxyphosphates (KVOPO 4 ), 18,175 and pyrophosphates (KVP 2 O 7 ) 176,177 exhibit high voltages, reaching 4 V and even beyond, whilst maintaining fast rate capabilities and good cyclability. Mixed polyanion compounds, such as K 6 (VO) 2 (V 2 O 3 ) 2 (PO 4 ) 4 (P 2 O 7 ), 178,179 also exhibit high voltages surpassing 4 V.…”

Conductive Metal–Organic Framework with Superior Redox Activity as a Stable High-Capacity Anode for High-Temperature K-Ion Batteries

“…Lithium-ion batteries (LIBs) with high energy density are currently the leading technology for electrochemical energy storage, but the rareness, ununiform distribution, and fast consumption of Li resources have caused concern about their sustainability and cost. , New rechargeable battery systems based on abundant resources are being intensively explored. In this regard, K-ion batteries (KIBs) are drawing increasing research interest due to the high natural abundance of K resources in the earth’s crust (1.5 wt %, in contrast to 0.0017 wt % for Li) and the lower K + /K potential. − Especially, it is identified that the K + /K potential could be even lower than that of both Li + /Li and Na + /Na in a common electrolyte of KPF 6 in EC/DEC, which promised significant potential for building high-voltage KIBs .…”