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

Most potassium-ion battery (PIB) cathode materials have deficient structural stability because of the huge radius of potassium ion, leading to inferior cycling performance. We report the controllable synthesis of a novel low-strain phosphate material K-3(VO)(HV2O3)(PO4)(2)(HPO4) (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(-1) under 20 mA g(-1), with a large average working potential of 4.11 V. It also manifests an excellent rate property of 54.4 mAh g(-1) under 5 A g(-1), with a high capacity preservation of 92.1 % over 2500 cycles. The outstanding potassium storage capability of KVP nanoruler cathode originates from a low-strain K+ uptake/removal mechanism, inherent semiconductor characteristic, and 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.

Automated summary

A controllable synthesis method for a novel low-strain phosphate material K-3(VO)(HV2O3)(PO4)(2)(HPO4) (referred to as KVP) nanoruler was introduced as an efficient cathode for PIBs, demonstrating excellent cycling performance, rate capability, and capacity retention. The outstanding potassium storage capability of KVP nanoruler cathode is attributed to its low-strain K+ uptake/removal mechanism, inherent semiconductor characteristic, and small K+ migration energy barrier.