Cation W-doping motivated novel layered K0.45Rb0.05 Mn 0.85-xWx Mg0.15O2 cathode for boosting potassium/sodium-ion storage

Abstract

<p>Novel layered K_0.45Rb_0.05Mn_0.85−xMg_0.15W_xO₂ cathode materials modified with different ratios of W-doping are fabricated for potassium (PIBs) and sodium ion batteries (SIBs) by a facile solid-phase sintering strategy. W-doping can dramatically amplify the lattice spacing, achieve narrow-sized primary particle and mitigate the lattice oxygen release from the surface of the material. Meanwhile, by comparing the SEM and XRD before and after cycling, the W-doping modification can effectively stabilize the lattice structure and inhibit the crack formation on the surface of the material. Further, W-doping alleviates the electrochemical polarization and lowers the diffusion barrier of potassium/sodium ions. Thus, benefiting from the reinforced structural stability, rapid ion mobility and conspicuous pseudocapacitance contribution, the K_0.45Rb_0.05Mn_0.84Mg_0.15W_0.01O₂ cathode harvests favourable potassium/sodium storage capability of 110.6 mAh/g at 20 mA g⁻¹ in PIBs and 109.9 mAh/g at 100 mA g⁻¹ in SIBs. Meanwhile, the favorable chemical performance can be also supported by the KRMMO-W1//Hard carbon K-/Na-ion full batteries, which increases the feasibility of practical applications.<br></p>