A multicationic-substituted configurational entropy-enabled NASICON cathode for high-power sodium-ion batteries

Na-superionic-conductor (NASICON)-type Na3V2(PO4)3 is considered as one of the potential cathodes for sodium-ion batteries (SIBs), but its inherent low electronic conductivity and non-adjustable voltage plateau is an urgent issue hindrance to its practical application. Hereof, the concept of multicationic-substituted high-entropy doping is innovatively utilized to modify the fine structure within crystals, enhance electronic conductivity, and achieve excellent local diffusion kinetics and high redox activity according to theoretical calculations. The carbon-free Na3V1.8(CrMnFeZnAl)0.2(PO4)3 (HE-NVP-0.2) cathode exhibits a maximum specific capacity of 119.8 mA h g−1, achieved through V3+/V4+/V5+ redox reactions, while maintaining an impressive capacity retention rate of 80 % after 3000 cycles at 10 C. Moreover, the in-situ X-ray diffraction (XRD) analysis reveals that the incorporation of multi-(high entropy) elements induces a stable transition state, facilitating rapid phase transitions. Combined with in-situ digital image correlation (DIC), reversible structural evolution has been verified at both micro and macro scales. More competitively, coupling with a hard carbon (HC) anode, the HE-NVP-0.2//HC full cells exhibit exceptional energy density/power density characteristics while simultaneously maintaining excellent high-rate performance and prolonged cycle life (2000 stable cycles at 50 C). The regulation of configurational entropy enables the realization of an intermediate phase in the equilibrium state and makes the unlikely potential regulation possible, presenting innovative approaches to expedite the commercialization of high-power SIBs.