Rational Architecture Design Enables Superior Na Storage in Greener NASICON-Na4MnV(PO4)3 Cathode

Na3V2(PO4)(3) has attracted great attention due to its high energy density and stable structure. However, in order to boost its application, the discharge potential of 3.3-3.4 V (vs Na+/Na) still needs to be improved and substitution of vanadium with other lower cost and earth-abundant active redox elements is imperative. Therefore, the Na superionic conductor (NASICON)-structured Na4MnV(PO4)(3) seems to be more attractive due to its lower toxicity and higher voltage platform resulting from the partial substitution of V with Mn. However, Na4MnV(PO4)(3) still suffers from poor electronic conductivity, leading to unsatisfactory capacity delivering and poor high-rate capability. In this work, a graphene aerogel-supported in situ carbon-coated Na4MnV(PO4)(3) material is synthesized through a feasible solution-route method. The elaborately designed Na4MnV(PO4)(3) can reach approximate to 380 Wh kg(-1) at 0.5 C (1 C = 110 mAh g(-1)) and realize superior high-rate capability evenat 50 C (60.1 mAh g(-1)) with a long cycle-life of 4000 cycles at 20 C. This impressive progress should be ascribed to the multifunctional 3D carbon framework and the distinctive structure of trigonal Na4MnV(PO4)(3), which are deeply investigated by both experiments and calculations.