Encapsulation of Na₄MnV(PO₄)₃ in robust dual-carbon framework rendering high-energy, durable sodium storage

Na 4 MnV(PO 4 ) 3 (NMVP) is a green, cheap, and high-energy cathode material for sodium-ion batteries. However, the low electrical conductivity severely limits its sodium storage performance. Herein, we report the spray-drying synthesis of robust and highly conductive reduced graphene oxide/amorphous carbon framework encapsulated NMVP (NMVP@rGO/AC) composite microspheres. The unique dual-carbon encapsulation architecture enables the NMVP@rGO/AC a high specific capacity (100 mAh g −1 at 100 mA g −1 ) with durable cyclability (capacity retention of 77.5% for 500 cycles). In situ XRD measurements reveal the reversible extraction/insertion of Na + via unique solid-solution and two-phase reactions during de-sodiation/sodiation processes. This work provides a versatile platform for the construction of rGO/AC dual-carbon encapsulated active materials for electrochemical energy storage.