No abstract

No abstract

No abstract

No abstract

The Mn-based mixed polyanion is expected to be a promising cathode material for sodium-ion batteries applied to largescale smart grid energy storage systems due to its stable threedimensional crystal structure, low cost, and high energy density. Herein, a novel carbon nanotube (CNT)-modified mixed-polyanion material (Na 4 Mn 2 Co(PO 4 ) 2 P 2 O 7 ) with a high voltage of 3.86 V is synthesized by a facile spray-drying method. The well-designed Na 4 Mn 2 Co-(PO 4 ) 2 P 2 O 7 /C-CNTs microsphere has excellent electronic and ionic conductivity by virtue of the carbon nanotube conductive skeleton. The as-prepared Na 4 Mn 2 Co(PO 4 ) 2 P 2 O 7 /C-CNTs composite exhibits a reversible initial discharge capacity of 96.1 mA h g −1 and an energy density of 371 Wh kg −1 at 0.1 C. Furthermore, Na 4 Mn 2 Co(PO 4 ) 2 P 2 O 7 / C-CNTs and hard carbon are assembled into a full battery, which delivers an initial discharge capacity of 88.8 mA h g −1 , a working voltage of 3.85 V, and a promising energy density of 249.9 Wh kg −1 at 0.1 C. Therefore, the outstanding performance makes the Na 4 Mn 2 Co(PO 4 ) 2 P 2 O 7 /C-CNTs material a potential candidate for large-scale applications of sodium-ion batteries. KEYWORDS: Na 4 Mn 2 Co(PO 4 ) 2 P 2 O 7 , CNTs, high voltage, spray-drying, sodium-ion batteries