Enhanced electrochemical performance of Na4MnCr(PO4)3@C cathode by multi-walled carbon nanotubes interconnection for Na-ion batteries

The development of high energy density and stable cathode materials for Na-ion batteries is an enormous puzzle. NASICON-structured Na4MnCr(PO4)3 (NMCP) has been reported as a novel and viable cathode material lately. Nonetheless, the inferior rate property and disappointing cycle stability hinder its commercial usage. Herein, a series of [email protected] structurally interconnected with multi-walled carbon nanotubes ([email protected]@x%MWCNTs, x = 0, 5, 10 and 15) were produced via a simple sol–gel strategy followed by an annealing treatment. The results indicate that the MWCNTs network could contribute to improving the electrochemical properties by accelerating electronic conductivity and increasing ionic diffusion property. As expected, the optimal composite ([email protected]@10%MWCNTs) delivers the specific capacity of 66.1 mAh/g at 500 mA g−1 and capacity retention of 61.8% after 100 cycles at 1000 mA g−1, while the pristine [email protected] presents the specific capacity of 2.8 mAh/g at 500 mA g−1 and capacity retention of 27.5% after 100 cycles at 1000 mA g−1. Moreover, When [email protected]@10%MWCNTs is applied as cathode to assemble full battery with WS2 anode, this battery delivers an initial discharge capacity of 181.3 mAh/g, acquiring a superior energy density of ∼435 Wh kg−1 with a working voltage of ∼2.4 V. These findings demonstrate that the MWCNTs network is favorable for the electrochemical enhancement of Na4MnCr(PO4)3@C, which offers a hopeful prospect for Na4MnCr(PO4)3 as a cathode for sodium-ion batteries in practical application.