Toward a High-Energy-Density Cathode with Enhanced Temperature Adaptability for Sodium-Ion Batteries: A Case Study of NaMnZr(PO) Microspheres with Embedded Dual-Carbon Networks.

Polyanionic cathode materials that have high energy density and good temperature adaptability are in high demand for practical applications in sodium-ion batteries (SIBs). In this study, a scalable spray-drying strategy has been proposed to construct interconnected conductive networks composed of amorphous carbon and reduced graphene oxide in NaMnZr(PO) microspheres (NMZP@C-rGO). The dual-carbon conductive networks provide fast electron migration pathways in the microspheres. Moreover, they significantly increase the porosity and specific surface area of the microspheres, which are conducive to accommodating the volume change and improving the electrode/electrolyte contact interface and the contribution of the pseudocapacitance effect to achieve fast sodium storage. As a result, NMZP@C-rGO exhibits excellent rate performance (50.9 mAh g at 50C and 30 °C, 35.4 mAh g at 50C and -15 °C) and long-term cycling stability (capacity retentions of 97.4 and 79.6% after 1500 cycles at 30 and -15 °C, respectively) in a wide temperature range.