Multiwalled carbon nanotube network connected Mg_0.5Ti₂(PO₄)₃ composites to improve sodium storage performance

The research on sodium-ion batteries (SIDs) has aroused intensive attention. In this work, the Mg_0.5Ti₂(PO₄)₃ (MTP) composite material with NASICON structure has been studied as an anode material in SIDs. The sol-gel method is used to synthesize the Mg_0.5Ti₂(PO₄)₃ with a conductive network that can be constructed by using carbon nanotubes (CNTs) and phenolic resin as the amorphous source of carbon coating. The CNT network is used not only to improve the outcome of electrolyte penetration and reduce the internal resistance to diffusion but also to create a fast path for electron transport, thereby elevating the level of electronic conductivity. The phenolic resin is generated on the surface of MTP which extends its cycle life. The carbon-coated Mg_0.5Ti₂(PO₄)₃ with 0.10 g CNTs (MTP-CNT10) displays optimal performance as an anode material in SIDs, and shows a discharge capacity of 298.8 mA h g^-1, 258.3 mA h g^-1 and 254.8 mA h g^-1 at 0.1C, 0.5C and 1C, respectively. Besides, the capacity retention rate reaches 92% after 300 cycles at 10C. This study contributes an effective solution to improving the electrochemical performance of electrode materials through the introduction of carbon coating and highly conductive materials.