Na2MnPO4F/Ti3C2-CQDs composite cathode material with enhanced electrochemical properties for lithium/sodium hybrid ion battery

Na2MnPO4F and Ti3C2‑carbon quantum dots (CQDs) nanocomposites were prepared by wet mixing method combined with spray drying method, and the two materials were further compounded by heat treatment to get different ratios of Na2MnPO4F/Ti3C2-CQDs cathode material (NTC), the effects of Ti3C2-CQDs on the structure and electrochemical performance of the composite of Na2MnPO4F as a lithium-ion battery cathode material were investigated. The results showed that Na2MnPO4F was uniformly attached to the surface and between layers of Ti3C2-CQDs. The initial specific discharge capacity of NTC-2 at 0.1C was 67.8 mAh·g−1, and the reversible capacity after 100 cycles was 60.7 mAh·g−1, the capacity retention rate was as high as 90%, which all showed that Ti3C2-CQDs can enhance the cycle performance, rate performance and capacity retention rate of Na2MnPO4F. It also showed good rate performance under high current density. After the high current test, the current returned to 0.1C, and the capacity can be restored to the original value, which showed that the material has good structural stability. Therefore, Ti3C2-CQDs doped Na2MnPO4F is an important way to improve the electrochemical performance of polyanionic compounds.