Nanosized porous carbon-coated NaTi₂(PO₄)₃ (NTP) particles with superior rate and low-temperature properties are synthesized by a hydrothermal process combined with different carbon coating steps. Their structures and electrochemical performances are analyzed by X-ray diffraction, scanning/transmission electron microscopies, Raman spectroscopy, N₂ adsorption/desorption measurement and galvanostatic cell cycling. The optimized carbon-coated NTP sample NTP@C-2 shows superb rate performance with a charge capacity of 110.9 mA h g⁻¹ at 30C rate, i.e. 97.0% retention of its capacity at 0.5C. After 1000 cycles at 10C, the reversible capacity can still reach 105.6 mA h g⁻¹ with a very slow capacity decay of 0.0022% per cycle. Even at −20 °C, NTP@C-2 can still deliver a capacity of 97.6 mA h g⁻¹ at 10C and 61.1 mA h g⁻¹ at 20C. These excellent electrochemical performances can be attributed to both the nanosized porous architecture and the highly graphitic carbon coating. The use of a small amount of Na₃V₂(PO₄)₃ intermediate powder accounts for the formation of more sp²-type carbon coating. Such an NTP powder provides a promising anode material for high power sodium-ion batteries.

中文翻译：

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多孔碳涂层的NaTi ₂（PO ₄）₃具有优异的速率和低温性能†

通过水热法结合不同的碳包覆步骤，合成了具有优异的速率和低温性能的纳米多孔碳包覆的NaTi ₂（PO ₄）₃（NTP）颗粒。通过X射线衍射，扫描/透射电子显微镜，拉曼光谱，N ₂吸附/解吸测量和恒电流循环，分析了它们的结构和电化学性能。优化的碳涂层NTP样品NTP @ C-2具有极好的速率性能，在30C速率下的充电容量为110.9 mA hg ^-1，即在0.5C时其容量保持97.0％。在10C下循环1000次后，可逆容量仍可达到105.6 mA hg ^-1每个循环的容量衰减非常缓慢，仅为0.0022％。即使在-20°C时，NTP @ C-2在10C时仍可提供97.6 mA hg ^-1的容量，而在20C时仍可提供61.1 mA hg ^-1的容量。这些出色的电化学性能可归因于纳米级多孔结构和高度石墨化的碳涂层。少量的Na ₃ V ₂（PO ₄）₃中间粉末的使用导致形成更多的sp ²型碳涂层。这种NTP粉末为高功率钠离子电池提供了一种有希望的负极材料。