Nitrogen Doped/Carbon Tuning Yolk‐Like TiO2 and Its Remarkable Impact on Sodium Storage Performances

Yolk‐like TiO2 are prepared through an asymmetric Ostwald ripening, which is simultaneously doped by nitrogen and wrapped by carbon from core to shell. It presents a high specific surface area (144.9 m2 g−1), well‐defined yolk‐like structure (600–700 nm), covered with interweaved nanosheets (3–5 nm) and tailored porosity (5–10 nm) configuration. When first utilized as anode material for sodium‐ion batteries (SIBs), it delivers a high reversible specific capacity of 242.7 mA h g−1 at 0.5 C and maintains a considerable capacity of 115.9 mA h g−1 especially at rate 20 C. Moreover, the reversible capacity can still reach 200.7 mA h g−1 after 550 cycles with full capacity retention at 1 C. Even cycled at extremely high rate 25 C, the capacity retention of 95.5% after 3000 cycles is acquired. Notably, an ultrahigh initial coulombic efficiency of 59.1% is achieved. The incorporation of nitrogen with narrowing the band gap accompanied with carbon uniformly coating from core to shell make the NC TiO2‐Y favor a bulk type conductor, resulting in fast electron transfer, which is beneficial to long‐term cycling stability and remarkable rate capability. It is of great significance to improve the energy‐storage properties through development of the bulk type conductor as anode materials in SIBs.