Boosting Charge Transfer Via Heterostructure Engineering of Ti 2 CT x /Na 2 Ti 3 O 7 Nanobelts Array for Superior Sodium Storage Performance.

The poor conductivity, inert charge transmission efficiency, and irreversible Na + trapping of Na 2 Ti 3 O 7 result in retardant electrons/ions transportation and deficient sodium-ion storage efficiency, leading to sluggish reaction kinetics. To address these issues, an urchin-like Ti 2 CT x /Na 2 Ti 3 O 7 (Ti 2 C/NTO) heterostructure sphere consisting of Ti 2 C/NTO heterostructure nanobelts array is developed via a facile one-step in situ hydrothermal strategy. The Ti 2 C/NTO heterostructure can obviously decrease Na + diffusion barriers and increase electronic conductivity to improve reaction kinetics due to the built-in electric field effect and high-quantity interface region. In addition, the urchin-like vertically aligned nanobelts can reduce the diffusion distance of electrons and ions, provide favored electrolyte infiltration, adapt large volume expansion, and mitigate the aggregation to maintain structural stability during cycles, further enhancing the reaction kinetics. Furthermore, the Ti 2 C/NTO heterostructure can effectively suppress many unwanted side reactions between reactive surface sites of NTO and electrolyte as well as irreversible trapping of Na + . As a result, systematic electrochemical investigations demonstrate that the Ti 2 C/NTO heterostructure as an anode material for record sodium-ion storage delivers the highest reversible capacity, the best cycling stability with 0.0065% decay rate for 4500 cycles at 2.0 A g -1 , and excellent rate capability of 172.1 mAh g -1 at 10.0 A g -1 .