Heterointerface with Continuous Channels Enables Fast Na⁺ Transport in Layered Na₂Ti₃O₇

High-power sodium-ion batteries are essential for grid energy storage; however, they are generally limited by Na + transport. Herein, we tailor a highly matched heterostructure (MgTi 3 O 7 @Na 2 Ti 3 O 7 ) via a facile in situ synthesis method. The similar crystal structures of Na 2 Ti 3 O 7 and MgTi 3 O 7 creat continuous Na + diffusion channels at the heterointerface, and the interactions at the interface creat a built-in interface electric field with a direction from MgTi 3 O 7 to Na 2 Ti 3 O 7 . As a result, the particular heterointerface enable rapid Na + diffusion in the MgTi 3 O 7 @Na 2 Ti 3 O 7 electrode. The heterostructure engineering regulate the electrochemical reaction mechanism, leading to the solid solution reaction in the MgTi 3 O 7 @Na 2 Ti 3 O 7 electrode, facilitating rapid Na + transport. Therefore, the MgTi 3 O 7 @Na 2 Ti 3 O 7 electrode exhibits an excellent rate capability (123 mAh/g at 20 C) and cycling performance. This work highlights the importance of a heterointerface with continuous channels in overcoming Na + transport limitations in electrodes and could serves as a guide for designing a heterointerface for high-power sodium-ion batteries.