Ultrahigh areal capacity and long cycling stability of sodium metal anodes boosted using a 3D-printed sodiophilic MXene/rGO microlattice aerogel.

Sodium metal has emerged as a highly promising anode material for sodium-based batteries, owing to its intrinsic advantages, including its high theoretical capacity, low working plateau and low cost. However, the uncontrolled formation of sodium dendrites accompanied by unrestricted volume expansion severely limits its application. To tackle these issues, we propose an approach to address these issues by adopting a three-dimensional (3D) structure of Ti ₃ C ₂ T _x /reduced graphene oxide (Ti ₃ C ₂ T _x /rGO) constructed by a direct-ink writing (DIW) 3D printing technique as the Na metal anode host electrode. The combination of the 3D-printed rGO skeleton offering artificial porous structures and the incorporation of sodiophilic Ti ₃ C ₂ T _x nanosheets provides abundant nucleation sites and promotes uniform sodium metal deposition. This specially designed architecture significantly enhances the Na metal cycling stability by effectively inhibiting dendrite formation. The experimental results show that the designed Ti ₃ C ₂ T _x /rGO electrode can achieve a high coulombic efficiency (CE) of 99.91% after 1800 cycles (3600 h) at 2 mA cm ^-2 with 2 mA h cm ^-2 . Notably, the adopted electrodes exhibit a long life span of more than 1400 h with a high CE over 99.93% when measured with an ultra-high capacity of 50 mA h cm ^-2 at 5 mA cm ^-2 . Furthermore, a 3D-printed full cell consisting of a Na@Ti ₃ C ₂ T _x /rGO anode and a 3D-printed Na ₃ V ₂ (PO ₄ ) ₃ C-rGO (NVP@C-rGO) cathode was successfully demonstrated. This 3D-printed cell could provide a notable capacity of 85.3 mA h g ^-1 at 100 mA g ^-1 after 500 cycles. The exceptional electrochemical performance achieved by the 3D-printed full cell paves the way for the development of practical sodium metal anodes.