In situ construction of a hierarchical TiO 2 /Ti 3 C 2 hybrid via water steam etching for high-performance potassium-ion batteries.

Potassium ion batteries (PIBs) have attracted great research interest in new-generation large-scale energy storage considering their abundant source, low cost, and suitable working potential. Herein, a hierarchical TiO 2 /Ti 3 C 2 hybrid is developed via a green, facile water steam etching method for realizing an efficient and durable anode material for PIBs. In this hierarchical assembly, the TiO 2 nanoparticles anchored on the Ti 3 C 2 surface contribute a high pseudocapacitance while mitigating the restacking of the Ti 3 C 2 MXene skeleton, which ensures mechanical robustness to accommodate large K + ions. Benefiting from the amalgamation of structural properties and the synergistic effects stemming from the individual constituents, the optimized TiO 2 /Ti 3 C 2 anode harvests remarkable performance in the potassium ion storage, including a high reversible capacity of ∼255 mA h g -1 at 0.2 A g -1 after 1300 cycles as well as an outstanding long-term cycling performance and rate capability (a high capacity of ∼230 mA h g -1 even after intensive 10 000 cycles at 2 A g -1 ). The excellent TiO 2 /Ti 3 C 2 anode enables the assembled pouch-cell coupling PTCDA cathode to deliver a capacity of ∼173 mA h g -1 at 0.05 A g -1 and retain 120 mA h g -1 after 30 cycles. The employment of the pouch-cell in successfully powering the LED module showcases its application prospect for advanced PIBs.