H.D. Shi, Y.F. Dong, S.H. Zheng, C. Dong, Z.-S. Wu*
Nanoscale Advances, 2020, 2, 4212 - 4219
DOI: 10.1039/D0NA00515K [PDF]
Potassium (K) metal batteries hold great promise as an advanced electrochemical energy storage system because of their high theoretical capacity and low cost. However, the practical application of K metal anodes has limited by their poor cycling life caused by dendrite growth and large volume changes during plating/stripping process. Herein, three-dimensional (3D)alkalized Ti3C2(a-Ti3C2) MXene nanoribbon frameworkswere demonstrated as advanced scaffolds for dendrite-free K metal anodes. Benefiting from 3D interconnected porous structure for sufficient K accommodation, improved surface area for low local current density, andpreintercalated K in expanded interlayer spacing, and abundant functional groups aspotassiophilic nuleation sitesfor uniform K plating/stripping, the as-formeda-Ti3C2frameworks successfully suppressed the K dendrites and volume changes at both high andcapacity current density. As a result, the a-Ti3C2based electrodes exhibited an ultrahigh Coulombic efficiency of 99.4% at a current density of 3 mA cm-2with a long lifespan up to 300 cycles, and excellent stability for 700 h even at a ultrahigh plating capacity of 10 mAh cm-2. When matchingK2Ti4O9cathodes, the resulteda-Ti3C2-K//K2Ti4O9full batteries offered greatly enhanced rate capacity of 82.9 mAh g-1at 500 mA g-1and excellent cycling stability with a high capacity retention (77.7% after 600 cycles) at 200 mA g-1, demonstrative of great potential ofa-Ti3C2for advanced K-metal batteries.