Vertical VOPO4·2H2O Nanosheets with Richly Exposed (200) Plane Enable Fast-Kinetics High-Mass-Loading Cathodes for Zn-Ion Batteries.

ABSTRACT

Extending the layer spacing of the (001) planes to regulate the mobility of Zn2+ is widely adopted to optimize the performance of VOPO4·2H2O cathode for zinc-ion batteries. However, the unique function originating from other planes is often neglected. Herein, an effective in situ conversion methodology is proposed for the synthesis of the (200) oriented growth of vertical VOPO4·2H2O nanosheets with oxygen vacancies (VOd-VOPO4). Theoretical simulation and ex situ characterizations collaboratively demonstrate that the richly exposed (200) plane with tetragonal channels can offer quick pathways for in-layer and cross-layer migration of Zn2+, exhibiting enhanced transfer kinetics with improved reversible capacity. Meanwhile, efficient electron migration in VOd-VOPO4 is guaranteed by the introduction of oxygen vacancies. Thus, the as-prepared VOd-VOPO4 harvests exceptional discharge capacity, impressive rate capability, and remarkable long-cycle stability at high mass loading. Notably, the VOd-VOPO4 electrode (15 mg cm-2) provides a capacity of 213.5 mAh g-1 with an ultrahigh areal capacity of 3.02 mAh cm-2 at 0.1 A g-1, showing great potential for applications. This study highlights the orientated growth strategy for facilitating ion storage and migration, offering novel perspectives on the development of high-performance electrodes and beyond.