Anions Regulation Engineering Enables Highly Reversible and Dendrite-Free Nickel Metal Anode with Ultrahigh Capacities.

The development of safe and high energy metal anodes represents a crucial research direction. Here, we report the achievement of highly reversible, dendrite-free transition metal anodes with ultrahigh capacities by regulating aqueous electrolytes. Using nickel (Ni) as a model, we provide theoretical and experimental evidence demonstrating the beneficial role of chloride ions in inhibiting and disrupting nickel hydroxide passivation layer on the Ni electrode. As a result, we have realized Ni anodes with an ultrahigh areal capacity of 1000 mAh cm -2 (volumetric capacity of ∼6000 mAh cm -3 ) and a Coulombic efficiency of 99.4% on a carbon substrate, surpassing the state-of-the-art metal electrodes by approximately two orders of magnitude. Furthermore, as a proof-of-concept, we have developed a series of full cells based on the Ni anode. The designed Ni-MnO 2 full battery exhibits a long lifespan of 2000 cycles, while the Ni-PbO 2 full battery achieves a high areal capacity of 200 mAh cm -2 . The findings of this study are important for enlightening a new arena towards the advancement of dendrite-free Ni metal anodes with ultrahigh capacities and long cycle life for various energy storage devices. This article is protected by copyright. All rights reserved.