Partial Sulfidation of the Electrochemically Exfoliated Layered Double Hydroxides toward Advanced Aqueous Zinc Batteries

Aqueous zinc-based batteries are a promising alternative to lithium batteries. These batteries, however, persistently suffer from uncontrollable dendrite growth and sustained water consumption at the Zn anodes, along with low and often fading capacity at the cathodes. Herein, Zn metal is simply encapsulated into a chitosan-containing polymer gel that not only suppresses hydrogen evolution but also enables dendrite-free Zn plating/stripping. A binder-free cathode based on the electrochemically exfoliated and partially sulfidated Ni-Co-Fe layered double hydroxide-reduced graphene oxide (SNS-rGO) nanocomposite is also reported. The fabricated devices (based on either Zn or chitosan-coated Zn) deliver near record-high values of specific capacity (756 mA h g-1cathode at 1 A g-1) and specific energy (1284 W h kg-1cathode), along with an outstanding specific power (108 kW kg-1cathode), an excellent output voltage (up to 1.9 V), and prolonged cycling stability at 100% depth-of-discharge. This interface engineering strategy, supported by the density functional theory calculations, provides a solid basis for further practical applications of aqueous Zn batteries. A stable and dendrite-free zinc anode is achieved by incorporating a chitosan-containing polymer gel as a protective coating. A facile and fast electrochemical exfoliation approach is also devised to efficiently exfoliate the layered double hydroxides into single- to few-layered 2D nanosheets. Partial sulfidation of the exfoliated nanosheets results in a cathodic active material with a near-record performance.image