Sulfur‐Rich Colloidal Nickel Sulfides as Bifunctional Catalyst for All‐Solid‐State, Flexible and Rechargeable Zn‐Air Batteries

Abstract

Earth‐abundant and high‐performance catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are highly desirable in development of energy‐efficient rechargeable Zn‐air batteries. In this work, sulfur‐rich colloidal nickel sulfides (NiSx) are prepared as OER/ORR bifunctional catalysts via a two‐step hydrothermal process. The NiSx nanoparticles (NPs) with large surface area show high OER activity and excellent stability, as evidenced by low overpotential of 301 mV, small Tafel slope of 41 mV dec−1 and high stability over 20 h of chronopotentiometry test. Due to their sulfur‐rich nature (i. e. Ni3S4 and NiS2), the obtained NiSx also exhibit good ORR activity. The introduction of graphene oxide (GO) in the starting materials leads to the formation of a composite catalyst composed of conductive sulfur‐doped reduced graphene oxide (S‐rGO) and NiSx. A high ORR onset potential of 0.91 V (vs. RHE) is obtained from the sulfur‐rich NiSx NPs coupled with the S‐rGO which facilitates the electron‐transfer and furnishes the bifunctional catalytic activity. Rechargeable Zn‐air batteries with NiSx/S‐rGO bifunctional catalyst deliver stable charge and discharge voltages of 2.1 and 1.1 V over 590 cycles. Furthermore, all‐solid‐state and foldable Zn‐air batteries using pliable and robust air cathodes of NiSx/S‐rGO show similar voltage profile as their non‐foldable counterparts. The foldable batteries exhibit stable cycling performance for up to 120 discharge/charge cycles at either flat or folded state, proving their high electrochemical and mechanical stability.

Manganese Oxide Nanorods Decorated Table Sugar Derived Carbon as Efficient Bifunctional Catalyst in Rechargeable Zn-Air Batteries

“…The onset potential is defined as overpotential at a current density of 0.1 mA cm −2 [9]. The relatively early onset potential and high limiting current density of AC-S and MnO x @AC-S indicate the high ORR catalytic activities of the activated carbon obtained from dehydration process [43,44]. Samples with such activated carbons show notably higher limiting current density than that of commercial carbon black, and they are comparable to that of Pt/C.…”

Facile synthesis of battery waste-derived graphene for transparent and conductive film application by an electrochemical exfoliation method

“…3c) located at 285.02, 285.59, 286.91, and 289.34 eV, for carbon in C]C/C-C, C-S, C]O, and O-C]O, respectively. 49,51 The O1s spectrum with a prominent peak can be deconvoluted into three peaks at 531.67, 532.65, and 533.81 eV, for oxygen in carboxyl, epoxy and hydroxyl groups, respectively. 52,53 The peak at 168.74 eV for S2p (Fig.…”

Nickel nanoparticles coated on the exfoliated graphene layer as an efficient and stable catalyst for oxygen reduction and hydrogen evolution in alkaline media

“…In regard to this, great progresses have been achieved under the Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. development of high-performance HER and ORR, excellent durability , cheaper and abundant electro-catalysts such as metal free electrocatalysts [22,23], transition-metals based hybrid [24], phosphide [25], oxide [26], sulfide [27][28][29] and carbon-based compounds [30][31][32][33][34].…”

“…3d transition metals encapsulation into graphene support has been suggested by several researchers as a strategy for HER and ORR in alkaline media [29,[44][45][46][47]. Toward this end, Li et al [30] synthesized the transition metal (Co and Ni) on a graphene protected Ni substrate by a simple electro-deposition method.…”