Ni₃S₂ Nanocomposite Structures Doped with Zn and Co as Long-Lifetime, High-Energy-Density, and Binder-Free Cathodes in Flexible Aqueous Nickel-Zinc Batteries

Abstract

Flexible rechargeable Zn//Ni batteries are attractive owing to their high energy density, good safety, inexpensive cost, and simple manufacturing process. However, the effects of metal doping on the properties of Ni 3 S 2 cathodes in Zn/Ni batteries are not well understood. Herein, a binder-free Ni 3 S 2 electrode is doped with Zn and Co and the nanocomposite structures are prepared on nickel foam (named ZCNS/NF) by a simple two-step hydrothermal technique. The ZCNS/NF//Zn battery delivers excellent electrochemical performance such as a working voltage window can be as high as 2.05 V, a capacity of 2.3 mAh cm −2 at 12 mA cm −2 , and 82% retention going through 2000 cycles at 20 mA cm −2 . The battery has a maximum output area energy density of 1.8 mWh cm −2 (462 Wh kg −1 ) and a power density of 36.8 mW cm −2 (9.2 kW kg −1 ). In addition, the flexible battery remains operational while being bent at a large angle and even punctured. The high performance and robustness of the composite cathode suggest that the design principle and materials have large commercial potential in Ni//Zn batteries.

Facile Synthesis of NixCo3−xS4 Microspheres for High-Performance Supercapacitors and Alkaline Aqueous Rechargeable NiCo-Zn Batteries

“…Thus, Ni 2.5 Co 0.5 S 4 -350 electrode was further explored in in-depth studies in aqueous alkaline Zn ion batteries, a Ni 2.5 Co 0.5 S 4 -350//Zn battery was fabricated by using the as-fabricated Ni 2.5 Co 0.5 S 4 -350 as cathode and commercial Zn plate as anode, respectively, and the mixed solution of 2 M KOH and 0.2 M Zn(Ac) 2 was used as an electrolyte. The cathode and anode reaction in an alkaline solution is expressed as follows [ 22 , 23 ]: Ni-Co-S +2OH − → NiSOH + CoSOH + 2e − CoSOH +OH − → CoS(OH) 2 + e − [Zn(OH) 4 ] 2− + 2e − → Zn + 4 OH − …”

“…So far, Co and Ni-based metal sulfides have been synthesized and used as electrode materials for alkaline aqueous energy storage devices such as supercapacitors and aqueous Ni-Zn batteries [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. Nickel cobalt bimetallic sulfides such as NiCo 2 S 4 , [ 26 , 27 , 28 ] CoNi 2 S 4 , [ 29 , 30 ] and Ni x Co 3−x S 4 , [ 31 ] are regarded to be the most attractive electrode materials for EESDs due to their low cost and synergistic electrochemical reaction sites.…”

Rational Design of Flexible Zn-Based Batteries for Wearable Electronic Devices

“…However, an inevitable problem of Ni–Zn batteries is that they have poor capacity retention and a high electron transport barrier, which hinders their further applications, especially in flexible energy storage devices. To tackle the above issues, Zhou et al developed a freestanding Ni 3 S 2 cathode by codoping Zn and Co on a nickel foam . Similar to other freestanding methods, this cathode was synthesized on the nickel foam by a simple two-step hydrothermal method (Figure f) and delivered an outstanding energy density and power density (462 Wh kg –1 and 9.2 kW kg –1 ) with excellent cycling stability (82% over 1000 cycles) due to the stable hilly shape formed by the cooperation of Zn and Co atoms.…”

Plasma Engineering of Basal Sulfur Sites on MoS2@Ni3S2 Nanorods for the Alkaline Hydrogen Evolution Reaction

“…[31] Figure 2d shows the three typical diffraction peaks at 44.5, 52.1, and 76.7°corresponding to the (111), (200), and (220) planes of the Ni substrate (PDF#04-0850). [32] The diffraction peaks marked by squares can be indexed to the (101), (110), (003), (211), and (300) planes of the Ni 3 S 2 nanorods (PDF#44-1418) [33] and those at 12.4, 27.8, 38.9, 47.9, 58.8, and 71.4°marked by pentagons are the (002), (004), (103), (105), (008), and (203) planes of the MoS 2 nanosheets (PDF#37-1492). [34] The reason for the small diffraction peaks of MoS 2 is mainly because the content of MoS 2 is very low compared to Ni 3 S 2 , and the depth of X-ray diffraction (XRD) measurement is also very deep to several microns.…”