Acetylene black

All the following reagents were utilized as purchased without further purification. Sulphuric acid (H₂SO₄), hydrochloric acid (HCl) and phosphoric acid (H₃PO₄) were bought from Mojallali Chemical Co. Graphite (cat #332461), europium(iii) nitrate pentahydrate (Eu(NO₃)₃·5H₂O), ammonium hydroxide (NH₄OH), hydrazine hydrate (N₂H₄) and poly(tetra fluoro ethylene) (PTFE) were acquired from Sigma-Aldrich Co. Acetylene black (>99.9%, S. A. 80 m² g⁻¹) was procured from Alfa Aesar Co. The remaining materials were obtained from Merck Chemical Co.

V₂O₃ (Sigma-Aldrich, 98%), VCl₃ (Sigma-Aldrich, 97%), V(acac)₃ (Sigma-Aldrich, 97%), VO₂ (Sigma-Aldrich, 99.9%), VOSO₄·xH₂O (Sigma-Aldrich, 97%), VO(acac)₂ (Sigma-Aldrich, 97%), V₂O₅ (Sinopharm, 99.5%), NH₄VO₃ (Aladdin, 99.0%), NaVO₃ (Aladdin, 99.0%), and Na₃VO₄·12H₂O (Aladdin, 99.0%) were used as vanadium sources in this work. H₃PO₄ (85%) and NaH₂PO₄·2H₂O (≥99%), Hydroxylamine (HONH₂·HCl, 99.5%) and (NaF, ≥98%) were purchased from Beijing Chemical Reagent Co. with analytical grade. Other reagents used for the preparation of coin cells were Na (Sinopharm, 99.8%), NaClO₄ (Alfa Aesar, 99%), fluoroethylene carbonate (FEC; Alfa Aesar, 99%), glass fiber separator (Whatman), KB (Lion, Carbon ECP600JD), and Acetylene black (AB; Alfa Aesar, ≥99.9%). The HC was purchased from KURARAY Co., Ltd, Japan. All reagents were used as received.

The electrochemical performance was investigated using two-electrode Swagelok-type cells. Each treatment was tested with at least three repeats. The charge-discharge voltage was between 1.4–2.1 V. Zinc metal foil was used as the anode. The aqueous electrolytes were 0.1 M LiCl and 0.1 M ZnCl₂ (both Sigma-Aldrich, Canada), and the pH was adjusted to 6.0 using LiOH and HCl. Absorbed Glass Mat (AGM. NSG Corporation) with a thickness of 2.5 mm was used as the separator. The composite cathode consisted of 83 wt % LiMn₂O₄ (MTI Co.), 10 wt % acetylene black (Alfa Aesar Co.) and 7 wt % polyvinylidene fluoride (PVDF, Arkema Inc.). N-methyl-2-pyrrolidinone was used as the dispersant (NMP, Sigma, 99.5% purity). The resultant slurry in NMP was coated onto graphite foil (SGL Group Co.). After drying at 70°C in an oven for 24 h, disks of 12 mm in diameter were cut (typical active material load of 2.4 mg cm^-2) and soaked in the electrolyte solution under vacuum (-0.1 MPa) for 30 min.

Acetylene black (AB, purity >99.9%) and iron powders (99.95% metals basis, density: 7.860 g/cm³) were purchased from Alfa Aesar Co. Ltd. (Louis, MO, USA) and Aladdin Co., Ltd. (Shanghai, China), respectively. PDMS (Sylgard 184, Dow Corning Co., Midland, MI, USA) was used as the host matrix for AB particles and iron powders.

Agaricus bisporus (white button, Pielachtaler Pilze, Austria) and Pleurotus eryngii (king oyster, Marchfelder Bio Edelpilze GmbH, Austria) mushrooms were purchased in a hydrated state from a local supermarket. Auricularia auricular‐judae (wood ear, Kreyenhop & Kluge GmbH & Co. KG, Germany) and Lentinula edodes (shiitake, Asia Express Food, Netherlands) mushrooms were purchased in a dehydrated state from a local Asian specialty food store. Acetylene black (50% compressed, purity 99.9%,) was purchased from Alfa Aesar (Ward Hill, USA), poly(vinylidene fluoride) (PVDF, Kynar 711) was kindly provided by Akerma (Colombes, France), 1‐methyl‐2‐pyrrolidone (NMP) was purchased from Sigma Aldrich (St. Louis, USA) and nickel foam sheet (Ni‐4753 Nickel foam sheet) from Recemat BV (Dodewaard, The Netherlands) for creating supercapacitors.

To fabricate the working electrode, CuS nanoplates, carbon black (acetylene black, Alfa Aesar), and polyvinylidene fluoride (PVDF, Sigma-Aldrich) are mixed in 1-methyl-2-pyrrolidone with a weight ratio of 8:1:1. The prepared slurry is coated on a Cu foil and vacuum-dried for 12 h. For the electrolyte, 1 M of sodium hexafluorophospate (NaPF₆) in diglyme is used. The electrolyte is stirred at 80 °C for 48 h inside a glove box under Ar atmosphere^{26 (link)}. A pure Na foil (Sigma-Aldrich) and a glass fiber (EL-CELL) are used as a reference electrode and a separator, respectively. A half-cell (ECC-STD, EL-CELL) is assembled inside a glove box under Ar atmosphere. The electrochemical cell test is performed using a PARSTAT MC 1000 cell tester (Princeton Applied Research). Charge/discharge profiles are obtained at 0.2 C, at a room temperature between 0.05 and 2.6 V. For ex situ experiments, an electrochemical cell is disassembled after a couple of charge/discharge cycles. For TEM analysis, an active material is thoroughly washed via active sonication for 3 h in dimethyl carbonate (DMC) and dispersed onto a grid for TEM examination. For XRD study, an active material is peeled off and loaded onto a sealed holder to prevent it from contacting with air. The holder is directly equipped inside the XRD machine.