Mpg2 multi channel workstation

The following battery components were used: carbon black (Super C65, TIMCAL), carboxymethyl cellulose (CMC, Grade: 2200, Lot No. B1118282, Daicel Fine Chem Ltd.), NaClO₄ (98%, Alfa Aesar, additionally dried), propylene carbonate (BASF, battery grade), 4-fluoro-1,3-dioxolan-2-one (FEC, Hisunny Chemical, battery grade), glass microfiber separator (GF/D, Cat No.1823-257, Whatman), and Cu foil (9 μm, MTI Corporation).
In a typical electrode preparation, the respective materials were combined with deionized water and mixed in a Fritsch Pulverisette 7 classic planetary mill for 1 h at 500 rpm. Mixing weight ratios were Sb:CB:CMC = 64%:21%:15% for pure Sb NCs (Fig. 2), and P/Sb:CB:CMC = 40%:40%:20% or P/Sb:CB:Cu:CMC = 40%:30%:10%:20% (Fig. 3). The aqueous slurries were coated onto Cu current collectors and then dried overnight at 80°C under vacuum prior to use. All electrochemical measurements were conducted in homemade, reusable and air-tight coin-type cells assembled in an Ar-filled glove box (O₂ < 1 ppm, H₂O < 1 ppm). Elemental sodium was employed as both reference and counter electrode. As electrolyte 1 M NaClO₄ in propylene carbonate with 10% fluoroethylene carbonate was used. Glass fiber was used as separator. Galvanostatic cycling tests were carried out at room temperature on MPG2 multi-channel workstation (BioLogic). Capacities were normalized by the mass of active material.

No binders or solvents were used to prepare the electrodes used in the coin-type cell batteries. Graphite was homogeneously distributed and pressed on the surface of TiN-coated stainless-steel cap, at the loading rate of 10 mg over ca. 1 cm². The coin-type cells were assembled in an argon-filled glove box (O₂ < 1 ppm, H₂O < 1 ppm) using a glass fiber separator soaked with the 5 M KFSI/EC/DMC electrolyte (0.15 ml per coin-type cell). Thin potassium film pressed on the Al foil was used as both the reference and counter electrodes. These cells were cycled between 3.2 and 5.25 V on an MPG2 multichannel workstation (Bio-Logic). Cut-off potential of 5.25 V vs. K⁺/K was used to ensure high cyclic stability of KFSI-graphite DIB. As follows from cyclic voltammetry measurements of 5 M KFSI/EC/DMC electrolyte, its oxidation starts at higher voltages (Supplementary Fig. 14).