An overview over the electrode preparation process and cell assembly of the coin cells is presented in Figure 3.5a. The cathode slurries were prepared by thoroughly mixing 80 wt%
of the active material, 10 wt% carbon Super C65 (TIMCAL), and 10 wt% PVDF (SOLVAY) with NMP in an agate mortar (structural formulas cf. Figure 3.5c). The slurries were spread on carbon-coated Al current collectors (COVERIS ADVANCED COATINGS) with the help of a doctor-blade coater. The electrode sheets were dried at 120 °C for 5 h in a vacuum oven (THERMO
SCIENTIFIC), calendered (INTERNATIONAL ROLLING MILLS device), and then vacuum dried a sec-ond time for 12 h at 120 °C before being transferred into an Ar-filled glove-box (VAC, < 0.1 ppm H2O, < 0.1 ppm O2). The CR2032 coin-type cells (details on the coin cell parts see Figure 3.5b) were assembled using the circular cathode (d = 14.3 mm), a Li foil anode (ALFA AESAR, 0.75 mm, 99.9%, metals basis), a microporous monolayer PP membrane separator (CELGARD
2400, 25 µm, polypropylene), and 1 M LiPF6 dissolved in ethylene carbonate (EC)/diethyl carbonate (DEC) in a ratio of 1:1 (v:v, by volume) as electrolyte (DAIKIN;structural formulas see Figure 3.5c). Galvanostatic cycling was performed on a BIOLOGIC VMP3 multichannel galvanostat in a potential window of 3.0–5.2 V at C rates of 0.1 C, 0.2 C, 0.5 C, and 1 C for three cycles each, followed by 20 cycles at 0.1 C. Current densities and specific capacities were calculated on basis of the weight of active material in the electrode.
3 Experimental Methods
Figure 3.5 (a) Overview over the electrode and cell preparation process using coin cells, (b) components of CR2032 coin cells, and (c) structural formulas of the PVDF (polyvinylidene difluoride) binder, the NMP (N-methyl-2-pyrrolidone) solvent as well as the EC (ethylene carbonate), DMC (dimethyl carbonate), and DEC (diethyl carbonate) electrolytes.
3.4 References
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3 Experimental Methods
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