Fig. 4. (a) Cyclic voltammograms of Cu/VGCF and flat-Cu substrates in 1 M LiPF6/EC : DEC (50 : 50 vol%) with 5 vol% FEC in the potential range of 0.0–3.0 V vs. Li/Li+. (b) Initial charge–discharge properties of Si electrodes prepared using commercially available Cu and Cu/VGCF substrates (solid line: 1st, dotted line: 2nd cycle).
