fig7

Figure 7. (A) Charge (delithiation) rate performance from C/20 to 4C with a discharge rate fixed at C/10, and (B) Nyquist plots of G-15% nSi and G-15% nSi-CNT electrodes (the inset is the equivalent circuit to fit the curves). nSi: Nano-silicon; CNT: carbon nanotube; R_s: ohmic resistance; R_SEI: SEI film resistance; SEI: solid electrolyte interphase; R_ct: charge transfer resistance; W: Warburg impedance; CPE_SEI: constant phase element for SEI; CPE_CT: constant phase element for charge transfer; Z_R: real impedance; -Z_I: negative imaginary impedance.