Figure 5
Mechanism of lithium ion storage on pure mSi and mSi@GNG: (a) pure mSi particle and conducting additives (e.g. carbon black). (b) SEI formation on the surface of pure mSi particles, occurring between 0.7 and 0.05 V during the initial discharge process. (c) Further lithiation at 0.05 V. Inhomogeneous point contact between mSi and conducting additives could cause non-uniform lithiation, resulting in stress concentration and the coexistence of c-mSi and meta-stable c-Li15Si4. (d) Broken lithiated mSi due to crystallization of Li15Si4 and stress-caused cracking after cycles. (e) mSi particle and GNG. (f) SEI formation on the surface of NG, occurring 1.1 V during the initial discharge process. (g) Further lithiation at 0.05 V. homogeneous contact between mSi and GNG could cause uniform lithiation. (h) Lithiated mSi@GNG due to no crystallization of Li15Si4 and no cracking after cycles.
