Effect of Microcracks on Graphite Anode Materials for Lithium-Ion Batteries

Modified graphite with microcracks was obtained by a combination of microwave heating and KOH activation. KOH enhanced the degree of order of the graphite, and K+ increased the spacing of the graphite layer. Microwave heating caused microcracks on graphite and promoted doping of K+ into the graphite. The microcracks could increase the contact area of electrode materials and electrolytes and decrease diffusion length. Furthermore, the uniform microcracks dispersed the pressure of the electrode wetted by the electrolyte, relieved stress during lithium removal and increased the degree of order of the graphite. The modified graphite has a capacity of 449 mAh g(-1) at 0.1 C, 380 mAh g(-1) at 0.25 C and 367 mAh g(-1) at 0.5 C. In addition, the capacity retention rate was 96.1% after one hundred cycles at 0.25 C, and the average coulombic efficiency was 99.4%.