Fig. 4: Theoretical and experimental performances of GPG for potassium ion batteries.
From: Van-der-Waals-forces-modulated graphene-P-phenyl-graphene carbon allotropes
a The van der Waals forces within 2LG (I) and GPG (II) and their energy barriers for potassium ion migration (a-I: interaction between graphite layers; a-II: interaction between GPG layers; a-III: visualized interaction between graphite layers with a potassium ion insertion; a-IV: visualized interaction between GPG layers with a potassium ion insertion; a-V: energy barrier for potassium ion migration in graphite layers; a-VI: energy barrier for potassium ion migration in GPG layers; Blue: Attractive force; Green: Neutral; Red: Repulsive force; Blue ball: Carbon atom; White ball: Hydrogen atom); b the charge-discharge profiles for potassium ion battery working at 1 C and 20 C; c the rate performance for PIBs and d the relative CE; e the charge-discharge profiles at ultra-high rate of 210 C (1 C = 300 mA g–1) for PIBs with RGO and GPG negative electrodes (insert) the enlarged charge-discharge curves at 1000 and 2000 min; f the long-term cycle stability and CE of GPG based PIB at 2 C for 20000 cycles (the testing temperature is 25 ± 1 °C and cutoff voltages is 0.01-3.0 V with a safe voltage range from −2.0 to 5.0 V for overpotential protection); g the comparison of our work with other battery systems.
