Graphene Modified LiFePO4 Cathode for Lithium Ion Battery beyond Theoretical Capacity
Lung-Hao Hu,
1 Feng-Yu Wu,
1 Cheng-Te Lin,
1 Andrei N. Khlobystov,
2 and Lain-Jong Li
1*
1Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
2School of Chemistry, University of Nottingham, UK
Nature Communications (9-Apr-2013)
The specific capacity of commercially available cathode carbon coated LiFePO4 is typically 120-160 mAh g-1, lower than the theoretical value 170 mAh g-1. We discover that the carbon coated LiFePO4 surface-modified with 2 wt% of the electrochemically exfoliated graphene layers is able to reach 208 mAh g-1 in specific capacity. The excess capacity is attributed to the reversible reduction-oxidation reaction between the lithium ions of the electrolyte and the exfoliated graphene flakes. The highly conductive grapheneflakes wrapping around carbon coated LiFePO4 also assist the electron migration during the charge/discharge processes, diminishing the irreversible capacity at the first cycle and leading to ~100% Coulombic efficiency. Such a scalable approach can be applied to other cathode systems, boosting up the capacity for various Li batteries.