Highly improved performances of LiMn0.7Fe0.3PO4 cathode with in situ electrochemically reduced graphene oxide

Graphene oxide, an oxidized derivative of graphene, has many intriguing properties, such as amphiphilicity, negative charge, and easy mass production. However, due to the electronic insulation, graphene oxide cannot be directly used as a conductive agent for lithium batteries before reduction. Here we have demonstrated the enhanced rate and cycle capability of LiMn0.7Fe0.3PO4 with in situ electrochemically reduced graphene oxide by starting from discharge to 1.5 V vs. Li+/Li. For example, LiMn0.7Fe0.3PO4 with 2 wt% electrochemically reduced graphene oxide can obtain a high discharge capacity of ∼83 mAh g−1 at 30C and capacity retention of ∼90% at 1C after 200 cycles, much higher performance than that without graphene oxide (∼10 mAh g−1 and ∼56%, respectively). Moreover, the cathode with in situ electrochemically reduced graphene oxide also shows better performances than that with the externally reduced graphene oxide. The boosted performance is attributed to the effective conductive network formed by the well-dispersed graphene oxide.