Improved electrochemical properties of LiFePO4/graphene cathode nanocomposite prepared by one-step hydrothermal method

摘要

LiFePO4/graphene active material (LFP/G) was successfully synthesized via a simple, low raw material cost and environment friendly hydrothermal method at 170 degrees C. LFP/G composite was prepared in a template-free method using graphene nano-sheets as a conductive additive (3.0 wt.%) without any carbon coating. Results indicated the presence of LFP crystallites of the olivine phase, which are randomly anchored on the surface of graphene. Electrochemical characteristics of the LFP/G modified electrode show well-defined peaks, smaller peak potential separation and higher cycling stability compared to those of the pristine LFP obtained in the absence of graphene. LFP/G delivered an initial discharge capacity of 157 mA h g(-1) at 0.2 C and 114 mA h g(-1) at 5 C and the values were compared to those of LFP (the capacities reach up to 120 mA h g(-1) at 0.1 C and 50 mA h g(-1) at 5 C). The electrochemical enhancement of LFP/G could be mainly ascribed to synergetic effects of bridging graphene nanosheets and creating an interconnected conducting network of cross-linking between neighboring crystallites. Such network would enhance the stability of the cathode composite and buffer spaces to accommodate the volume pulsation during charge/discharge cycling. (C) 2014 Elsevier B.V. All rights reserved.