Building Ionic/Electronic Three-Dimensional Conductive Framework to Enhance the Electrochemical Performance of LiVPO4f Cathode for Lithium Ion Batteries

Abstract

LiVPO4F has high charge-discharge plateau and good safety, making it a promising high-voltage cathode material for lithium ion batteries (LIBs).1 , 2 Nevertheless, LiVPO4F suffers low electronic and ionic conductivity, which brings poor rate capability as well as cycle performance. Moreover, the reaction at the electrode/electrolyte interface at high voltage with high oxidative V4+ causes low cycle property and low initial coulombic efficiency.3 Therefore, mastering the electrode/electrolyte interface is of great significance for application of LiVPO4F. Surface coating and bulk doping are usually used to overcome these issues in some well-known electrode materials. Coating with highly disperse graphene is able to effectively improve the electronic conductivity of the materials.4 , 5 Li3PO4 is a fast ionic conductor and is also used as inorganic coating material to enhance the ionic transmission of the electrode materials for LIBs.6 Also, Li3PO4 is expected to act as a barrier that restrains the side reaction at the electrode/electrolyte interface at high voltage.7 In this report, we construct the ionic/electronic 3D conductive framework to enhance the comprehensive performance of LiVPO4F. As shown in the schematic diagram (Fig. 1), in this ideal architecture, the nano Li3PO4 are dispersed in the space of thin graphene layers, and the LiVPO4F particles are well wrapped by graphene. We expect the Li3PO4 and graphene co-coated LiVPO4F to deliver impressive electrochemical performance, including superior cycle performance, good rate capability, and high initial coulombic efficiency. Reference 1. J. Wang, X. Li, Z. Wang, H. Guo, Y. Li, Z. He and B. Huang, J. Alloy. Compd., 581,836 (2013).2. J. Wang, X. Li, Z. Wang, H. Guo, Y. Zhang, X. Xiong and Z. He, Electrochim. Acta, 91,75 (2013).3. X. Sun, Y. Xu, M. Jia, P. Ding, Y. Liu and K. Chen, J. Mater. Chem. A, 1,2501 (2013).4. J. Wang, X. Li, Z. Wang, B. Huang, Z. Wang and H. Guo, J. Power Sources, 251,325 (2014).5. H. Li and H. Zhou, Chem. Commun., 48,1201 (2012).6. L.-X. Yuan, Z.-H. Wang, W.-X. Zhang, X.-L. Hu, J.-T. Chen, Y.-H. Huang and J. B. Goodenough, Energ. Environ. Sci., 4,269 (2011).7. X. Li, R. Yang, B. Cheng, Q. Hao, H. Xu, J. Yang and Y. Qian, Mater. Lett., 66,168 (2012).