Electrochemical Performance of Nanosized Disordered LiVOPO4

Yong Shi; Hui Zhou; Ieuan D Seymour; Sylvia Britto; Jatinkumar Rana; Linda W Wangoh; Yiqing Huang; Qiyue Yin; Philip J Reeves; Mateusz Zuba; Youngmin Chung; Fredrick Omenya; Natasha A Chernova; Guangwen Zhou; Louis F J Piper; Clare P Grey; M Stanley Whittingham

doi:10.1021/acsomega.8b00763

Electrochemical Performance of Nanosized Disordered LiVOPO₄

ACS Omega. 2018 Jul 3;3(7):7310-7323. doi: 10.1021/acsomega.8b00763. eCollection 2018 Jul 31.

Authors

Yong Shi¹, Hui Zhou¹, Ieuan D Seymour², Sylvia Britto², Jatinkumar Rana^{1

1}, Linda W Wangoh^{1

1}, Yiqing Huang¹, Qiyue Yin¹, Philip J Reeves², Mateusz Zuba¹, Youngmin Chung¹, Fredrick Omenya¹, Natasha A Chernova¹, Guangwen Zhou^{1

1}, Louis F J Piper^{1

1}, Clare P Grey², M Stanley Whittingham^{1

1}

Affiliations

¹ Chemistry and Materials Science and Engineering, NECCES, Department of Mechanical Engineering and Materials Science and Engineering Program, and Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, New York 13902, United States.
² Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.

Abstract

ε-LiVOPO₄ is a promising multielectron cathode material for Li-ion batteries that can accommodate two electrons per vanadium, leading to higher energy densities. However, poor electronic conductivity and low lithium ion diffusivity currently result in low rate capability and poor cycle life. To enhance the electrochemical performance of ε-LiVOPO₄, in this work, we optimized its solid-state synthesis route using in situ synchrotron X-ray diffraction and applied a combination of high-energy ball-milling with electronically and ionically conductive coatings aiming to improve bulk and surface Li diffusion. We show that high-energy ball-milling, while reducing the particle size also introduces structural disorder, as evidenced by ⁷Li and ³¹P NMR and X-ray absorption spectroscopy. We also show that a combination of electronically and ionically conductive coatings helps to utilize close to theoretical capacity for ε-LiVOPO₄ at C/50 (1 C = 153 mA h g^-1) and to enhance rate performance and capacity retention. The optimized ε-LiVOPO₄/Li₃VO₄/acetylene black composite yields the high cycling capacity of 250 mA h g^-1 at C/5 for over 70 cycles.