A Lithium-Ion Rechargeable Full Cell Using the Flower-like Na₃V₂(PO₄)₃@C Cathode and Li₄Ti₅O₁₂ Anode

Abstract

In the present work, we have demonstrated that nanopetal-assembled hierarchical carbon-coated Na3V2(PO4)3 (nNVP@C) microflowers, synthesized via a microwave-assisted hydrothermal route, play an important role for yielding superior electrochemical characteristics of a Li4Ti5O12 (LTO)//nNVP@C full cell. Thus, the full cell yields superior power density with decent discharge capacity after extended cycling and good rate performance. The nanosize petals help Li+ to diffuse faster in NVP particles, and the inner mesoporous morphology of microflowers allows the electrolyte to easily penetrate into the embedded NVP@C nanocrystals. Furthermore, the homogeneous carbon coating provides an elastic buffer to mitigate the strain developed during Na+ extraction and subsequent Li+ insertion and extraction. The LTO//nNVP@C full cell is claimed to be suitable for power applications, where relatively thinner electrodes would be flooded with a sufficient amount of the lithium salt-containing organic electrolyte. To improve the cycleability characteristics, one requires to match carefully the Li+ activity in the organic electrolyte with electrode capacity. This would ensure stoichiometric lithium-ion insertion in the LTO electrode together with predominant lithium-ion insertion in the nNVP@C cathode.