Cross-Linking Hollow Carbon Sheet Encapsulated CuP2 Nanocomposites for High Energy Density Sodium-Ion Batteries

Author: Chen, S. Q., Wu, F. X., Shen, L. F., Huang, Y. Y., Sinha, S. K., Srot, V., van Aken, P. A., Maier, J., Yu, Y.

Journal: Acs Nano

DOI:  10.1021/acsnano.8b02721

Keywords: sodium-ion battery, cross-linking strategy, porous carbon shell, CuP2 composites, full cell, solid-electrolyte interphase, high-performance anode, high-capacity, hard carbon, low-cost, li-ion, coated na3v2(po4)(3), high-power, long-life, cathode

Abstract: 

Sodium-ion batteries (SIB) are regarded as the most promising competitors to lithium-ion batteries in spite of expected electrochemical disadvantages. Here a cross-linking strategy is proposed to mitigate the typical SIB problems. We present a SIB full battery that exhibits a working potential of 3.3 V and an energy density of 180 Wh kg(-1) with good cycle life. The anode is composed of cross-linking hollow carbon sheet encapsulated CuP2 nanoparticles (CHCS-CuP2) and a cathode of carbon coated Na3V2(PO4)(2)F-3 (C-NVPF). For the preparation of the CHCS-CuP2 nanocomposites, we develop an in situ phosphorization approach, which is superior to mechanical mixing. Such CHCS-CuP2 nanocomposites deliver a high reversible capacity of 451 mAh g(-1) at 80 mA g(-1), showing an excellent capacity retention ratio of 91% in 200 cycles together with good rate capability and stable cycling performance. Post mortem analysis reveals that the linking hollow carbon sheet structure as well as the initially formed SEI layers are well preserved. Moreover, the inner electrochemical resistances do not significantly change. We believe that the presented battery system provides significant progress regarding practical application of SIB.