Novel Centrifugation-Assisted Preparation (CAP) of Additive-Free Carbon-Decorated Fe3O4 Electrodes with Superior Electrochemical Performances for Lithium-Ion Batteries

2015 AIChE Conference

Novel Centrifugation-Assisted Preparation (CAP) of Additive-Free Carbon-Decorated Fe₃O₄ Electrodes with Superior Electrochemical Performances for Lithium-ion Batteries

Jian Zhu (speaker); K. Y. Simon Ng; Da Deng*

Department of Chemical Engineering and Materials Science, Wayne State University,

5050 Anthony Wayne Dr, Detroit, MI, United States, 48202

Email: da.deng@wayne.edu

Abstract

Lithium ion batteries (LIBs) are the dominant power sources for portable electronic devices, and are penetrating into the market of electric vehicles and sustainable energy grid. There is an increasing demand for higher energy and high powder LIBs. The electrochemical performances of LIBs are mainly determined by the electrodes selected. Taking anode for example, the theoretical capacity of commercial anode of graphite is only 372 mA h/g, and its performance is about to saturate after few decades of development. To further increase the energy density, carbon must be replaced by environmentally friendly and inexpensive materials with high capacity and excellent reversibility. On the other hand, the current conventional procedure in the preparation of electrodes is time consuming involving multiple steps, including materials preparation, slurry formation, coating on to current collectors, and drying in vacuum. Various additives, including binder polyvinylidene fluoride (PVDF), conductive enhancer carbon black (CB), and organic solvent N-Methyl-2-pyrrolidone (NMP), are required in electrode preparation. The complicated procedure and various additives lead to the high cost of electrodes. It would be beneficial but is still challenging to develop facile methods for electrode preparation with simplified procedure, without using any additives, but with superior electrochemical performances.

Herein, we demonstrated a novel and facile centrifugation-assisted preparation (CAP) of additive-free negative electrode of carbon-decorated Fe₃O₄ materials for high energy LIBs (Figure 1a). Notably, the materials were directly synthesized on the current collectors. No additives, such as PVDF binder, carbon black conductivity enhancer and NMP solvent which are typically used in conventional electrodes, were required. Interestingly, the as-prepared of carbon-decorated Fe₃O₄ negative electrodes exhibited superior electrochemical performance with stable specific capacity of 800 mAh/g (more than two times of theoretical capacity of graphite at 372 mAh/g) for at least 240 cycles at 100mA/g; (Figure 1b) no significant capacity decay was observed when the testing currents were increased, up to 1500 mA/g, demonstrating excellent rate performances for high power LIBs (Figure 1c). We believe that our facile CAP method could be used for the preparation of electrodes, including cathodes and anodes with or without additives, based on other active materials.

Figure 1. (a) Schematic of three steps of CAP of additive-free electrodes with carbon-decorated Fe₃O₄ on Cu current collector and corresponding optical images on the bottom; (b) excellent cycling performance tested at current of 100 mA/g for 240 cycles; and (c) rate performances and Coulombic efficiency at different currents from 100 to 1500 mA/g of the CAP electrodes of carbon-decorated Fe₃O₄ without any additives.