Fabrication of layered electrode using stamping method and its electrochemical performance as anode electrode for lithium ion battery

Abstract

This work is a study on the improving of cyclability, rate capability and energy density in electrodes by arrangement of monolayer and multi-layer. First, hollow Fe3O4/carbon particles were prepared and used as a monolayer and multi-layer electrode, and their electrochemical properties were evaluated. A monolayer or multi-layered electrode of hexagonally ordered microparticles is prepared. The monolayer electrode is produced by heat treatment of a polyvinyl alcohol film comprising a monolayer of microspheres. The electrode is prepared by stamping with microspheres assembled into the monolayer using an ordered patterning micro-framework polydimethylsiloxane on polyvinyl alcohol spin-coated cupper foil. Multi-layer structure can be fabricated by repeating spin coating and stamping of PVA on cupper foil. The morphological and structural characterizations of the mono- and multi-layer electrode are conducted by employing scanning electron microscopy, focused-ion beam SEM, transmission electron microscopy, and X-ray diffractometery. As the number of layers increased, the cell capacity increased and the loading level of the anode active material could be increased. Even though the multi-layer electrodes are composed of only active materials without the use of any polymeric binder or carbon additives such as acetylene black and Super-P, the electrode exhibited a cycling stability and rate capability with a coulombic efficiency of 99% at a high current rate due to the good structural stability and lower electrical resistance as a result of the ordered monolayer structure. Hollow particles have been confirmed that it has excellent cyclability and capacity even at a high rate. In the case of the mono-r and multi-layer electrodes, there is no conductive material or binder, but has a better life characteristic during 500 charge / discharge cycles than the hollow particle electrode using a conductive material or a binder. The monolayer electrode maintained the hollow structure and the monolayer structure even after 500 cycles of charging and discharging. Further, mono- and multi-layer were confirmed that a conductive material and a binder were not used and that the material had a high capacity per volume. The multi-layer structure can easily control the thickness and the loading level of the electrodes by adjusting the number of layers. The electrode thickness and loading level increase linearly as the number of layers increases. As the number of layers was increased in the multi-layer electrode, the capacity per unit weight was not increased but the capacity per unit volume was increased.