Organic Semiconductor Cocrystal for Highly Conductive Lithium Host Electrode

Abstract

In this work, a highly conductive organic cocrystal is investigated as an anode material for conducting agent-free lithium-ion battery (LIB) electrodes. A unique morphology of semiconducting fullerene (C-60) and contorted hexabenzocoronene (cHBC) is developed as a cocrystal that efficiently enhances the electron transfer during discharge and charge processes due to the formation of a well-defined junction between C-60 and cHBC. In particular, the present study reveals the exact cocrystal phase of orthorhombic Pnnm using grazing incidence X-ray diffraction characterization and computational methods. The detailed cocrystal structure analysis indicates that the columnar structure of C-60/cHBC cocrystal facilitates the reliable vacant sites for Li+ storage, which ultimately enhances the reversible capacity to 330 mAh g(-1) at 0.1 A g(-1) with long cyclability of 600 cycles in the absence of a conducting agent. Furthermore, the rate performance of the C-60/cHBC cocrystal anode is improved compared to that of the graphite anode, indicating that the cocrystal formation between C-60 and cHBC enhances the charge transport at a high current density. It demonstrates that the approach of this study can be a promising strategy for preparing conducting agent-free organic cocrystal anodes, which also provides a viable design rule for high-performance LIBs electrodes.