Synthesis of Copper-Based Nanomaterial for Conductive Electrode and Lithium Ion Battery Anodes

Abstract

Cu-based nanomaterial synthesis has been considered as the major issue due to its remarkable electrical, optical, catalytic, and electrochemical property. Over the past decade, various synthetic methods of Cu-based nanomaterial have been investigated for suitable applications. In particular, the synthesized copper-based nanomaterial has been widely applied to the use of conductive electrodes and lithium ion batteries, because of inherent high conductivity, low cost, and high theoretical capacity. However, several limitations, such as complex manufacturing process, storage oxidation problem, and cracking problem during charge/discharge process, have hindered in the synthesis and application of Cu-based nanomaterial. In this work, the study has primarily focused on a new simple synthetic method of Cu-based nanomaterial for enhanced application performance. Firstly, the Cu3Sn alloy nanoparticles were introduced as good oxidation-resistance materials and conductive electrode using pressure-assisted fabrication method at room temperature. The Cu3Sn nanoparticles showed the promising electrode properties such as oxidation-resistivity, low-cost materials, simple process-ability, and room temperature electrode fabrication-ability, as an electrode material. The electrical resistivity of the pressed Cu3Sn nanoparticles electrode exhibited 19.8 µΩ∙cm at 131.3 MPa. Secondly, novel self-reducible Cu-inks, composed by formate, alkanol amine groups and poly alcohols, were introduced for the air sinter-able fabrication of Cu electrode films. The proposed Cu-ink had a good self-reducible activity induced by the decomposition of Cu-ink ligand and the reduction assistance effect of the polyol solvents. This self-reducible ability of Cu-ink ensured the sintering of conductive Cu electrode film under air condition. The optimized properties of the sintered Cu electrode film made using 3 wt% gCu-ink showed a resistivity of 17 µΩ • cm at a 350 ℃ air sintering temperature. Finally, synthesis of expanded graphite/Cu oxide nanoparticle composite (GCuO) was introduced to increase energy density and stability of lithium-ion batteries. GCuO was prepared by thermal treat treatment of a Cu ion complex and graphite. In this process, gasses (H2 and CO2) generated from the thermal decomposition of the Cu ion complex decomposition, which induced Cu oxide nanoparticle formation and graphite interlayer expansion (from 0.34 to 0.40 nm). The GCuO has good potential for effective Li ion intercalation into anodes for next generation batteries. The electrochemical properties of GCuO were determined using Li ion cells. GCuO cells exhibited a high energy density (263 Wh kg-1), discharging capacity (532 mAh g-1 at 0.2 C), rate retention capability (from 0.2 to 10 C), and stable long-term cycle-ability (83% capacity retention after 250 cycles).