Kun Liu, Xianhang Lu, Ming Hao, Yunhe Fu, Yuanhua Xie, Yaoshuai Ba, Dechun Ba, Northeastern University, Shenyang, China
The functional and integrated development of new energy vehicles and smartphones has driven an urgent demand for lithium-ion batteries (LIBs) with "high energy density and high safety." Composite copper current collectors (CCCCs), featuring a "sandwich-like" structure with a polymer film as the substrate and conductive layers coated on both sides, have emerged as a promising solution to synergistically improve the energy density and safety of LIBs. However, the industrial adoption of CCCCs faces significant challenges, primarily due to the low melting point of polymer films and the limited deposition efficiency of copper coatings. This study introduces a new process for preparing CCCCs that combines vacuum evaporation coating with electroplating techniques. By thoroughly investigating the heat transfer dynamics during the vacuum evaporation process and reasonably designing the equipment structure and process parameters, we have successfully managed the thermal effects on the polymer film and enhanced the coating efficiency. This approach has enabled the high-quality production of CCCCs. The structure of the CCCC was evaluated through four-probe method, X-ray diffraction, and uniaxial tensile tests. The results revealed that the CCCCs exhibit electrical conductivity (~5×10⁷ S m^-1) comparable to pure copper foil, possess a good copper crystal structure, and meet the necessary tensile strength criteria, laying the foundation for high-performance battery applications. Furthermore, we prepared CCCC-graphite (Gr) electrodes and evaluated their performance through cyclic voltammetry, rate capability, and cycling stability tests. The electrochemical performance of CCCC-Gr was found to be comparable to that of traditional copper foil-Gr electrodes. Notably, at a current density of 372 mA g^-1, the CCCC-Gr delivered a high specific capacity of ~310 mAh g^-1, indicating its excellent electrochemical and structural stability, and providing new ideas for the practical application of CCCCs.