From Checkerboard‐Like Sand Barriers to 3D Cu@CNF Composite Current Collectors for High‐Performance Batteries

Abstract

While the architecture, surface morphology, and electrical conductivity of current collectors may significantly affect the performance of electrochemical cells, many challenges still remain in design and cost‐effective fabrication of highly efficient current collectors for a new generation of energy storage and conversion devices. Here the findings in design and fabrication of a 3D checkerboard‐like Cu@CNF composite current collector for lithium‐ion batteries are reported. The surface of the current collector is modified with patterned grooves and amorphous carbon nanofibers, imitating the checkerboard‐like sand barriers in desert regions. Due to a combined effect of the grooves and the carbon nanofibers, a battery based on this current collector retains a reversible capacity of 410.1 mAh g−1 (beyond the theoretical capacity of carbonaceous materials of 372 mAh g−1) with good capacity retention (greater than 84.9% of the initial capacity after 50 cycles), resulting in 66.2% and 42.6% improvement in reversible capacity and capacity retention, respectively, compared to the batteries using traditional Cu current collectors. Based on the excellent electrochemical performance, this composite current collector is believed to be an attractive alternative to the traditional commercially used current collectors for the anode of high‐power energy storage systems.

Honeycomb‐Inspired Surface‐Patterned Cu@CuO Composite Current Collector for Lithium‐Ion Batteries

“…For example, we fabricated a checkerboard‐like current collector by means of lithography and chemical vapor deposition. Due to a combined effect of the grooves and carbon nanofibers, the battery maintained a capacity of 410.1 mAh g −1 after 50 cycles . In addition, the CuO/Cu composite current collector, consisting of a square blind hole array and CuO nanosheets inside the blind holes, was also synthesized through lithography.…”

Using Orthogonal Ploughing/Extrusion to Fabricate Three-Dimensional On-Chip-Structured Current Collector for Lithium-Ion Batteries

“…These microstructures are supposed to be beneficial to increase the surface area of the current collector so as to accommodate more electrode material, which can improve the volume capacity density. Besides, as the surface area increases, the effective contact point between the electrode materials and current collector can be greatly intensified . In addition, these structures, e.g., grooves, burrs, and reentrant cavities, are considered as effective factors to strengthen the bonding interface between the electrode and active materials .…”

“…Therefore, the level of bonding force between the current collector and electrode material can reflect the cycle life of the battery to a certain extent. Thus, we assessed the bonding force through quantifying the surface friction Figure e provides the point-surface friction coefficient curves of the electrodes based on these two types of current collectors.…”

“…There is a very small reaction peak at about 1.7 V in the discharge cycle and 2.35 V in the charge cycle for the first CV curve, which marks the reaction of CuO with Li + . However, the subsequent cyclic CV curve does not include such peaks of CuO because the produced CuO is negligible . It is also noteworthy that these curves tend to reclose in the subsequent scan, which suggests that the electrode reaction of this active material is more reversible and stable …”

“…Following this idea, many studies focus more on creating complex features (e.g., 3D, graphical pattern, voiding, multiscale) ,,− to achieve special functions (e.g., improving integral conductivity, enhancing mechanical intensity, mitigating expansion and pulverization, increasing specific surface area, and reducing impedance) ,,− of current collectors. However, most of the reported current collectors have to face the following issues.…”