Boosted Storage Kinetics in Thick Hierarchical Micro–Nano Carbon Architectures for High Areal Capacity Li‐Ion Batteries

A practical and effective approach to increase the energy storage capacity of lithium ion batteries (LIBs) is to boost their areal capacity. Developing thick electrodes is one of the most crucial ways to achieve high areal capacity but limited by sluggish ion/electron transport, poor mechanical stability, and high‐cost manufacturing strategies. Here we address these constraints by engineering a unique hierarchical‐networked 10 mm thick all‐carbon electrode, providing a scalable strategy to produce high areal capacity LIB electrodes. The hierarchical‐networked structure utilizes micrometer‐sized carbon fibers (MCFs) as building blocks, nano‐sized carbon nanotubes (CNTs) as good continuous network with excellent electrical conductivity, and pyrolytic carbon as the binder and active material with excellent storage capacity. The combination of the above features endows our HNT‐MCF/CNT/PC electrode with excellent performance including high reversible capacity of 15.44 mAh cm−2 at 2.0 mA cm−2 and exhibits excellent rate capability of 2.50 mAh cm−2 under 10.0 mA cm−2 current density. The Li‐ion storage mechanism in HNT‐MCF/CNT/PC involves dual‐storage mechanism including intercalation and surface adsorption (pseudocapacitance) confirmed by the cyclic voltammetry and symmetric cell analysis. This work provides insights into the construction of high mechanical stability thick electrode for the next generation high areal capacity LIBs and beyond. A scalable manufacturing strategy is employed toconstruct mechanically strong 3D hierarchical networked architecture that consist of microscale carbon fiber, nanoscale CNT and pyrolytic carbon (PC) binder as novel thick carbon‐based anode for high‐areal‐capacity batteryelectrodes. Cyclic voltammetry and symmetric cell analysis confirms the Li‐ion storage mechanism in the thick electrode involves hybrid storage including surface adsorption and intercalation.