Carbon-Based Materials for Energy-Storage Devices, from Current Collectors to Electrodes

The rational design of carbon-based materials is attractive for the development of energy-storage devices. Especially well-organized carbon materials with high electrical conductivity, large surface areas, synergetic active sites, and controllable pore sizes have advantages for highly efficient electrochemical reactions. Herein, we report 3D hybrid nano- and micro-structured carbon-based materials for energy storage devices, such as supercapacitors, Li-based batteries, and aqueous electrolyte-based batteries.<br/>Firstly, we developed a three-dimensional carbon-based current collector with high electrical conductivity and a large surface area. The large surface area and high electrical conductivity are crucial factors for high-performance current collectors. However, the carbon-based current collector has a relatively lower electrical conductivity than the metal-based current collector. We solved this issue by utilizing the metal particles embedded in the graphene-based structure. The Ni-OH-loaded current collectors as a pseudo-capacitor showed 197.5 Wh/kg of high energy density and 815.5 W/kg of power density in a two-electrode system.<br/>Second, we utilized the carbon-coating technique with a cost-efficient phenolic resin for the silicon-based anode in Li-ion batteries. Silicon, as an abundant resource, has a high theoretical capacity (3579 mAh/g), but its large volume change during the repetitive charge-discharge process is a critical problem for high-performance Li-ion batteries. We solved it by using a carbon-coated silicon anode. This anode achieved 3092 mAh/g of high specific capacity and almost 100% capacity retention at 0.05C after 50 cycles.<br/>Finally, we introduced the carbon-based protection layer on the zinc anode in aqueous Zn-ion batteries (AZIB). AZIB has numerous advantages, such as non-flammable electrolytes, abundant resources, and reversibility. However, the irregular dendrite formation on the Zn surface is a critical issue in aqueous Zn batteries. The introduction of an optimized carbon-coated Zn anode accomplished an outstanding cycling performance of more than 1000 hours at 4mA/cm² in a symmetrical cell test.<br/>In summary, we designed carbon-based materials with a large surface area, high electrical conductivity, and high mechanical strength from the current collector to the electrode for an efficient electrochemical reaction. Our strategies could solve many issues in various energy-storage devices, such as high charge transfer resistance, huge volume expansion of active materials, and irregular dendrite formation. These results indicate that the rational design of carbon-based materials can provide a positive perspective for the study of next-generation batteries.