Interface Controlled Hybrid Carbon Bilayer Anode for Improved Ion Transport and Reaction Stability of Li Ion Battery

Li ion batteries (LIB) with high energy density and high power density are required due to the emerging market of electrical vehicles and other smart products. The dominant anode in current commercial LIBs is graphite owing to its low redox potential, good stability, and low cost. However, its effective capacity is drastically reduced owing to poor reaction rate during fast charge and discharge. To overcome this, graphite is mixed with other carbon materials, such as soft carbon (SC) and hard carbon (HC), as well as non-carbon materials. Carbon-based materials have a low cost and require relatively simple processing, and they are more chemically and mechanically stable than non carbon materials. They are the primary choices for mixtures with spherical crystalline graphite(SCG). Among carbon-based materials, SC is less expensive than HC and does not require high-temperature heat treatment. Although SC has a lower energy density than SCG, it allows for the rapid movement of ions through multiple edge planes. In this study we fabricated a novel bi-layered and patterned anode electrode to enhance the performance of the electrode by converging the idea of material blending, bi-layer structure, and patterned interface. The bilayer structure, which is different from that of the conventionally blended SCG/SC electrode, aims to stabilize the reaction with the electrolyte at the electrode surface while fully utilizing the bottom section of the electrode. Specifically, in our bilayer structure, the blended SC/SCG material was placed at the bottom and SCG alone was coated onto the top to maintain a stable electrode surface. The electrode pattern interfaces, which are optimized by controlling the pattern size, secure excellent mechanical adhesion and low internal resistance. The electrochemical performance of the bi-layered and patterned electrode was measured and compared with a single SCG electrode and with a conventionally blended SCG/SG electrode. The discharging current density, initial coulombic efficiency, and voltage plateau of these alternative structures were also compared by fabricating half cell. The improved performances of bi-layered and patterned electrode in the half-cell battery achieved high capacity retention of of 85.9% after 500 cycles at 1C. In addition, the full cell also attained and high energy density of 178.7.7Wh kg⁻¹ at 10C, which is 2.3 times higher than that of the single-layer SCG electrode