Promoting Transport Kinetics in Li-Ion Battery with Aligned Porous Electrode Architectures.

Developing scalable energy storage systems with high energy and power densities is essential to meeting the ever-growing portable electronics and electric vehicle markets, which calls for development of thick electrode designs to improve the active material loading and greatly enhance the overall energy density. However, rate capabilities in lithium-ion batteries usually fall off rapidly with increasing electrode thickness due to hindered ionic transport kinetics, which is especially the issue for conversion-based electroactive materials. To alleviate the transport constrains, rational design of three-dimensional porous electrodes with aligned channels is critically needed. Herein, magnetite (Fe3O4) with high theoretical capacity is employed as a model material, and with the assistance of micrometer-sized graphine oxide (GO) sheets, aligned Fe3O4/GO (AGF) electrodes with well-defined ionic transport channels are formed through a facile ice-templating method. The as-fabricated AGF electrodes exhibit excellent rate capacity compared with conventional slurry-casted electrodes with an areal capacity of ∼3.6 mAh·cm-2 under 10 mA·cm-2. Furthermore, clear evidence provided by galvanostatic charge-discharge profiles, cyclic voltammetry, and symmetric cell electrochemical impedance spectroscopy confirms the facile ionic transport kinetics in this proposed design.