Hierarchical 3D Electrode Design with High Mass Loading Enabling High-Energy-Density Flexible Lithium-Ion Batteries

Flexible lithium-ion batteries (LIBs) have garnered considerable attention due to their increasing utilization in flexible and wearable electronic devices. However, the practical implementation of flexible LIBs in these devices has been hindered by the dual challenge of attaining both high energy density and exceptional flexibility. In this study, we introduce a hierarchical 3D electrode (H3DE) with a substantial mass loading capacity, which enables the creation of highly flexible LIBs boasting an exceptionally high energy density.<br/>The H3DE boasts a bicontinuous architecture, ensuring that active materials and conductive agents are uniformly dispersed throughout the 3D framework, irrespective of the specific type of active material employed. This seamless integration of the electrode and electrolyte facilitates rapid ion and electron transportation, thereby enhancing redox kinetics and reducing internal cell resistance. Furthermore, the H3DE displays remarkable structural resilience and flexibility even under repeated mechanical deformations.<br/>Capitalizing on these remarkable physicochemical attributes, pouch-type flexible LIBs employing the H3DE exhibit consistent cycling performance under various bending conditions. They achieve a groundbreaking energy density of 438.6 Wh kg⁻¹ and 20.4 mWh cm⁻², as well as an areal capacity of 5.6 mAh cm⁻², surpassing the performance of all previously documented flexible LIBs. This research offers a practical solution for the development of high-energy-density flexible LIBs suitable for a wide array of energy storage devices.