High encapsulation efficiency of ionic liquid microcapsules for sable silicon anode

Silicon anode is subjected to volume changes throughout charge-discharge cycles, and the volume fluctuation can seriously undermine Si electrode structure and hinder continuous ion transport pathway. To address this issue, ionic liquid encapsulated polystyrene microcapsules (IL-MS) with high encapsulation efficiency and sub-micron diameter are synthesized through a PVA-modified solvent evaporation method. The obtained IL-MS can be uniformly dispersed in the Si anode to reconstruct the Li + conduction pathway and enhance its cycling stability. By controlling the core-shell mass ratio and polystyrene concentration during the emulsification process, the IL-MS demonstrate a high encapsulation efficiency of 68 % and their diameters are monodispersed at approximately 1.46 μm. Notably, when the pre-embedded IL-MS in Si anode were ruptured during charging and discharging, the Si anode with IL-MS not only facilitates stress dissipation of Si particles, but also improves the ionic conductivity of Si anode by reconstructing the ionic conduction pathway. As a result, upon reaching 200 cycles at a current intensity of 0.84 A/g, the electrode with 10 wt% IL-MS maintains a capacity of 1732.1 mAh/g, demonstrating an ultra-stable cycling performance. Therefore, pre-embedding the IL-MS in the electrode is an effective strategy for improving the ionic conductivity and the electrochemical performance of Si anodes.