How Binder Nanofibration Affects the Active-Material Microenvironment in Battery Electrodes?

Binder morphology is a critical factor determining the electrode microstructures and properties, which fundamentally controls the charge transport and mechanical performance of the resultant battery. In this case, polytetrafluoroethylene (PTFE) binder is of great interest as it exhibits unique nanofibration capability and mechanical flexibility, which has been broadly applied for dry processing of battery electrodes. However, there is a lack of fundamental study on how binder nanofibration affects the electrochemomechanical properties of electrodes. Here, similar to the fibrous structures of the cell microenvironment, the attempt is to answer this question from the viewpoint of active-material microenvironment (ME@AM). First, the PTFE nanofibration degree is adjusted by electrode calendering treatment and binder loading. Second, the microstructures, mechanical relaxation behavior, bending capability, and liquid–electrolyte wetting capability of the fibrous ME@AM are comparatively investigated in detail by dynamic mechanical testing. Finally, the superiority of highly fibrous ME@AM in electrochemical performance is confirmed by the C-rate and cycling stability testing of half-cells. This study indicates that a highly fibrous ME@AM can remarkably improve the electrochemomechanical properties of electrodes by enhanced capillary action with liquid electrolyte, good electrode flexibility, and structural stability under compression. © 2024 Wiley-VCH GmbH.