Highly Single‐Phase Conductive Carboxylated MXene Ink for Extremely Fast‐Charging Silicon‐Based Anodes and High‐Voltage Cathodes in Li‐Ion Batteries

Abstract The demand for smart electronics drives innovation in advanced Li‐ion batteries, focusing on microstructural and interfacial modifications in composite electrodes. This, in turn, drives innovation in electrode additives to replace traditional binders and carbon black. A key focus is the development of single‐phase conductive networks that combine high mechanical strength, efficient electron transport, and stability during high‐voltage operation. In this study, it is proposed and demonstrated that a carboxyl‐functionalized MXene metallic membrane can function as an electron transfer bridge, interconnected conductive membrane for commercial Li‐ion battery anodes, such as silicon‐carbon (Si/C) composites, and high‐voltage cathodes like LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NCM622). The interconnected MXene membrane demonstrates excellent rate performance in Si/C||Li cell (with 80.3% capacity retention after 195 cycles at 30 C) and Si/C||NCM622 full cell (with 70.0% capacity retention after 420 cycles at 5 C) coupled with high‐voltage operation (4.5 V vs Li/Li + ). The MXene membrane plays a key part in adjusting the solvation structure of Li + and facilitating the integration of Li⁺ and electron dual‐conducting transport pathways, which is crucial for improving the stability of electrodes. This work provides valuable insights for the strategic design of binder‐free electrodes, paving the way for enhanced cyclability and improved power density in Li‐ion batteries.