Shrinking Lithium-Ion Batteries by Replacing Metal Current Collectors with MXene Films

The demand for high-performance energy storage devices has been rapidly increasing due to the growing need for renewable energy integration and portable electronics. Traditional lithium-ion batteries have become the preferred choice for numerous applications due to their impressive energy density, but they are reaching limitations of capacity. At the cell level, around 25 w% consists of passive components like current collectors, conductive additives, binders, and separators. Especially, copper (Cu) and aluminum (Al) foils have been commonly used as current collectors for the anode and cathode in lithium-ion batteries (LIBs), contributing around 7 wt% and 8 wt%, respectively, to the overall weight. Despite constituting a considerable portion of the battery, these passive components often receive less attention in the development of high-power batteries. In recent years, the focus has been on decreasing the thickness of these metal current collectors and developing lightweight alternative materials to enhance energy efficiency to potentially boost the performance metrics of a Li-ion battery cell to boost the performance metrics of a Li-ion battery cell. MXenes, a family of two-dimensional transition metal carbides, nitrides, and carbonitrides emerge as a promising solution to address this limitation. In particular, Ti 3 C 2 T x MXene possesses a 2D morphology with excellent electrical conductivity (up to 20,000 S/cm), high surface area, good mechanical properties, and hydrophilicity. These attributes, coupled with ease of processing, make it very suitable for battery passive components. In this study, we focus on replacing the conventional copper current collector with thinner MXene film current collectors for high-mass loading graphite anode electrodes. Our results show improved capacities and rate performances of electrode materials using Ti 3 C 2 T x MXene current collectors while also reducing electrode weight and thickness. The electrode-level gravimetric capacity significantly increased by 98.5 mAh g -1 (from 140 mAh g -1 for Cu@graphite to 238.5 mAh g -1 for MXene@graphite). The areal and volumetric capacities increased as well. This study highlights the potential of MXene current collectors in improving the performance of lithium-ion batteries, paving the way for more efficient and lightweight energy storage solutions.