MXene Film Could Lead to Smaller, Lighter Lithium-Ion Batteries

Drexel University researchers have made a breakthrough in lithium-ion battery design by introducing MXene-based current collectors. The team showed that titanium carbide (Ti3C2Tx) MXene films can replace traditional copper current collectors with a nearly 90% increase in electrode-level capacity. The results suggest a pathway toward smaller, lighter, and more recyclable energy-storage devices for various applications.

Can MXene films replace copper in lithium-ion batteries? Adapted from images used courtesy of Adobe Stock and Canva

MXene as a Functional Replacement for Copper

The researchers focused on Ti3C2Tx MXene, an electrically conductive two-dimensional transition metal carbide. The team fabricated 2-μm-thick MXene films with a 14,000 S/cm conductivity, compared to the 11.8-μm copper foils (8.96 g/cm^3) used in standard lithium-ion cells. At roughly one-tenth the weight and one-fifth the thickness of copper, the MXene collector substantially reduced inactive material mass.

MXene-based anodes stayed strongly adhered to thick graphite electrodes with uniform coatings, even when electrodes reached 400 μm thick (well beyond where copper substrates typically crack). When the team performed X-ray diffraction and scanning electron microscopy, the interface remained structurally sound with excellent contact between the MXene collector and graphite layer. The MXene interface also had lower charge-transfer impedance (36 Ω versus 80 Ω for copper), meaning electrons moved through it more efficiently.

Gravimetric capacity normalized to the active material mass (A). Gravimetric capacity normalized to the total electrode mass (B). Images used courtesy of Dieng et al.Images used courtesy of Dieng et al.

The team used electrochemical testing to quantify the performance advantages. When normalized to total electrode mass, MXene on graphite anodes delivered 273 mA h/g compared to 147 mA h/g for copper-based electrodes (i.e., a capacity increase of about 127 mA h/g, or 89%). The MXene films also exhibited excellent rate capability, maintaining higher discharge capacities across current rates from 0.1 C to 1 C and demonstrating low polarization during cycling. After 200 charge-discharge cycles, capacity retention exceeded 95%, with a Coulombic efficiency above 98%.

The study demonstrated the MXene collectors’ recyclability. Using a mild 5 M NaCl solution without harsh chemicals, the researchers could disassemble cycled electrodes and recover both the MXene film and graphite active material. The recovered MXene maintained 91% of its mass and 6,400 S/cm conductivity, ~46% of its original value, while retaining its layered morphology. When reused, the recycled MXene on graphite electrodes achieved 200 mA h/g, still outperforming conventional copper-based designs.

Current Collectors in Energy-Dense Battery Design

Lithium-ion batteries have been the norm in electronics for decades, but the weight and volume of passive components, such as current collectors, hinder their miniaturization. These collectors, typically copper or aluminum foils, contribute up to 15% of a battery’s total mass.

Aluminum and copper are historically used for the cathode and anode, respectively. Image used courtesy of Samsung SDI

While not storing energy, current collectors and their physical and electrical properties significantly affect a battery’s energy density, thermal stability, and lifetime. Copper foils are widely used for anodes due to their high conductivity and electrochemical stability, but their density limits the energy-to-weight ratio. Aluminum is used on the cathode side but similarly contributes to volume and manufacturing complexity.

Thinning metal foils creates real challenges for maintaining mechanical strength and electrode adhesion. Pushing too far risks wrinkling, delamination, or cracking during drying and cycling, which hurts performance.

Scientists have explored carbon-based alternatives like graphite papers, carbon nanotube mats, and fiber composites because they’re lightweight. However, these materials typically fall short as they don’t conduct electricity well enough (usually below 1,000 S/cm) and don’t make good contact with active materials.

Toward Lightweight and Circular Batteries

The Drexel team’s MXene current collectors represent a real advance in battery design. They cut the collector’s weight from about 8% to just 1% of the total electrode mass, which means more room for active material and better energy density overall. The ability to recycle the same MXene films through a low-energy saltwater process proves that the technology is sustainable and can fit into a circular economy for energy storage manufacturing. According to the researchers, the eventual integration of MXene components could change the way future battery materials are selected.

The study was published in Cell Reports Physical Science.