MXene Film/Foam Bilayer Anodes with Enhanced Electrochemical Performance for Self-Standing Lithium-Ion Batteries

The structural design of self-standing electrodes without binders and current collectors is critical for maximizing the energy density of lithium-ion batteries, yet achieving electrical conductivity, ion accessibility, and mechanical integrity in a single architecture remains challenging. Although Ti3C2Tx MXene is a promising candidate, owing to its high metallic conductivity and structural robustness, conventional dense films suffer from restacking-induced restricted electrolyte penetration and Li+ diffusion. Conversely, porous MXene foams can mitigate restacking but exhibit weak electrical contact and limited mechanical robustness. To overcome this structural trade-off, we designed a self-standing MXene film/foam bilayer anode integrating a compact film layer with a porous foam layer, which was followed by air annealing to generate TiO2/TiOx-containing active sites. Among the various film/foam ratios systematically evaluated, the optimal 2:8 bilayer electrode exhibited low charge-transfer resistance and fast redox kinetics, delivering 83.24 mAh g−1 at 1000 mA g−1 and retaining 195.12 mAh g−1 at 50 mA g−1 after 200 cycles, outperforming the single-architecture electrodes. These results demonstrate that the bilayer design effectively combines the structural and electrical stability of the film with the rapid ion transport and abundant active sites of the foam, offering a promising strategy for high-performance self-standing anodes.