Preparation And Energy Storage Application Of Ti₃C₂ Ultrathin Nanosheet Flexible Electrode

MXene is an emerging 2D transition metal carbide,nitride and carbonitride material,which has attracted growing attention due to its high electrical conductivity,good flexibility and excellent hydrophilicity.Among MXene materials,Ti₃C₂ is used widely in the field of energy storage.However,the tight self-stacking of Ti₃C₂ nanosheets limits the rich accessibility of electrolyte ions,thereby preventing the further improvement of energy storage capacity.At the same time,Ti₃C₂is easy to oxidize,leading to the loss of its nanostructure and functional properties,which limits the application of such materials.In this paper,Ti₃C₂-based flexible films were designed and synthesized with ultra-high storage capacity,rate performance and cycle durability to explore its application in supercapacitors.The specific research contents are as follows:1.The preparation and application of MPFs/Ti₃C₂ composite electrodeTo solve the problem of easy self-stacking of Ti₃C₂ nanosheets,Ti₃C₂/MPFs(metal porphyrin frameworks)composite membranes were designed and synthesized with interlayer hydrogen bonding.In this system,vacuum-assisted suction filtration was used to prepare Ti₃C₂/MPFs composite membrane.The terminal groups(-O,-OH and-F)on the surface of Ti₃C₂ are directly bonded to the hydrogen atoms in the carboxyl group(-COOH)of MPFs nanosheets through hydrogen bonding.The synergistic effect of Ti₃C₂ and MPFs effectively prevents the self-stacking of Ti₃C₂ and MPFs,providing a 3D interconnected"MPFs-to-Ti₃C₂-to-MPFs"conductive network with a porous structure,which promotes rapid ion and electron transmission and shorten the transmission path.The interlayer hydrogen bonding in the Ti₃C₂/MPFs hybrid film can alleviate severe volume changes caused by phase separation and structural collapse during rapid charge/discharge,and contribute to long-term rate capability and cyclability,even during bending and folding to maintain good electrode structural integrity.2.The preparation and energy storage of ultra large-size Ti₃C₂ nanosheetsTo overcome the problem of easy oxidation of Ti₃C₂,ultra large-size anti-oxidation wrinkle Ti₃C₂ nanosheets were designed and synthesized.In this system,sodium sulfide nonahydrate(Na₂S·9H₂O)was added and the solvothermal method was used to prepare large-size pleated Ti₃C₂nanosheets.The experiment suggest that the formed alkaline solution through the addition of Na₂S·9H₂O can effectively inhibit the oxidation of Ti₃C₂.Even reacting for a long time at high temperature,Ti₃C₂nanosheets will not be oxidized.At the same time,Ti₃C₂ flexible thin film electrode with 3D porous structure was prepared by vacuum assisted suction filtration.The honeycomb 3D pore structure is used for electrolyte ion storage and rapid ion transmission,and shortens the ion transmission path,which provides an extremely high potential for ion diffusion.Furthermore,the 3D porous network-like interlayer structure increases the specific surface area,which is benefit to the improvement of the electrochemical performance of the thin-film electrode.