Application Of Methanesulfonic Acid Electrolyte In MXenes

Energy is vital to human development.Fossil energy consumption and production will seriously affect the world economy and ecological balance.With the explosive demand for environmentally friendly,high-performance renewable energy storage equipment,electrochemical energy is an unavoidable part of the green energy.Supercapacitors have attracted much attention due to their high specific capacitance,cycling stability,high power density,environmentally friendly and low power consumption,no memory effect,and safety.MXenes are remarkable electrode materials for supercapacitors,because of their metallic conductivity and hydrophilic tunable transition metal oxide-like surface termination that can undergo redox reactions.which highlight them as competitive alternatives to other electrode materials.Several MXenes,including Ti₃C₂T_x,Ti₂CT_x,Mo₂CT_x,Mo_1.33CT_x,Nb₄C₃T_x and V₂CT_x,have emerged as promising electrodes for supercapacitors.In particular,Ti₃C₂T_x achieved outstanding performance in common but hazardous sulfuric acid?H₂SO₄?electrolyte.In this work,a more environmentally friendly alternative acidic electrolyte,methanesulfonic acid?MSA CH₃SO₃H?is proposed.The energy storage performance of Ti₃C₂T_x in aqueous and neat MSA ionic liquid electrolytes is investigated.The specific capacitance of 298 F g^-11 was obtained at a scan rate of 5 mV s^-1 in 4M MSA,and it exhibits excellent cycle stability with retention of nearly 100%over 10,000 cycles.This electrochemical performance is similar to that of Ti₃C₂T_x in H₂SO₄,but using a greener electrolyte.In-situ X-ray diffraction analysis reveals the intercalation nature of the charge storage mechanism.Specifically,the lattice changes up to 5.16?during cycling,which is the largest reversible volume change observed in MXenes in aqueous electrolytes.In recent years,with the development of wearable electrical devices,flexible and cycling stability supercapacitors have aroused considerable interest.As the solid-state electrolyte is good safety,relatively light weight,and excellent cycling performance with high energy density,it is widely used in flexible energy storage electrode materials.Polyvinyl alcohol?PVA?can be mixed with various aqueous solutions to be gel-electrolyte,such as strong acids?H₂SO₄ and H₃PO₄?,strong bases?KOH?,and neutral?LiCl?,which draw many researchers attentions with advantages of non-toxicity,low cost,and good film formation and practicalit.In this experiment,a carbon cloth was used as the substrate,Ti₃C₂T_x was used as the electrode material,and PVA was mixed with methanesulfonic acid to make a gel electrolyte to assemble an all-solid-state flexible supercapacitor.These solid capacitors have remarkable capacity and good cycle stability,which shows a high capacitance of 345.6 mF cm^-2at 5 mV s^-1 and reach almost 95%capacitance retention after 1000 cycles.Interestingly,this symmetry all-solid-state supercapacitor shows good flexibility and excellent electrochemical performance stability with 0–180°static bending.What is more,all solid-state supercapacitors perform well under extreme conditions either high or low temperature.It has been proven that whether methanesulfonic acid is used as an aqueous electrolyte or a solid electrolyte from many aspects,Ti₃C₂T_x has outstanding electrochemical performance,whose application is expected in further pratical applications.In this research we develop a new electrolyte materials for high performance storage to fabricate energy storage devices and explained the intrinsic mechanism,sheding lighs on the development of supercapacitors.