Preparation And Performace Of Titanium-based Oxides In Magnesium-lithium Hybrid Batteries

With the rapid development of the electronic industry,higher requriements have been put forword for energy storage equipments.Because of the safety problem,the traditional lithium ion batteries can not meet the development of electronic field.Magnesium ion battery is one of the candidates to replace lithium ion battery due to its high theoretical volume,high safety and other advantages.Owing to low pratical specific capacity,traditional magnesium ion batteries can not meet the rapid development of modern electronic industry.However,magnesium-lithium hybrid batteries combining lithium ion fast kinetics feature and the advantages of magnesium metal have become an important part of the energy storage field.While,magnesium-lithium hybrid batteries are in the early stage of development and still face many challenges.One of the biggest challenges is the development of high-performance electrode materials.Therefore,the development of new electrode materials for magnesium-lithium hybrid batteries is urgent.Titanium-based compounds,such as TiO₂,LiCrTiO₄ and MLi₂Ti₆O₁₄?M=Sr,Ba,Pb?etc.,because of their unique physical and chemical properties?abundant resources and low price,moderate charge and discharge platform,good circulation stability,high specific capacity?,have attracted much attention and have been regarded as the most promising electrode material of lithium ion batteries.However,such materials are rarely applied in magnesium-lithium hybrid batteries.In this paper,TiO₂,LiCrTiO₄ and MLi₂Ti₆O₁₄?M=Sr,Ba,Pb?were prepared by the sol-gel method with butyl titanate as the titanium source,and their electrochemical properties and reaction mechanism in magnesium-lithium hybrid batteries were investigated.The main research contents are as follows:1.CNTs@TiO₂ nanocables,TiO₂ nanotubes and TiO₂ nanoparticles were successfully prepared by the sol-gel method followed with calcination,and their electrochemical properties in magnesium-lithium hybrid electrolyte were studied.The results show that the CNTs@TiO₂ nanocable has a high specific capacity,which can reach 161.9 mA h g^-1 after 100 cycles at 50 mA g^-1.In addition,we also studied the ion storage mechanism in magnesium-lithium hybrid electrolyte.The results show that the whole electrode raeaction depends on the intercalation and extraction of lithium ions.2.One-dimensional LiCrTiO₄ nanowires,CNTs@LiCrTiO₄ hybrid nanotubes and LiCrTiO₄ nanoparticles were prepared by the sol-gel method followed with calcination,and their electrochemical properties were studied as cathode materials for Mg-Li hybrid batteries.The results show that the one-dimensional LiCrTiO₄ nanowires have excellent electrochemical properties.After 100 cycles at the current density of 50 mA g^-1,its capacity can reach 127.0 mA h g^-1.In addition,the material also has excellent rate properties.For example,when the current density is 30,60,100,200 and 500 mA g^-1,the discharge capacities are 162.3,154.0,149.6,143.3 and 110.1 mA h g^-1,respectively.Finally,the ion storage mechanism in the magnesium-lithium hybrid electrolyte was investigated and found that Li⁺ions were mainly embedded into the material to participate in the reaction.3.MLi₂Ti₆O₁₄?M=Sr,Ba,Pb?were successfully prepared by a sol-gel method followed with calcination,and their electrochemical properties in magnesium-lithium hybrid electrolyte were explored.Among them,PbLi₂Ti₆O₁₄ exhibits excellent electrochemical properties due to its high electronic conductivity,small polarization value,low charge transfer resistance,and fast ion diffusion rate.The material has a capacity of 76.3 mA h g^-1 after 300 cycles at 50 mA g^-1.In addition,we also studied the ion storage mechanism in magnesium-lithium hybrid electrolyte,and the experiment showed that only Li⁺was embedded into the material to participate in the reaction.