LiIonBattery(LIB)-WelcometoCatalysisDatabase：锂离子电池(LIB)-欢迎催化数据库课件

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Li Ion Battery(LIB),K.Devaki,(CH09M001),Li Ion Battery(LIB)K.Devaki,Battery:Transducer which converts chemical energy into electrical energy and vive versa.,Chemical reactions:Oxidation and reduction,Free energy change of the processes appears as electrical energy.,Primary battery-not rechargeable,Secondary battery-rechargeable,Battery,Battery:Transducer which conv,Why Li-Ion Battery?,Why Li-Ion Battery?,Lead acid battery,Appealing to industrial applications due to,Reliable,Inexpensive,Disadvantages,Low life cycle,Low energy density,(30 40 Wh/Kg),Ni metal hydride battery,Appealing to hybrid electric vehicle applications due to,Rechargeable,No memory effect,High power density,High energy density,Currently available battery capacity:1.5 kWh,Disadvantages,Self discharge rates,Lead acid batteryAppealing to,Recharge-ability,:,Basically,when the direction of electron discharge(negative to positive)is reversed,restoring power.,Memory Effect,:,When a battery is repeatedly recharged before it has discharged more than half of its power,it will“forget”its original power capacity.,Cadmium crystals have the memory effect(NiCd),Recharge-ability:Basically,J.Mater.Chem.,19(2009)5871,Schematic of Li ion battery,Schematic of Li Ion Battery,The cathode half reaction(with charging being forwards)is:,LiCoO,2,Li,1-x,CoO,2,+xLi,+,+xe,-,The anode half reaction is:,xLi,+,+xe,-,+6C Li,x,C,6,J.Mater.Chem.,19(2009)587,Contains an anode,a cathode,an electrolyte and separator.,Harnesses a set of reversible oxidation/reduction reactions.,Li ion dissolved by a discharge reaction and returns to metallic lithium by a charging reaction,Electrolyte provides for the separation of Li ions and electron transport.,In a perfect battery the Li ion transport number will be unity.,Cell potential is determined by G=-EF,The electrode system must be both a good ionic and an electronic conductor.,It is necessary to add an electronically conductive material such as carbon black.,To hold the electrode together,a binder is also needed.,Li Ion Battery,Contains an anode,a cathode,Advantages,Li has greatest,electrochemical potential,Lighter than others,Shape and size variation,High open circuit voltage,No memory effect,Low discharge rate 5-10%.,Disadvantages,Internal resistance of lithium ion battery is high as compared to other batteries.,Due to overcharging and high temperature capacity will diminish.,Advantages Li has greatest Dis,Existing Li-Ion Electrodes,Graphite 370 mA.h/g,LiCoO,2,140 mA.h/g,Graphite 370 mA.h/gLiCoO2 1,LiIonBattery(LIB)-WelcometoCatalysisDatabase：锂离子电池(LIB)-欢迎催化数据库课件,The development of materials for LIB centres around,“intercalation”,and suitable electrolyte with appropriate,“potential window”.,Intercalation is an equilibrium process and governed by the free energy considerations.,Entropy factor may predominate over the enthalpy factor.,The lattice in which intercalation takes place should be capable of interacting electronically without affecting the translational entropy of the intercalant.,The value of the equilibrium constant of the intercalation and deintercalation reaction should be near 1.,Intercalation,The development of materials f,Should be completely reversible.,Should be geometrically and electronically fitting to the inter planar spacing.,Should be capable of electron exchange.,Other substrates like mesoporous carbon and other pillared materials can also be considered.,Intercalation,Should be completely reversib,The selection of the electrolyte depends on the potential window.,Potentials are beyond water potential and hence non aqueous electrolyte.,It should not reactive with Li,+,ions,since it will decide the transport of the Li,+,ions for the intercalation reaction.,The electrolyte solution commonly comprises a lithium salt dissolved in a mixture of organic solvents.,Examples include,LiPF,6,or LiBOB,(the BOB is the anion with the boron coordinated by two oxalate groups)in an ethylene carbonate/dimethyl carbonate solvent.,Electrolyte,LiIonBattery(LIB)-WelcometoCatalysisDatabase：锂离子电池(LIB)-欢迎催化数据库课件,Graphite is commonly selected anode material in LIB due to its,High coulombic efficiency.,However,the specific capacity of graphite is relatively low,(theoretical value:372mA.h/g),since every six carbon atoms can host only one lithium ion by forming an intercalation compound,(LiC6).,Sn:993 mA.h/g,Si:4200 mA.h/g)than graphite via the formation of alloys with lithium or through the reversible reactions with lithium ions.,Drawback of these substances as anode materials is the huge,volume variation during the charge/discharge process,which causes the pulverization of the electrode,resulting in poor reversibility.,Graphite,LiIonBattery(LIB)-WelcometoCatalysisDatabase：锂离子电池(LIB)-欢迎催化数据库课件,Reducing the size of these materials to,nanometer scale,can partially suppress the expansion and shrinkage of the anode,materials.,B