li-ion battery introduction锂离子电池介绍-新.ppt

Li-ion Battery Chemical Capacity/Energy Qmax： Amount of charge can be extracted from the fully charged cell to the end of discharge voltage (EDV). Battery chemical capacity (no load) In Unit of: Ah/kg, Ah/l, Wh/kg, Wh/l /l, /kg -- protable equipments(phone, pad, etc.), ploymer Li-ion Battery Ah, Wh-- comparing different battery with same chemical materials in Ah, but Wh for different chemical battery. Fig. x Voltage profile during low-rate discharge of battery Page ? * Li-ion Battery Battery Impedance Battery Impedance：dV=I*R, after transient process Nyquist plot: Voltage responses on current of different frequency A1:1ms.high frequency，imaginary part=0，real part=min，pure impedance A2:~1ms.passivating layer(hinder the reactions)，geometric capacitance(passivating lay inserted)+inpedance(slowed charge transfer), parallel，semicircle A3:10~200ms. same situation on electrode boundary, elongared semicircle, overlap with A2 A4:2~5Hz. active material distribute, electrolyte in pores decrease, =impedance↑, stretching real value of A2,3,5 A5:0.5~1s A6:1000s Relaxation time Page ? * Li-ion battery Battery Impedance Battery Impedance：dV=I*R, after transient process Nyquist plot: Voltage responses on current of different frequency A1:1ms. A2:~1ms. A3:10~200ms. A4:200~500ms A5:0.5~1s.suface effects finished，diffusion effects take over, increasing both real and imaginary parts of impedance equally. But deviations happens due to non- homogeneous particle size and shapes. A6:1000s.real sesistance stop increasing， IR drop constant，DC resistance. Relaxation time Page ? * Battery Impedance：dV=I*R, after transient process Nyquist plot: Voltage responses on current of different frequency 40mΩ 60~70mΩ 100mΩ A1 A2 A3 A4 A5 A6 1ms. ~1ms.