Week 5 Challenge

Ans 1).

The statement above is false

because considering the simple fact that Uc has high power density and batteries have high energy density and batteries cannot provide such sudden peak demand

so in conclusion we can say that ultra capacitors aree best for facing such sudden change in consumption rate as well as the energy generated through regenrative braking can be stored more fast in comparisin to any other batteries or energy storage device as of now .

on the down side if we consider such a battery which can meet such sudden power demand than it will be a lot costlier to design such a power pack

ans 2 & 3).

• Lead acid battery
• Nickel cadmium battery
• Nickel Metal hydride battery
• Lithium ion (specify chemistry) battery
• Ultra Capacitor

Lithium-ion: There are many types of lithium ion battery. They are mainly classified on the basis of cathode material used cause anode remains same in all the cases. In plot we have shown the average energy density of it. Now li-ion is widely used in EVs, mobile phones and many more applications. They rule the above plot, cause they have high energy density and high cell voltage as well amongst all.

Lead-acid: LA batteries has low energy density as compared to NiMH and NiCd but cell voltage value is high. Lead–acid batteries are used in emergency lighting and to power sump pumps in case of power failure. They were the first choice of energy in BEV. But now they have been replaced by other batteries cause they require frequent maintenance.

Ultracapacitor: It can be seen that UC can't be used for high energy demanding applications. Its voltage is greater than that of Lead acid NiCd and NiMH. They are widely used in Electric or hybrid vehicles - to provide a quick burst of acceleration over short distances, or to start the main motor.

NiMH & NiCd: Nickel metal hydride and Nickel cadmium have almost similar cell voltage value but energy density of NiMH is very high than NiCd. NiMH batteries are highly recommend in applications that call for long duration but not a high amp load. Nicd are best suitable for portable power application.

plot of Energy density Vs. cell voltage is shown below:

ans 4).

the statement is true

because as we know from the battery chemistry the positive electrode (cathode) loses the electron and this electron travels to the anode as a reverse voltage is apllied to the battery. We shold remember that in almost all the electronics devices cathode is -ive and anode is +ive but battery being the active material has cathode termed as +ive and anode as negative. Thats why behaviour of electrodes in batteries is explained in two ways i.e while charging and discharging. Below fig represents what has been theoretically said.

the charge and discharge process in a battery is illustrated in below image