Week 5 Challenge

1)

Incorrect, batteries are not a better choice in the given driving scenario to explain whether batteries are a better power source choice than supercapacitors for aggressive drivers who accelerate and brake rapidly.

• An aggressive driver accelerates quickly and brakes hard
• To meet this condition, instantaneous high power is required
• Batteries have a lower specific capacity than supercapacitors
• For such short-term instant high power, adding battery packs is not effective
• However, the specific capacity of a supercapacitor is ten times that of a battery, and the specific capacity is about 10 kW/kg
• The sudden load can meet the rapid acceleration and sudden braking, which will generate a large regenerative current. This current can be used to charge the battery, but it is not used efficiently.

2)

• Lead acid batteries can be used in IC engine vehicles to supply the auxillary 12V system load and in emergency lighting because of low energy density, simple construction and stable operation
• Nickel cadmium batteries has less cell voltage and little higher energy density than lead acid hence it is can be used in toy cars, calcul
• Nickel Metal Hydride batteries can be used in wide electronic devices because of high energy density. Voltage is less hence it is sufficient to power electronic devices such as computers, cellular phone
• Lithium - ion batteries have high energy density and high cell voltage. Lithium is also light in weight and hence it can be used in Battery Electric Vehicle, Smartphones, Laptop

3)

• Lead acid, nickel cadmium, lithium titanate, lithium manganate and lithium cobalt oxide have lower power densities. Therefore, they can be used in low power applications
• NiMH batteries have a higher power density than other batteries, so they can be used in HEVs and portable power tools that require high power
• Lithium nickel manganese cobalt batteries have a higher power density compared to other batteries except nickel metal hydride batteries. Therefore, it is used in systems with high power and high energy requirements
• The power density of supercapacitors is much higher than that of any other energy storage cell, and the power density is ten times higher than that of lithium-ion batteries, which can provide power at peak loads without stress.

4)

True

• During discharge, lithium ions from the -ve anode pass through the electrolyte and intercalate in the +ve cathode.
• During charging, electrons in the external circuit move from the anode to the cathode.
• Electrons flow to balance the battery voltage. In an electrochemical process, the anode is -ve and the cathode is +ve.
• During the first charge, lithium ions from the cathode bind to the anode and form an inseparable layer on the anode.
• A solid electrolyte interface (SEI) forms at the anode. If the anode comes into contact with the electrolyte, it breaks down. SEI protects the anode.