Challenge

Week 5 Challenge

1. The given statement is TRUE.

UltraCapacitor is specifically used to supply and absorb the transients of the vehicle dynamics.
UC is a high power density and low energy density ESS where there is rapid charging and discharging.
In Other energy storage systems (ESS) like Li-ion batteries there will be chemical reactions taking place while charging and discharging,this is the reason why they cannot charge and discharge quickly. Unlike other batteries, in UC charge is accumulated on the electrodes which facilitates fast charging and discharging.
In quick acceleration the power required is very high in a short span of time so UC can discharge quickly, while quick deceleration where vehicle at high speed comes to Zero speed or lower speed in less time so the kinetic energy available from the vehicle is high which needs to harnessed using regenerative braking in this UC can be charged quickly harnessing most of the regenrative energy.

2,3.

Average value taken

In above plot red colour plot is Power density and blue colour plot is Energy density.

Cell voltages of NiMH and NiCd are low (1.2V) compared to other batteries and highest is for LiC of 3.6V.
So for a given capacity of battery weight of lithium battery is lower than Nickel batteries as cells required will be more.
UltraCapacitor is high power and lower energy device, which makes it suitable for transient condition of the vehicle power requirement.
Lead Acid battery has lower energy density compared other electrochemical batteries.
Lithium ion battery has high energy density and moderately high power density, which is the reason why it is used extensively is pure electric vehicles.

Given statement is TRUE.

In a li-ion battery.
negative electrode- graphite
positive electrode- Lithium cobalt oxide.
graphite do not have any li-ions at initially as it is pure graphite where there gaps between atoms of graphite to accommodate lithium ions.
Where as in positive electrode lithium ions are itercated between carbon atoms.
When it is connected for charging due to the potential difference across the electrode the positive electrodes give up positively charged lithium ions which travel through the electrolyte to the negative electrode and enters the space between carbon atoms in graphite.

Ship work like this
in your own course.