Week 1 Understanding Different Battery Chemistry

Lithium cobalt oxide (LCO)

These kind of batteries have high specific energy but low specific power. This means that they do not perform well in high-load applications, but they can deliver power over a long period.

The cathode has a layered structure in which.During discharge the lithium ions move from anode to cathode on charge the flow is from cathode to anode.

At the anode,lithium is oxidised,lithium ions are released from the carbon,along with electrons

LiC6== xLi+Xe +C6

At the cathode the lithium ions are absorded by the lithium dioxide,and the electrode is reduced as it also recieves.

Li1-xCo2+xLi+xe ==LiCoO2

Overall reaction

C6+LiCo2==LixC6+Li1-xCoO2

2.LMO : Lithium maganese oxide

These kind of Batteries use lithium manganese oxide as the cathode material. This chemistry creates a three-dimensional structure that improves ion flow, lowers internal resistance, and increases current handling while improving thermal stability and safety.

The architecture of the three dimensional spinel structure that improves ion flow on the electrodes,which results in the lower internal resistance and improved current handling.A further advantege is high thermal stability and enhanced safety,but the cycle and the calender life are limited.

Low internal resistance enables fast charging and high current discharging in a 18650 package.Li-manganese can be discharged currents of 20-30 A with moderate heat build up.It is also possible to apply one second load pulses of upto 50A.A continous high load at this current will cause heat buildup and the cell temperature cannot exceed 80C.Li-Mg is used for power tools,medical instruments as well has hybrid and electric vehicles.

During discharge

At the anode,Lithium is oxidised.Lithium ions are released from the carbon,along with electrons

LiC6==xLi+xe +C6

At the cathode,Lithium ions are absorbed by the lithium dioxide and the electrode is reduced as it also recieves the electrons from the circuit

Li1-xMn2O4+xLi ++xe==LiMnO2

The overall reaction is :

LiC6+Mn2O4==C6+LiMnO2

3.NCA : Nickiel cobalt aluminium oxide

These kind of batteries combine the benefits of the three main elements used in the cathode: nickel, manganese, and cobalt. Nickel on its own has high specific energy but is not stable. Manganese is exceptionally stable but has a low specific energy. Combining them yields a stable chemistry with a high specific energy.

High energy and power density as well has good life span make NCA a candidate for Ev powertrains high cost and marginal safety and negatives.

During discharge

At anode,Lithium is oxidised,Li-ions are oxidised from the carbons along with electrons

LiC6==xLi++xe-+C6

At cathode,Li-ions are absorbed by the lithium dioxide and the electrode is reduced has it recieves

Li1-xMnO2+xLi+xe==LiMnO2

overall reaction

Li1=xMnO2+LiC6==Li1-xMnO2+C6

4.NMC : Nickiel manganese cobalt oxide

These kind of batteries offer high specific energy with decent specific power and a long lifecycle. This means they can deliver a relatively high amount of current for extended periods.

one of the most successful Li-Ion system is the LiMn And Co combination.Similar to Lithium Manganese,these systems can be tailored to serve 4000Mah and higher but at reduced loading capability and shorter life cycle,Silicon added to graphite had the drawback that the anode grows and shrinks with charge and discharge,making the cell mechnically unstable.The secret of NMC lies in nickel and manganese.An anology of this table salt in which the main ingrediets sodium and chloride are toxic on their own but mixing serves as seasoning salt and food preserver.Nickel is known for its high specific energy but poor stability,manganese has benifits of forming a spinel structure to achieve low internal resistance but offers low specific energy.Combination of metal enhaces each other stability.

During discharge

At the anode lithium is oxidised,Lithium ions are released from the carbon along with eectrons

LiC6==xLi++xe-+C6

At the cathode,Li ions are absorbed by the Lithiumdioxide,and the electrode is reduced as it also recieves the electrons form the circuit

Li-xMnO2+LiC6==LiMnO2

overall reaction

Li1-xMO2+LiC6==Li1-xMO2+C6

5.LFP :

These kind of Batteries use phosphate as the cathode material and a graphitic carbon electrode as the anode. LFP batteries have a long life cycle with good thermal stability and electrochemical performance.

The cell has high discahrge rate and because phospate(PO) can cope with high temperature ,The battery has good thermal stability,improving its safety.This makes it a good choice for things like electric vehicel and power tools and for storing energy at power stations it also has a long cycle life meaning it can be discharged and charged many times.However it has a lower energy density than a lithium cobalt cell and higher self discharge rate.A lithium orin phospate battery cell is similar to lithium cobalt oxide cell.The anode is still graphite and electrolyte is also much the same.The differemces is that the llithium cobalt dioxide cathode has been replaced with more stable lithium iron.

During discharge

At anode,lithium is oxidised,lithium ions are released from the carbon along with electrons

LiC6==xLi++xe+C6

At cathode,lithium ions are absorbed by the lithiumdioxide and the electrodes is reduceded as it also recieves the electrons from the circuit

FePo4+Li+e==LiFePo4

overall reaction

LiFePo4+6C==LiC6+FePo4

6.LTO :Lithium Titanium Oxide

All of the previous lithium battery types we have discussed are unique in the chemical makeup of the cathode material. Lithium titanate (LTO) batteries replace the graphite in the anode with lithium titanate and use LMO or NMC as the cathode chemistry.The result is an extremely safe battery with a long lifespan that charges faster than any other lithium battery type.

During discharge :

At the anode,Lithium is oxidised,Li ions are released from the carbon along with electrons

Li4Ti5O12==Ti5O12+4Li+4e

At the cathode,lithium ions are absorded by the lithium dioxide and the electrode is reduced as it also recieves the electrons from the circuit

4Mn2O4+4Li+4e=4LiMn2O4

overall reaction

Li4Ti5O12+4Mn2O4==4LiMn2O4+Ti5O12