Week 1 Understanding Different Battery Chemistry

1) Prepare a table which includes materials & chemical reactions occurring at the anode and cathode of LCO, LMO, NCA, NMC, LFP and LTO type of lithium ion cells.Give your detailed explanation on it.

• Lithium ion batteries can be designed for optimal capacity with the drawback of limited loading, slow charging and reduced longiveity. An industrial battery may have a moderate amphere rating but the focus is on durability. Specific energy only provides part of battery performance. 
• Before looking into the materials and chemical reactions of different types of lithium ion batteries. A battery is made up of an anode, cathode, separator, electrolyte and two current collectors (Positive and negative). The anode and cathode store the lithium.
• The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa through the seperator. The movement of the lithium ions creates free electrons in the anode which creates a charge at the positive current collector. The electrical current then flows from the current collector through a device being powered to the negative current collector. The seperator blocks the flow of electrons inside the battery.

• The 6 commonly used lithium ion batteries are listed below.

  • Lithium cobalt oxide (LiCoO2) - LCO.
  • Lithium Manganese oxide (LiMn2O4) - LMO.
  • Lithium Nickel Manganese cobalt oxide (liNiMnCoO2) - NMC.
  • Lithium Iron phosphate (LiFePO4) - LFP.
  • Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2) - NCA.
  • Lithium Titanate (Li2TiO3) - LTO.

  Each Lithium ion batteries provides different characteristics and are used in different applications accordingly.  

• Lithium cobalt oxide (LCO) battery was invented in the year 1991. Its anode material is LiaC6, the cathode material is LibCoO2 and the carrier is Li+. It is used in various applications ranging from electronic devices to all laptops and phone batteries. The majority of lithium ion batteries for portable devices are cobalt based. The system contains a cobalt oxide cathode (positive electrode) and graphite carbon anode (negative electrode).

                  Co+LiCoO2 Li, Co+ LiCoO2

• Lithium ion manganese oxide battety (LMO) is a lithium ion cell that uses manganese dioxide MnO2 as a cathode material. They function through the same intercalation/ de-intercalation mechanism as other commercilized secondary battery technologies such as LiCoO2. Cathodes based on manganese oxide components are earth - abundant, inexpensive, non - toxic and provide better thermal stability.

                    MnO2 + Li + +e--->LiMnO4 

• Lithium Nickel cobalt aluminium oxides (NCA) battery has been around since 1999 for special applications. It shares similarities with NMC by offering high specific energy, reasonably good specific power and a long life span. 

Li-MO₂+ LiCn Entladung

LIMO₂+nC

• Lithium Nickel Manganese Cobalt Oxide (NMC) battery offer a combination a nickel, Manganese and cobalt. They are sometimes known as Lithium Manganese Cobalt oxide batteries. NMC batteries have a high specific energy or power. 

LiCoO1/2LiCoO, +1/6Co,O,+1/60 Li-NiO(1-2)LINIO,+LINI-O, (x <0.5)

Lia-NIO Li-N-[Ni4-2/319-4/3+ (2x-1)/30 (x>05)

LiNiO(21)Li-/2-Ni/2-10+1/20

• Lithium iron phosphate battery (LiFeO4) batteries which is known as Li - phosphate batteries as well. They use phosphate as cathode material. In addition they benefit from the low resistance properties that enchance their thermal stability and safety. 

                        LiFePO4 + 6C LIC + FePO4

• Lithium Titanate oxide (LTO) batteries is a type of rechargable battery which has the advantage of being faster to charge than other lithium ion batteries but its disadvantage of having a much lower energy density.

                  LiTiO2 + 3Li + 3e→ LiTi5O12,

                   Liz TiO₁₂+2Li+ + 2e → LisTi5O12

2) Compare the differences between each type of Li+ion batteries based on their characteristics

            The Major 6 types of lithium ion batteries was discussed early, Now the major differences in the characteristics can be found when choosing a battery. The major things that can be differenciated from one another.

• Nominal voltage : It is the system voltage at which the device is designed to operate. The rated voltage is usually higher than the nominal voltage to ensure the safe operation of the device.
• Cycle : The charge and discharge when took place for a single time makes a cycle. The higher the cycles can take place, the higher the cycles can takes place then the lifespan is higher.
• Thermal runway : The thermal runway begins when the heat generated within a battery exceeds the amount of heat that is dissipated to its surroundings.Internal battery temperature will continue to rise, causing the battery current to rise creating a domino effect. The rise in temperature in a single battery will begin to affect other batteries nearby and the pattern will continue.
• Specific energy : It is the amount of energy stored per unit mass (Wh/Kg). This is a very important deciding factor that decides how much energy or power from different batteries with the same amount of weight.

Specific energy of different types of lithium based batteries :

The main differences between the lithium ion batteries can be differentiated on the characteristics.

• Nominal Voltage : Most of the batteries are very close when it comes to characteristics. LMO (3.7) has the highest range and LTO (2.4) has the lowest range in volts.
• Cycle life : They differ by a significant amount from each other. LTO battery has the longest life cycle so that it can last longer period of time and it is exactly opposite for the LMO type batteries.
• Charge current rate : Higher the charge current, the less time the battery will take to get fully charged. LTO and LTP are highest NCA comes close to its condenders.
• Discharge current rate : If we need higher discharge rates and faster charging times we should choose a high rated battery instead. LTO has a discharge rate 10 times higher than the others and it t=is one of the safest batteries.
• Thermal runaway : A thermal runaway occurs in situations where an increase in temperature changes the conditions in a way that causes increase in temperature often leading a destructive result. LTO has the highest temperature rating in this and NCA and LCP has its lowest.
• Specific energy : The specific energy density can be calculated by integrating from 0 to t_cutoff. We can obtain the specific energy density in Wh Kg^-1. Lithium ion with cobalt cathodes offer the highest energy densities. This types of applications are cell phones, laptops and digital cameras. Power density indicates how much power a battery can deliver on demand.

For ease of choosing a battery from laymans perspective, the 6 key features are given a value within 0-5 range for all of the, are given with the same parameters which are considered in case of 5 point hexagonal analysis of the batteries. They are

1. Specific energy.
2. Specific power.
3. Safety.
4. Performance.
5. Life span.
6. Cost.