Week 1 Understanding Different Battery Chemistry

Battery:

A battery is a device which converts chemical energy contained within its active materials directly into electrical energy by means of electrochemical Oxidation-Reduction (Redox) reaction. This type of reaction involves the transfer of eectrons from one material to another via an electric circuit. It consisting of one or more electrochemical cells with external connections for powering electrical devices such as flashlights, mobile phones, and electric cars. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the anode.

Types of Batteries:

Batteries are basically two types:

• Primary Batteries (Non-Rechargeable Batteries): These are known as one time used batteries, because they can not rechargeable.

• Secondary Batteries (Rechargeable Batteries): These are known as reusable batteries, because they can rechargeable.

During discharge the electrons flow from anode to cathode i.e.; the flow of current is from cathode to anode. Vice-versa during charging.

Lithium-ion Battery:

Lithium-ion is named for its active materials; the words are either written in full or shortened by their chemical symbols. A series of letters and numbers strung together can be hard to remember and even harder to pronounce, and battery chemistries are also identified in abbreviated letters.

Types of Lithium ion Battery Technologies:

• Lithium Cobalt Oxide (LCO)
• Lithium Manganies Oxide (LMO)
• Lithium Nickel Cobalt Aluminium (NCA)
• Nickel Manganies Cobalt (NMC)
• Lithium Titanite (LTO)
• Lithium Iron Phospate (LFP)

Chemical Reactions of Li-ion Cells:

LCO:

Anode Reaction (Discharge): `Li^(+)C_6 rightarrow xLi^(+)+C_6+xe^-`

Cathode Reaction (Discharge): `Li_(1-x) +CoO_2+xLi+xe^(-) rightarrowLiCoO_2`

Overal Reaction: `C_6+LiCoO_2 Leftrightarrow Li_xC_6+Li_(1-x) CoO_2`

LMO:

Anode Reaction (Discharge): `Li^(+)C_6 rightarrow xLi^(+)+C_6+xe^-`

Cathode Reaction (Discharge):  `Li_(1-x) +Mn_2O_4+xLi+xe^(-) rightarrow LiMnO_2`

Overal Reaction: `LiC_6+Mn_2O_4 Leftrightarrow C_6 + LiMnO_2`

NMC: 

Anode Reaction (Discharge): `Li^(+)C_6 rightarrow xLi^(+)+C_6+xe^-`

Cathode Reaction (Discharge): `Li_(1-x) +MO_2+xLi^(+) +xe^(_) rightarrow LiMO_2`

Overal Reaction: `Li_(1-x) +MO_2+LiC_6 Leftrightarrow Li_(1-x) MO_2+C_6`

LFP:

Anode Reaction (Discharge): `Li^(+)C_6 rightarrow xLi^(+)+C_6+xe^-`

Cathode Reaction (Discharge): `LiFe_3PO_4+xLi^(+) +xe^(+) rightarrow LiFe_2 PO_4`

Overal Reaction: `LiFePO_4 +6C Leftrightarrow LiC_6+FePO_4`

NCA:

Anode Reaction (Discharge): `Li^(+)C_6 rightarrow xLi^(+)+C_6+xe^-`

Cathode Reaction (Discharge): `Li_(1-x) +MO_2+xLi^(+) +xe^(_) rightarrow LiMO_2`

Overal Reaction: `Li_(1-x) MO_2+LiC_6 Leftrightarrow Li_(1-x) MO_2+ C_6`

LTO:

Anode Reaction (Discharge): `Li^(+)C_6 rightarrow xLi^(+)+C_6+xe^-`

Cathode Reaction (Discharge):  `4Mn_2O_4 +4Li^(+) + 4e^(_) rightarrow 4LiMn_2O_4`

Overal Reaction: `Li_4Ti_5 O_2+4Mn_2O_4 Leftrightarrow 4LiMn_2O_4 +Ti_5O_12`

                                                     Typical specific energy of lead-, nickel-and lithium-based batteries

Li-aluminum (NCA) is the clear winner by storing more capacity than other systems, this only applies to specific energy. In terms of specific power and thermal stability, Li-manganese (LMO) and Li-phosphate (LFP) are superior. Li-titanate (LTO) may have low capacity but this chemistry outlives most other batteries in terms of life span and also has the best cold temperature performance. Moving towards the electric powertrain, safety and cycle life will gain dominance over capacity. (LCO stands for Li-cobalt, the original Li-ion.)

 Structure of Lithium ion Batteries:

Reference:

• https://batteryuniversity.com/