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

Solution:-

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 separator. 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 (cell phone, computer, etc.) to the negative current collector. The separator blocks the flow of electrons inside the battery.

CHARGE/DISCHARGE

While the battery is discharging and providing an electric current, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device, the opposite happens: Lithium ions are released by the cathode and received by the anode.

Working:- Instead of Oxidation and reduction, transport pf Li^+ ions from one electrode to another electrode through electrolyte by the transport of electrons through external circuit

The LiCoO_2 is coated with aluminium current collector and the graphite is coated with copper current collector to ease the flow of electrons.

The separator only allows the lithium ions to pass through it, but doesn’t allows electrons to pass. The electrons then moves through the external circuit and travel back to the lithium ions from which its was separated. The separator in the lithium-ion cell is to electrically isolate the positive and negative electrodes to avoid self-discharge of the cell and short circuit. The separator is often made from fibre, glass mat or polymer

While the battery is discharging and providing an electric current, the anode releases lithium ions to the cathode, generating a flow of electrons from one side to the other. When plugging in the device, the opposite happens

Sr. no	Battery type	Cathode	Anode	Reaction at Cathode	Reaction at Anode	Cell Reaction
1	Lithium Cobalt Oxide (LCO)	`LiCoO_2`	`LiC_6`	`Li_(1-x)CoO_2 + xLi^+ + xe^(-) to LiCoO_2`	`Li_xC_6 to xLi^+ + xe^(-) + C_6`	`C_6 + LiCoO_2 leftrightarrow LiC_6 + CoO_2`
2	Lithium Manganese Oxide (LMO)	`LiMn_2O_4`	`LiC_6`	`Li_(1-x)Mn_2O_4 + xLi^+ + xe^(-) to LiMn_2O_4`	`Li_xC_6 to xLi^+ + xe^(-) + C_6`	`C_6 + LiMn_2O_4 leftrightarrow LiC_6 + Mn_2O_4`
3	Lithium Nickel Cobalt Aluminium Oxide (NCA))	`LiNiCoAlO_2`	`LiC_6`	`Li_(1-x)NiCoAlO_2 + xLi^+ + xe^(-) to LiNiCoAlO_2`	`Li_xC_6 to xLi^+ + xe^(-) + C_6`	`C_6 + LiNiCoAlO_2 leftrightarrow LiC_6 + NiCoAlO_2`
4	Lithium Nickel Manganese Cobalt Oxide (NMC)	`LiNi_0.8Mn_0.1Co_0.1O_2`	`LiC_6`	`Li_(1-x)Ni_0.8Mn_0.1Co_0.1O_2 + xLi^+ + xe^(-) to LiNi_0.8Mn_0.1Co_0.1O_2`	`Li_xC_6 to xLi^+ + xe^(-) + C_6`	`C_6 + LiNi_0.8Mn_0.1Co_0.1O_2 leftrightarrow LiC_6 + Ni_0.8Mn_0.1Co_0.1O_2`
5	Lithium Iron Phosphate (LFP)	`LiFePO_4`	`LiC_6`	`Li_(1-x)FePO_4 + xLi^+ + xe^(-) to LiFePO_4`	`Li_xC_6 to xLi^+ + xe^(-) + C_6`	`C_6 + LiFePO_4 leftrightarrow LiC_6 + FePO_4`
6	Lithium Titanium Oxide (LTO)	`LiMn_2O_4`	`Li_4Ti_5O_12`	`4Li_(1-x)Mn_2O_4 + 4Li^+ + 4e^(-) to 4LiMn_2O_4`	`Li_4Ti_5O_(12) to Ti_5O_12 + 4Li^+ + 4e^(-)`	`Li_4Ti_5O_12 + 4Mn_2O_4 leftrightarrow 4LiMn_2O_4 + Ti_5O_12`

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

Solution:- Lithium-ion batteries are used in most aspects of our everyday lives. Most devices like smartphones and laptops cannot operate without these batteries. Lithium-ion batteries have also become very important in the field of electromobility as it is now the battery of choice in most electric vehicles. Its high specific energy gives it an advantage over other batteries.

There are different types of lithium-ion batteries and the main difference between them lies in their cathode materials. Different kinds of lithium-ion batteries offer different features, with trade-offs between specific power, specific energy, safety, lifespan, cost, and performance.

The six lithium-ion battery types that we will be comparing are Lithium Cobalt Oxide, Lithium Manganese Oxide, Lithium Nickel Manganese Cobalt Oxide, Lithium Iron Phosphate, Lithium Nickel Cobalt Aluminum Oxide, and Lithium Titanate. Firstly, an understanding of the key terms below will allow for a simpler and easier comparison.

Specific energy: This defines the battery capacity in weight (Wh/kg). The capacity relates to the runtime. Products requiring long runtimes at moderate load are optimized for high specific energy.

Specific power: It's the ability to deliver high current and indicates loading capability. Batteries for power tools are made for high specific power and come with reduced specific energy.

A high specific power usually comes with a reduced specific energy and vice versa. The pouring of a bottled water in a glass is a perfect analogy of the relationship between specific power and specific energy.The water in the bottle can be thought of as specific energy. Pouring the water at a slow rate doesn’t provide enough force (low specific power) but the water lasts longer in the bottle (high specific energy). On the other hand, if we pour the water out at a faster rate it provides a greater impact (high specific power). However, the water wouldn’t last very long in the bottle ( low specific energy).

Performance: This measures how well the battery works over a wide range of temperature. Most batteries are sensitive to heat and cold and require climate control. Heat reduces the life, and cold lowers the performance temporarily.

Lifespan: This reflects cycle life and longevity and is related to factors such as temperature, depth of discharge and load. Hot climates accelerate capacity loss. Cobalt blended lithium ion also usually have a graphite anode that limits the cycle life.

Safety: This relates to factors such as the thermal stability of the materials used in the batteries. The materials should have the ability to sustain high temperatures before becoming unstable. Instability can lead to thermal runaway in which flaming gases are vented. Fully charging the battery and keeping it beyond the designated age reduces safety.

Cost: Demand for electric vehicles has generally been lower than anticipated and this is mainly due to the cost of lithium-ion batteries. Hence cost is a huge factor when selecting the type of lithium-ion battery.

Comparison

Lithium Cobalt Oxide has a high specific energy as compared to the other batteries which makes it the preferred choice for laptops and mobile phones. It also has a low cost and a moderate performance. However, it is highly unfavourable in all the other aspects when compared to the other lithium-ion batteries. It has a low specific power, low safety, and a low lifespan.

Lithium Manganese Oxide has a moderate specific power, moderate specific energy, and a moderate level of safety when compared to the other types of lithium-ion batteries. It has the added advantage of a low cost. The downsides are its low performance and low lifespan. It is usually used in medical devices and power tools.

Lithium Nickel Manganese Cobalt Oxide has two major advantages as compared to the other batteries. The first one is its high specific energy which makes it desirable in electric powertrains, electric vehicles and electric bikes. The other is its low cost. It is moderate in terms of specific power, safety, lifespan and performance when compared to the other lithium-ion batteries. It can be optimised to either have a high specific power or a high specific energy.

Lithium Iron Phosphate only has one major disadvantage when compared to other types of lithium-ion batteries and that is its low specific energy. Other than that, it has a moderate to high rating in all the other characteristics. It has high specific power, offers a high level of safety, has a high lifespan and comes at a low cost. The performance of this battery is also moderate. It is often employed in electric motorcycles and other applications that require a long lifespan and high level of safety.

Lithium Nickel Cobalt Aluminum Oxide only offers one strong advantage and that is a high specific energy. Apart from this, it doesn’t really offer much as compared to the five other batteries. It provides a low level of safety as compared to the other batteries. It is also pretty moderate in the rest of the characteristics like performance, cost, specific power and lifespan. Its high specific energy and moderate lifespan makes it a good candidate for electric powertrains.

Lithium Titanate offers high safety, high performance and a high lifespan which are very important features every battery should have. Its specific energy is low compared to the five other lithium-ion batteries but it compensates for this with a moderate specific power. The only major disadvantage of lithium titanate as compared to the other lithium-ion batteries is its extremely high cost. Another important feature of this battery worthy of mention is its remarkably fast recharge time. It can be used for storing solar energy and creating smart grids.

Much work is still being done on lithium ion batteries in various laboratories. Lithium vanadium phosphate (LVP) battery is a proposed type of lithium-ion battery that uses a vanadium phosphate in the cathode. It has already made its way into the Subaru prototype G4e, doubling energy density.