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

ANS:

Batery

Batteries are a collection of one or more cells whose chemical reactions create a flow of electrons in a circuit. All batteries are made up of three basic components: an anode (the '-' side), a cathode (the '+' side), and some kind of electrolyte (a substance that chemically reacts with the anode and cathode).

When the anode and cathode of a battery is connected to a circuit, a chemical reaction takes place between the anode and the electrolyte. This reaction causes electrons to flow through the circuit and back into the cathode where another chemical reaction takes place. When the material in the cathode or anode is consumed or no longer able to be used in the reaction, the battery is unable to produce electricity. At that point, your battery is "dead."

Types of Battery:

1. Primary Cells: These types of batteries are basically considered as Non-rechargeable batteries because they can be used only once. These                                             batteries cannot be recharged and used again. 

2. Secondary Cells : These types of batteries are generally called as Rechargable batteries which can be recharged and can be reused. Though the                                          cost is high, but they can be recharged and reused and can have a huge life span when properly used and safely charged.

Types of Rechargable Batteries:

• Lead-Acid Batteries
• Nickel-Cadmium (Ni-Cd) Batteries
• Nickel-Metal Hydride (NiMH) Batteries 
• Lithium-Ion Batteries

Lithium-Ion (Li-ion) Batteries:

Lithium-ion batteries are a type of rechargeable battery in which lithium ions move from the negative electrode (anode) to the positive electrode (cathode) during discharge, and from the cathode to the anode during charge.

lithium-ion battery is composed of 1) the anode and the cathode; 2) a separator between the two electrodes; and 3) an electrolyte that fills the remaining space of the battery. The anode and cathode are capable of storing lithium ions. Energy is stored and released as lithium ions travel between these electrodes through the electrolyte.

Types of LI-ion Batteries:

• Lithium Cobalt Oxide (LiCoO2)- LCO
• Lithium Manganese Oxide (LiMn2O4)- LMO
• Lithium Nickel Manganese Cobalt Oxide (LiNiMnCoO2)- NMC
• Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO2)- NCA
• Lithium Iron Phosphate (LiFePO4)- LFP
• Lithium Titanate (Li2TiO3)- LTO

Comparison Table:

Chemical Reaction:

The reactions at which takes place at anode, cathode and the overall reactions are shown below.

In these equations the discharging denotes Left to right and charging denotes from Right to Left. 

(1)LCO (Lithium Cobalt oxide):

At anode:

  LiC₆ → C₆ + Li⁺ + e^-

At cathode:

CoO₂ + Li⁺ +e^- → LicoO₂

Overall relation:

LicoO₂ + C₆ → LiC₆ +CoO₂

Lithium cobalt oxide (LiCoO2₂) batteries are made from lithium carbonate and cobalt and feature very stable capacities along with high-specific energy, making them a popular choice for use with mobile devices such as smartphones, laptops, and digital cameras.

Internally, they are composed of a cobalt oxide cathode and a carbon graphite anode. During discharge, lithium ions travel from anode to cathode, and the process reverses during the recharging cycle. These batteries do have some drawbacks, including a relatively short life cycle, low thermal stability, and smaller load capabilities—meaning they need frequent recharging.

(2)LMO (Lithium Manganese Oxide):

At anode:

LiC₆ → C₆ + Li⁺ + e^-

 At cathode:

MnO₂ + Li⁺ + e^- → LiMnO₂

Overall relation:

LiMnO₂ + C₆ → LiC₆ + MnO₂

Lithium manganese oxide (MnO₂) batteries actually come in two versions- one with a spinel structure (LiMn₂O₄), which features a cathode 3D framework for the insertion and desertion of Li-ions during the charge and discharge cycle of the battery. The other comes in layered rock-salt structure (Li₂MnO₃) with alternating layers of lithium-ions and lithium/manganese ions on the cathode.

Both offer fast charging and high-current discharging with increased thermal stability over cobalt oxide batteries and provide enhanced safety as a result, making them ideal for medical devices, electric vehicles, and power tools.

(3)NCA (Lithium Nickel Cobalt Aluminium Oxide):

At anode:

LiC₆ → C₆ + Li⁺ + e^-

 At cathode:

NiCoAlO₂ + Li⁺ + e^- → LiNiCoAlO₂

Overall relation:

C₆Li +NiCoAlO₂ →LiCoAlO₂ +C₆

Lithium nickel cobalt aluminum oxide (LiNiCoAlO2) batteries are not conventional in the consumer industry but have promise for EV manufacturers (and other specialized applications), as they provide high-specific energy options, reasonably good specific power, and a decent lifespan.

These types are not as safe as the others listed here and as such, require special safety monitoring measures to be employed for use in EVs. They are also more costly to manufacture, limiting their viability for use in other applications.

(4)NMC (Lithium Nickel Manganese Cobalt oxide):

At anode:

LiC₆ → C₆ + Li⁺ + e^-

 At cathode:

NiMnCoO₂ + Li⁺ + e^- → LiNiMnCoO₂

Overall relation:

LiC₆ + NiMnCoO₂ → LiNiMnCoO₂ + C₆

Lithium nickel manganese cobalt oxide (LiNiMnCoO₂) batteries are made using several different elements commonly found in other Li-ion batteries and use a combination of nickel, manganese, and cobalt for the cathode. While the exact material ratios vary by manufacturer, the common combinations are usually 60% nickel, 20% manganese, and 20% cobalt.

Like the other types, these batteries can have either high-specific energy or high-specific power (not both), but the inclusion of nickel provides the cell with the high-specific energy, although it also has reduced stability.

Manganese, on the other hand, provides low internal resistance but has the drawback of low specific energy. Combining the two, however, enhances each other’s strengths, making them suitable for EV powertrains and cordless power tools.

(5)LFP(Lithium Iron Phosphte):

At anode:

LiC₆ → C₆ + Li⁺ + e^-

 At cathode:

FePo₄ + Li⁺ + e^- → LiFePO₄

Overall relation:

LiC₆ + FePo₄ →  LiFePO4 + C₆  

Lithium iron phosphate (LiFePO₄) batteries use the iron phosphate for the cathode along with a graphite electrode combined with metallic current collector grid for the anode. These batteries are more tolerant at full-charge conditions and are less prone to stress than other Li-ion batteries when subjected to prolonged high voltages.

As a result, these types benefit from low-resistant properties, thereby increasing their safety and thermal abilities, making them ideal for electric motorcycles and vehicles. The only drawback is their low-voltage capacities and offers less energy than other types of Li-ion batteries.

(6)LTO(Lithium Titanium Oxide)

At anode:

Li₂TiO₃ → TiO₂ +Li⁺ + e^-

At cathode:

Mn₂O₄ + Li + e^- → LiMn₂O₄

Overall relation:

Li₂TiO₃ + 2 Mn₂O₄  → 2LiMn₂O₄ + TiO₃

Lithium titanate (LTO) batteries replace the graphite in the anode with lithium-titanate nanocrystals, giving it a larger surface area over carbon, allowing the electrons to enter and exit the anode very quickly. This, in turn, makes it one of the more faster-charging batteries in the Li-ion category.

They do have their disadvantages, however, as they have lower inherent voltage and lower specific-energy ratings over conventional lithium technologies. That being said, they are one of the safer platforms regarding thermal tolerances, making them incredibly safe for use in EVs and e-bikes with possibilities in the military and aerospace industries.

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

ANS:

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 a high current and indicates loading capability. Batteries for power tools are made for high specific power and come with a reduced specific energy.

A high specific power usually comes with reduced specific energy and vice versa. The pouring of 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 temperatures. Most batteries are sensitive to heat and cold and require climate control. Heat reduces life, and cold lowers 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 batteries 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.

Now that we have an understanding of the major battery characteristics, we will use them as the basis for the comparison of our six types of lithium-ion batteries. The characteristics are rated as either high, moderate, or low. The table below provides a simple comparison of the six lithium-ion battery types.

In the following table the six types of lithium-ion batteries are compared relative to one another.

• SP stands for specific power
• SE stands for specific energy
• SF stands for safety
• LS stands for lifespan
• CS stands for cost
• PF stands for performance
• L stands for low
• M stands for moderate
• H stands for high

Summary of the table

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

Lithium Manganese Oxide has 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 optimized to either have high specific power or 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 moderate to high ratings 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 a high level of safety.

Lithium Nickel Cobalt Aluminum Oxide offers one strong advantage as compared to the five other batteries and that is high specific energy. It is pretty moderate in the rest of the characteristics like performance, cost, specific power, and lifespan. The only downside to this battery type is its low level of safety. Its high specific energy and moderate lifespan make 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 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.