Week 1 Understanding Different Battery Chemistry

From Live Session

Introduction

BATTERY:

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).

There are two types of batteries

* Primary batteries are “single use” and cannot be recharged. Dry cells and (most) alkaline batteries are examples of primary batteries.

* The second type is rechargeable and is called a secondary battery. Examples of secondary batteries include nickel-cadmium (NiCd), lead acid, and lithium ion batteries.

Lithium batteries are more popular today than ever before. You’ll find them in your cell phone, laptop computer, cordless power tools, and even electric vehicles. However, just because all of these electronics use lithium batteries doesn’t mean they use the same type of lithium batteries. We’ll take a closer look at the six main types of lithium batteries reveals pros and cons, as well as the best applications for each.

A lithum-ion battery is a type of rechargeable battery composed of cell in which lithium ions move from the negative electrode through an electrolyte to the positive electrode during discharge and back when charging.

* Lithium ion batteries can be desigend for optimal capacity with the drawback of limited loading, slow charging and reduced longivity. An industrial battery may have a moderate amphere rating but focus is on durability

* A battery is made up of an anode, cathode, separator, electrolyte and two current collectors (positive and negative). The anode and cathode storen the lithium.

* The movement of the lithium ions creates free electrons in the anode which creates charge at the positive current collector through a device being powerd to the negative cureant collector. The seperator block the flow of electrons inside the battery.

What is the chemistry involved in lithium-ion batteries?

Inside a lithium-ion battery, oxidation-reduction (Redox) reactions take place.

Reduction takes place at the cathode. There, cobalt oxide combines with lithium ions to form lithium-cobalt oxide (LiCoO₂). The half_reaction is:

CoO₂ + Li⁺ + e^- → LiCoO₂

Oxidation takes place at the anode. There, the graphite intercalation compound LiC₆ forms graphite (C₆) and lithium ions. The half-reaction is:

LiC₆ → C₆ + Li⁺ + e^-

Here is the full reaction (left to right = discharging, right to left = charging):

LiC₆ + CoO₂ ⇄ C₆ + LiCoO₂

How does recharging a lithium-ion battery work?

When the lithium-ion battery in your mobile phone is powering it, positively charged lithium ions (Li+) move from the negative anode to the positive cathode. They do this by moving through the electrolyte until they reach the positive electrode. There, they are deposited. The electrons, on the other hand, move from the anode to the cathode.

• NMC (NCM) – Lithium Nickel Cobalt Manganese Oxide (LiNiCoMnO₂)
• LFP – Lithium Iron Phosphate (LiFePO4/C)
• NCA – Lithium Nickel Cobalt Aluminium Oxide (LiNiCoAlO₂)
• LMO – Lithium Manganese Oxide (LiMn₂O₄)
• LCO – Lithium Cobalt Oxide (LiCoO₂)
• LTO - Lithium titanate (Li2CO3)

Lithium batteries are more popular today than ever before. You’ll find them in your cell phone, laptop computer, cordless power tools, and even electric vehicles. However, just because all of these electronics use lithium batteries doesn’t mean they use the same type of lithium batteries. We’ll take a closer look at the six main types of lithium batteries reveals pros and cons, as well as the best applications for each.

* Lithium cobalt battery. Lithium cobalt oxide is one of the most common Lithium-ions, it has a chemical symbol which is LiCoO2 and is abbreviated as LCO. For simplification, Li-cobalt –which is the short term- can also be used for this type battery. Cobalt is the core active material which defines the character of the battery.

LCO (Lithium cobalt oxide) 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 the portable devices are cobalt based. The system contains a cobalt oxide cathode (positive electrode) and graphite carbon anode (negative electrode).

The main advantages of the LCO batteries are:

• High energy density.
• Long runtime making it optimum for new technologies

The main disadvantages of the LCO batteries are:

• It has a relatively low discharge current so high load can lead to pack overheat
• The safety circuit of the LCO battery is typically limited to a 1C for charging and discharging.
• The internal resistance increases with cycling and aging. This high internal resistance can cause the battery to become unserviceable due to a large voltage drop under the load after a couple of years of use.

LITHIUM IRON PHOSPHATE(LFP): 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.

LFP battery cells have a nominal voltage of 3.2 volts, so connecting four of them in series results in a 12.8-volt battery. This makes LFP batteries the most common type of lithium battery for replacing lead-acid deep-cycle batteries.

* Lithium Manganese Oxide (LMO) 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.

LMO batteries are commonly found in portable power tools, medical instruments, and some hybrid and electric vehicles.

* Lithium nickel manganese cobalt oxide (NMC) 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.

Similar to LMO batteries, NMC batteries are popular in power tools as well as electronic powertrains for e-bike, scooters, and some electric vehicles.

*Lithium nickel cobalt aluminum oxide (NCA) 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

The ability to perform in high-load applications with a long battery life makes NCA batteries popular in the electric vehicle market. Specifically, NCA is the battery of choice for Tesla.

*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.

Many applications use LTO batteries. Electric vehicles and charging stations, uninterrupted power supplies, wind and solar energy storage, solar street lights, telecommunications systems, and aerospace and military equipment are just some of the use cases.

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

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).

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.