Li-Ion, LiFePo4 and LiPo batteries

Li-Ion batteries

The lithium cobalt battery uses lithium cobalt oxide as the cathode material. This is suitable for supplying energy for electronic applications. To supply energy to large electrical applications, batteries with a positive electrode nickel-manganese-aluminum-lithium are used. There are also differences between lithium cobalt oxide batteries and nickel-manganese-aluminum-lithium batteries in terms of battery life, safety, and cost. In terms of performance, the lithium cobalt oxide, lithium manganate and lithium nickel oxide battery has higher energy density and increased operational safety compared to lithium cobalt oxide. From an economic point of view, cobalt being an expensive metal makes this type of battery have a higher production cost.

Lithium-Ion Polymer (LiPo) Batteries

Li-Po batteries, although they function like lithium-ion batteries with lithium as the main active element, differ from them by replacing the porous separator and electrolyte with a gelled electrolyte, which allows them to be stored in a discharged state for a long period of time without the risk of irreversible damage. LiPo batteries are durable and do not present a risk of electrolyte leakage; they are made of laminated foils and do not require a metal casing or a separator between the electrodes, which makes them thinner and lighter than lithium-ion batteries by approximately 20%. Thanks to the technology, they can be manufactured in a very wide range of sizes, the packs are flexible and have the appearance of bags. In order not to affect the durability of LiPo batteries, the following must be avoided:

• Overcharging – Stop charging when the battery reaches 100% charge. Overcharging shortens the lifespan and can damage it. During charging, quantities of gas may accumulate, leading to an increase in the volume of the battery, which must be taken into account when choosing it and sizing the location in which it is placed. As the number of cycles increases, the LiPo battery will increase in volume.
• Overheating – Do not use LiPo batteries at temperatures above 60°C.
• Deep discharge – Charge batteries before they are completely discharged. LiPo batteries come with management systems that protect the batteries from: overcharging, deep discharge, overcurrent and short circuit.

Comparison of Li-Ion vs LiFePO4 batteries

In recent times, LiFePO4 (lithium-iron-phosphate) batteries have taken the place of lithium-ion batteries in passenger vehicles. To understand the reasons, we will analyze it from several perspectives. From a safety point of view, iron-phosphate batteries perform better on impact than lithium-ion ones. In addition, the thermal stability of lithium iron phosphate batteries is much better than that of lithium-ion batteries. They are stable even at extremely high temperatures (500°C) and even at temperatures higher than 500°C they do not produce violent combustion. In contrast, lithium-ion batteries begin to melt at around 300°C and cause spontaneous fires. Energy density is better for lithium-ion batteries (250Wh/kg) than lithium-iron-phosphate batteries (180Wh/kg). Low temperature capacity (-20°C) is better in lithium-ion batteries than in lithium iron phosphate batteries. Charging efficiency is also better for lithium-ion batteries compared to lithium iron phosphate batteries. Battery life is defined as the number of charge-discharge cycles until the battery can no longer be charged to more than 80% of its declared capacity. In the case of lithium-iron-phosphate batteries, this duration reaches 3500 cycles, unlike that of lithium-ion batteries, which is only 2500 cycles. From the above analysis, it can be seen that lithium iron phosphate batteries have obvious advantages in terms of safety and cycle life, while lithium-ion batteries are superior in energy density, low-temperature discharge, and charging efficiency.

Graphene Lithium-Ion Batteries

Graphene is a lightweight, very strong and superconducting nano-material. It is the two-dimensional version of graphite; the carbon atoms are arranged in a planar hexagonal lattice. It is the best conductor known to date. Although discovered in 1947, it was not isolated until 2004 by Andre Geim and Konstantin Novoselov, who were awarded the Nobel Prize in Physics in 2010 for this achievement. By adding graphene to lithium-ion batteries, the transfer of ions between electrodes (both during charging and discharging) increases by more than 10 times. This translates into the possibility of rapid charging of the batteries (15-20 minutes) without heating up. The advantage of fast charging, the specific energy of approximately 165Wh/kg, the number of over 2500 charge-discharge cycles and a low self-discharge rate (approximately 3%) recommend it as a solution for powering electric cars.

Sodium-ion batteries

Sodium-ion batteries are not a new technology. Research into sodium-ion and lithium-ion batteries was conducted at about the same time, but their fates were very different. Lithium-ion batteries have dominated the market, while sodium-ion batteries have stagnated and are still in the early stages of industrialization. The reason appears to have been their lower energy density. However, considering the increasing demand for batteries, especially in the automotive industry, and taking into account the amount of natural resources needed to manufacture these types of batteries and the global distribution of natural resources, sodium batteries seem to be returning to the attention of the scientific world. The lithium reserve in the earth’s crust is only 0.0017%, distributed mainly in South America, compared to the sodium reserve of over 2%, distributed evenly across the globe. However, to overcome the “handicap” of energy density (sodium is an element with a larger mass and atomic radius than lithium), the performance of the materials for the sodium-ion battery electrodes must be improved. Sodium-ion batteries have sufficient reserves of raw materials and, once the energy density problem is solved by alloying the electrodes with low-cost materials, it will lead to the creation of cheap and stable batteries in terms of safety during manufacturing and operation. In the near future, for electric vehicles that require low weight for extended range, lithium-ion batteries will continue to be the main equipment option. For areas where these parameters are not important, sodium-ion batteries will offer an advantage in operational safety and will gain market share.