Lithium batteries have become popular in new mobile devices, laptops, and even other devices such as robots, vacuum cleaners, cordless tools, and so on. However, there are not only these batteries but also nickel batteries, which are also very popular, even if they are used for other types of devices.
- Lithium batteries are a type of rechargeable battery that uses lithium-ion (Li-ion) technology. They have a high energy density and a long lifespan, making them popular for use in portable devices such as laptops and smartphones.
- LiPo (Lithium Polymer) batteries are a type of rechargeable lithium-ion battery that uses a solid polymer electrolyte instead of a liquid one. LiPo batteries are lighter and thinner than traditional lithium-ion batteries and are commonly used in drones and other remote-controlled devices.
- Nickel batteries are rechargeable batteries that use nickel-cadmium (NiCd) or nickel-metal Hydride (NiMH) technology. They are less commonly used than lithium-ion batteries because they have a lower energy density and a shorter lifespan. However, they are still widely used in some applications because of their low cost and stability in extreme temperatures.
Therefore, in this article, I will show you everything you need to know about these rechargeable batteries, their differences, and their main advantages and disadvantages…
History of rechargeable batteries
The first rechargeable battery in history was a lead-acid battery, i.e. a secondary battery or accumulator as it is often called. This type of battery can still be found in many vehicles today. It was developed in France in the mid-19th century. Previously, all batteries were primary cells, which meant they could not be recharged.
In 1899, Waldemar Jungner in Sweden invented the nickel-cadmium (NiCd) battery, which used cadmium as the positive electrode (cathode) and nickel as the negative electrode (anode). This type of battery also became popular, although its high price compared to lead limited its use in certain areas.
Later, in 1990, European environmentalists became concerned about the environmental damage caused by NiCd batteries, and they were eventually restricted in the European Union by the Battery Directive 2006/66/EC. They are currently only available for industrial use, but there is no good enough alternative.
An alternative for this type of rechargeable battery also came from nickel, but this time in the form of NiMH (nickel metal hydride). This type of battery is more environmentally friendly, but has similar properties to NiCd and has therefore become one of the most commonly used batteries in all kinds of everyday devices: Watches, flashlights, remote controls, scales, some wireless peripherals, etc.
Since the introduction of lithium batteries in 1991 by Sony, most efforts have been focused on improving the capacity and energy density that can be stored in this type of battery, as well as optimizing other features such as extending service life, environmental friendliness, faster charging, and so on. Lithium has great advantages, which is why it is currently used in mobile devices, robots, laptops, electric vehicles, digital cameras, wireless tools, etc.
The market for battery-powered devices is huge and growing. As a result, the battery business has become one of the most profitable businesses. Moreover, companies’ marketing departments sell them as environmentally friendly, although the production and recycling of batteries is a challenge.
Features of the rechargeable battery
When selecting a new battery for a device, you should know some of the key features to look for:
Battery type: there are a variety of battery types and formats that you should know, otherwise they may not be compatible with the device. For example, we have button cell batteries, coin cell batteries, etc.
Voltage: This is the voltage that the battery can supply. While it can be fixed later with additional circuitry, it is also important depending on what you want to use it for.
Discharge Curve: This is a graph of the voltage as a function of the percentage of capacity discharged. A flat discharge curve would be optimal, as this means that the voltage will remain constant as the battery wears down. That is, from 100% to 0% depletion would result in a stable voltage.
Capacity: is the amount of electrical energy contained in an electrochemical reaction. It can be measured in various units, such as Whr or watts per hour it can deliver, or mAh or milliamps per hour. For example, a 3000 mAh battery can deliver 3 A for one hour, or 1.5 A for two hours, and so on.
Energy density: specific is the energy that can be extracted per unit mass of the cell (or sometimes per unit mass of the active electrode material). It is the product of the specific capacity and the operating voltage during a complete discharge cycle. The higher it is, the better, because the more energy you get for the same weight.
Power Density: This is the power that can be obtained per unit mass of the cell and is measured in W/kg or watts per kilogram. That is, for each kilogram of the battery, how many watts of power it can deliver?
Temperature dependence: according to kinetic theories, the rate of reaction in the cell depends on temperature. Internal resistance also varies with temperature; low temperatures result in higher internal resistance. At very low temperatures, the electrolyte may freeze and provide a lower voltage because the movement of ions is prevented. At very high temperatures, chemicals may decompose or there may be enough energy to cause undesirable reversible reactions, reducing efficiency.
Lifetime: Another very important factor, because it determines how long the battery will last. The lifetime of a rechargeable battery is defined as the number of charge/discharge cycles a secondary cell can go through before its capacity drops to 80% of its original value. This varies greatly depending on the type of battery (lithium, nickel…). Some can last thousands of cycles before becoming less and less efficient.
Deep discharge capacity: there is a logarithmic dependence between the depth of discharge and the battery life, so if the battery is not fully discharged, the battery life can be significantly extended; for example, if you keep the battery between 40% and 80% of charge, it will last longer than if it is fully discharged or higher.
For nearly half a century, rechargeable nickel-cadmium (NiCd) batteries were used almost exclusively in devices that required a battery. However, after these were curtailed in the 1990s due to environmental concerns, the now familiar nickel-metal hydride or NiMH batteries became popular.
This type of battery differs from lithium batteries in that the cells have a nickel structure similar to NiCd and usually have a button, cylindrical, prismatic, or rectangular case. They are the most common batteries in all sorts of everyday items that use them, from flashlights to watches to radio-controlled toys.
Advantages
- The advantages of NiMH batteries are:
They can have a higher density than NiCd batteries, which means up to 30-40% higher charge. - They are not as susceptible to the memory effect as NiCd.
- They are easy to store and transport. They are not subject to inspection.
- They are environmentally friendly because they contain only non-toxic, non-hazardous materials such as cadmium (heavy metal).
- The nickel content makes recycling practical.
Disadvantages
The most serious disadvantages are:
- Limited useful life. Capacity is limited after a deep discharge.
- Requires a complex charging algorithm.
- They do not tolerate overcharging well. Therefore, it is not good to let them charge longer than the estimated time.
- Generates heat during charging.
- High self-discharge when not in use.
- Efficiency decreases when the battery is stored at higher temperatures. When stored in a cool place, the battery should be charged to 40%.
- Rechargeable lithium-ion (Li-ion) batteries.
John B. Goodenough invented the lithium cobalt oxide cell in 1922. A few years earlier, however, Sony had already announced that it held an international patent on the lithium cobalt oxide cathode. After years of patent disputes, Sony managed to win the legal battle for what is now the most important battery.
These lithium batteries have a higher energy density, so they can store more charge in the same space, which is a big advantage. The cells can have a voltage of up to 3.6 V, and improved active materials and electrolytes can further increase the density of these batteries.
The charging characteristics are also very good, the discharge curve is quite flat at 3.7-2.8 V/cell, and there is little memory effect. The production price has dropped exponentially as technology has improved. In 1994, for example, 18650 batteries with a capacity of 1100 mAh could cost as much as $10 each. By 2001, capacities of 1900 mAh were achieved at production costs of less than $3, and this trend has continued to the present.
It’s also worth mentioning that lithium batteries are virtually maintenance-free, which is a big advantage over other batteries such as lead-acid. You also don’t have to worry about deliberately discharging them completely, as this is not necessary. And the self-discharge rate is even less than half that of nickel-based batteries, which is a good thing.
The nominal cell voltage of 3.60V can directly power digital devices such as laptops, mobile devices, etc.
Disadvantages include the need for protective circuitry to prevent possible spontaneous combustion or explosion. Another disadvantage is the high price.
Lithium-ion battery types are distinguished by the electrochemical systems used in them:
- (+) MLi / organic electrolyte / C (-), where the letter M stands for the base metal of the electrode.
- C – cobalt
- N – nickel
- M – manganese
- V – vanadium
- T – titanium
Lithium-ion batteries have hermetic cases containing protective control circuits. The electrode materials are deposited on very thin layers (copper and aluminum) separated by a separator.
Advantages of lithium batteries (Li-Ion)
The main advantages of lithium batteries include:
- High density.
- Low self-discharge rate, less than half of NiCd and NiMH.
- Not affected by the memory effect.
- Low maintenance
- Regular discharges are not required.
- Disadvantages of a lithium-ion battery (Li-Ion)
- On the other hand, lithium-ion batteries have the following disadvantages:
- It needs a protection circuit to limit the voltage and current.
- It ages and has a limited life, similar to other chemicals.
- Strict transportation regulations apply to this type of battery, as there is a risk of ignition or explosion if it reacts with atmospheric oxygen.
Lithium polymer battery (Li-Po)
At the beginning of the 21st century, the first lithium polymer batteries were developed. They became very popular as an alternative to Li-ion batteries, although there are actually more Li-ion batteries on the market than Li-Po batteries. While they have advantages over Li-ion batteries, they also have some limitations.
In this case, the batteries differ in the type of electrolyte used, which is a lithium polymer. It was first developed in the 1970s, using a polymer to create a solid, dry, plastic-like electrolyte. This allows ion exchange and replaces the electrolyte-saturated porous separator of Li-ion. As a result, they are less prone to leakage.
The solid polymer has poor conductivity at room temperature, and the battery must be heated to 50-60°C (122-140°F) for current to flow, which was not the case with Li-ion batteries. For a modern lithium polymer cell to conduct current at room temperature, the electrolyte must gel. In other words, today’s Li-Po batteries do not have a polymer, but a gel.
Lithium polymers can be made in a variety of ways, such as:
- Li-cobalt
- NMC
- Li-Phosphate
- Li-manganese
For this reason, the lithium polymer battery is not considered special compared to the lithium-ion battery. Most lithium polymer secondary cells for the consumer market are based on lithium cobalt circuits. To the user, a lithium polymer battery is essentially the same as a lithium-ion battery. Both systems use the same anode and cathode material and contain a similar amount of electrolyte.
Although the characteristics and efficiency of both systems are similar, lithium polymer is special because it is a microporous electrolyte and replaces the traditional porous separator. The gelled electrolyte becomes a catalyst that improves electrical conductivity. Lithium polymer offers slightly higher specific energy, and batteries that use it can be thinner than traditional lithium-ion cells.
However, in exchange for these advantages, production costs can be 10-30% higher than Li-ion. For this reason, they are not found in most devices that continue to use Li-Ion. They are only common in some premium models where the price is not an issue.
While a conventional Li-ion battery requires a rigid case to compress the electrodes, lithium polymer uses laminated plates that do not need to be compressed. Such an aluminum housing reduces the weight by more than 20%, and thanks to thin-film technology, the format can be freely chosen, and the battery can be manufactured in any shape.
Finally, the charging and discharging characteristics of lithium polymer are identical to those of other lithium-ion systems and do not require a special charger. The safety aspects are also similar.
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