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Comparison of Nickel Batteries and Lithium Ion Batteries

Apr. 09, 2022

Comparison of Nickel Batteries and Lithium Ion Batteries

Are NiMH batteries the same as Li-ion batteries?

NiMH batteries

A nickel-metal hybrid battery (NiMh) is a rechargeable battery. A chemical reaction occurs at the positive electrode, similar to the chemical reaction that occurs in nickel-cadmium batteries. The difference is the negative pole. Because NiMH batteries use hydrogen storage alloys instead of cadmium. The nickel-metal hybrid battery has 2-3 times the capacity of an equivalent nickel-cadmium battery of the same size. Its energy density is close to that of lithium-ion batteries.

Nickel-metal hydride batteries are widely used in hybrid vehicles, and according to a survey conducted in 2008, it was estimated that more than 2 million hybrid vehicles worldwide use nickel-metal hydride batteries.

In parts of the world, such as the European Union, nickel-metal hydride batteries are replacing nickel-cadmium batteries.

In Japan, about 22 percent of all portable rechargeable batteries sold in 2010 were NiMH batteries. However, this percentage continues to decline due to rapid technological advancements in the field of lithium-ion batteries.

Lithium Ion Battery

Lithium-ion batteries are used in almost all electronic devices and electric vehicles. Although more expensive than traditional alkaline batteries, lithium-ion batteries have a much longer lifespan.

Lithium-ion batteries are made from so-called batteries. Each cell consists of three parts: a positive electrode, a negative electrode, and a chemical component called an electrolyte between the positive and negative electrodes.

The positive electrode of the battery is designed with lithium cobalt oxide. The negative electrode is designed with graphite. such as oxides or sulfides. The electrolyte must have a long shelf life and provide high mobility for lithium ions. The electrolyte can be a liquid, polymer or solid electrolyte.

Lithium-ion batteries have the same structure. After the battery is charged, the lithium cobalt oxide "positive electrode" releases lithium ions, which travel throughout the electrolyte and move to the negative electrode "graphite", where they disappear. During this process, the battery stores energy. During charging and discharging; lithium ions return from the negative electrode to the positive electrode again through the electrolyte, thereby generating energy to provide power to the devices connected to the battery.

Can Li-ion batteries use NiMH chargers?

Lithium-ion and NiMH batteries are two types of rechargeable batteries used for similar purposes, but their chemistry is completely different. Lithium-ion batteries provide more power than NiMH batteries, almost 3 times. Lithium-ion batteries can also operate at higher voltages than NiMH batteries. However, due to the absence of active lithium, NiMH batteries are safer than Li-ion batteries when overcharged.

Lithium-ion and NiMH batteries require complex chargers. However, they each have a different charging philosophy. Lithium-ion batteries have internal circuitry that monitors the charge rate and shuts down power if a problem is detected. There are two identical lithium-ion batteries. Therefore, Li-Ion chargers offer a variety of variable voltages that can accumulate changes from each cell.

NiMH chargers lack the safety features required by Li-ion batteries. So NiMH battery chargers and Li-ion battery chargers are different. Charging Li-Ion batteries with NiMH chargers is extremely dangerous.

Characteristics of NiMH and Li-Ion Batteries

NiMH batteries

NiMH batteries have lower capacity than Li-ion batteries. No memory effect. Their operating temperature is between -5 and 95 degrees Fahrenheit. These life cycles are about 500~800 cycles. NiMH batteries are safer than Li-ion batteries. Especially in the case of overheating and overcharging.

NiMH batteries are more environmentally friendly than NiCd batteries.

Lithium Ion Battery

Unlike previous batteries, lithium-ion batteries have built-in electronic controllers. These controllers regulate how the battery is charged and discharged. These controllers prevent overcharging and overheating that can cause lithium-ion batteries to explode under certain conditions.

During charging and discharging of lithium-ion batteries, electrons flow in the opposite direction of the movement of ions around the external circuit. It is important to take care not to let electrons flow through the electrolyte itself. The electrolyte is actually an insulating barrier and does not affect the movement of electrons.

The movement of ions in the electrolyte and the reverse movement of electrons in the external circuit are two interrelated processes. If any of these movements stops, the other stops too. When the battery is fully discharged, preventing the movement of ions in the electrolyte, the electrons also stop moving in the external circuit. That's why your device loses power.

The discharge rate is high when the equipment supplying the lithium-ion battery power is turned on; however, the discharge can occur even when the power to the machine is turned off. This is one of the disadvantages of lithium-ion batteries.