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Which Is Better, Nimh or Li-Ion Batteries?

nimh or li ion batteries

Both NiMH and Li-ion batteries are non-polluting and environmentally friendly batteries that are widely used in the market and are an important area for the development of new energy batteries. So which is better, NiMH batteries or Li-ion batteries? I will analyse them from several aspects, and hope I can give you help.

#1-What Is a Nimh Battery?

nimh battery

Nickel-metal hydride battery is a kind of battery with good performance. NiMH batteries are divided into high-voltage NiMH batteries and low-voltage NiMH batteries. The positive active substance of NiMH battery is Ni(OH)2 (called NiO electrode), the negative active substance is metal hydride, also called hydrogen storage alloy (electrode called hydrogen storage electrode), and the electrolyte is 6 mol/L potassium hydroxide solution.

#2-What Is a Lithium Battery?

lithium battery

Lithium batteries are a class of batteries made of lithium metal or lithium alloy as the positive/negative electrode material, using a non-aqueous electrolyte solution. Lithium batteries can be broadly divided into two categories: lithium metal batteries and lithium ion batteries. Lithium ion batteries do not contain lithium in its metallic form and are rechargeable.

#3-Which Is Better, Nimh or Li-Ion Batteries?

better nimh or li ion

The design of NiMH battery chargers and Li-ion battery chargers are both based on voltage in principle, and the charging schemes designed for the presence or absence of memory effects are different. The advantages and disadvantages of the two products are as follows.

① Advantages and disadvantages of NiMH batteries

Advantages: low price, high versatility, high current, environmentally stable.

Disadvantages: high weight and short battery life.

Higher capacity for the same volume. Taking a common five-cell battery as an example, NiMH batteries have a nominal capacity of up to 2900mAh (mAh), while NiCd batteries only have 1100mAh (mAh). NiMH batteries have a higher output current than carbon zinc or alkaline batteries, making them relatively more suitable for high power consumption products, and some special models of the power type even have a higher output current than ordinary NiCd batteries.

Long cycle life, over 500 cycles under correct use conditions. Poor heat resistance, try not to let the temperature of the battery higher than 45 degrees. Otherwise the life span will be reduced very quickly and the internal resistance of the battery will increase. Overcharging has a great impact on battery life and is dangerous, so stop charging when the battery is fully charged.

Both NiMH and NiCd batteries operate at 1.2V, but NiMH has a higher volume-to-energy ratio than NiCd batteries. Due to the excellent large discharge rate of NiCd batteries, NiMH batteries cannot yet replace NiCd batteries in many power tools. Therefore, NiCd batteries are temporarily allowed to be used in the field of power tools in the ROSH standard.

②, Advantages and disadvantages of lithium batteries

Advantages: no memory effect, lighter weight.

Disadvantages: high cost, smaller current, not resistant to overfilling (compared with NiMH).

There are primary lithium batteries (non-rechargeable) and secondary lithium batteries (rechargeable), and secondary lithium batteries are divided into Li-ion lithium-ion batteries and Li-Polymer lithium-polymer batteries.

Compared to NiMH batteries, they are lighter in weight and have a 48% higher volumetric energy density ratio. Because of this, Li-ion secondary batteries are gradually being produced and sold in larger quantities than NiMH batteries. These batteries have a small self-discharge and no memory effect, and can be charged and discharged more than 600 times.

Lithium batteries do not tolerate overcharging and are at risk of explosion if used carelessly, so they require an internal control IC to prevent overcharging, but the cost is also much higher. Li-ion batteries were not standardised, so there were times when they were not available after production had stopped, but this has now improved considerably.

Li-ion batteries are more suitable for mobile phones than NiMH batteries, but in the use of digital cameras, as the demand for current in digital cameras is quite high, the power consumption is also much greater than that of mobile phones, NiMH batteries are slightly better at high current output.

#4-Which Is Safer, Li-Ion or Nimh Batteries?

safer li ion or nimh

The main reason is that the specific heat capacity and energy density of NiMH batteries are relatively low, while the melting point is as high as 400°C. When subjected to collision, extrusion, puncture and short circuit, the temperature of the battery will not rise sharply and lead to spontaneous combustion.

It is also worth noting that Toyota has sold over 20 million NiMH battery-equipped twin-engine models to date, yet no cases of spontaneous combustion have ever been reported.

In contrast, lithium batteries have a high energy density due to the strong lithium ion activity, and some types of lithium batteries are made of flammable raw materials. Once the temperature of the battery rises due to various factors, the electrolyte inside will undergo a violent chemical reaction, which may lead to spontaneous combustion.

#5-Which Has a Longer Lifespan, Li-Ion or Nimh Batteries?

NiMH batteries have a longer lifespan because they have a certain memory effect, so when using NiMH batteries, major car manufacturers will give them a “shallow charge and discharge” battery management strategy.

In other words, the battery will stop discharging and start charging when 60% of the battery power is left, and the NiMH battery will not be fully charged to full capacity.

The current mainstream lithium iron phosphate battery, although the life of the battery can also reach 3000 charge and discharge cycles, but compared to the NiMH battery is still a far cry. As for the ternary lithium battery, the theoretical life is 2000 charge/discharge cycles, So NiMH batteries are longer than lithium batteries.

Carl Zhang

Carl Zhang

I am a senior sales with 15 years in the battery industry and a bachelor's degree in economics.
I will be sharing some of my expertise on batteries and my insights into the battery industry in my blog, which should help you with your purchases in China.

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