Nickel-metal hydride (NiMH) batteries are high-performance rechargeable batteries. They are divided into high-voltage and low-voltage types. As fossil fuels become increasingly scarce due to large-scale human exploitation, the development and utilization of hydrogen energy has received growing attention in recent years. NiMH batteries, as an important direction for hydrogen energy applications, are attracting increasing attention.
Which is safer, lithium-ion batteries or nickel-metal hydride batteries?
Compared to lithium batteries, nickel-metal hydride (NiMH) batteries are safer, mainly because NiMH batteries have lower specific heat capacity and energy density, but a melting point as high as 400°C. When subjected to impacts, compression, punctures, short circuits, etc., the battery temperature will not rise sharply and cause spontaneous combustion.
Furthermore, nickel-metal hydride batteries have become very mature after years of technological development, and their high quality and stability also contribute to improving battery safety. It is worth noting that Toyota has sold more than 20 million hybrid vehicles equipped with nickel-metal hydride batteries to date, yet there has never been a case of spontaneous combustion.
In contrast, lithium batteries have high energy density due to the high activity of lithium ions. However, some types of lithium batteries use flammable raw materials. If the battery experiences a short circuit and the temperature rises due to various factors, the electrolyte inside will undergo a violent chemical reaction, which may lead to spontaneous combustion of the battery. In recent years, spontaneous combustion of new energy vehicles equipped with lithium batteries has become quite common.
Which has a longer lifespan: lithium-ion batteries or nickel-metal hydride batteries?
Nickel-metal hydride (NiMH) batteries have a longer lifespan because they have a memory effect. Therefore, major car manufacturers use a "shallow charge and shallow discharge" battery management strategy when using NiMH batteries. Usually, most vehicles equipped with NiMH batteries are hybrid electric vehicles, and the maximum battery capacity will not exceed 40%.
In other words, when the battery has 60% charge remaining, it will stop discharging and start charging. Moreover, nickel-metal hydride batteries will not be fully charged. With this battery management strategy, overcharging and over-discharging can be avoided to the greatest extent, thereby extending their lifespan. Theoretically, nickel-metal hydride batteries can achieve tens of thousands of charge-discharge cycles.
While the mainstream lithium iron phosphate batteries can achieve a lifespan of 3,000 charge-discharge cycles, this is still far less than that of nickel-metal hydride (NiMH) batteries. As for ternary lithium batteries, the theoretical lifespan is 2,000 charge-discharge cycles, but research has shown that after 900 cycles, the battery capacity decreases by about 50%. Therefore, in terms of lifespan, NiMH batteries are superior to lithium batteries.
