What is a NiMH power battery?
NiMH battery is a kind of battery with good performance.
NiMH batteries are divided into:
Ni-MH rechargeable batteries, power Ni-MH batteries, high-capacity Ni-MH batteries, high-voltage Ni-MH batteries and low-voltage Ni-MH batteries.
The positive active material of nickel-hydrogen battery is Ni(OH)2 (called NiO electrode), the negative active material is metal hydride, also called hydrogen storage alloy (electrode is called hydrogen storage electrode), and the electrolyte is 6mol/L potassium hydroxide solution.
Advantages of NiMH batteries
1. Good power performance: A large number of metal materials are used inside the nickel-metal hydride battery, which has good electrical conductivity and can adapt to high-power discharge. The current specific power reaches more than 1500W/kg.
2. Good low temperature performance: The inorganic electrolyte system is used, and the low temperature performance is relatively better than that of lithium series batteries.
3. The application is relatively mature: the current commercialized hybrid electric vehicles such as Toyota's Prius and Honda's Insight hybrid electric vehicles use nickel-metal hydride batteries.
4. The battery management system is relatively simple: the battery is relatively resistant to overcharge and overdischarge, and it is not necessary to monitor the voltage of each single battery. During the charging process, the battery can achieve self-balancing through the side reaction of consuming gas (oxygen), and it is not necessary to use a special balancing circuit.
5. High cycle life: Ni-MH power lithium-ion battery packs currently used in electric vehicles can achieve more than 1,000 deep cycles at 80% discharge point, which is more than three times that of lead-acid batteries, and the 100% DOD cycle life is also More than 500 times, it can be used for more than five years in a hybrid car;
Disadvantages of NiMH batteries
1. The specific energy of the battery is low: generally 50~70W·h/kg. Although it is 2 to 3 times that of lead-acid batteries, compared with lithium series batteries, there is a big difference.
2. Low nominal voltage: When the nominal voltage of 1.2V is combined into a vehicle power supply system of hundreds of volts, more batteries are required in series, and the consistency and reliability of the batteries are required to be higher.
3. Poor charging performance at high temperature: The charging efficiency is reduced at high temperature, and the reduction in reaction efficiency will further increase the battery temperature, which may eventually lead to thermal runaway and safety problems.
4. Large self-discharge: Among the commonly used lead-acid, nickel-hydrogen and lithium series power batteries, the self-discharge of nickel-hydrogen batteries is relatively large. Generally, the self-discharge reaches 10% to 30% after being fully charged and left at room temperature for 28 days.
5. High cost of materials: Ni-MH batteries use a lot of precious metals such as nickel, cobalt, etc., which makes the cost of battery raw materials relatively high.
Ni-MH battery applications
Widely used in professional electronic equipment, automobiles, industrial applications, lighting, communications, power tools, home appliances and backup power supplies, portable printers, mobile tools, digital products; medical equipment, telecommunication equipment, LCD TVs; communication instruments, lasers Instruments, instrumentation and electric toys, etc.
Status of NiMH batteries
As the advantages of ternary lithium batteries and lithium iron phosphate batteries are more mature and prices are getting lower and lower, nickel-metal hydride batteries are almost completely replaced by lithium batteries in the field of power batteries, and lithium batteries are gradually replaced in the field of home appliance remote controls.
Nickel-Metal Hydride Replacement Batteries: Lithium Iron Phosphate Deep Cycle Batterie