What are the disadvantages of Ni-Mh batteries?

Nickel metal hydride battery(NI-MH) is improved by nickel cadmium battery (NiCd battery), and the absorbing hydrogen to make the metal (rare earth alloy or the observatory) instead of cadmium (Cd), can be recycled, belongs to the environmental protection batteries.

The advantages and disadvantages of nickel metal hydride batteries (NI-MH) is as follows:

The same volume capacity is higher, the common v batteries, for example, nominal capacity is 2900 mah of Ni-Mh batteries (mah), and nickel cadmium battery only 1100 mah (mah).

Ni-Mh batteries than zinc carbon batteries or alkaline batteries have a larger output current, relatively more suitable for high power products, some of the dynamic type of special models than ordinary nickel-cadmium batteries have even larger output current.

Less obvious memory effect, and even many brands of Ni-Mh batteries have declared that no memory effect.

Long cycle life, under the condition of the correct use of recycled more than 500 times.

Old model of high nickel metal hydride battery self-discharge rate, full electric room temperature storage self-discharge rate of 30 ~ 35%, but the new Ni-Mh batteries have a fairly low self-discharge rate.

High temperature resistant performance is poor, try not to let the battery temperature is higher than 45 degrees.Otherwise life will soon be lower, the battery internal resistance will increase.

Excessive charging a great influence on battery life, has certain risk, so stop charging when the battery is full.

Nickel metal hydride batteries (NI-MH) is improved by nickel cadmium battery (NiCdbattery), and the absorbing hydrogen to make the metal (rare earth alloy or the observatory) instead of cadmium (Cd), can be recycled, belongs to the environmental protection batteries.

The advantages and disadvantages of nickel metal hydride batteries (NI-MH) is as follows:

The same volume capacity is higher, the common v batteries, for example, nominal capacity is 2900 mah of Ni-Mh batteries (mah), and nickel cadmium battery only 1100 mah (mah).

Ni-Mh batteries than zinc carbon batteries or alkaline batteries have a larger output current, relatively more suitable for high power products, some of the dynamic type of special models than ordinary nickel-cadmium batteries have even larger output current.

Less obvious memory effect, and even many brands of Ni-Mh batteries have declared that no memory effect.

Long cycle life, under the condition of the correct use of recycled more than 500 times.

Old model of high nickel metal hydride battery self-discharge rate, full electric room temperature storage self-discharge rate of 30 ~ 35%, but the new Ni-Mh batteries have a fairly low self-discharge rate.

High temperature resistant performance is poor, try not to let the battery temperature is higher than 45 degrees.Otherwise life will soon be lower, the battery internal resistance will increase.

Excessive charging a great influence on battery life, has certain risk, so stop charging when the battery is full.

Nickel metal hydride battery is a kind of good performance of battery.Nickel metal hydride batteries are divided into high pressure low nickel metal hydride batteries and nickel-metal hydride batteries.Nickel metal hydride battery cathode active material of Ni (OH) 2 (called a NiO electrode), the cathode active material for metal hydride, also known as the hydrogen storage alloy electrodes (called a hydrogen storage electrode), the electrolyte is 6 mol/L potassium hydroxide solution.Nickel metal hydride batteries as an important direction of hydrogen energy application is more and more attention by people.

As fossil fuels in the human development and utilization of massive cases less and less, in recent years, the development and utilization of hydrogen energy is becoming more and more attention.Nickel metal hydride batteries as an important direction of hydrogen energy application is more and more attention by people.Although Ni-Mh batteries is indeed a good battery performance, but the space with nickel metal hydride batteries are the Ni-Mh batteries (hydrogen pressure of 3.92 MPa, 40 kg/cm2), such as high pressure hydrogen storage in the thin wall container used easily, and the Ni-Mh batteries need noble metal catalyst, make it become very expensive, the cost of it is acceptable for civil, therefore, abroad since the 70 s began to explore civil low-voltage Ni-Mh batteries.Nickel metal hydride batteries are divided into high pressure low nickel metal hydride batteries and nickel-metal hydride batteries.High nickel metal hydride batteries are in the early 1970 s by American M.K lein and J.F.S tockel and developed in the first place.Use Ni-Mh batteries instead of cadmium nickel battery and applied to all kinds ofspecial trend has been formed.

Nickel metal hydride battery cathode active material of Ni (OH) 2 (called a NiO electrode), the cathode active material for metal hydride, also known as the hydrogen storage alloy electrodes (called a hydrogen storage electrode), the electrolyte is 6 mol/L potassium hydroxide solution.Active material composition of electrode pole piece craft ways mainly have sintering type, slurry type nickel, nickel foam type, fiber type and embedded infiltration type, such as different process of the preparation of electrode on the capacity, large current discharge performance there is a big difference, generally under conditions of use different battery production process.Communications USES mostly civil battery slurry type cathode and anode of nickel foam constitutes a battery.Charge and discharge chemical reaction [1] as follows:

The positive: Ni (OH) 2 + OH - = NiOOH + H2O + e -

Negative: M + H2O + e = MHab + OH -

The total response: Ni (OH) 2 + M = NiOOH + MH

Note: M: hydrogen alloy;Hab: hydrogen adsorption;The reactive process from left to right as the charging process;The reactive process from right to left for discharge process.

Charging the positive of Ni (OH) 2 and OH - reaction to generate NiOOH and H2O, at the same time release e - generated with MH and OH -, Ni (OH) 2 and M is the total reaction generated NiOOH, hydrogen storage alloy hydrogen storage;Discharging the contrary, MHab release H +, H + and OH - generated H2O and e -, NiOOH, H2O, and e - to regenerate the Ni (OH) 2 and OH -.Battery electromotive force is 1.319 V.

Nickel metal hydride batteries are divided into high pressure low nickel metal hydride batteries and nickel-metal hydride batteries.

Low nickel metal hydride battery has the following characteristics: (1) the battery voltage is 1.2 ~ 1.3 V, and cadmium nickel battery fairly;(2) the high energy density, cadmium nickel battery is more than 1.5 times;(3) can fast charge and discharge, low temperature performance good;(4) can be sealed, resistant to over charge and discharge ability;(5) no generation dendritic crystals, can prevent the short circuit inside the battery;(6) safe and reliable to the environment pollution-free, no memory effect, etc.[1]

High pressure Ni-Mh batteries has the following characteristics: (1) reliability.Good over discharge, over charging protection, resistant to high charge and discharge rate and no dendrite formation.Has a good ratio characteristics.Its quality given to 60 a. h/kg, cadmium nickel battery is five times.(2) the long cycle life, can amount to thousands of times.(3) the whole sealing, less maintenance.(4) the low temperature performance is good, in - 10 ℃, the capacity has no apparent change.

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