The introduction of nimh batteries

nieq“Metal” parts of the nimh batteries are actually intermetallic compound. Many types of intermetallic compound has been used in the manufacture of nickel metal hydride batteries, they are mainly divided into two broad categories. Is one of the most common AB5 type, A is A mixture of rare earth elements (or) and titanium (Ti); B is the nickel (Ni), cobalt (Co) and manganese (Mn), (or) and aluminum (Al). And some of the high capacity battery electrodes “contains A variety of ingredients” is mainly composed of AB2, here is A titanium (Ti) and vanadium (V), and B is the zirconium (Zr) and nickel (Ni), plus some chromium (Cr), cobalt (Co), iron (Fe) and manganese (Mn) (or). [1]
All these compounds are the same roles: reversibly to form metal hydride. When the battery is being charged, potassium hydroxide (KOH) hydrogen ions (H +) in the electrolyte can be released, by these compounds absorb it, avoid the formation of hydrogen (H2), to maintain the battery internal pressure and volume. When the battery is discharging, the hydrogen ion will be back to the original place by the reverse process.
A, the weight
For each cell battery voltage, nickel-metal hydride and nickel cadmium is 1.2 V, and the lithium battery is 3.6 V, the lithium battery voltage is 3 times of other two. And the weight of the same type battery almost equal with nickel cadmium batteries, lithium-ion batteries, nickel metal hydride batteries are heavy. Weight is different, each battery itself, but for 3.6 V lithium battery high voltage, under the condition of the same voltage output make the individual cells number can be reduced a third right and reduce battery weight and volume after molding.
Second, memory effect
Nickel metal hydride batteries and nickel-cadmium batteries are same memory effect, but far less than the nickel cadmium battery, is greater than the lithium ion battery. Before each charge is not necessary for discharge operation (instead of may because of nonstandard discharge damage the battery), once every 3 months to fully charge and discharge can reduce memory effects (actually memory effect is not obvious, don’t too care about can be ignored). Relative to lithium batteries because almost no memory effect, simple in use is very convenient. It don’t have to completely ignore how much residual voltage, can be recharged directly, can shorten the charge time nature.
Third, self-discharge rate
Nickel cadmium battery for 15 ~ 30% (month). Nickel metal hydride battery for 25 ~ 35% (month), lithium battery is 2 ~ 5% (month). More than nimh battery self-discharge rate is maximum, and lithium batteries of the special features compared with other two kinds of battery discharge rate is extremely low.
Four, charging mode
Nickel metal hydride batteries and lithium battery can’t resistance to overcharge. With constant current charging nimh batteries, therefore, PICK the CUT control mode in the charging voltage reaches the highest, stop charging for the best way to recharge. While lithium-ion batteries use constant current, constant voltage way charge is best, if the nickel cadmium battery charger – DV control manner of hydride and lithium-ion batteries.

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