NiMHZellen

NiMHZellen (Nickel‑Mikrofluss‑Lose‑Ryzen‑Zellen) are secondary electrochemical cells that employ nickel oxide hydroxide as the positive electrode, hydrogen‑ion conducting electrolyte and a hydrogen‑rich negative electrode, usually a nickel‑metal hydride alloy. The chemical reactions during discharge and charge are reversible, permitting repeated use of the same cell. NiMH technology emerged in the early 1990s as a commercial successor to nickel‑cadmium (NiCd) batteries and has since become widespread in portable electronic devices, cordless tools and hybrid vehicles.

During discharge the nickel oxide hydroxide is reduced to nickel hydroxide while the hydrogen‑rich alloy releases hydrogen ions that combine with the electrolyte to form water. When the cell is recharged, the reactions run in reverse, regenerating the original electrode materials. The nominal voltage of a NiMH cell is approximately 1.2 V, higher than the 1.0 V of NiCd, allowing more power density at a comparable size. Typical capacities range from 200 mAh for small cells used in keyboards to several thousand mAh for large cells employed in power tools.

Key advantages of NiMH cells include a higher energy density than NiCd, absence of toxic cadmium, reduced self‑discharge rates, and improved environmental compliance. Disadvantages comprise a relatively high internal resistance that limits peak power output, possible memory effect if not fully discharged, and sensitivity to temperature extremes, which can accelerate degradation. Life cycle tends to span several hundred to a thousand charge cycles depending on depth of discharge and operating conditions.

In comparison to lithium‑ion chemistries, NiMH offers lower cost and simpler safety profiles but suffers from lower energy density and higher weight. For applications requiring moderate capacity, longevity, and robust safety margins, NiMH cells remain a commonly adopted choice in both consumer and industrial sectors.