Nickel-Metal Hydride (NiMH)
Battery Chemistries · 9 specs
Direct Answer
Nickel-Metal Hydride (NiMH) is the dominant rechargeable consumer chemistry for standard cylindrical battery formats (AA, AAA, C, D). Operating at 1.2V nominal, NiMH provides 60–120 Wh/kg specific energy, eliminates toxic cadmium, and modern Low Self-Discharge (LSD / Eneloop) formulations retain 70–85% of charge after several years of storage.
Source: IEC 61951-2 / ANSI C18.2M · Last reviewed Aug 28, 2026
Specs
| Nominal Cell Voltage | 1.20 V |
| Gravimetric Energy Density | 60 – 120 Wh/kg |
| Volumetric Energy Density | 180 – 300 Wh/L |
| Cycle Life (to 80% Capacity) | 500 – 1,500 Cycles |
| Thermal Runaway Threshold | > 250 °C |
| Operating Temperature Range | -20 to +50 °C |
| Self-Discharge Rate | 10–20% / Month (Standard) | < 1% / Month (LSD) |
| Primary Anode Material | Hydrogen-absorbing Rare Earth Alloy (AB5 or AB2 Metal Hydride) |
| Primary Cathode Material | Nickel Oxyhydroxide (NiOOH) |
Rechargeable Alternative to Disposable Alkaline
Although rated at 1.2V nominal compared to 1.5V for primary alkaline cells, NiMH maintains a steady 1.25V–1.20V output under high-current loads where alkaline voltage drops rapidly to 1.0V. As a result, NiMH outperforms alkaline cells in digital cameras, flashes, and motorized toys while being rechargeable hundreds of times.