___ have a much longer life cycle than lead-acid batteries and offer reasonable energy and power capabilities.

• A. Hydrogen fuel cell batteries
• B. Ultracapacitors
• C. Nickel-metal hydride batteries
• D. Lithium-ion batteries

Answer: (D)

Lithium-ion batteries excel because they combine a much longer cycle life than lead-acid with a practical balance of energy storage and deliverable power. Lead-acid typically lasts only a few hundred cycles and is heavy for the amount of energy it stores, which limits both lifespan and efficiency. Lithium-ion chemistries can endure hundreds to thousands of cycles while providing higher energy density (more energy per weight) and good power output, so devices stay charged longer and still perform well under load. Ultracapacitors, while they endure vastly more cycles, store far less energy, which makes them less suitable when you need substantial energy storage. Nickel-metal hydride lasts longer than lead-acid but generally doesn’t reach the cycle life and energy density of lithium-ion. Hydrogen fuel cells aren’t batteries and require a continuous fuel supply and infrastructure. So, lithium-ion batteries best meet the described combination of long life and solid energy and power capabilities.