Nickel hydroxide (Ni(OH)2) is commonly used as an active material in rechargeable batteries, particularly in nickel-metal hydride (NiMH) batteries. NiMH batteries have been widely used in various applications, including portable electronics, hybrid vehicles, and renewable energy systems. Here are some key applications of nickel hydroxide in batteries:

  1. Nickel-Metal Hydride (NiMH) Batteries: Nickel hydroxide serves as the positive electrode (cathode) material in NiMH batteries. It undergoes reversible electrochemical reactions during charge and discharge cycles. During charging, nickel hydroxide is oxidized to form nickel oxyhydroxide (NiOOH) and releases hydroxide ions. During discharge, the hydroxide ions are consumed, and nickel hydroxide is reduced back to its original form. This reversible redox reaction allows for repeated charging and discharging cycles, making NiMH batteries rechargeable.
  2. Portable Electronics: NiMH batteries have been widely used in various portable electronic devices, including digital cameras, cordless phones, portable music players, and flashlights. They offer a good balance of energy density, power output, and affordability, making them a popular choice for these applications.
  3. Hybrid and Electric Vehicles: Nickel hydroxide-based NiMH batteries have been used in hybrid vehicles as a part of the energy storage system. They provide a higher energy density compared to traditional lead-acid batteries, allowing for longer electric driving ranges. While newer electric vehicles (EVs) predominantly use lithium-ion batteries, NiMH batteries are still used in some hybrid models.
  4. Renewable Energy Systems: NiMH batteries find applications in renewable energy systems, such as solar power and wind power storage. They can store excess energy generated during peak production and release it during periods of low production or high demand. Their robustness, low self-discharge rates, and relative safety make them suitable for these energy storage applications.

While nickel hydroxide has been widely used in NiMH batteries, its use has declined in recent years due to the emergence of lithium-ion batteries. Lithium-ion batteries offer higher energy density, longer cycle life, and improved performance, which has led to their dominance in many applications. Nonetheless, nickel hydroxide-based NiMH batteries still have a place in certain industries and applications.