Nickel Based Cells
Nickel-Iron Cells:
Nickel-Iron Batteries have proven to be very reliable, but most PV modules do not have a high enough peak power voltage to charge them adequately.Nickel-Iron cells were the first rechargeable Nickel cell, one of many with a voltage around 1.2V, invented in 1890 by Thomas Edison. The cell consisted of a Nickel hydroxide cathode, an Iron anode and an alkaline electrolyte using Potassium Hydroxide (KOH). The invention of this rechargeable nickel battery paved the way for the development of two other types of Nickel-based cells, the common Nickel Cadmium cell (Ni-Cd is the name used by everyone now) and Nickel-Metal Hydride cells (known as Ni-MH cells in the portable computer world). Continue reading to learn more about these constantly developing variations on a cell.
Nickel-Cadium Batteries
Features:
Nickel Cadmium is well suited for motor driven applications, such as power tools and even electric cars, because of it's high energy density. Energy density is a term used to define how much energy can be produced by a cell compared to it's weight, measured in Watt-hours per kilogram (1 Wh = 3600 Joules), so if a battery can supply large amounts of energy and is contained in a small package, it will have a desirably high energy density.
Design:
Nickel Cadmium batteries were originally designed with a solid Nickel Hydroxide cathode and a solid Cadmium anode. Unfortunately the use of a solid anode and cathode offers very low energy densities, because only a fraction of the electrode components are available to each other. As time passed, a "wound" cell was adopted, giving the Ni-Cd a higher energy density.
Nickel-Metal Hydride Batteries
Features and Design:
Nickel-Metal Hydride cells are the newer cousin of Ni-Cd cells, offer most of the same features, and even appear that they will surpass the Ni-Cd battery in the future as the technology used to create the anode storage metal. Ni-MH cells incorporate a different type of structure at the anode that allows Hydrogen to be stored in a specialized metal structure, instead of using a solid metal or compound as an anode. One drawback to the Ni-MH design is the rapid loss of charge, known as self-discharge, that amounts to a dead cell within a month just sitting in storage.
