Phonetically, the word "Lithium-ion" does sound similar to "iron," but the term "Lithium-ion" refers specifically to the type of battery chemistry where lithium ions move between the anode and cathode during charging and discharging. The "ion" in "Lithium-ion" simply describes the ionic form of lithium involved in the battery's operation, not to be confused with "iron," which is a different element altogether.

To clarify:

Lithium-ion (Li-ion) is the general category name for a broad range of rechargeable batteries that use lithium as a primary component. This category includes various specific chemistries like Lithium Cobalt Oxide (LiCoO₂), Lithium Manganese Oxide (LiMn₂O₄), and Lithium Iron Phosphate (LiFePO₄), among others.
Lithium Iron Phosphate (LiFePO₄) is one specific chemistry within the Lithium-ion family. Here, "ferrous" (derived from "ferrum," the Latin word for iron) refers to the iron component in the cathode material. This chemistry is known for its stability, long cycle life, and safety, though it has a lower energy density compared to some other Lithium-ion chemistries like Lithium Cobalt Oxide.

So, while "Lithium-ion" batteries encompass a variety of specific chemistries, including Lithium Cobalt Oxide and Lithium Manganese Oxide, "Lithium Iron Phosphate" is a distinct subset of this larger category, with its own unique characteristics. The term "Lithium-ion" is indeed an umbrella term for all these lithium-based chemistries.