Sodiumion

Sodium ion, or Na+, is the monovalent cation formed from the alkali metal sodium. In chemistry it carries a single positive charge and tends to form salts with various anions. In aqueous solution it exists as a highly hydrated ion, commonly represented as Na(H2O)6+. Sodium salts are widespread in nature and industry, with sodium chloride (table salt) being the most familiar.

Sodium is the seventh most abundant element in the Earth's crust and is a major constituent of seawater. It occurs mainly in the form of compounds such as halides and silicates. In biological and environmental contexts, Na+ is essential for maintaining osmotic balance and electrochemical gradients. It is a key contributor to nerve impulse transmission and muscle function, notably through the sodium–potassium pump that maintains cellular electrical activity.

In energy storage research, sodium ions are used in sodium-ion batteries as charge carriers. These batteries aim to offer a lower-cost alternative to lithium-ion systems by leveraging the abundance of sodium. Progress has been made in identifying suitable electrode materials for both the cathode and anode, including layered transition metal oxides and hard carbon. Challenges remain in achieving energy density and cycle life comparable to lithium-based systems, but sodium-ion technology is advancing, particularly for grid storage and large-scale applications.

Handling and safety considerations reflect the form involved. Sodium metal is highly reactive with water and air and requires careful handling. Sodium ions in solution are common in biology and the environment and are generally managed through standard chemical and health practices; excessive dietary sodium can have health implications.