'电池' (diàn chí) literally means 'electric pool'—'电' (diàn) means 'electricity' or 'electric', and '池' (chí) means 'pool' or 'reservoir'. Together, they form a compound noun meaning 'battery', reflecting the idea of a container that stores electrical energy. Unlike English 'battery', which has military origins, Chinese uses a descriptive, functional metaphor: electricity held in reserve, like water in a pool.

This word is used for all common types of batteries—AA, AAA, lithium-ion phone batteries, car batteries, and rechargeable units. It appears frequently in daily life: buying batteries, replacing them in remotes or toys, discussing battery life, or warning about disposal. It's neutral in register, appropriate for spoken and written contexts, and rarely used metaphorically. Note that it’s always a countable noun requiring measure words like '个' or '节' (e.g., 一节电池), not used alone as an uncountable mass noun.