Electrochemistry is the branch of physical chemistry that studies the relationship between electricity, as a measurable and quantitative phenomenon, and identifiable chemical change, with either electricity considered an outcome of a particular chemical change or vice versa. These reactions involve electric charges moving between electrodes and an electrolyte (or ionic species in a solution). Thus electrochemistry deals with the interaction between electrical energy and chemical change.When a chemical reaction is caused by an externally supplied current, as in electrolysis, or if an electric current is produced by a spontaneous chemical reaction as in a battery, it is called an electrochemical reaction. Chemical reactions where electrons are transferred directly between molecules and/or atoms are called oxidation-reduction or (redox) reactions. In general, electrochemistry describes the overall reactions when individual redox reactions are separate but connected by an external electric circuit and an intervening electrolyte.

電化學是物理化學的一個分支，研究電作為一種可測量和定量的現象與可識別的化學變化之間的關系，電被認為是特定化學變化的結果，反之亦然。這些反應涉及電極和電解質（或溶液中的離子物質）之間移動的電荷。因此，電化學研究電能和化學變化之間的相互作用。當化學反應是由外部提供的電流引起的，如在電解中，或如果電流是由電池中的自發化學反應產生的，則稱為電化學反應。電子直接在分子和/或原子之間轉移的化學反應稱為氧化還原或（氧化還原）反應。一般來說，電化學描述的是單個氧化還原反應是分開的，但由外部電路和中間電解質連接的總反應。