An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across membrane. The gradient consist of two parts, the electrical potential and a difference in the chemical concentration across a membrane. The difference of electrochemical potentials can be interpreted as a type of potential energy available for work in a cell. The energy is stored in the form of chemical potential, which accounts for an ion's concentration gradient across a cell membrane, and electrostatic energy, which accounts for an ion's tendency to move under influence of the transmembrane potential.
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