Electrochemical energy storage devices

An electrochemical energy storage system, comprising

• a plurality of energy storage cells, wherein each energy storage cell of said plurality of energy storage cells comprises a negative electrode, a positive electrode, and an electrolyte disposed between the negative electrode and the positive electrode, wherein the electrolyte and at least one of the negative electrode and the positive electrode are in a liquid state at an operating temperature of the energy storage cell, wherein the plurality of energy storage cells are connected in series or parallel,
• wherein the electrochemical energy storage system has a first potential difference between the negative electrode and the positive electrode at a first temperature that is less than about 50° C. and a second potential difference between the negative electrode and positive electrode at a second temperature of at least about 250° C.;
• a frame supporting the plurality of energy storage cells, wherein the frame comprises at least one fluid flow path for bringing a thermal management fluid in thermal communication with at least a subset of the plurality of energy storage cells;
• and
• a thermal insulation surrounding elements of the frame, wherein the thermal insulation enables the electrochemical energy storage system to operate continuously in a self-heated configuration to maintain the operating temperature without an energy source that provides additional energy.