Abstract: An electrochemical device includes a compound that is an isatin derivative. The electrochemical device may be a lithium ion battery, a sodium ion battery, or a redox flow battery, and the isatin derivative may be a bipolar redox active material.

Abstract: An electrochemical device includes a compound that is an isatin derivative. The electrochemical device may be a lithium ion battery, a sodium ion battery, or a redox flow battery, and the isatin derivative may be a bipolar redox active material.

Abstract: A battery cell may include an electrolyte, a first electrode including a first electrode layer and a first current collector, a second electrode including a second electrode layer and a second current collector, a separator interposed between the first electrode and the second electrode, and at least one protective layer. For example, a protective layer may be interposed between the first electrode layer and the first current collector, the second electrode layer and the second current collector, the separator and the first electrode, and/or the separator and the second electrode. When activated, the one or more protective layers may reduce or interrupt current flow through the battery cell. The composition of the one or more protective layers may include one or more small molecule additives to increase its stability and conductivity, thus improving the performance as well as the safety profile of the battery cell.

Abstract: An electrochemical device includes a compound that is an isatin derivative. The electrochemical device may be a lithium ion battery, a sodium ion battery, or a redox flow battery, and the isatin derivative may be a bipolar redox active material.