In advanced lithium-ion batteries in which a high-voltage cathode, a high-capacity silicon anode, or both are used, a large amount of Li+ ions are irreversibly consumed during initial charge/discharge cycling.  During cycling, not all of the lithium ions diffuse into the anode and some are consumed in side reactions between the electrode and electrolyte. Particularly during fast charging of the battery, lithium dendrites form, which further reduces battery cycle life and causes safety concerns.  Previous approaches compensate for the needed Li+ ion by depositing lithium powder, which is expensive and requires use of toxic solvents to disperse the powder.  Also, preparation of highly uniform lithium compensation layers by dispersion of lithium powders is challenging. Therefore, there is a need for an inexpensive, less toxic and more consistent source of lithium ions for lithium compensation, especially for use in high-voltage cells.

Researchers at PNNL have developed a lithium-ion battery system comprising an anode, an anode current collector, and a layer of lithium metal in contact with the current collector, but not in contact with the anode. The lithium compensation layer dissolves into the electrolyte to compensate for the loss of lithium ions during usage of the full cell. The specific placement of the lithium compensation layer, such that there is no direct physical contact between the lithium compensation layer and the anode, provides certain advantages.