Towards the Integration of Direct Contact Prelithiation into the Manufacturing Process for Large-Format Lithium-Ion Batteries

The increasing requirements for high-performance lithium-ion batteries from applications such as electric aviation and electric mobility require further improvement of this energy storage technology. Prelithiation is a method to improve the energy density and lifespan by integrating additional lithium during battery cell production to compensate for occurring irreversible losses of active lithium, which lead to a reduced energy density and capacity fade. Direct contact prelithation incorporates lithium metal in contact to the anode active material to generate a lithium reservoir, which can be consumed by parasitic reactions inside the cell. One factor limiting direct contact prelithiation to laboratory scale is the missing knowledge how to integrate direct contact prelithiation into the manufacturing system of battery cells and how subsequent process steps after lithium insertion are affected. The presented work investigates the effect of direct contact prelithiation on the cell assembly and cell finalization processes of the lithium-ion battery production chain. The occurring challenges to integrate the formed anode-lithium-composite in the cell assembly processes are likely to be similar to those for pure lithium electrodes. The electrolyte filling and formation processes show a high need for adaptation regarding direct contact prelithiation, since the first lithiation of the anode and the formation of the solid electrolyte interphase is already initiated with electrolyte filling. Successful industrialization of direct contact prelithiation requires attention to safety concerns due to exothermic chemical reactions, accurate determination of the solid electrolyte interphase to ensure high cell quality, and streamlining of the currently time-consuming formation process.