Prelithiation

Prelithiation is a battery-manufacturing technique in which extra lithium is intentionally introduced into an electrode or cell before normal operation to compensate for lithium consumed during initial irreversible processes. The need for prelithiation arises primarily from first-cycle irreversible capacity loss (ICL) due to solid electrolyte interphase (SEI) formation, side reactions, and structural changes in high-capacity anode materials (for example silicon, tin, or conversion-type oxides). By restoring lithium inventory, prelithiation improves first-cycle coulombic efficiency, usable capacity, and cycle-life performance in full cells.

Common prelithiation approaches include electrochemical methods (lithiation in a half-cell or via lithium metal contact), chemical reagents (solutions of lithium-organic complexes such as lithium naphthalenide or stabilized lithium metal powder, SLMP), physical deposition (thermal evaporation, sputtering or vapor deposition of lithium), and use of sacrificial lithium-containing salts or additives. Process choices depend on material compatibility, desired lithium dose, manufacturing constraints and safety considerations.

Advantages of prelithiation include enabling practical use of high-capacity anodes, reducing the need for excess lithium in the cathode, and improving energy density. Challenges include handling reactive lithium, ensuring uniform lithium distribution, potential side reactions or gas evolution, added cost and process complexity, and long-term stability of prelithiated electrodes. Prelithiation is widely used in research and in some commercial cell designs as a pathway to integrate advanced electrode chemistries while managing lithium balance.