Prelithiation

Prelithiation introduces extra active lithium ions through various lithium sources. These extra lithium ions contribute to the formation of the solid electrolyte interphase (SEI), hence improving the delivered energy density of the cell.

When a lithium ion battery is formed after assembly, SEI on the anode is made. This consumes a large amount of lithium ions and results in a low initial coulombic efficiency and severe decay of energy density. Typically 5 to 15% of the capacity of the cathode is consumed in these reactions when a commercial graphite anode is used. For the case of silicon-based anodes, the lithium loss could more severely impair the energy density.

Prelithiation options fall into two broad categories: cathode-side sacrificial additives, which release extra lithium from the cathode during the first charge and never take part in cycling again, and anode-side methods that deliver lithium metal or lithium ions directly onto or into the anode before the cell is ever assembled.

Cathode-Side Sacrificial Additives

These additives are blended into the cathode slurry in small quantities. Materials include:

  • LFO – Li5FeO4, emerges as a promising candidate for the cathode additive role. boasts a remarkably high theoretical capacity 867 mAh/g, translating to over 700 mAh/g in practical use for storing lithium ions unlike the main cathode material, LFO releases its lithium ions permanently, transforming into an inactive material, amorphous LiFeO2 upon fulfilling its purpose can be easily mixed with LFP cathode powder in the cathode slurry result in uniform coating [4].
  • LNO – Li2NiO2, a lithium-rich nickelate additive with a theoretical first-charge capacity around 320-340 mAh/g. Like LFO it is designed to be irreversible: on first charge to around 4.3 V vs Li/Li+ it undergoes a phase transition into LiNiO2 and NiO, releasing oxygen gas and permanently giving up its lithium to compensate first-cycle losses elsewhere in the cell. Its first-cycle efficiency (roughly 30%) is lower than LFO’s, and the oxygen evolution needs to be managed in cell design, but it has been demonstrated at pouch-cell scale (around 8 wt% loading) supporting good capacity retention over hundreds of cycles [5].

References

  1. Yang, C., Ma, H., Yuan, R. et al. Roll-to-roll prelithiation of lithium-ion battery anodes by transfer printing. Nat Energy 8, 703–713 (2023)
  2. Yi Cui, Pre-Lithiation of High-Capacity Battery Electrodes, Stanford University SLAC National Accelerator Laboratory
  3. Xueqing Min, Gaojie Xu, Bin Xie, Peng Guan, Mingliang Sun, Guanglei Cui, Challenges of prelithiation strategies for next generation high energy lithium-ion batteries, Energy Storage Materials, Volume 47, 2022
  4. Zero degradation CATL battery material (?) – Li5FeO4 (LFO), Commercial Solar Guy

Anode-Side Prelithiation Methods

Rather than sacrificing cathode capacity, these methods put lithium directly onto or into the anode before or during cell assembly. Three approaches dominate the literature and, increasingly, production lines.

Stabilized lithium metal powder (SLMP) is lithium metal microparticles coated with a thin, controlled passivation layer (typically lithium carbonate) so the powder can be handled in a dry room rather than reacting immediately with air. It is applied to the finished anode as a coating — by doctor-blading a dispersion, or by roll-to-roll transfer printing directly onto the electrode web (see reference 1 below) — and once wetted with electrolyte the coating breaks down and the lithium reacts directly with the anode surface, donating its capacity before the first formation cycle. SLMP has been demonstrated on both graphite and silicon-containing anodes, where it is particularly valuable because silicon’s much larger first-cycle irreversible loss is harder to compensate from the cathode side alone. The scalability challenge is less about the chemistry and more about handling: getting a uniform, defect-free powder coating at web speed, in a controlled dry-room environment, without introducing pyrophoric-particle safety risks into a production line built around roll-to-roll processing.

Chemical prelithiation immerses the finished anode in a solution containing a strongly reducing lithium donor — lithium-biphenyl or lithium-naphthalene in an ether solvent are the common examples — which transfers lithium to the electrode on contact. It avoids handling raw lithium metal powder, but the reaction only proceeds where the solution touches the electrode surface, so lithiation of a thick or dense electrode can be uneven, and the solvents involved can attack some binder systems. It also does not fit naturally into a continuous roll-to-roll line, since it needs a dip or soak step and solvent recovery.

Electrochemical prelithiation lithiates the anode by running it as the working electrode against a sacrificial lithium counter-electrode, either in a temporary half-cell or by briefly short-circuiting the assembled electrode against lithium foil. It gives the most precise control over exactly how much lithium is added, but that precision comes at the cost of a manufacturing step that is hard to make continuous: it typically means building and then disassembling a cell, or otherwise interrupting the normal assembly sequence, and a heavily lithiated electrode can also lose mechanical strength before it is reassembled into the final cell.

Across all three anode-side methods, the common thread is that the chemistry to compensate first-cycle loss is well understood; what limits adoption is fitting the process into a roll-to-roll gigafactory line without adding a slow, batch-style step or a new dry-room handling risk. That is also why cathode-side additives — which need no new process step beyond mixing the slurry — remain the default choice for cells that do not need silicon-anode levels of compensation.

Further References

  1. Selective elemental substitutions of transition metals to modulate the reversibility of Li2NiO2 cathode additives for high-energy lithium-ion batteries. ScienceDirect, 2026. sciencedirect.com/science/article/abs/pii/S2405829726001893
  2. Prelithiation strategies for enhancing the performance of lithium-ion batteries. PMC. pmc.ncbi.nlm.nih.gov/articles/PMC11733674/

See also: Binders, Solid Electrolyte Interphase