Prelithiation techniques have emerged as a critical innovation in battery manufacturing, designed to compensate for lithium losses during initial cycles while simultaneously enabling more efficient lithium recovery during recycling. These methods fall into two primary categories: sacrificial lithium additives and direct coating methods. Both approaches influence black mass composition, require adjustments to hydrometallurgical processing, and introduce economic considerations for recovered lithium value chains. Additionally, safety controls must address reactive lithium residues during shredding.

Sacrificial lithium additives, such as Li5FeO4 and Li2O, are incorporated into the anode or cathode during cell manufacturing. These compounds release lithium ions during the first charge cycle, replenishing the irreversible capacity loss that occurs due to solid electrolyte interphase (SEI) formation. Li5FeO4 offers a high theoretical capacity of 700 mAh/g and decomposes into electrochemically inactive LiFeO2 and Li2O, which remain in the electrode. Li2O, with a higher lithium content, decomposes into oxygen and lithium ions but requires careful handling due to its reactivity with moisture. The presence of these decomposition products in spent batteries alters black mass composition, introducing additional metal oxides that must be accounted for during recycling.

Direct coating methods involve pre-depositing lithium metal or lithium-containing compounds onto anode materials before cell assembly. Techniques such as physical vapor deposition, electrochemical prelithiation, or slurry-based coating create a lithium reservoir that migrates into the anode during cycling. Unlike sacrificial additives, direct coatings often leave minimal residual compounds, simplifying black mass processing. However, they require precise control during manufacturing to prevent premature reactions with electrolytes or moisture exposure.

The choice between sacrificial additives and direct coatings significantly impacts hydrometallurgical recycling. Black mass derived from cells with Li5FeO4 contains iron oxides, necessitating additional leaching steps to separate iron from valuable metals like nickel, cobalt, and manganese. Sulfuric acid leaching, commonly used in lithium-ion battery recycling, must be adjusted to account for the solubility of LiFeO2. In contrast, black mass from Li2O-containing cells introduces excess lithium oxides, which can be recovered through water leaching before acid treatment. Direct coating methods produce cleaner black mass with fewer secondary phases, streamlining metal recovery but requiring specialized processes to extract lithium from prelithiated graphite or silicon anodes.

Economic models for recovered lithium value chains must consider the trade-offs between additive costs, processing complexity, and lithium yield. Sacrificial additives increase initial material expenses but improve overall lithium recovery rates, justifying their use in high-value applications. For example, Li5FeO4-additive-based recycling can recover up to 95% of available lithium, whereas direct coating methods may achieve slightly lower yields due to lithium trapped in SEI layers. However, direct coatings reduce downstream processing costs by minimizing impurity removal steps. The economic viability of each method depends on lithium market prices, recycling infrastructure, and regulatory incentives for sustainable material recovery.

Safety controls are paramount when handling prelithiated anodes during shredding and mechanical processing. Residual lithium in spent anodes, particularly from direct coatings, reacts exothermically with moisture or oxygen, posing fire and explosion risks. Shredding must occur in inert atmospheres or with nitrogen blanketing to prevent ignition. Moisture content in black mass should be monitored and controlled below 50 ppm to minimize reactivity. Additionally, thermal imaging and gas detection systems are essential for early hazard identification in recycling facilities.

The integration of prelithiation techniques into battery design aligns with circular economy principles by enhancing lithium recovery efficiency. Sacrificial additives offer a balance between performance and recyclability but require adapted hydrometallurgical processes. Direct coatings simplify recycling but demand stringent safety protocols. As battery manufacturers and recyclers collaborate to standardize these methods, the industry moves closer to closed-loop lithium utilization, reducing reliance on primary lithium resources and minimizing environmental impact. Future advancements will likely focus on optimizing additive formulations and coating techniques to further improve recovery rates while maintaining cost competitiveness.