Hydrogen-enabled battery recycling: Technologies, process integration, and techno-economic analysis

The growing demand for electric vehicles and portable electronics has created unprecedented accumulation of lithium-ion battery waste, generating urgent environmental and economic imperatives for sustainable recycling. This comprehensive review examines the integration of green hydrogen technologies with battery recycling processes through systematic analysis of 170 peer-reviewed studies published between 2020–2025. Hydrogen reduction methods achieve exceptional metal recovery rates (lithium 99.3%, cobalt 99.4%, nickel 99.8%) while consuming only 2.1 kWh/kg of processed material. A critical analysis of environmental performance reveals that hydrogen reduction produces zero direct CO₂ emissions during metal recovery phases; however, complete cradle-to-gate life-cycle assessment accounting for electrolyzer manufacturing, renewable electricity generation, and facility construction yields 0.15–0.30 kg CO₂-eq/kg—still representing 80–90% reduction versus pyrometallurgical methods (8.5 kg CO₂-eq/kg). Techno-economic analysis demonstrates internal rates of return between 18–42% and 2–8 year payback periods when facilities access premium battery-grade material markets, though financial viability shows high sensitivity to metal price fluctuations (±20% price changes = ±25% IRR variation). Alkaline electrolysis technology reaches full commercialization (TRL 9), while Anion-Exchange Membrane systems remain at TRL 6–7 due to membrane durability limitations requiring 50,000+ operating hour validation. Hydrogen reduction processes currently operate at TRL 5–7 depending on specific process variants; integrated facility operations remain at TRL 4–5. Critical barriers to commercial deployment include: (1) scaling hydrogen reduction from batch to continuous fluidized-bed reactors while maintaining ±5°C temperature precision; (2) hydrogen infrastructure development or on-site electrolysis cost amortization; (3) achieving >99.9% purity specifications through multi-stage purification; (4) supply chain optimization for consistent 1,000+ ton/year feedstock. This review identifies that process intensification through microwave-assisted heating and integration with second-life battery systems offer promising pathways for reducing processing times by 50% while maximizing resource utilization. Future research priorities must address AEM membrane degradation mechanisms, continuous reactor thermal management, and cost-effective purification methods. The convergence of declining renewable energy costs and circular economy policy creates near-term deployment opportunity, contingent upon resolving identified TRL advancement gaps and supply chain constraints.