Electrolyte recovery from spent lithium-ion batteries presents significant technical challenges due to the complex composition and hazardous nature of these materials. A comprehensive recovery flowsheet must integrate mechanical, thermal, and chemical processing steps to maximize the reclamation of valuable electrolyte components such as lithium salts, organic carbonates, and fluorinated additives. The following sequential approach outlines an optimized recovery pathway for mixed chemistry battery streams.

The first stage involves mechanical pre-treatment to access the electrolyte. Battery packs undergo discharge and dismantling to module or cell level. Automated disassembly lines with robotic arms and vision systems separate metallic casings, followed by shredding under inert atmosphere to prevent combustion. The shredded material passes through a sieving system to separate coarse metallic fractions from finer electrode and separator materials. A cyclone separator further isolates the electrolyte-soaked polymer and powder fractions, which carry the majority of the liquid electrolyte components. For a typical NMC battery stream, this step recovers approximately 60-70% of the original electrolyte mass in the fines fraction.

Thermal processing follows mechanical separation. The electrolyte-rich fines undergo vacuum distillation at controlled temperature profiles. Initial heating to 80-100°C under 10-20 mbar pressure evaporates volatile dimethyl carbonate and diethyl carbonate solvents, which condense in a chilled recovery unit. Subsequent temperature increase to 150-180°C recovers ethylene carbonate and propylene carbonate. The distillation system incorporates multiple condensation stages with temperature-controlled traps to separate solvent fractions by boiling point. Thermal gravimetric analysis indicates 85-90% recovery efficiency for organic carbonates using this approach. Residual solids from distillation proceed to lithium salt recovery.

Chemical processing targets the remaining electrolyte components in the thermally treated solids. The material undergoes leaching in a closed reactor using supercritical CO2 with ethanol as a modifier. This extracts lithium hexafluorophosphate and fluorinated additives with minimal decomposition. The supercritical fluid system operates at 80°C and 150 bar, achieving extraction efficiencies of 75-80% for lithium salts. Subsequent purification employs nanofiltration membranes with 200-300 Dalton cutoff to separate lithium salts from organic residues. The final lithium salt solution undergoes crystallization to produce battery-grade LiPF6 or conversion to more stable compounds like LiF.

Control systems integrate these processing stages through a distributed architecture. Programmable logic controllers manage individual unit operations with supervisory control and data acquisition systems providing overall coordination. Critical parameters include oxygen levels in mechanical processing, temperature and pressure profiles in thermal stages, and flow rates in chemical extraction. Mass balance tracking employs real-time sensors for solvent vapors, lithium concentration, and flow rates. A typical mass balance for 1000 kg of processed batteries yields 120-150 kg of recovered organic solvents and 8-10 kg of lithium salts.

Optimization for mixed chemistry streams requires adaptive processing. Nickel-rich chemistries demand lower thermal treatment temperatures to prevent nickel-catalyzed electrolyte decomposition, while LFP batteries tolerate higher temperatures. Automated sorting based on X-ray fluorescence analysis enables stream-specific parameter adjustment. Machine learning algorithms process historical recovery data to optimize temperature profiles and solvent ratios for different input mixtures.

Equipment interfacing challenges center on material transfer between processing stages. Airtight conveyors transport shredded materials to thermal systems, while specialized pumps handle supercritical fluids between extraction and separation units. All connections incorporate explosion-proof designs and leak detection systems. Maintenance protocols emphasize cleaning cycles to prevent cross-contamination between different battery chemistry streams.

The integrated flowsheet demonstrates significant advantages over single-method approaches. Combined mechanical-thermal-chemical processing achieves 70-75% total electrolyte component recovery compared to 40-50% for standalone methods. Energy consumption analysis shows 30% reduction versus separate processing lines due to heat integration between thermal and chemical stages. The modular design accommodates varying feed compositions while maintaining consistent output quality through advanced control strategies.

Future developments may incorporate solvent extraction improvements using ionic liquids and membrane-based separation enhancements. However, the current integrated flowsheet provides a technically viable solution for large-scale electrolyte recovery, addressing both economic and environmental requirements for sustainable battery recycling. Process validation at pilot scale confirms the technical feasibility, with commercial deployment requiring further scale-up engineering and regulatory approvals for handling fluorinated compounds.