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ver the past decade, battery recycling was promoted as a cornerstone of the clean energy transition. Governments invested heavily, mining companies entered the space, and several startups promised a “closed‑loop” system in which end‑of‑life batteries would be transformed directly back into battery‑grade lithium, nickel, cobalt and graphite. However, with the collapse of a major advanced recycling project in 2025 and a general slowdown across the sector, a difficult but necessary question is raised: why has the promise of battery-to-battery recycling failed to materialize?

The answer lies not in market sentiment, but in process engineering. Battery materials are not simple commodities. They are the result of a long chain of chemical and physical transformations, and most recycling approaches underestimate the complexity of reversing that chain.

A modern lithium‑ion battery is built from materials that have been refined, purified, synthesized and structurally engineered through multiple industrial steps. Consider the path of a typical cathode material: mining and concentration, refining to high‑purity minerals/metals, conversion to chemical salts (e.g. nickel sulfate, lithium hydroxide), synthesis of precursor materials with controlled stoichiometry, cathode manufacturing with precise particle morphology, cell assembly, formation and aging.

Each step adds purity, structure and performance characteristics. By the time a material becomes “battery‑grade,” it is no longer a simple chemical; it is a highly engineered product with strict impurity limits and controlled physical properties. Battery recycling processes often attempt to bypass this entire chain.

Most battery recycling operations begin with black mass, a mixture produced by shredding batteries. Black mass typically contains: nickel manganese cobalt (NMC), lithium iron phosphate (LFP), lithium cobalt oxide and other mixed chemistries, graphite, electrolyte residues and aluminum, copper, plastics, binders and fluorinated compounds.

This heterogeneous feedstock is then fed into hydrometallurgical circuits that attempt to extract lithium, nickel, cobalt and manganese in a single integrated process.

The challenge is obvious to any metallurgist: mixed feedstock produces mixed impurities, and no amount of downstream purification can fully compensate for upstream variability.

The result is that recycled outputs often fall short of battery‑grade specifications; not because battery recycling is impossible, but because the process is fundamentally misaligned with how battery materials are originally produced.

Battery‑grade materials require purity levels above 99.5 per cent, tight control of trace impurities (often at the parts per million level), precise stoichiometry, controlled particle size distribution and morphology, and consistent chemical composition across batches.

Recycled materials struggle to meet these requirements for several reasons:
• Mixed chemistries introduce incompatible elements (e.g. iron from LFP contaminating NMC streams);
• Electrolyte residues (e.g. LiPF6) introduce fluorine and phosphorus impurities that are extremely difficult to remove to battery‑grade levels;
• Shredding contamination adds aluminum, copper, plastics and binder‑derived fluorinated compounds; and
• Hydrometallurgical circuits cannot replicate precursor synthesis or cathode manufacturing, which require controlled co‑precipitation, morphology engineering and crystal‑structure development.

In practice, many battery recyclers produced intermediate products, such as crude sulfate solutions or mixed hydroxide precipitates, that required further refining by established chemical producers. The economics quickly deteriorated when companies realized they could not sell battery‑grade materials directly.

Sorting batteries by chemistry before shredding improves recycling quality, but it does not solve the fundamental purity and structural challenges.

Battery recycling remains essential, but the industry must shift from hype to engineering reality. A more viable model includes:

1. Recycling into intermediate products for other industries, such as for metallurgical operations, alloy production, ceramics, catalysts and chemical intermediates. This avoids the purity and morphology requirements of battery‑grade materials.

2. Standardization and pre‑processing of feedstock. OEMs and battery recyclers must collaborate to sort chemistries, remove contaminants and stabilize feedstock quality before hydrometallurgical processing.

3. Integration with existing chemical refiners. Instead of trying to produce battery‑grade materials in one step, recyclers can supply intermediate feedstock to established refiners who already operate at the required purity levels.

4. Acknowledging that “battery‑to‑battery” recycling is a multi‑stage industrial chain and must be treated as such.

A realistic path forward recognizes that battery recycling will play a critical role in the clean energy transition, but not by shortcutting the supply chain. Instead, success will come from integrating recycling into the broader materials ecosystem, producing intermediate products where appropriate and aligning processes with the true nature of battery‑grade materials. And, as interest in rare earth elements recycling gathers investment and policy momentum, we have the opportunity to build on the lessons from battery materials and set a more stable and technically sound path.

Innovation in these fields will continue, but only when grounded in the fundamentals of process engineering.

Manochehr Oliazadeh is technical director, studies, mining, mineral processing and metals at Worley Canada.