Battery Upcycling: Researchers Build Cells From Mixed Battery Waste That Last Nearly Twice as Long

Today, spent lithium-ion batteries are mainly recycled for their metals, while the graphite is often lost along the way. Researchers at Worcester Polytechnic Institute (WPI) have now presented a battery upcycling process that turns mixed battery waste into both a high-performance cathode and battery-grade graphite anode material. Cells built exclusively from these materials withstood roughly twice as many charge cycles as their counterparts made from commercial materials. The results were published in the journal Advanced Energy Materials.

In short: The core idea of battery upcycling is that the materials in spent batteries are not merely recovered but converted into something more valuable and better performing than the original. Using the WPI method, mixed low-nickel cathode waste was turned into an NMC622 cathode and recovered graphite into a new anode, and pouch cells built from them still retained 70% of their capacity after 2,590 cycles.

Why Is Mixed Battery Waste So Hard to Process Today?

As electric vehicles and energy storage systems spread, demand for critical raw materials and the volume of discarded batteries are rising at the same time. It is no coincidence that the lithium-ion battery recycling market is expected to grow several times over in the coming decade. For processors, however, composition is as much of a challenge as volume.

The batteries arriving at recycling plants are rarely uniform. Different manufacturers, model years and cathode chemistries are mixed together, so the black mass produced after shredding varies widely in composition. Most current processes focus on the valuable metals in the cathode – nickel, cobalt, manganese and lithium – but it is difficult to turn mixed waste into a high-value product. Older, low-nickel cathode materials are particularly unprofitable.

Graphite fares even worse, even though earlier work by the WPI group puts it at roughly 12–21% of the mass of spent batteries. In high-temperature smelting (pyrometallurgy) it typically burns off, while in water-based chemical processing (hydrometallurgy) it ends up in the solid residue left after leaching. A 2025 study estimates that more than 500,000 tonnes of spent battery graphite are landfilled worldwide every year.

Several alternative approaches have emerged in recent months. One example is Cornell University’s chemical bath process, which restores the capacity of spent cells without dismantling the electrodes. The WPI approach follows a different logic: rather than repairing the waste, it aims to upgrade it.

How WPI’s Battery Upcycling Method Works

The research was led by Yan Wang, the William B. Smith Professor of Mechanical and Materials Engineering at WPI, with Zeyi Yao as first author. The work consists of two linked processes: one produces the cathode from the waste, the other the anode.

On the cathode side, the starting material is mixed, low-nickel black mass. This is brought into solution through a hydrometallurgical route, and the metals are then resynthesised – using a composition-adjustable process that targets the right metal ratio – into the high-performance cathode material NMC622. NMC622 is a lithium oxide of nickel, manganese and cobalt in a 6:2:2 ratio and one of the widely used cathode types in today’s electric vehicles. Tests showed faster lithium-ion transport and more stable cycling in the resulting material.

The literature distinguishes between direct regeneration and upcycling. The former restores degraded material to its original state, while the latter adapts existing material to the needs of future batteries. The WPI process does the latter: low-value, low-nickel waste becomes a more advanced, higher-value cathode, which is one of the strongest economic arguments for battery upcycling.

Graphite: The Forgotten Anode Material Makes a Comeback

What sets the study apart is that it takes graphite seriously. The researchers treated the solid residue left after leaching the cathode material not as waste but as a secondary raw material. The graphite was purified and surface-modified, producing battery-grade anode material in a closed loop.

According to the measurements, the recycled graphite showed better interfacial kinetics and greater durability. In practice, this shows up in the behaviour of the solid electrolyte interphase (SEI), a thin layer that forms on the anode surface in every lithium-ion battery. To a certain extent it is protective, but if it grows too thick it traps lithium and degrades cell performance. After cycling, a layer of about 320 nanometres formed on commercial graphite, while the fully upcycled material pairing showed only around 240 nanometres – the thinnest of all variants tested.

Recovering graphite is not just a technical issue but also a matter of supply security. Natural graphite is on the European Union’s list of critical raw materials, and global anode material supply is heavily concentrated in one or two countries.

Nearly Twice the Cycle Life in Pouch Cells

In the decisive experiment, the researchers built full pouch cells containing only upcycled cathode and anode materials. These were compared with cells of identical design made from commercial materials.

The result was striking: the cells made from waste showed fewer side reactions and achieved roughly twice the cycle life. They retained 70% of their original capacity after 2,590 charge-discharge cycles. This is notable because electric vehicle batteries are typically considered spent once their capacity drops to 70–80%.

The finding also challenges a long-standing assumption. Many people consider recycled battery materials inherently inferior to primary, mined materials. The WPI experiment suggests that with the right processing, the opposite can be achieved.

What Do the Environmental and Economic Analyses Show?

Using techno-economic and life-cycle analyses, the researchers compared the full process with a reference recycling route. According to the analysis, the process:

• utilises more than 95% of the recycled material,
• could increase process profitability by 22.9%,
• could reduce greenhouse gas emissions by 27.0%,
• could cut energy consumption by 29.4%.

Graphite recovery adds extra processing steps, and these were included in the balance. Even so, the picture was more favourable than for cathode-only solutions. For comparison, an earlier process by the same group, published in Energy Storage Materials, showed 8.6% energy savings and 13.9% lower carbon emissions compared with conventional hydrometallurgy. The two results rely on different reference routes and are therefore not directly comparable, but the direction is clear.

The team has since moved further. With $1 million in support from the US Department of Energy, they are developing a one-step molten salt process that would turn mixed, low-nickel cathode waste into single-crystal NMC622 without additional sorting. Together with Argonne National Laboratory, they have also shown that a mixture of lithium iron phosphate (LFP) and lithium manganese oxide (LMO) cathodes can be converted into higher-energy lithium manganese iron phosphate (LMFP).

Where Caution Is Needed

The results are promising, but the limitations should be clearly understood:

• This is lab-scale work. The pouch cell tests demonstrate the potential well, but industrial-scale continuous production has yet to be proven.
• The environmental figures are model-based. The 27% and 29.4% reductions are estimates relative to a reference route, not measured data from an operating plant.
• Real-world waste is dirtier. The authors themselves note that residual aluminium, copper, iron, electrolyte decomposition products and binders can fluctuate significantly in real mixed battery feedstocks. Higher contamination would increase the purification burden.
• NMC622 contains cobalt. The market is increasingly shifting towards cobalt-free LFP and even more nickel-rich cathodes, so the value of the method also depends on which cathode materials will be in demand over the next decade.
• Patents and non-public data. The authors declare two patent filings: a granted US utility patent covering the cathode upcycling and a provisional application covering graphite recovery. The study’s data are not publicly available and can only be obtained on request. This is common in applied research but worth knowing.
• No collection, no feedstock. However advanced the technology, it can only work with properly collected batteries. Batteries thrown into household waste also pose a serious fire hazard at waste management facilities.

Why Does This Matter for Europe and Hungary?

The EU Battery Regulation sets ambitious targets. By the end of 2027, 50% of lithium must be recovered from waste batteries, rising to 80% by the end of 2031. From 2031, new industrial and EV batteries must contain at least 16% recycled cobalt, 6% lithium and 6% nickel. The regulation sets no separate recovery target for graphite, even though it is a critical raw material. A process that turns graphite into a valuable product as well could fill exactly this gap.

Hungary has become one of Europe’s battery manufacturing hubs, and in the coming years the batteries of the first large generation of electric cars will join production scrap in the waste stream. The domestic debate has so far focused mainly on where and with what technology dismantling and processing plants should be built. In the long run, however, a decisive question is what happens to the black mass. Today it largely goes to processors abroad, but if it could be turned directly into high-value cathode and anode materials, this could also improve the economics of a domestic value chain.

Upcycling, however, is only one part of circularity. The development of a fluorine-free battery binder, for example, shows that processing can be made easier at the design stage. The two approaches complement each other well.

The Bottom Line From a Waste Management Perspective

The WPI research signals a shift in thinking – in the authors’ words, from conventional resource recovery towards value-added remanufacturing. Until now, the goal of battery recycling has been to recover as much metal from waste as possible. Upcycling instead asks what better product can be made from that waste. In this case, the answer is a cell made from waste from cathode to anode that outlasts its counterpart built from mined materials.

Whether this becomes a real industrial shift depends on industrial-scale trials, on handling the contamination of real waste and on the effectiveness of collection systems. The direction, however, is clear: an old battery is not a burden but the raw material of the next generation.

Frequently Asked Questions: Battery Upcycling

What is battery upcycling?

Battery upcycling is a recycling approach that turns the materials of spent batteries into something more valuable and better performing than the original. While direct regeneration restores degraded material to its original state, upcycling adapts it to the needs of future batteries. With the WPI method, for example, low-nickel waste became a high-performance NMC622 cathode.

How does the WPI method differ from conventional battery recycling?

The WPI method produces the anode from waste as well as the cathode. Conventional processes mainly recover nickel, cobalt, manganese and lithium, while graphite often burns off or remains in the leaching residue. The researchers purified and surface-modified this residue, recovering battery-grade graphite anode material in a closed loop instead of discarding it.

How much longer do cells made from upcycled materials last?

Pouch cells built exclusively from upcycled materials lasted roughly twice as many cycles as cells made from commercial materials. They retained 70% of their original capacity after 2,590 charge-discharge cycles and showed fewer side reactions. The interphase layer forming on the graphite was also thinner than on the commercial material.

What are the environmental and economic benefits of the method?

According to the techno-economic and life-cycle analyses, the process utilises more than 95% of the recycled material. Compared with a reference recycling route, it could cut greenhouse gas emissions by 27% and energy use by 29.4%, while raising profitability by 22.9%. These are model-based estimates rather than data measured at an operating plant, so they indicate direction, not guaranteed results.

When could the process be used industrially?

There is no set date yet, because the results are lab-scale. It must first be shown that the process works in industrial-scale continuous production and can cope with fluctuating aluminium, copper, iron and binder contamination in real mixed battery waste. Meanwhile, the research team is also developing a one-step molten salt version.

Why does graphite recovery matter for Europe?

Graphite recovery matters because natural graphite is one of the European Union’s critical raw materials, and anode material supply is heavily concentrated in a few countries. Yet the EU Battery Regulation sets no separate recovery target for graphite, so the graphite in spent batteries is still largely lost today.

🔗 Official sources and references: 👉

• Worcester Polytechnic Institute: WPI Battery Upcycling Research Published in Advanced Energy Materials Shows Upcycled Materials Can Outperform Commercial Counterparts, 16 October 2026.
• Yao, Z., Hou, J., Meng, Z., … Wang, Y.: Upcycling Strategy for Mixed Spent Batteries to Enable NMC622 & Graphite Full Batteries. Advanced Energy Materials, published online 8 October 2026. DOI: 10.1002/aenm.71680
• Worcester Polytechnic Institute: New Worcester Polytechnic Institute Research Could Give Used Electric Vehicle Batteries a Second Life as Higher-Performance Materials, 2026.
• WPI Energy Lab (Yan Wang’s research group): Battery recycling research

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