A research team from the University of California San Diego (UC San Diego), Toyota Research Institute of North America and others has developed a binder called "PCC" that keeps electrodes strong during use but allows the electrode material to be separated with water afterward. In a peer-reviewed paper published on October 9, 2026 in the journal Nature Communications, the team reports a method that replaces conventional fluorine-based binders with a combination of polymer materials that can be processed using water as the solvent. The material holds electrode components firmly in place while the battery is in use and lets them be separated easily once it reaches the end of its life. If both properties can be achieved together, it could reduce the burden on both manufacturing and recycling processes. However, water simplifies only the step of separating the electrode layer; it does not eliminate the processing needed to regenerate degraded materials.
The binder holding the electrode together shapes how hard recycling is
Lithium-ion battery electrodes are made by mixing particles of active material that store electricity with carbon and other conductive materials, then coating the mixture onto metal foil. The binder's job is to link the particles together and fix them to the foil (the current collector) that carries current out. Although it makes up only a small share of the electrode, it greatly influences how easily the electrode can be coated during manufacturing, how durable it is, and how its materials can be separated after use.
Polyvinylidene fluoride (PVDF), widely used in cathodes, has strong adhesion and is electrochemically stable. However, manufacturing electrodes with it requires an organic solvent, N-methyl-2-pyrrolidone (NMP). Beyond drying after coating, equipment to recover and purify the solvent is essential. Recycling also takes effort, such as peeling the electrode layer off the current collector and dealing with residual fluorine-containing components.
Binders that can use water as a solvent, on the other hand, are already in practical use. Cellulose-derived materials and others are used in anodes, and fluorine-free water-soluble binders have also been studied for cathodes.
For example, in 2024, Felix Leibetseder and colleagues reported in the journal Advanced Energy Materials on a cathode that used a different water-soluble polymer. They also ran an experiment in which a nickel-containing NMC622 cathode was treated with ultrasound in water to separate the electrode layer.
The novelty of PCC, therefore, does not lie in the ability to process and separate with water as such. Its distinguishing feature is that, while securing the strength an electrode needs and stability during charging and discharging, the team tested in a series of experiments its potential application to a variety of cathodes and anodes, as well as the reuse of recovered materials.
Citric acid adds three types of bonding to secure electrode strength
PCC is a binder made by combining polyacrylic acid (PAA) and carboxymethyl cellulose (CMC) in a 1:1 ratio and adding citric acid.
PAA readily forms a uniform film and gives the electrode flexibility. CMC, meanwhile, increases rigidity and holds the active material particles together. The team used lithium hydroxide to adjust the PAA dispersion to pH 6, and used citric acid for cross-linking, which connects the polymers to one another.
According to the authors, PCC's network structure is supported mainly by three kinds of interactions.
First, there are hydrogen bonds that draw the polymers together. Second, ester bonds, a type of covalent bond, link the polymer chains. Third, ionic interactions involving lithium ions reinforce the connection between particles and binder.
The team investigated the material's structure and mechanical stability using spectroscopic and thermal analyses, as well as bending tests on the electrodes and tape-based peel tests.
Strengthening the cross-linking between polymers is not always better, though. If the network becomes too dense, the electrolyte has difficulty penetrating it, which impedes the movement of lithium ions.
The paper reports that a composition with PAA and CMC blended 1:1 and 5 to 8 wt% citric acid performed well. What matters is balancing enough strength to hold the electrode materials firmly with a structure that does not obstruct ion movement inside the battery.
In the manufacturing experiments, lithium iron phosphate (LFP) cathodes were made with 97 wt% active material, 1 wt% conductive carbon and 2 wt% binder.
Electrodes using PCC were dried at 60°C for 4 hours, whereas the PVDF electrodes used for comparison were dried under vacuum at 120°C for 12 hours.
With PCC, electrodes could be made at a lower temperature and in a shorter time. However, this is a comparison under laboratory conditions, and it cannot be used directly to calculate energy savings in a factory's drying equipment.
The test batteries also used an organic carbonate electrolyte containing the lithium salt LiPF6. Water is used in electrode manufacturing and in the separation step during recycling; the electrolyte inside the battery has not been replaced with water.
1,600 charge-discharge cycles confirm durability, but stacked cells remain a challenge
The team examined whether electrodes using PCC could maintain performance through repeated charging and discharging.
First, they evaluated the cathode's performance in half cells combining an LFP cathode with lithium metal.
The initial discharge specific capacity was 160.2 mAh/g for the electrode using PCC and 160.5 mAh/g for the electrode using conventional PVDF. The amount of electricity obtainable per gram of active material was nearly the same, so changing the binder barely reduced the initial capacity.
The team also tested single-layer pouch cells that combine a graphite anode and an LFP cathode, closer to actual lithium-ion batteries.
At a temperature of 25±2°C and a charge-discharge rate of C/3, the cells retained 76.4% of their initial capacity after 1,600 cycles. C/3 denotes a current at which the reference capacity is charged or discharged in roughly 3 hours.
This result does not, however, show that the same lifetime would be obtained under fast charging or the varied operating conditions of automotive batteries.
The team also found that cells with multiple stacked electrodes need further improvement.
A five-layer pouch cell had an initial capacity of 156.1 mAh and a capacity retention of 74.5% after 700 cycles. By comparison, at the same 700-cycle mark, the single-layer cell retained 83.5%.
The authors suggest that differences in pressure when electrodes are stacked, in electrolyte distribution and similar factors may have played a role. Good performance in a single-layer cell does not necessarily mean the same performance can be maintained in a larger cell with stacked electrodes.
The team also tested nickel-rich cathodes, manganese-containing phosphate cathodes and silicon anodes.
However, 1,600-cycle pouch-cell tests were not run for every material. For example, the silicon anode used 20 wt% binder, a different formulation from the 2 wt% in the LFP cathode.
Optimization for each type of material will remain necessary, but the potential to apply the binder to both cathodes and anodes matters because it could lead to shared manufacturing and recycling processes.
Soaking in water for 5 minutes with stirring separates the electrode layer, but heat treatment is still required
In the recycling experiments, the team used graphite/LFP pouch cells that had been charged and discharged for 100 cycles.
The researchers disassembled the batteries, placed the PCC cathodes in 20 mL of deionized water and stirred them for 5 minutes. As a result, the electrode layer separated from the aluminum current collector.
For the PVDF cathodes used for comparison, separating the electrode layer took 20 mL of NMP and 2 hours of stirring.
This result suggests that using PCC could substantially shorten the electrode-layer separation step.
Still, being easily separated with water does not mean the material can be reused as-is in new batteries.
Regenerating spent active material requires replenishing lithium and high-temperature heat treatment. The steps carried out in the paper are summarized below.
| Step | LFP cathode using PCC | Graphite anode using PCC |
|---|---|---|
| Separation from current collector | Stirred for 5 minutes in 20 mL of deionized water | Stirred for 5 minutes in 20 mL of deionized water |
| Powder recovery and drying | Centrifugation, three water washes, 12 hours of vacuum drying at 80°C | Centrifugation, three water washes, 12 hours of vacuum drying at 80°C |
| Regeneration of active material | Lithium carbonate added; calcined under argon at 540°C for 3 hours, then at 650°C for 10 hours | Heat-treated under argon at 1,000°C for 4 hours |
Source: Methods section "Direct recycling of LFP and graphite" of the paper published on October 9, 2026. The steps are organized into separation, powder recovery and drying, and material regeneration for laboratory cells used for 100 cycles. The 5-minute figure is the time taken to separate the electrode layer; it does not indicate the total recycling time or the processing speed of industrial equipment.
Compared with methods that recover metals element by element from used batteries and rebuild materials, an approach that reuses the active material while preserving its crystal structure and composition as far as possible is called "direct recycling."
Because LFP does not contain expensive metals such as nickel and cobalt, metal recovery alone makes it hard to earn sufficient revenue. The authors explain that regenerating the material while preserving as much of its value as an active material as possible has an advantage.
The team analyzed the crystal structure and composition of the regenerated LFP and evaluated its performance by building coin cells with the recovered powder.
For LFP regenerated from electrodes using PCC, no fluorine was detected in surface analysis by X-ray photoelectron spectroscopy.
However, in these experiments the team did not quantitatively measure, on a mass basis, how much of the input material was actually recovered.
Recovery of the material's structure and battery performance after regeneration is a separate matter from recovering 100% of the material. Verification, including recovery rates, will be needed for practical use.
Greenhouse gas emissions cut by about 6.9% in modeling; effects at mass-production scale remain to be verified
The team also conducted a life-cycle assessment of the environmental impact of using PCC.
It estimates that, compared with using conventional PVDF, greenhouse gas emissions during manufacturing could be cut by about 6.9% and energy demand by about 9.3%.
The comparison is for a graphite/LFP cell with a capacity of 0.25 kWh, with greenhouse gas emissions falling from 12.81 kg to 11.924 kg per cell. Emissions are expressed in carbon dioxide equivalents.
These are, however, estimates from a model assuming industrial-scale production in the United States, not measured emissions from the small pouch cells made in the laboratory.
The estimates rest on several assumptions.
For example, 95% of the NMP used in PVDF processing is assumed to be recovered. For the active material, 95% is assumed to remain after pretreatment, and 90% of that is regenerated. The overall recovery rate in this case is 85.5%.
Importantly, this 85.5% figure is a computational assumption, not a recovery rate actually measured in experiments using PCC.
Furthermore, the paper does not carry out a formal sensitivity analysis or quantitative uncertainty assessment. The actual environmental benefit could vary depending on the configuration of manufacturing facilities, solvent recovery efficiency and other factors.
Caution is also needed in evaluating costs.
The table of recycling costs in the paper mainly covers input costs required for processing and does not include capital investment, labor, maintenance or similar expenses. The difference between revenue from recovered materials and input costs therefore cannot be taken directly as a recycling plant's profit.
In addition, while PCC itself contains no fluorine, fluorine derived from LiPF6 remains in the battery's electrolyte.
In other words, switching the binder to PCC does not completely remove fluorine or waste from the battery. What is expected is a reduction in the processing and recovery burden attributable to PVDF.
UC San Diego says it will go on to optimize for each electrode material and scale up manufacturing toward commercial production, aiming for practical use through collaboration with industry.
To get to mass production, it will need to be confirmed that sufficient adhesion and ease of ion movement can be maintained even under conditions in which thick electrodes are coated continuously, and how much material can actually be recovered and reused from real spent batteries.
If these challenges can be overcome, battery makers could choose binders by considering not only processability in manufacturing and durability during charging and discharging but also recycling after use. Rethinking the small amount of material that underpins battery performance could potentially change the entire process from manufacturing through disposal and reuse.