Battery materials · Water-based electrode binders

Water-based electrode binders, from material interface to electrode process.

For power and energy-storage batteries, CASU focuses on water-based binder systems for both cathodes and anodes — starting at the interface between binder, active material, conductive additive and current collector, and evaluating formulations under actual mixing, coating, drying and calendering conditions.

CASU has worked with BASF on water-based anode binders for more than five years.

Electrode anatomy Submit an electrode question

Electrode anatomy

Where the binder works inside an electrode.

From aluminium foil to copper foil, cathode, separator and anode stack into one cell unit. The binder network is only a few per cent of the formulation, yet it connects every layer. Hover over the legend to see what each layer does.

Aluminium current collectorThe cathode-side collector. Aqueous cathodes must protect its passive film.
Cathode active particlesLFP or NMC particles that set capacity and voltage.
Conductive additiveBuilds electron pathways between particles and is dispersed together with the binder.
Binder networkTies particles, conductive additive and collector together — one network on each electrode.
SeparatorKeeps the electrodes apart while letting ions through; ceramic coatings rely on binders too.
Graphite particlesThe layered backbone of the anode; aqueous SBR + CMC is the industry mainstream.
Silicon-containing particlesHigher capacity, large volume change in cycling — a harder job for the binder.
Copper current collectorThe anode-side collector; adhesion decides whether the electrode survives calendering and slitting.
Lithium ionsDuring charging they move from the cathode through the separator to the anode.

Cathode & anode

Same water-based approach. Different problems at each electrode.

Water is already the mainstream solvent for anodes; for cathodes it is advancing system by system. The difference comes from the current collector, the potential window and the water sensitivity of the active material.

Dimension	Anode (graphite / Si-containing)	Cathode (LFP / NMC-NCA)
Current collector	Copper foil	Aluminium foil, whose passive film is vulnerable in alkaline slurry
Potential window	Low; reductive stability and SEI	High; binder oxidative stability and CEI, with higher cut-off voltage for NMC
Industry mainstream	Aqueous: SBR + CMC; PAA / PAA-Li often added for silicon	PVDF in NMP; aqueous routes more practical for LFP
Component roles	SBR: elastic particulate bonding and Cu adhesion; CMC: thickening, dispersion, co-binding; PAA: dense carboxyl groups interacting strongly with Si	Candidates include CMC, PAA-type, acrylic / acrylonitrile copolymer latexes; each needs oxidative-stability and adhesion checks
Key processing risks	Settling or gelation, binder migration during drying, calendering springback, Si swelling	Li leaching → pH rise → Al corrosion and H₂ pinholes; particle-surface change; residual moisture
Typical mitigations	Addition sequence and dispersion, drying-rate control, functional latex and blends	pH adjustment (weak acid or PAA), carbon-coated Al, particle coatings, shorter water contact, intensified drying
Key validation	Peel, springback, electrolyte swelling, ICE, DCIR, fast-charge plating, cycling swelling	Slurry pH over time, Al interface, residual moisture, ICE and capacity, DCIR, high-temperature storage and gassing

Aqueous cathodes

Why aqueous cathodes are hard: a chain from particle to current collector.

01
Particles meet water
Li⁺/H⁺ exchange at the surface; residual alkali dissolves.
02
Slurry pH rises
In a 2020 ORNL study, after three days in water, Ni-rich NCA / NMC532 reached pH 11.5–12.5 and Ni-free materials 9.0–10.5.
03
Aluminium passive film is attacked
Corrosion and H₂ evolution, pinholes and blisters, weaker adhesion, higher interfacial resistance.
04
Residual moisture after drying
Reacts with LiPF₆ to form HF, affecting ICE and life.

Typical mitigations

pH adjustment with weak acids or PAA; carbon-coated aluminium foil; particle coatings; shorter water contact and slurry hold times; intensified vacuum drying.

Why LFP is more practical

LFP is nickel-free with a lower potential and shows a smaller pH rise in water; its main challenge is dispersing small, carbon-coated particles in water. Nickel-rich cathodes are still mainly processed with PVDF in NMP.

Data: Hawley et al., J. Power Sources 466 (2020) 228315 (ORNL).

Anode routes

Graphite, silicon-containing, silicon-rich: different routes, different binder jobs.

Power cells are mainly LFP–graphite and NMC/NCA–graphite; SiOx / Si-C-containing anodes appear mainly in high-energy or fast-charge projects, with silicon level, surface state and chemistry confirmed per project.

GIn engineering use

Graphite anodes

Main task: Stabilise the slurry, build cohesion and copper adhesion, and keep the electrode intact through calendering, slitting and electrolyte exposure.
Candidate roles: Carboxylated SBR latex provides elastic particulate bonding and copper adhesion; water-soluble CMC provides thickening, dispersion and co-binding; PAA / polyacrylates are an independent variable assessed against project goals. They are not interchangeable.
Watch: Colloidal stability, CMC compatibility, coatability, peel, springback, electrolyte sensitivity.

Si-LIn use + ongoing development

Low-Si / SiOx / Si-C anodes

Main task: On top of graphite processability, manage silicon volume change, interfacial contact and SEI stability.
Candidate roles: Functionalised SBR / CMC, PAA / polyacrylates, or blends combining elasticity with strong interaction.
Watch: Si level, particle surface, prelithiation, swelling, impedance, fast charge. For PAA, the degree of neutralisation affects slurry pH, viscosity and ICE and must be fixed before comparison.

Si-HDevelopment frontier / early commercial (system-dependent)

Silicon-rich / silicon-dominant anodes

Main task: The binder must move from fixing particles to a recoverable, stress-dissipating network that takes part in interface stability.
Candidate roles: Strongly carboxylic PAA / polyacrylates, modified polysaccharides, composite or in-situ cross-linked polymer networks.
Watch: Cross-link density versus extensibility, ion transport, ICE, thickness change, long-term interface evolution.

By battery type

Start with the battery type to ask the right questions.

The same binder system has different jobs in different chemistries and applications. Below are common industry considerations; actual requirements depend on cell design.

Cell chemistry (Li-ion, Na-ion, etc.) is treated as a separate project input, judged apart from application and cell architecture.
Type	Typical pairing	Service priorities	Cathode-side focus	Anode-side focus	Aqueous route
LFP stationary	LFP / graphite	Cycle and calendar life, consistency, cost	Dispersion of small carbon-coated particles; cracking in high-loading coatings	Integrity at low dosage; long-term wet adhesion	Anode mature; cathode assessable
LFP traction	LFP / graphite	Fast charge, low temperature, volumetric density	Adhesion and conductive network at high compaction	Ion pathways, plating, springback	Anode mature; cathode assessable
NMC / Ni-rich traction	NMC, NCA / graphite or Si	Energy density, fast charge, safety margin	Oxidative stability, residual alkali, humidity control	Si swelling, Cu adhesion	Anode mature; aqueous cathode challenging
Si-C fast charge	NMC or LFP / graphite + SiOx, Si-C	Fast charge, energy density	Per cathode	Volume change, SEI, PAA neutralisation, elastic blends	Aqueous anode mainstream
Sodium-ion	Layered oxide, polyanion or Prussian-type / hard carbon	Low-T, cost, safety	Layered oxides sensitive to water and alkali	Hard-carbon porosity and CMC uptake; Al foil possible on anode	Anode assessable; cathode system-dependent
Hybrid solid–liquid (semi-solid)	Mostly conventional electrodes + in-situ solidified or gel electrolyte	Safety, energy density	Compatibility with in-situ polymerisation	As liquid cells, plus compatibility	Most public routes start from wet electrodes
All-solid-state (sulfide)	Composite cathode / Si–graphite–SE composite or Li metal	Safety, energy density	Solid–solid contact, pressure dependence	Contact retention under volume change	Aqueous generally unsuitable (sulfides react with water)

Selection logic

Start from the electrode and converge in four steps.

Choosing a binder system is not picking a grade; it is fixing the electrode, materials, process and pass criteria in order.

01
Separate cathode and anode
Current collector, potential window and failure modes differ, so solutions split from the start.
Questions to answerCathode or anode? Copper, aluminium or carbon-coated aluminium foil?
02
Chemistry and active material
LFP, NMC, graphite, silicon or hard carbon each set their own dispersion and interface demands.
Questions to answerWhat are the particle size, surface area, surface state and silicon level?
03
Match the process window
The formulation must stay controllable on the existing mixing, coating, drying and calendering line.
Questions to answerWhat are the solids, coating speed, drying capacity and target density?
04
Define the pass criteria
Same-condition references decide whether a solution continues, changes or stops.
Questions to answerWhich metrics, against which reference, with what pass line?

Process window

From slurry to cell: find the variables across nine steps.

This chain applies to aqueous or wet particulate coating; dry, all-solid-state and lithium-metal / anode-free routes need redefined steps and observables.

Step	Control	Observe	Binder-related issues
1 Mixing & dispersion	Sequence, solids, shear history, temperature, pH (cathode: track over time)	Viscosity curve, thixotropy, fineness, zeta potential	Incomplete CMC dissolution, latex breakdown, cathode pH drift
2 Storage & delivery	Hold time, agitation, filtration, line shear	Viscosity drift, settling, filter ΔP, bubbles	Settling, shear-induced coagulation, gelation
3 Coating	Method, speed, wet thickness, loading	Loading uniformity, edges, streaks, pinholes	Levelling, edge build-up, cathode pinholes (H₂-related)
4 Drying	Temperature profile, airflow, zones, residual moisture	Binder distribution (cross-section EDS), cracks, curl	Binder migration to the surface, weaker base adhesion, higher surface resistance; thick-coating cracks
5 Calendering	Density, roll temperature, passes	Springback, porosity, peel, bend, dusting	Excess springback, brittleness, edge dusting
6 Slitting & assembly	Blade, tension, winding / stacking	Burrs, dusting, edge cracks	Insufficient cohesion
7 Vacuum drying	Temperature, vacuum, time	Electrode moisture	Residual water reacting with LiPF₆ to form HF
8 Filling & formation	Electrolyte, protocol, temperature, pressure	ICE, gassing, thickness	Binder swelling; SEI / CEI differences
9 Cell validation	Reference, areal capacity, N/P, temperature, rate	DCIR / EIS, rate, low-T, fast charge, cycling, swelling, teardown	Is the binder the principal cause?

Troubleshooting

Start from the symptom, and rule out non-binder causes first.

Many “binder problems” originate in materials, process or test conditions. Common checks are listed below.

Symptom	Possible factors (incl. non-binder)	Check first
Settling, separation	Insufficient thickening, poor dispersion, particle changes	Viscosity and thixotropy, sequence, CMC dissolution
Gelation or viscosity drift	Shear-induced latex coagulation, pH change, cathode residual alkali	Hold time and shear history, pH over time
Pinholes or bubbles	Entrained air; H₂ from Al corrosion in aqueous cathodes	Degassing, slurry pH, foil surface
Drying cracks (thick coatings)	Fast drying, capillary stress, low flexibility	Drying profile, loading, binder ratio
Low peel, base delamination	Binder migration, collector surface, dosage	Cross-section binder distribution, collector, drying rate
High springback	Elastic fraction, particle hardness, density window	Density–springback curve
Dusting, edge cracks	Low cohesion, over-compaction, blade condition	Bend test, edge morphology
High DCIR	Binder-rich surface, weak conductive network, interphases	Cross-section, EIS, reference electrode
Fast-charge plating	Tortuosity, dense surface layer, loading	Porosity, surface morphology, N/P
Cycling swelling	Si volume change, network recovery, SEI growth	Si level, teardown failure location

Trends

Technology trends, by maturity.

Public industry signals as of October 2026, ordered by maturity from engineering use to chemistry change.

01 · In engineering use

Aqueous graphite anodes

SBR + CMC is the industry mainstream for graphite; competition has moved to low dosage and consistency under fast charge and long cycling.

02 · Scale-up

Binders and blends for silicon anodes

SiOx / Si-C use is expanding in high-energy and fast-charge projects; blends of elastic and strongly interacting components and PAA neutralisation are key variables.

03 · System by system

Aqueous cathodes

LFP is the more practical entry point; Ni-rich NMC is still mainly PVDF / NMP. pH, the aluminium interface and residual moisture decide feasibility.

04 · Early industrialisation

Dry (solvent-free) electrodes

Powder mixing, fibrillation or hot-press film forming replace slurry coating. Some manufacturers report production use, but wet processing remains mainstream. PTFE-type binders face PFAS scrutiny; fluorine-free alternatives are under research. Dry processing is a separate branch; waterborne-latex experience does not transfer directly.

05 · Research frontier

All-solid-state composite electrodes

Sulfide solid electrolytes decompose on contact with water and oxides are moisture-sensitive, so aqueous slurries are generally unsuitable; published work mostly uses low-polarity solvents or dry forming. Tracked here as a watch item only.

06 · Chemistry change

Sodium-ion

Hard carbon dominates Na-ion anodes; because sodium does not alloy with aluminium, the anode can use aluminium foil, changing the adhesion substrate. Layered-oxide cathodes are more moisture- and alkali-sensitive; polyanionic materials are comparatively stable. Lithium-ion experience needs separate validation.

FAQ

Twelve questions engineers often ask.

Can water-based binders be used for cathodes?

Yes, but it is harder than for anodes. Cathode particles leach lithium in water, raising slurry pH and risking aluminium-collector corrosion, and residual moisture must be tightly controlled. LFP is less water-sensitive and is the more practical aqueous route; nickel-rich cathodes are still mainly processed with PVDF in NMP.

Why do SBR and CMC usually appear together?

They do different jobs: SBR latex provides elastic bonding and copper adhesion; CMC thickens and stabilises the slurry and contributes to bonding. SBR alone cannot keep graphite slurry stable, and CMC alone gives brittle electrodes.

Do silicon anodes always need PAA?

No. PAA-type binders interact strongly with silicon and are common in Si-containing anodes, but they are stiff, and the degree of neutralisation affects pH, viscosity and ICE. The choice and any blend depend on silicon level, particle surface and process, and need controlled comparison.

Is higher peel strength always better?

No. Peel describes one interface; cohesion, springback, electrolyte swelling, resistance and cycling must be read together. Peel values without method and conditions are not comparable.

Can sodium-ion cells reuse lithium-ion anode binder solutions?

Not directly. Hard carbon differs from graphite in porosity and surface chemistry; Na-ion anodes can use aluminium foil, changing the adhesion substrate; layered-oxide cathodes are more moisture-sensitive. Separate validation is required.

Will dry electrodes replace aqueous processing?

Dry processing is a separate branch that removes solvent and drying energy. It is in early industrialisation, and wet processing remains mainstream. Binder forms and test methods differ, so the two are not simple substitutes.

Do all-solid-state batteries use water-based binders?

Sulfide and other solid electrolytes decompose in water, so composite electrodes for all-solid-state cells generally avoid aqueous slurries; published work uses low-polarity solvents or dry processing. Most public hybrid solid–liquid (“semi-solid”) routes start from conventional electrodes and are closer to aqueous anode practice.

What stages does a new binder evaluation go through?

Typically slurry and electrode screening, then coin-cell or small-pouch comparison, then validation closer to line conditions. Each step fixes a reference system and method, and defines the decision it must support.

Is lower binder dosage always better?

Lower dosage raises the active-material fraction and lowers resistance, but it narrows the margin for cohesion and adhesion. Dosage is set together with particle surface area, press density and cycling targets, and reduced step by step while the electrode stays intact.

Do separator coatings need binders too?

Yes. Ceramic or boehmite coatings are held on the separator by a binder, which affects coating adhesion, thermal shrinkage and air permeability; aqueous systems are one of the main routes.

How do we know the binder is the cause?

Use references: keep active material, conductive additive and process fixed and change only the binder, while checking slurry, drying and test conditions. The troubleshooting table on this page lists common non-binder causes.

Can you provide samples or technical information?

Yes, arranged project by project. Tell us the application, electrode system and current issue via the contact page, and we will set out the next steps for information, samples and evaluation.

Glossary

Water-based binder: An electrode binder dispersed or dissolved in water, including latex types (e.g. SBR) and water-soluble types (e.g. CMC, PAA).
Carboxylated SBR latex: Common elastic particulate binder for anodes, bonding particles by point contact and adhering to copper foil.
CMC: Water-soluble thickener, dispersant and co-binder; degree of substitution and molecular weight affect viscosity and stability.
PAA / PAA-Li: High-carboxyl polymers that interact strongly with silicon; neutralisation affects pH, viscosity and ICE.
PVDF / NMP: Mainstream solvent-based cathode binder system; PVDF dissolved in N-methyl-2-pyrrolidone.
Lithium leaching / residual alkali: Li⁺/H⁺ exchange of cathode particles in water and dissolution of surface LiOH, Li₂CO₃; stronger for Ni-rich materials.
Carbon-coated aluminium foil: Aluminium foil with a conductive coating that improves adhesion, lowers interfacial resistance and mitigates corrosion in aqueous processing.
Binder migration: Binder enrichment toward the coating surface as solvent evaporates during drying.
Peel strength: Adhesion between coating and current collector; method, angle, width and conditions must be stated.
Springback: Recovery of electrode thickness after calendering.
SEI / CEI: Interphases formed between anode / cathode and electrolyte.
ICE: Initial coulombic efficiency of the first charge–discharge.
DCIR / EIS: Direct-current internal resistance / electrochemical impedance spectroscopy; state SOC, temperature and method.
Hybrid solid–liquid battery: Category term used in GB/T 48093.1-2026, often called “semi-solid”.
Dry electrode: Solvent-free electrode forming from powders, commonly using PTFE fibrillation.
Slurry rheology / thixotropy: How slurry viscosity changes with shear rate and time; it sets the coating window and storage stability.
Areal loading / press density: Active-material mass per unit area / electrode density after calendering.
Lithium plating: Lithium deposited on the anode surface during fast charging or at low temperature, affecting safety and life.
LFP: Olivine lithium iron phosphate cathode with lower potential and lower water sensitivity, a mainstream cathode for storage and traction.
NMC / NCA (Ni-rich): Layered-oxide cathodes with high energy density, more sensitive to water, humidity and high potential.
Hard carbon: The mainstream sodium-ion anode; its porosity and surface chemistry affect ICE and slurry behaviour.
All-solid-state battery: A cell whose ion transport runs entirely through solid electrolytes; sulfide electrolytes decompose in water.
Separator coating: A ceramic or polymer layer on the separator for heat resistance and safety, held in place by a binder.
Cross-linking: Chemical or physical links between polymer chains that raise network cohesion and resistance to deformation.
PFAS: Per- and polyfluoroalkyl substances; the EU’s universal restriction proposal brings fluoropolymers into scope.

Project brief

Turn your electrode question into a testable project brief.

Bring this information and the discussion gets to the point faster. A first conversation needs no confidential formulations — ranges or “unknown” are fine.

A
Application & cell
Application; chemistry (LFP, NMC with Ni level, sodium-ion, etc.); cell format and approximate capacity; main target (fast charge, low-T, life, cost, energy density).
B
Electrode & materials
Cathode or anode; active material (graphite, SiOx, Si-C with approximate Si level, hard carbon; LFP particle size and coating, NMC grade); conductive additive; current collector (Cu, Al, carbon-coated Al).
C
Incumbent system
Binder type and approximate dosage; slurry solids; any aqueous-cathode trials so far.
D
Process window
Mixer and addition sequence; coating method and speed; drying zones and temperatures; target loading and density; springback.
E
Symptoms & goal
Current issues; the decision the next test must support (e.g. “is a pilot worthwhile?”).
F
Samples & timing
Available samples or reference electrodes; desired milestones; applicable standards or customer specifications.

Build a project brief online Contact us directly

Sources

References and further reading.

Public research, manufacturer documentation and industry signals behind the technical judgements on this page.

Water-based electrode binders, from material interface to electrode process.

Where the binder works inside an electrode.

Same water-based approach. Different problems at each electrode.

Why aqueous cathodes are hard: a chain from particle to current collector.

Particles meet water

Slurry pH rises

Aluminium passive film is attacked

Residual moisture after drying

Typical mitigations

Why LFP is more practical

Graphite, silicon-containing, silicon-rich: different routes, different binder jobs.

Graphite anodes

Low-Si / SiOx / Si-C anodes

Silicon-rich / silicon-dominant anodes

Start with the battery type to ask the right questions.

Start from the electrode and converge in four steps.

Separate cathode and anode

Chemistry and active material

Match the process window

Define the pass criteria

From slurry to cell: find the variables across nine steps.

Start from the symptom, and rule out non-binder causes first.

Technology trends, by maturity.

Aqueous graphite anodes

Binders and blends for silicon anodes

Aqueous cathodes

Dry (solvent-free) electrodes

All-solid-state composite electrodes

Sodium-ion

Twelve questions engineers often ask.

Turn your electrode question into a testable project brief.

Application & cell

Electrode & materials

Incumbent system

Process window

Symptoms & goal

Samples & timing

References and further reading.