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Li-ion Degradation

Lithium Plating Anode Overpotential Simulator

Estimate lithium plating risk in Li-ion cells using Butler-Volmer kinetics. Sweep anode chemistry, C rate, cell temperature, electrode thickness and particle size to see the anode overpotential, plating margin and cycle life update in real time and find a design that survives low-temperature fast charging.

Parameters
Anode material
Sets lithiation potential U and reference exchange current j0
Charging C rate
C
1C = full charge in one hour; fast charging starts at 2C
Cell temperature T
°C
Low T lowers j0 → larger overpotential → higher plating risk
Anode thickness
μm
Thicker electrodes give more capacity but plate more easily
Active particle size
μm
Electrolyte concentration
mol/L
Cycles so far
cycle
Aging accelerates the fade rate
Results
—
Current density (mA/cm²)
—
Exchange current j₀ (mA/cm²)
—
Anode overpotential (mV)
—
Plating margin (mV)
—
Plating risk
—
Cycle life forecast
—
Cell cross-section & Li plating layer

Li⁺ ions intercalating into the anode (dark grey) together with a Li-metal layer and dendrites that grow when the overpotential is too large. Colour indicates plating risk (green = safe, red = severe).

Plating margin vs cell temperature
Anode material comparison — overpotential & margin
Theory & Key Formulas

$$\eta = \frac{RT}{\alpha F}\ln\frac{j}{j_0},\quad U_{anode} = U_{lithiation} - \eta < 0 \Rightarrow \text{Plating}$$

U_lithiation = 0.1V for graphite, η is the Butler-Volmer overpotential, j₀ falls rapidly with low T (Arrhenius).

$$j_0 = j_{0,\text{ref}}\exp\!\left[-\frac{E_a}{R}\!\left(\frac{1}{T}-\frac{1}{T_{\text{ref}}}\right)\right]$$

E_a ≈ 40 kJ/mol activation energy, T_ref = 298.15 K. The exchange current density is referenced at 25°C.

Lithium Plating — Anode Overpotential & Low-Temperature Fast Charging

🙋
I keep hearing about "lithium plating" in Li-ion batteries. Lithium ions plating out as metal in a lithium battery — isn't that just normal?
🎓
It sounds normal but it is actually the worst kind of degradation. In a healthy charge, Li⁺ ions migrate through the electrolyte and slide between the graphite layers — that is intercalation. Plating is the opposite failure: when the anode potential drops below 0V vs Li/Li+, Li⁺ never makes it inside and instead deposits as metallic lithium on the surface. Once plated, it does not fully strip back during the next discharge; it tears the SEI, grows into dendrites and can pierce the separator, triggering an internal short and thermal runaway. That makes plating the single most safety-critical aging mode for Li-ion cells.
🙋
So when does plating actually happen? Normal charging is fine, right?
🎓
Three conditions stack up: low temperature, fast charging and thick electrodes. The Butler-Volmer equation says the anode potential is pushed down by an overpotential η = (RT/αF) ln(j/j₀). The exchange current density j₀ follows an Arrhenius law and at -10°C it can drop to one third of its room-temperature value. The same current j then produces a much larger η and U_anode = 0.1 - η dives below zero. Move the cell-temperature slider on the left down to -10°C and you will see the plating margin go deeply negative. That is exactly why Tesla and BMW reduce charging current at low temperature.
🙋
When I switched the anode material to LTO the risk dropped to "low" instantly. Is the difference really that big?
🎓
Yes. LTO (lithium titanate) lithiates at 1.55V vs Li/Li+, an enormous head start. Even if η climbs above 1V, U_anode = 1.55 - 1.0 = 0.55V is still safely positive. That is why LTO cells from Toshiba's SCiB family routinely last more than 10,000 cycles and tolerate cold fast charging. The trade-off is energy density: LTO stores roughly half of what graphite does, so it is found in buses and industrial storage. Si-blend anodes (U≈0.3V) sit between graphite and LTO and are today the favourite for high-energy EVs that also want fast charging.
🙋
If plating does happen, can you detect it while the car is on the road?
🎓
That is the job of the BMS. Differential voltage analysis (dV/dQ) and differential thermal voltammetry (dT/dV) are the classic methods, and after a fast charge the relaxation curve shows a characteristic plateau where plated Li strips back into the electrolyte. Production BMSs cannot run heavy DVA in real time, so they precompute a 3-D map of SOC, temperature and C rate and derate the allowable current along the plating boundary. Ahmed Pesaran's group at NREL has published widely on this; the newer in-situ NMR and neutron diffraction work is starting to provide real-time Li-metal quantification in the lab.
🙋
So that's why the predicted cycle life drops when I push "cycles so far" to 2000?
🎓
Exactly. As the cell ages, the SEI thickens, effective j₀ falls and the same fast-charge profile that was safe at 200 cycles can sit on the plating boundary at 2000. This tool uses a 50% fade-rate increase per 1000 cycles as a stand-in. Real cells couple plating with SEI growth, cathode loss and electrolyte breakdown, so for an absolute lifetime forecast you need EIS measurements and ECM fitting — but to ask "is graphite, Si-blend or LTO better for this duty cycle?" this kind of Butler-Volmer model is exactly the right granularity.

Frequently Asked Questions

The anode overpotential follows the Butler-Volmer equation η = (RT/αF) ln(j/j₀). The exchange current density j₀ has a strong Arrhenius temperature dependence and drops sharply when the cell is cold. At low temperature the same charging current density j produces a much larger η, so the anode potential U_anode = U_lithiation - η falls below 0V vs Li/Li+ and metallic Li deposits. Fast charging compounds this by raising j itself, which further increases ln(j/j₀) and pushes the cell deep into the plating regime.
LTO (lithium titanate) has U_lithiation = 1.55V vs Li/Li+, so even with η exceeding 1V the anode potential stays above 0V. Plating is essentially eliminated and cycle life can exceed 10,000 cycles. Si-blend anodes (U around 0.3V) have somewhat more headroom than graphite (U=0.1V) and tolerate higher charge rates. Energy density ranks LTO < graphite < Si-blend, so high-energy EV cells favour Si-blend, long-life industrial / bus packs use LTO, and graphite remains the default.
Common methods are (1) differential voltage analysis DVA tracking peaks in dV/dQ, (2) differential thermal voltammetry DTV using the thermal response, (3) post-charge voltage relaxation analysis showing a plateau from plated Li re-intercalation, and (4) in-situ NMR or neutron diffraction in research. Production BMS units mostly rely on (3) and on temperature-dependent current limits — Tesla's cold-weather charging maps are a well-known example — that derate the allowable current as a function of SOC, temperature and C rate.
The tool only models plating-induced degradation: an empirical fade rate of 0.02%/cycle without plating, plus a margin-proportional acceleration when plating starts. Real cell aging combines SEI growth, cathode degradation, electrolyte decomposition and mechanical stress, so this tool is best used for relative comparisons between design candidates rather than absolute lifetime forecasting. Quantitative lifetime needs dQ/dV analysis and ECM-EIS equivalent-circuit fitting against measurement data.

Real-world applications

EV fast-charging profiles: Tesla Superchargers, IONITY and other 150–350 kW networks need a temperature-aware current taper. A Butler-Volmer model like this one is used to map the boundary at, say, -10°C, 60% SOC and 2.5C and to feed that boundary into the vehicle's BMS charging table. Crossing the boundary even once per visit can age cells noticeably and turn into a warranty recall after a few dozen fast charges.

Stationary storage design: Residential and grid-scale packs are asked to last 10–15 years (3,000–5,000 cycles). LTO-based products (Toshiba SCiB, Altairnano) lithiate at 1.55V and essentially never plate, so they hold up even with cold operation and high C rates. Design teams use simulators like this one to compare candidate chemistries up front and find the LCOE crossover point between NMC/graphite and LTO solutions.

Cell design — electrode thickness & particle size: Pushing anode coating thickness above 100 μm for higher energy density starves the deep electrode of Li⁺ and lowers the effective j₀, accelerating plating. Smaller particles shorten the diffusion length but raise the surface area and the first-cycle SEI loss. This tool quantifies the thickness/particle-size trade-off and helps pick the operating point.

Pre-screening before full multiphysics: Before running COMSOL Battery Module, ANSYS Fluent Battery or Simcenter Battery Design Studio, a quick 0D Butler-Volmer check answers "does this duty cycle even enter the plating regime?" If the boundary conditions are off by 10×, you want to know before refining the mesh. Coupling with NREL's MSMD framework gives even higher fidelity once the operating point is locked in.

Common pitfalls and cautions

The most common misconception is that "as long as the C rate is low, plating cannot happen at low temperature." Lowering j does reduce η, but j₀ has already collapsed at low T, and SEI resistance plus solid-state diffusion limits push the real anode potential lower than the simple model predicts. At -10°C plating has been reported even at 0.5C in published measurements, so treat the tool's output as a baseline and always confirm with DVA or differential-pressure measurements on real cells.

Next, reusing the same cycle-life equation across chemistries. The fade expression here (0.05 + |margin|/100·0.2) is calibrated to NMC/graphite-style behaviour. LFP, LTO, solid-state and Na-ion cells need their own coefficients; LFP in particular has a long voltage plateau that makes SOC estimation difficult and breaks the margin interpretation. Always recalibrate the fade rate against capacity-retention data for each chemistry.

Finally, treating U_lithiation as a constant. The graphite anode potential drops from roughly 0.2V at 0% SOC to 0.06V near 100% SOC. We use a single value of 0.1V as a representative midpoint, but near full charge U is lower and even a small η pushes the cell into plating. Production strategies — tapering current above 80% SOC (CCCV → step-CV), pulse charging — explicitly handle this. Doyle-Newman and Single Particle Models include the SOC dependence directly.

How to Use

  1. Set charge C-rate (0.5C to 3C) and cell temperature (0–60°C) to define electrochemical conditions for your Li-ion cell.
  2. Input graphite anode thickness (50–200 µm) and particle size (0.5–10 µm) to establish surface area and diffusion pathways.
  3. Run the simulator to compute exchange current density (j₀) via Butler-Volmer kinetics, then extract anode overpotential (mV) and plating margin relative to −0.2 V lithium plating threshold.
  4. Interpret plating risk (Safe/Caution/Critical) and projected cycle life degradation from lithium dendrite formation.

Worked Example

A 2.8 Ah pouch cell with 100 µm graphite anode (5 µm particles) charged at 2C and 25°C: charge current density ≈ 3.2 mA/cm², j₀ ≈ 0.15 mA/cm² (standard graphite), computed overpotential ≈ −145 mV. Plating margin = −200 − (−145) = 55 mV (Safe). At 3C and 0°C, overpotential shifts to −185 mV, margin narrows to 15 mV (Caution), forecast cycle life drops 12–18% from accelerated plating kinetics.

Practical Notes

  1. Thinner anodes (≤75 µm) concentrate current density, raising overpotential risk; pair with lower C-rates for automotive cold-start packs.
  2. Sub-5 µm particles reduce effective j₀ by 25–40% due to higher surface roughness; balance with calendering pressure to avoid lithium trapping.
  3. Temperature drop from 25°C to −10°C increases overpotential by ~60 mV; critical for arctic fast-charging where margin collapses below 5 mV, triggering irreversible plating within 50 cycles.
  4. SEI (solid electrolyte interphase) resistance growth adds effective overpotential; use this simulator for freshly formed cells; re-baseline after 10 formation cycles.