This simulator models a generic 3 Ah NMC-style teaching lithium-ion cell. Open a wound cell, follow the charge carriers on their two separate paths — lithium ions through the electrolyte-filled separator, electrons through the external circuit — and watch terminal voltage, polarization and delivered energy evolve as you discharge, rest or change the load.
• A real-time 3D cutaway of a wound cell — graphite negative electrode, metal-oxide positive electrode, porous separator/electrolyte, copper and aluminum current collectors, welded tabs, the vented cylindrical can, and the external cell load — with home view, focus-selected-part, full-enclosure toggle, exploded view, auto-rotate, expand and label controls. • Experiment controls for initial SOC (new trial), pack current from −6 A charge to +12 A discharge, ambient temperature (−10 to 45°C) and cell series resistance (0.01 to 0.15 Ω). • Live readouts for state of charge, terminal voltage, pack current, terminal power, cell temperature and delivered energy, plus an operating-sequence readout, switch-state panel and a cell-readings table. • Playback controls: pause/resume, advance 1 s or 60 s, and a speed selector from real time up to 1 hour per second. • An Analysis tab with two charts (operating point and current/voltage history), the model equations (V = OCV(SOC) − IR₀ − Vp, dSOC/dt, dVp/dt, and energy integral) and snapshot measurements. • A Test & diagnose tab with four guided experiments (1C discharge, doubled current, a resistive cell, and voltage relaxation after resting), a model-verification bench of automated checks, and a timestamped event log with a trial-report export. • A Learn & assess tab covering separate transport paths, the complete discharge circuit, why loaded voltage differs from open-circuit voltage, and the difference between ampere-hours and watt-hours, plus a two-question knowledge-check quiz and a written model-scope statement.
During discharge, lithium leaves the lithiated graphite negative electrode. Electrons flow out through the copper current collector, around the external circuit and load, and back in through the aluminum collector to the positive electrode — while lithium ions cross the porous separator through the electrolyte to complete the internal half of the circuit. The separator is an electronic insulator: it never carries electrons, only ions. Reversing the applied current in the simulator reverses both flows, letting you see charge and discharge as mirror-image transport processes.
Terminal voltage under load equals the open-circuit voltage at the current SOC, minus an immediate ohmic drop (I·R₀) and a polarization voltage (Vp) that builds and relaxes over roughly 40 seconds. Pressing "Rest circuit" in the simulator removes the load and lets you watch the ohmic drop vanish instantly while polarization decays over the following seconds — a direct illustration of why a battery's voltage recovers somewhat after you stop drawing current. This is a teaching model: it has no diffusion PDE, aging, hysteresis, lithium plating or gas generation, and coulombic efficiency is fixed at one.
No. The separator is a porous, electrically insulating layer that allows only ionic transport through the electrolyte. Electrons travel exclusively through the external circuit — collectors, tabs and the load — never through the separator.
Applying current introduces an immediate ohmic drop (I times the series resistance R₀) plus a polarization voltage that builds over time. The simulator lets you increase the series resistance control to see this drop grow, and you can rest the circuit to watch polarization relax back toward the open-circuit voltage.
Ampere-hours measure charge moved (current integrated over time); watt-hours measure energy delivered (voltage times current, integrated over time). Because terminal voltage is not constant across a discharge, the delivered energy in watt-hours does not scale linearly with charge removed in ampere-hours — the Analysis tab tracks both.
This is a generic 3 Ah NMC-style teaching cell with an interpolated OCV–SOC curve, a 35 mΩ series resistance and a 20 mΩ / 40 s polarization branch. It excludes diffusion PDEs, aging, hysteresis, lithium plating, gas generation and manufacturer-specific limits, and the ion/electron markers in the 3D view are illustrative and greatly slowed down.