UHPC Glossary

Short, citable definitions of the terms used across this guide.

Coulombic efficiency (CE)

The ratio of discharge charge to charge charge in one cycle, CE = Q_d / Q_c. Its deviation from 1 measures how much charge is lost to side reactions each cycle. See Coulombic efficiency & cycle life.

Coulombic inefficiency (CIE)

CIE = 1 − CE. Normalised by cycle time, CIE/h, it gives a per-hour rate that makes different cycling rates comparable.

Capacity fade

The irreversible loss of cyclable capacity over cycling, driven by loss of lithium inventory and loss of active material.

Charge-endpoint slippage

The forward drift of each cycle's charge endpoint on a cumulative-capacity axis; a proxy for self-discharge-like side reactions.

Loss of lithium inventory (LLI)

Irreversible immobilisation of active lithium, for example by SEI growth — a primary source of capacity fade.

Loss of active material (LAM)

Deactivation of electrode material or impedance rise that reduces usable capacity.

Full-scale range (FSR)

The basis for quoting current accuracy: a fixed tolerance set by the range, not by the reading. See Measurement & precision.

Electrochemical impedance spectroscopy (EIS)

A small-signal frequency-sweep method that separates ohmic, interfacial, and diffusion resistances; often run alongside UHPC.