Battery Fundamentals & Electrochemistry Flashcards
7 cards from real BMS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Battery Fundamentals & Electrochemistry flashcards as text
What is the Nernst equation used to calculate in electrochemistry?
Answer: Equilibrium cell potential at non-standard conditions
The Nernst equation relates the equilibrium cell potential to the standard electrode potential, temperature, and the concentrations of reactants and products.
Which phenomenon describes the gradual loss of lithium inventory due to irreversible side reactions at the anode?
Answer: Loss of lithium inventory (LLI)
Loss of lithium inventory (LLI) refers to lithium that becomes electrochemically inactive due to SEI growth, lithium plating, or other side reactions, reducing capacity.
A galvanic cell has a positive standard cell potential (E°cell > 0). What does this indicate?
Answer: The reaction is spontaneous and produces electrical energy
A positive E°cell means the Gibbs free energy change (ΔG) is negative, confirming the electrochemical reaction proceeds spontaneously.
In a lithium-ion cell, what role does the separator play?
Answer: It prevents electronic contact between electrodes while allowing ionic transport
The separator is an electrically insulating but ionically permeable membrane that prevents short circuits while enabling lithium-ion flow between anode and cathode.
What is the primary cause of voltage hysteresis observed during charge and discharge of a battery?
Answer: Polarization effects including ohmic, activation, and concentration losses
Voltage hysteresis arises from polarization losses — ohmic resistance, activation overpotential, and concentration overpotential — causing charge voltage to be higher and discharge voltage to be lower than OCV.
Which electrochemical technique applies a small AC signal across a range of frequencies to characterize battery internal impedance?
Answer: Electrochemical impedance spectroscopy (EIS)
EIS applies sinusoidal voltage or current perturbations at multiple frequencies to separate and quantify ohmic, charge-transfer, and diffusion impedance components.
How does increasing C-rate generally affect the usable capacity of a lithium-ion battery?
Answer: Usable capacity decreases because polarization losses cause earlier voltage cutoff
At higher C-rates, increased polarization losses cause the terminal voltage to reach the cutoff threshold sooner, reducing the amount of capacity that can be extracted.