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 definition of Coulombic efficiency (CE) in a battery cycle?
Answer: Ratio of charge extracted on discharge to charge input on charge
Coulombic efficiency is the ratio of discharge capacity to charge capacity in a given cycle, reflecting how much charge is lost to side reactions.
Which factor most significantly reduces ionic conductivity of a liquid electrolyte at low temperatures?
Answer: Higher viscosity reducing ion mobility
At low temperatures, electrolyte viscosity increases substantially, slowing ionic mobility and reducing the electrolyte's ability to conduct lithium ions efficiently.
In a lead-acid battery, what is the active material at the positive electrode during discharge?
Answer: Lead dioxide (PbO₂)
During discharge, PbO₂ at the positive electrode is reduced to PbSO₄ as it reacts with sulfate ions from the electrolyte.
What does the term 'intercalation' mean in the context of lithium-ion batteries?
Answer: The insertion of lithium ions into the layered host structure of an electrode without destroying it
Intercalation is the reversible insertion of guest ions (Li⁺) into the interstitial spaces of a host crystal lattice, enabling repeated charge-discharge cycling.
What is the standard reduction potential reference electrode used in aqueous electrochemistry?
Answer: Standard hydrogen electrode (SHE)
The Standard Hydrogen Electrode (SHE) is defined as 0.00 V and serves as the universal reference against which all other electrode potentials are measured.
Which aging mechanism is primarily responsible for capacity fade in NMC cathode materials at elevated voltages?
Answer: Transition metal dissolution and cathode structural degradation
At high voltages, NMC cathodes undergo transition metal (Mn, Ni, Co) dissolution into the electrolyte and phase transformations, causing structural degradation and capacity loss.
What is the relationship between a battery's energy density and power density, often visualized on a Ragone plot?
Answer: Energy density and power density are generally inversely related — high power comes at the cost of lower energy
The Ragone plot shows that devices optimized for high power (like supercapacitors) sacrifice energy density, while high-energy devices (like batteries) deliver lower peak power.