Electrolyte Conductivity and Lithium Ion Battery Manufacturing Vocabulary

Vocabulary flashcards about Electrolyte Conductivity and Lithium Ion Battery Manufacturing.

Ohmic losses

Losses in Li-ion batteries can be significant (∆VOhmic = 0.25V).

Resistance (R)

R = l / (A * κ), where l is the distance of current flow, A is the area over which current flows, and κ is conductivity.

Conductivity (κ)

κ = c * (D+ + D-), where c is electrolyte ion concentration, D+ is positive ion diffusivity and D- is negative ion diffusivity.

Intercalation / Insertion Reaction

Lithium moves into unoccupied sites in the crystal lattice; the lattice may dilate/shrink, but it does not change.

Anti-site defects

Ions swap places, e.g., Ni2+ and Li+. In LFP, Fe atoms block 1D lithium transport channels.

Alloying/Formation Reaction

Lithium alloys with a metal/semiconductor: xLi + yM → LixMy.

Conversion/Displacement Reactions

xLi + MNy → LixNy + M, where Lithium displaces the M from the compound MNy (transition metal oxides, nitrides, phosphides, fluorides).

Formation Cycling

A passivation layer (solid electrolyte interphase, SEI) forms during the initial charge cycle. The SEI protects active materials from further reactions with electrolyte components. Key to stability of cell - lifetime and safety!

Shutdown separators

Polyethylene (PE) melts at 135°C and polypropylene (PP) melts at 170°C. The inner PE layer melts first, and PP provides structural stability to locally shut off battery operation.

Current interrupt device (CID)

Device that cuts off the electrical circuit permanently when triggered by excessive cell pressure, high temperature, or high voltage.

Battery Management System (BMS)

Ensures secure and optimal performance of battery and estimates state-of-function (SOF) based on state of charge (SOC) and state-of-health (SOH).

Electrochemical Degradation

Side reactions (i.e. e– oxidizes electrolyte), electrolyte breakdown, corrosion, lithium plating at the anode surface.

Mechanical Degradation

Volume changes cause stress and structural changes (fracture, delamination, …).

Thermal effects

Resistive heating (i.e., binder melts and changes resistances).

Coulombic efficiency (CE)

Coulombic Efficiency = (Qdischarge) / (Qcharge). Used to predict lifetimes.

Energy cells

Thicker electrodes for more active material (higher energy density). Longer charge/discharge, both charge and discharge are chemistry limited.

Power cells

Thicker current collectors (to minimize resistance and enhance power dissipation) and thinner electrodes (to reduce ionic and electronic resistance). Fast charge & discharge, charging is chemistry limited (less than energy cell), discharge is temperature limited.

Micro Hybrids (Low voltage hybrids)

12V/24V system to power auxiliary systems (e.g., air conditioner, radio) when the car is idling.

Mild/strong hybrids (High voltage hybrids, HEV)

100s of Volts used for load leveling, charged during breaking and discharged during acceleration.

Plug-in hybrid electric vehicles (PHEV)

All-electric drive possible; the battery can be charged externally (or internally).

Full electric vehicles (BEV)

Battery fulfills all vehicle driving requirements; driving range directly related to battery capacity.

Levelized Cost of Electricity (LCOE)

Compares the total costs of a power generation/storage system to the lifetime energy generation/throughput; the constant electricity price [$/kWh] that would be required over the life of the plant to cover all operating expenses, payment of debt and accrued interest on initial project expenses, and the payment of an acceptable return to investors.

Abatement costs (AC)

Indicates how much a policy/project costs per unit of environmental impact reduction provided.