Intro

Question 1

Electrochemical Cell

Answer 1

A device facilitating the generation of electrical energy from chemical reactions or vice versa.

Question 2

Supercapacitor

Answer 2

A device facilitating the generation of electrical energy from stored charges on/near electrode surfaces. They typically have higher power and higher cycle life, but lower energy and lower charge retention traits than electrochemical cells.

Question 3

Anode (-)

Answer 3

The negative terminal/electrode/half-cell during use/discharge of a battery. Oxidation reactions occur here.

Question 4

Half-Cell

Answer 4

A full electrochemical cell consists of two half-cells, one for the oxidation reactions (losing electrons to their current collector) and the other for the reduction reactions (gaining electrons from their current collector). A half-cell can also refer to an electrochemical cell in which one electrode is a pure reference electrode, like lithium metal.

Question 5

Cathode (+)

Answer 5

The positive terminal/electrode/half-cell during use/discharge of a battery. Reduction reactions occur here.

Question 6

Battery

Answer 6

A device consisting of one or more electrochemical cells, in which chemical energy is converted into electricity and used as a power source.

Question 7

Primary Battery

Answer 7

A battery utilizing an irreversible electrochemical reaction and assembled in a fully charged state.

Question 8

Secondary Battery

Answer 8

A battery utilizing a reversible electrochemical reaction and typically assembled in an uncharged state that requires a specialized formation charge before use.

Question 9

Formation

Answer 9

An electrochemical process typically involving a few slow charge and discharge cycles, with some associated irreversible losses, that stabilizes secondary batteries for long term use by passivating the electrodes from unwanted and irreversible reactions within their voltage and temperature range of operation.

Question 10

C-Rate

Answer 10

The current rate during charge/discharge, relative to the overall capacity of the cell, where 1C indicates a current that would fully charge the cell in 1 hour and C/2 would require 2 hours to fully charge.

Question 11

Cycle Life

Answer 11

The total number of charge/discharge cycles the cell can sustain before its capacity is significantly reduced, with typical standards rated at 80% of the original capacity.

Question 12

Coulombic Efficiency

Answer 12

Capacity retention for each cycle (discharge capacity divided by the charge capacity).

Question 13

Capacity

Answer 13

The amount of charge a battery or cell is able to store, in Ampere-hours. This relates to the amount of controlled reactions in the system. Depending on cell design, this translates to the maximum amount of energy a given chemistry can store.

Question 14

Specific Capacity

Answer 14

The capacity relative to the mass of a cell component containing active material. The value most common academically is relative to active material itself, representing the best-cast scenario, but the most commercially relevant value is relative to the overall cell and/or pack weights (Ah/kg)

Question 15

Power

Answer 15

The amount of work a battery or cell can perform. P = V * I

Question 16

Energy Density

Answer 16

Energy is the amount of time a battery or cell can sustain a given amount of work (Wh). E = P * t, which is commonly reported on a Wh/L basis.

Question 17

Specific Energy

Answer 17

Similar to Energy Density, but in terms of Wh/kg.

Question 18

Active Material (AM)

Answer 18

The electrode component(s) responsible for storing energy. Active materials with high voltages vs. Li/Li+ are cathodes, while those with low voltages vs. Li/Li+ are anodes.

Question 19

Intercalation (AM)

Answer 19

An intercalating active material is one that allows reversible insertion of ions between lattice sites. Most traditional Li+ systems use intercalation mechanisms at both electrodes.

Question 20

Conversion (AM)

Answer 20

Also called alloying. A conversion active material is one that forms new compounds at specific stoichiometries with the captured Li. This is associated with large structural changes, including up to 300% volume changes, that are a source of significant mechanical limitations. However, this class of active material has roughly an order of magnitude increase in Li absorption capacity.

Question 21

Conductive Additive

Answer 21

The electrode component(s) responsible for providing electronic conductivity to the matrix containing active material, intimately associated with the binder.

Question 22

Binder

Answer 22

The electrode component(s) responsible for binding all the electrode components to each other and to the current collector. This is usually a high molecular weight linear chain polymer.

Question 23

Current Collector

Answer 23

The substrate for each electrode, serving as a mechanical backbone and a conduit for electron transport between the two half-cells of an electrochemical cell. Aluminum is most common for cathodes, copper for anodes.

Question 24

Electrolyte

Answer 24

The medium through which ions transport between half-cells. Electrolytes are most commonly a combination of solvent(s) and the dissociated ions from a salt, such as 1 M LiPF6 in 3/7 EC/EMC (ethylene carbonate/ethyl methyl carbonate).

Question 25

SEI

Answer 25

Solid Electrolyte Interphase: A layer of electrolyte decomposition byproducts that grows on the anode surfaces and, when properly formed, facilitates Li+ transport during charge/discharge, while limiting further SEI growth upon cycling.