Category:OSW78ae8fbed378512a8d9d9bc3e8291e43: Difference between revisions

Cell components comprise the individual parts of a battery cell prior to its assembly into a complete cell. Cell components can be considered the stage between raw materials and complete cells, as cell components generally consist of raw materials processed to adopt the chemical and physical properties required to optimally function for the purpose of electrochemical energy storage.

Cell components may be classified into active components, which participate in the electrochemical reaction, and inactive components, which do not participate in the electrochemical reaction but are necessary and help facilitate the electrochemical reaction. Cell components may be solid or liquid, porous or non-porous, and may be monolithic materials or composite mixtures.

Cell components comprise the individual parts of a battery cell prior to its assembly into a complete cell. Cell components can be considered the stage between raw materials and complete cells, as cell components generally consist of raw materials processed to adopt the chemical and physical properties required to optimally function for the purpose of electrochemical energy storage.

Cell components may be classified into active components, which participate in the electrochemical reaction, and inactive components, which do not participate in the electrochemical reaction but are necessary and help facilitate the electrochemical reaction. Cell components may be solid or liquid, porous or non-porous, and may be monolithic materials or composite mixtures.

When working with cells at the lab-scale, cell components are often optimized to be handled one piece at a time, often by hand or in some cases by a small robot. At lab-scale, volumes are not large and components are produced as needed or desired. It is important to note that since the size of the components is generally smaller, defects in the components tend to have a larger effect on the results. Cell components may be artisanally made in the lab or purchased commercially, and complete cell assemblies are often a mixture of the two.

At the lab-scale, coin cells or small pouch cells are most often the form factor used. Coin cells are typically chosen from several industrial standard sizes, such as CR2032, and consist of several subcomponents which can be assembled into a complete cell. Pouch cells can be handmade and readily customized in size and number of layers according to need or desire. Pouch cells also require several subcomponents in order to be assembled into a complete cell.

Cells used for scientific research may not have all the cell components listed below, which are typical for most commercial Li-ion battery cells. Research may focus on reducing, replacing, or eliminating certain cell components for the sake of improving performance.

Custom-designed cells may be purpose-built for use in advanced characterization techniques, such as in situ or operando. These types of cells will have additional components related to their end-use.

Cathode

The cathode is the positive electrode of the battery cell. Typically, the cathode consists of the cathode active material (CAM), a conductive additive, a binder, and the current collector.

Anode

The anode is the negative electrode of the battery cell. Typically, the anode consists of the anode active material (AAM), conductive additive, a binder, and the current collector.

Inactive components of a battery cell do not directly contribute to the electrochemical energy storage reaction, but improve its facilitation, such as ensuring electronic conductivity, mechanical strength, or ionic conductivity. The most typical inactive components include the electrolyte, separator, current collector, and casing or housing. Depending on the form factor, the casing or housing may consist of different materials, and there may be additional components such as a spring, gasket, and spacer. Although inactive components are intended to be inactive, they are not always inert and can still degrade over time during the cell's operational lifetime due to various mechanical, thermal, or (electro)chemical degradation mechanisms.

BinaryElectrolyte

The electrolyte is necessary to conductive electro-active ions between the anode and the cathode. The electrolyte also serves to block electronic conductivity so that work can be derived from the current flowing through an external circuit. The electrolyte may be solid, liquid, or a gel. Many commercial cells use a liquid electrolyte, which consists of a solvent, salt, and possibly additives.

Separator

The separator is an inactive component which physically separates the anode and the cathode. Its main purpose is to prevent internal short-circuiting.

Binder

The binder is an inactive component which serves to keep the active material mechanically attached to the current collector.

CurrentCollector

The current collector facilitates electronic conductivity from the electrode to the cell's terminals. Many commercial cells use metal foils like Cu and Al as the current collector.

Spacer

In coin cell form factors, a spacer is used to take up excess space in an assembled coin cell and apply uniform pressure to the electrodes so that the electrodes remain aligned, the electrolyte maintains contact with the electrodes, and the electrodes are as close to each other to shorten ionic conduction pathways. Spacers are commercially available in various thicknesses and may be used singularly or in pairs.

WaveSpring

In coin cell form factors, the wave spring applies pressure to the spacer to maintain pressure and therefore electrode alignment inside the cell.

Gasket

In coin cell form factors, the gasket provides a tight seal between the coin cell base and lid to prevent the electrolyte from leaking, to prevent contact with outside moisture and air, and to electrically isolate the positive and negative terminals of the coin cell, thereby preventing an external short-circuit.

When battery cells are scaled up to pilot- and full-scale production, there are some changes to form factor which can then involve different components. For more information, see the cell components page. For example, prismatic cells are not typically made at the lab-scale but involve cell (sub)components that are unique to the prismatic cell for factor. Pouch cells may also include additional components in order for them to be collected into larger assemblies for modules and packs or for other functionalities, such as sensors or labels.