View source for Electrolyte

{{Short description|Substance whose dissolved ions conduct electricity}}
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{{For|the R.E.M. song|Electrolite}}
{{Use dmy dates|date=April 2017}}

An '''electrolyte''' is a substance that conducts [[electricity]] through the movement of [[ion]]s, but not through the movement of [[electron]]s.<ref>{{Cite journal|last1=Enderby|first1=J E|last2=Neilson|first2=G W|date=1981-06-01|title=The structure of electrolyte solutions|url=https://iopscience.iop.org/article/10.1088/0034-4885/44/6/001|journal=Reports on Progress in Physics|volume=44|issue=6|pages=593–653|doi=10.1088/0034-4885/44/6/001|s2cid=250852242|issn=0034-4885|access-date=18 December 2021|archive-date=18 December 2021|archive-url=https://web.archive.org/web/20211218145748/https://iopscience.iop.org/article/10.1088/0034-4885/44/6/001|url-status=live|url-access=subscription}}</ref><ref name="Petrovic-2020">{{Cite book|last=Petrovic|first=Slobodan|title=Battery technology crash course: a concise introduction|date=29 October 2020|publisher=Springer |isbn=978-3-030-57269-3|oclc=1202758685}}</ref><ref>{{Cite book|last1=Winie|first1=Tan|url=https://books.google.com/books?id=l-C7DwAAQBAJ&dq=introduction+electrolytes&pg=PA137|title=Polymer Electrolytes: Characterization Techniques and Energy Applications|last2 =Arof|first2=Abdul K.|last3=Thomas|first3=Sabu|date=2020-02-18|publisher=John Wiley & Sons|isbn=978-3-527-34200-6|language=en}}</ref> This includes most soluble [[Salt (chemistry)|salts]], [[acid]]s, and [[Base (chemistry)|bases]], dissolved in a [[polar solvent]] like water. Upon dissolving, the substance separates into [[cation]]s and [[anion]]s, which disperse uniformly throughout the solvent.<ref>{{cite journal | author=M Andreev | author2 = JJ de Pablo | author3 = A Chremos | author4=J F Douglas | title=Influence of ion solvation on the properties of electrolyte solutions|journal=The Journal of Physical Chemistry B| volume = 122 | pages = 4029–4034 | year=2018 | issue = 14 | doi= 10.1021/acs.jpcb.8b00518| pmid = 29611710 }}</ref> [[Solid-state electrolyte]]s also exist. In medicine and sometimes in chemistry, the term electrolyte refers to the substance that is dissolved.<ref>{{Cite book|last=Wilkins|first=Lippincott Williams &|url=https://books.google.com/books?id=Xs0YqSKqAlcC&dq=basics+electrolyte&pg=PA18|title=Fluids and Electrolytes|date=2007|publisher=Lippincott Williams & Wilkins|isbn=978-1-58255-923-0|language=en}}</ref><ref>{{Cite web|date=2011-02-02|title=electrolyte|url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/electrolyte|url-status=live|access-date=2021-12-18|website=National Cancer Institute|language=en|archive-url=https://web.archive.org/web/20180423090514/https://www.cancer.gov/publications/dictionaries/cancer-terms/def/electrolyte |archive-date=23 April 2018 }}</ref>

Electrically, such a solution is neutral. If an [[electric potential]] is applied to such a solution, the cations of the solution are drawn to the [[electrode]] that has an abundance of [[electron]]s, while the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. Some gases, such as [[hydrogen chloride]] (HCl), under conditions of high temperature or low pressure can also function as electrolytes.{{Clarify|date=January 2021}} Electrolyte solutions can also result from the dissolution of some biological (e.g., [[DNA]], [[polypeptides]]) or [[synthetic polymer]]s (e.g., [[polystyrene sulfonate]]), termed "[[polyelectrolyte]]s", which contain charged [[functional group]]s. A substance that dissociates into ions in solution or in the melt acquires the capacity to conduct electricity. [[Sodium]], [[potassium]], [[chloride]], [[calcium]], [[magnesium]], and [[phosphate]] in a liquid phase are examples of electrolytes.

In medicine, [[oral rehydration therapy|electrolyte replacement]] is needed when a person has prolonged [[vomiting]] or [[diarrhea]], and as a response to sweating due to strenuous athletic activity. Commercial electrolyte solutions are available, particularly for sick children (such as [[Oral rehydration therapy|oral rehydration]] solution, [[Suero Oral]], or [[Pedialyte]]) and athletes ([[sports drink]]s). Electrolyte monitoring is important in the treatment of [[anorexia nervosa|anorexia]] and [[bulimia]].

In science, electrolytes are one of the main components of [[electrochemical cell]]s.<ref name="Petrovic-2020"/>

In clinical [[medicine]], mentions of electrolytes usually refer [[metonym]]ically to the ions, and (especially) to their [[concentration]]s (in blood, serum, urine, or other fluids). Thus, mentions of electrolyte levels usually refer to the various ion concentrations, not to the fluid volumes.

== Etymology ==
The word ''electrolyte'' derives from [[Ancient Greek]] ήλεκτρο- (''ēlectro''-), prefix originally meaning ''amber'' but in modern contexts related to electricity, and λυτός (''lytos''), meaning "able to be taken apart".<ref>{{cite book |last1=Xu |first1=Kang |title=Electrolytes, interfaces and interphases: fundamentals and applications in batteries |date=2023 |publisher=Royal Society of Chemistry |location=London |isbn=978-1-83916-617-4 |pages=1–5 |url=https://books.rsc.org/books/monograph/2103/chapter/7535139/What-Is-an-Electrolyte |access-date=10 March 2025}}</ref>

== History ==
[[File:Arrhenius2.jpg|thumb|[[Svante Arrhenius]], father of the concept of electrolyte dissociation in [[aqueous solution]] for which he received the [[Nobel Prize in Chemistry]] in 1903 ]]
In his 1884 dissertation, [[Svante Arrhenius]] put forth his explanation of solid crystalline salts disassociating into paired charged particles when dissolved, for which he won the 1903 [[Nobel Prize]] in Chemistry.<ref>{{cite web|url=https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1903/index.html|title=The Nobel Prize in Chemistry 1903|access-date=5 January 2017|archive-date=8 July 2018|archive-url=https://web.archive.org/web/20180708044958/https://www.nobelprize.org/nobel_prizes/chemistry/laureates/1903/index.html|url-status=live}}</ref><ref name="columbia">{{cite book|editor1-last=Harris|editor1-first=William|editor2-last=Levey|editor2-first=Judith|title=The New Columbia Encyclopedia|date=1975|publisher=Columbia University|location=New York City|isbn=978-0-231035-729|page=[https://archive.org/details/newcolumbiaencyc00harr/page/155 155]|edition=4th|url-access=registration|url=https://archive.org/details/newcolumbiaencyc00harr/page/155}}</ref><ref name="EncBrit">{{cite book|editor1-last=McHenry|editor1-first=Charles|title=The New Encyclopædia Britannica|date=1992|publisher=Encyclopædia Britannica, Inc.|location=Chicago|isbn=978-085-229553-3|page=587|volume=1|edition=15|bibcode=1991neb..book.....G}}</ref><ref name="SciBio">{{cite book|editor1-last=Cillispie|editor1-first=Charles|title=Dictionary of Scientific Biography|date=1970|publisher=Charles Scribner's Sons|location=New York City|isbn=978-0-684101-125|pages=296–302|edition=1}}</ref> Arrhenius's explanation was that in forming a solution, the salt dissociates into charged particles, to which [[Michael Faraday]] (1791–1867) had given the name "[[ion]]s" many years earlier. Faraday's belief had been that ions were produced in the process of [[electrolysis]]. Arrhenius proposed that, even in the absence of an electric current, solutions of salts contained ions. He thus proposed that chemical reactions in solution were reactions between ions.<ref name="columbia"/><ref name="EncBrit"/><ref name="SciBio"/>

Shortly after Arrhenius's hypothesis of ions, [[Franz Hofmeister]] and Siegmund Lewith<ref>{{cite journal | author=Franz Hofmeister | title=Zur Lehre Von Der Wirkung Der Salze|journal=Naunyn-Schmiedeberg's Arch. Pharmacol.|year=1888}}</ref><ref>{{cite journal| author=W. Kunz| author2=J. Henle| author3=B. W. Ninham| title='Zur Lehre von der Wirkung der Salze' (about the science of the effect of salts): Franz Hofmeister's historical papers| url=https://linkinghub.elsevier.com/retrieve/pii/S1359029404000317| journal=Current Opinion in Colloid & Interface Science| year=2004| volume=9| issue=1–2| pages=19–37| doi=10.1016/j.cocis.2004.05.005| access-date=8 November 2021| archive-date=20 January 2022| archive-url=https://web.archive.org/web/20220120080518/https://linkinghub.elsevier.com/retrieve/pii/S1359029404000317| url-status=live| url-access=subscription}}</ref><ref>{{cite journal | doi = 10.1039/D2CP00847E | volume=24 | title=Understanding specific ion effects and the Hofmeister series | year=2022 | journal=Physical Chemistry Chemical Physics | pages=12682–12718 | last1 = Gregory | first1 = Kasimir P. | last2 = Elliott | first2 = Gareth R. | last3 = Robertson | first3 = Hayden | last4 = Kumar | first4 = Anand | last5 = Wanless | first5 = Erica J. | last6 = Webber | first6 = Grant B. | last7 = Craig | first7 = Vincent S. J. | last8 = Andersson | first8 = Gunther G. | last9 = Page | first9 = Alister J. | issue=21 | pmid=35543205 | bibcode=2022PCCP...2412682G | doi-access = free }}</ref> found that different ion types displayed different effects on such things as the solubility of proteins. A consistent ordering of these different ions on the magnitude of their effect arises consistently in many other systems as well. This has since become known as the [[Hofmeister series]].

While the origins of these effects are not abundantly clear and have been debated throughout the past century, it has been suggested that the charge density of these ions is important<ref>{{cite journal | author=Kasimir P. Gregory | author2=Erica J. Wanless | author3=Grant B. Webber| author4=Vince S. J. Craig | author5=Alister J. Page | title=The Electrostatic Origins of Specific Ion Effects: Quantifying the Hofmeister Series for Anions|journal=Chem. Sci.|year=2021| volume=12 | issue=45 | pages=15007–15015 |doi=10.1039/D1SC03568A| pmid=34976339 | pmc=8612401 | s2cid=244578563 }}</ref> and might actually have explanations originating from the work of [[Charles-Augustin de Coulomb]] over 200 years ago.

== Formation ==
Electrolyte solutions are normally formed when salt is placed into a [[solvent]] such as water and the individual components dissociate due to the [[thermodynamic]] interactions between solvent and solute molecules, in a process called "[[solvation]]". For example, when table salt ([[sodium chloride]]), NaCl, is placed in water, the salt (a solid) dissolves into its component ions, according to the dissociation reaction:{{cn|date=November 2021}}

: NaCl<sub>(s)</sub> → Na<sup>+</sup><sub>(aq)</sub> + Cl<sup>−</sup><sub>(aq)</sub>

It is also possible for substances to react with water, producing ions.  For example, [[carbon dioxide]] gas dissolves in water to produce a solution that contains [[hydronium]], [[carbonate]], and [[Carbonic Acid|hydrogen carbonate]] ions.<ref>{{Cite journal |date=25 May 2011 |title=Lesson 3: Ocean Acidification |url=https://www.st.nmfs.noaa.gov/Assets/Nemo/documents/lessons/Lesson_3/Lesson_3-Teacher%27s_Guide.pdf |journal=NOAA Teacher's Guide |issue=Lesson 3}}</ref>

[[Molten salt]]s can also be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. In particular, [[ionic liquid]]s, which are molten salts with melting points below 100&nbsp;°C,<ref>{{cite journal |year=2002 |script-title=zh:离子液体研究进展 |url=http://files.instrument.com.cn/FilesCenter/20100725/201072512514137980.pdf |journal={{lang|zh-hans|化学通报}} |language=zh-hans |issue=4 |page=243 |last1=Shi |first1=Jiahua |last2=Sun |first2=Xun |first3=Yang |last3=Chunhe |last4=Gao |first4=Qingyu |last5=Li |first5=Yongfang |access-date=2017-03-01 |issn=0441-3776 |archive-url=https://web.archive.org/web/20170302031247/http://files.instrument.com.cn/FilesCenter/20100725/201072512514137980.pdf |archive-date=2 March 2017 }}</ref> are a type of highly conductive non-aqueous electrolytes and thus have found more and more applications in fuel cells and batteries.<ref>
{{cite journal
 |author1=Jiangshui Luo |author2=Jin Hu |author3=Wolfgang Saak |author4=Rüdiger Beckhaus |author5=Gunther Wittstock |author6=Ivo F. J. Vankelecom |author7=Carsten Agert |author8=Olaf Conrad |s2cid=94400312 |year=2011
 |title=Protic ionic liquid and ionic melts prepared from methanesulfonic acid and 1H-1,2,4-triazole as high temperature PEMFC electrolytes
 |journal=[[Journal of Materials Chemistry]]
 |volume=21
 |issue=28 |pages=10426–10436
 |doi=10.1039/C0JM04306K
|url=https://lirias.kuleuven.be/handle/123456789/313759 |url-access=subscription }}</ref>

An electrolyte in a solution may be described as "concentrated" if it has a high concentration of ions, or "dilute" if it has a low concentration. If a high proportion of the solute dissociates to form free ions, the electrolyte is strong; if most of the solute does not dissociate, the electrolyte is weak. The properties of electrolytes may be exploited using electrolysis to extract constituent elements and compounds contained within the solution.{{cn|date=November 2021}}

Alkaline earth metals form hydroxides that are strong electrolytes with limited solubility in water, due to the strong attraction between their constituent ions. This limits their application to situations where high solubility is required.<ref>Brown, Chemistry: The Central Science, 14th edition, pg. 680.</ref>

In 2021, researchers have found that electrolyte can "substantially facilitate electrochemical corrosion studies in less conductive media".<ref>{{Cite journal|last1=Matějovský|first1=Lukáš|last2=Staš|first2=Martin|last3=Dumská|first3=Karolina|last4=Pospíšil|first4=Milan|last5=Macák|first5=Jan|date=2021-01-01|title=Electrochemical corrosion tests in an environment of low-conductive ethanol-gasoline blends: Part 1 – Testing of supporting electrolytes|url=https://www.sciencedirect.com/science/article/pii/S1572665720311085|journal=Journal of Electroanalytical Chemistry|language=en|volume=880|article-number=114879|doi=10.1016/j.jelechem.2020.114879|s2cid=229508133|issn=1572-6657|url-access=subscription}}</ref>

== Physiological importance ==
{{See also|Electrochemical gradient|Acid–base homeostasis|Electrolyte imbalance}}

In [[physiology]], the primary ions of electrolytes are [[sodium]] (Na<sup>+</sup>), [[potassium]] (K<sup>+</sup>), [[calcium]] (Ca<sup>2+</sup>), [[magnesium]] (Mg<sup>2+</sup>), [[chloride]] (Cl<sup>−</sup>), [[Monohydrogen phosphate|hydrogen phosphate]] (HPO<sub>4</sub><sup>2−</sup>), and [[hydrogen carbonate]] (HCO<sub>3</sub><sup>−</sup>).<ref name="Alfarouk-2020">{{cite journal |last1=Alfarouk |first1=Khalid O. |last2=Ahmed |first2=Samrein B. M. |last3=Ahmed |first3=Ahmed |last4=Elliott |first4=Robert L. |last5=Ibrahim |first5=Muntaser E. |last6=Ali |first6=Heyam S. |last7=Wales |first7=Christian C. |last8=Nourwali |first8=Ibrahim |last9=Aljarbou |first9=Ahmed N. |last10=Bashir |first10=Adil H. H. |last11=Alhoufie |first11=Sari T. S. |last12=Alqahtani |first12=Saad Saeed |last13=Cardone |first13=Rosa A. |last14=Fais |first14=Stefano |last15=Harguindey |first15=Salvador |last16=Reshkin |first16=Stephan J. |title=The Interplay of Dysregulated pH and Electrolyte Imbalance in Cancer |journal=Cancers |date=7 April 2020 |volume=12 |issue=4 |page=898 |doi=10.3390/cancers12040898|pmid=32272658 |pmc=7226178 |doi-access=free }}</ref>{{Failed verification|date=December 2021}} The electric charge symbols of plus (+) and minus (−)  indicate that the substance is ionic in nature and has an imbalanced distribution of electrons, the result of [[Dissociation (chemistry)|chemical dissociation]]. Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte;<ref>{{Cite journal |year=1986 |script-title=zh:细胞膜钠泵及其临床意义 |url=http://www.cnki.com.cn/Article/CJFDTotal-SHYX198601021.htm |journal={{lang|zh-hans|上海医学}} [Shanghai Medicine] |language=zh-hans |issue=1 |page=1 |last1=Ye |first1=Shenglong (叶胜龙) |last2=Tang |first2=Zhaoyou (汤钊猷) |access-date=3 March 2017 |archive-date=3 March 2017 |archive-url=https://web.archive.org/web/20170303201749/http://www.cnki.com.cn/Article/CJFDTotal-SHYX198601021.htm }}</ref> both are involved in fluid balance and [[blood pressure]] control.<ref>{{Cite journal|year=2004|others=张定昌|script-title=zh:电解质紊乱对晚期肿瘤的治疗影响 |journal={{lang|zh-hans|中华中西医杂志}} [Chinese Magazine of Chinese and Western Medicine]| language = zh-hans|issue=10|quote={{lang|zh-hans|在正常人体内, 钠离子占细胞外液阳离子总量的92%, 钾离子占细胞内液阳离子总量的98%左右.钠、钾离子的相对平衡, 维持着整个细胞的功能和结构的完整.钠、钾是人体内最主要的电解质成分...}} |last1=Tu |first1=Zhiquan (涂志全)}}</ref>

All known multicellular lifeforms require a subtle and complex '''electrolyte balance''' between the [[intracellular]] and [[extracellular]] environments.<ref name="Alfarouk-2020"/> In particular, the maintenance of precise [[osmotic]] [[ion gradient|gradient]]s of electrolytes is important. Such gradients affect and regulate the [[Fluid replacement|hydration]] of the body as well as [[Acid–base homeostasis|blood pH]], and are critical for [[nerve]] and [[muscle]] function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control.<ref>{{Citation |last1=Open Resources for Nursing |title=Chapter 15 Fluids and Electrolytes |date=2021 |work=Nursing Fundamentals [Internet] |url=https://www.ncbi.nlm.nih.gov/books/NBK591820/ |access-date=2024-02-28 |publisher=Chippewa Valley Technical College |language=en |last2=Ernstmeyer |first2=Kimberly |last3=Christman |first3=Elizabeth}}</ref>

Both muscle tissue and [[neuron]]s are considered electric tissues of the body. Muscles and neurons are activated by electrolyte activity between the [[extracellular fluid]] or [[interstitial fluid]], and [[intracellular fluid]]. Electrolytes may enter or leave the cell membrane through specialized protein structures embedded in the [[plasma membrane]] called "[[ion channels]]". For example, [[muscle contraction]] is dependent upon the presence of calcium (Ca<sup>2+</sup>), sodium (Na<sup>+</sup>), and potassium (K<sup>+</sup>). Without sufficient levels of these key electrolytes, muscle weakness or severe muscle contractions may occur.{{cn|date=November 2021}}<ref>{{Cite web |title=Reproductive Consequences of Electrolyte Disturbances in Domestic Animals |url=https://www.researchgate.net/figure/The-most-significant-electrolytes-in-animal-organisms_tbl1_361737152}}</ref>

Electrolyte balance is maintained by oral, or in emergencies, intravenous (IV) intake of electrolyte-containing substances, and is regulated by [[hormone]]s, in general with the [[kidney]]s flushing out excess levels. In humans, electrolyte [[homeostasis]] is regulated by hormones such as [[antidiuretic hormone]]s, [[aldosterone]] and [[parathyroid hormone]]s. Serious [[electrolyte disturbance]]s, such as [[dehydration]] and [[Water intoxication|overhydration]], may lead to cardiac and neurological complications and, unless they are rapidly resolved, will result in a [[medical emergency]].{{cn|date=April 2025}}

=== Measurement ===
Measurement of electrolytes is a commonly performed diagnostic procedure, performed via [[blood test]]ing  with [[ion-selective electrode]]s or [[urinalysis]] by [[medical technologist]]s. The interpretation of these values is somewhat meaningless without analysis of the [[medical history|clinical history]] and is often impossible without parallel measurements of [[renal function]]. The electrolytes measured most often are sodium and potassium. Chloride levels are rarely measured except for [[arterial blood gas]] interpretations since they are inherently linked to sodium levels. One important test conducted on urine is the [[specific gravity]] test to determine the occurrence of an [[electrolyte imbalance]].{{cn|date=November 2021}}

[[Conductivity cell|Conductivity cells]] are another kind of tools used to measure the electrolyte solution's strength to conduct electricity.<ref>{{Cite web |date=2025-10-15 |title=Conductivity Cell Care and Maintenance Procedures |url=https://www.horiba.com/ind/water-quality/support/technical-tips/electrodes/conductivity-cell-care-and-maintenance-procedures/ |access-date=2025-05-19 |website=www.horiba.com |language=en-IN}}</ref>

=== Rehydration ===
According to a study paid for by the [[Gatorade|Gatorade Sports Science Institute]], electrolyte drinks containing sodium and potassium salts replenish the body's water and electrolyte concentrations after dehydration caused by [[exercise]], [[Alcohol abuse|excessive alcohol consumption]], [[diaphoresis]] (heavy sweating), diarrhea, vomiting, [[Substance intoxication|intoxication]] or starvation; the study says that athletes exercising in extreme conditions (for three or more hours continuously, e.g. a [[marathon]] or [[triathlon]]) who do not consume electrolytes risk [[dehydration]] (or [[hyponatremia]]).<ref>{{cite journal |author1=J, Estevez E |author2=Baquero E |author3=Mora-Rodriguez R |title=Anaerobic performance when rehydrating with water or commercially available sports drinks during prolonged exercise in the heat |journal=Applied Physiology, Nutrition, and Metabolism |volume=33 |pages=290–298 |year=2008 |doi=10.1139/H07-188 |pmid=18347684 |issue=2}}</ref>{{needs independent confirmation|reason=Study was paid for
by a grant from the Gatorade Sports Science Institute|date=June 2024}}

A home-made electrolyte drink can be made by using water, sugar and salt [[mixing ratio|in precise proportions]].<ref>{{cite web|url=https://www.webmd.com/hw-popup/rehydration-drinks |archive-url=https://web.archive.org/web/20081023055047/https://www.webmd.com/hw-popup/rehydration-drinks |archive-date=2008-10-23 |title=Rehydration drinks |publisher=Webmd.com |date=2008-04-28 |access-date=2018-12-25}}</ref> It is important to include [[glucose]] (sugar) to utilise the co-transport mechanism of sodium and glucose{{Clarify|date=May 2025}}. Commercial preparations are also available<ref>{{cite web |url=http://rehydrate.org/resources/suppliers.htm |title=Oral Rehydration Salt Suppliers |publisher=Rehydrate.org |date=2014-10-07 |access-date=2014-12-04 |archive-date=7 December 2014 |archive-url=https://web.archive.org/web/20141207213450/http://rehydrate.org/resources/suppliers.htm |url-status=live }}</ref> for both human and veterinary use.

Electrolytes are commonly found in [[fruit juice]]s, sports drinks, milk, nuts, and many fruits and vegetables (whole or in juice form) (e.g., potatoes, [[avocado]]s).

== Electrochemistry ==
{{Main|Electrolysis}}
When [[electrode]]s are placed in an electrolyte and a [[voltage]] is applied, the electrolyte will conduct electricity. Lone [[electron]]s normally cannot pass through the electrolyte; instead, a chemical reaction occurs at the [[cathode]], providing electrons to the electrolyte.   Another reaction occurs at the [[anode]], consuming electrons from the electrolyte. As a result, a negative charge cloud develops in the electrolyte around the cathode, and a positive charge develops around the anode. The ions in the electrolyte neutralize these charges, enabling the electrons to keep flowing and the reactions to continue.{{cn|date=November 2021}}
[[File:Chloralkali membrane.svg|600px|thumb|right|[[Electrolytic cell]] producing [[chlorine]] (Cl<sub>2</sub>) and [[sodium hydroxide]] (NaOH) from a solution of common salt]]
For example, in a solution of ordinary table salt (sodium chloride, NaCl) in water, the cathode reaction will be

: 2 H<sub>2</sub>O + 2e<sup>−</sup> → 2 OH<sup>−</sup> + H<sub>2</sub>

and [[hydrogen]] gas will bubble up; the anode reaction is

: 2 NaCl → 2 Na<sup>+</sup> + Cl<sub>2</sub> + 2e<sup>−</sup>

and [[chlorine]] gas will be liberated into solution where it reacts with the sodium and hydroxyl ions to produce [[sodium hypochlorite]] - household [[bleach]]. The positively charged sodium ions Na<sup>+</sup> will react toward the cathode, neutralizing the negative charge of OH<sup>−</sup> there, and the negatively charged hydroxide ions OH<sup>−</sup> will react toward the anode, neutralizing the positive charge of Na<sup>+</sup> there. Without the ions from the electrolyte, the charges around the electrode would slow down continued electron flow; [[diffusion]] of H<sup>+</sup> and OH<sup>−</sup> through water to the other electrode takes longer than movement of the much more prevalent salt ions.
Electrolytes dissociate in water because water molecules are dipoles and the dipoles orient in an energetically favorable manner to [[Solvation|solvate]] the ions.{{cn|date=April 2025}}

In other systems, the electrode reactions can involve the metals of the electrodes as well as the ions of the electrolyte.<ref>{{Cite web |date=2015-12-27 |title=17.1: Electrochemical Cells |url=https://chem.libretexts.org/Bookshelves/General_Chemistry/Map%3A_Principles_of_Modern_Chemistry_(Oxtoby_et_al.)/Unit_4%3A_Equilibrium_in_Chemical_Reactions/17%3A_Electrochemistry/17.1%3A_Electrochemical_Cells |access-date=2025-07-07 |website=Chemistry LibreTexts |language=en}}</ref>

Electrolytic conductors are used in electronic devices where the chemical reaction at a metal-electrolyte interface yields useful effects.
* In [[battery (electricity)|batteries]], two materials with different electron affinities are used as electrodes; electrons flow from one electrode to the other outside of the battery, while inside the battery the circuit is closed by the electrolyte's ions. Here, the electrode reactions convert chemical energy to electrical energy.<ref name="Wladyslaw Wieczorek-2011">{{cite journal|author1=Kamil Perzyna |author2=Regina Borkowska |author3=Jaroslaw Syzdek |author4=Aldona Zalewska |author5=Wladyslaw Wieczorek |title=The effect of additive of Lewis acid type on lithium–gel electrolyte characteristics|journal=Electrochimica Acta| volume=57|pages=58–65|year=2011|doi=10.1016/j.electacta.2011.06.014}}</ref>
* In some [[fuel cell]]s, a solid electrolyte or [[proton conductor]] connects the plates electrically while keeping the hydrogen and oxygen fuel gases separated.<ref name="Jan Fransaer-2015"/>
* In [[electroplating]] tanks, the electrolyte simultaneously deposits metal onto the object to be plated, and electrically connects that object in the circuit.{{cn|date=April 2025}}
* In operation-hours gauges, two thin columns of [[mercury (element)|mercury]] are separated by a small electrolyte-filled gap, and, as charge is passed through the device, the metal dissolves on one side and plates out on the other, causing the visible gap to slowly move along.{{cn|date=April 2025}}
* In [[electrolytic capacitor]]s the chemical effect is used to produce an extremely thin [[dielectric]] or [[Electrical insulation|insulating]] coating, while the electrolyte layer behaves as one capacitor plate.{{cn|date=April 2025}}
* In some [[hygrometer]]s the humidity of air is sensed by measuring the conductivity of a nearly dry electrolyte.{{cn|date=April 2025}}
* Hot, softened glass is an electrolytic conductor, and some glass manufacturers keep the glass molten by passing a large current through it.{{cn|date=April 2025}}

== Solid electrolytes ==
{{Main|Fast-ion conductor|Solid-state electrolyte}}
Solid electrolytes can be mostly divided into four groups described below.

=== Gel electrolytes ===
Gel electrolytes – closely resemble liquid electrolytes. In essence, they are liquids in a flexible [[crystal structure|lattice framework]]. Various [[Food additive|additive]]s are often applied to increase the [[Electrical conductivity|conductivity]] of such systems.<ref name="Wladyslaw Wieczorek-2011" /><ref name="dry">{{cite web |url=http://www.evworld.com/article.cfm?storyid=933 |title=The Roll-to-Roll Battery Revolution |publisher=Ev World |access-date=2010-08-20 |archive-url=https://web.archive.org/web/20110710210351/http://www.evworld.com/article.cfm?storyid=933 |archive-date=10 July 2011 }}</ref>

=== Ceramic electrolytes ===
Solid ceramic electrolytes – [[ion]]s migrate through the ceramic phase by means of vacancies or [[interstitial compound|interstitials]] within the [[Crystal lattice|lattice]]. There are also [[Glass-ceramic|glassy-ceramic]] electrolytes.{{cn|date=April 2025}}

=== Polymer electrolytes ===
{{Main|Polymer electrolytes}}
Dry polymer electrolytes differ from liquid and gel electrolytes in that salt is dissolved directly into the solid medium. Usually it is a relatively high-[[Relative permittivity|dielectric constant]] [[polymer]] ([[polyethylene oxide|PEO]], [[Poly(methyl methacrylate)|PMMA]], [[Polyacrylonitrile|PAN]], [[polyphosphazene]]s, [[siloxane]]s, etc.) and a salt with low [[lattice energy]]. In order to increase the [[mechanical strength]] and conductivity of such electrolytes, very often [[composite material|composites]] are made, and inert ceramic phase is introduced. There are two major classes of such electrolytes: polymer-in-ceramic, and ceramic-in-polymer.<ref name="SyzdekBorkowska2007">{{cite journal|vauthors=Syzdek J, Borkowska R, Perzyna K, Tarascon JM, Wieczorek W|title=Novel composite polymeric electrolytes with surface-modified inorganic fillers|journal=Journal of Power Sources|volume=173|issue=2|year=2007|pages=712–720|issn=0378-7753|doi=10.1016/j.jpowsour.2007.05.061|bibcode=2007JPS...173..712S}}</ref><ref name="SyzdekArmand2010">{{cite journal|vauthors=Syzdek J, Armand M, Marcinek M, Zalewska A, Żukowska G, Wieczorek W|title=Detailed studies on the fillers modification and their influence on composite, poly(oxyethylene)-based polymeric electrolytes|journal=Electrochimica Acta|volume=55|issue=4|year=2010|pages=1314–1322|issn=0013-4686|doi=10.1016/j.electacta.2009.04.025}}</ref><ref name="SyzdekArmand2009">{{cite journal|vauthors=Syzdek J, Armand M, Gizowska M, Marcinek M, Sasim E, Szafran M, Wieczorek W|title=Ceramic-in-polymer versus polymer-in-ceramic polymeric electrolytes—A novel approach|journal=Journal of Power Sources|volume=194|issue=1|year=2009|pages=66–72|issn=0378-7753|doi=10.1016/j.jpowsour.2009.01.070|bibcode=2009JPS...194...66S}}</ref>

=== Organic plastic electrolytes ===
Organic ionic plastic crystals – are a type [[salt (chemistry)|organic salts]] exhibiting [[mesophase]]s (i.e. a [[state of matter]] intermediate between liquid and solid), in which mobile ions are orientationally or rotationally disordered while their centers are located at the ordered sites in the crystal structure.<ref name="Jan Fransaer-2015" /> They have various forms of disorder due to one or more solid–solid [[phase transition]]s below the [[melting point]] and have therefore [[Plasticity (physics)|plastic]] properties and good mechanical flexibility as well as an improved electrode-electrolyte interfacial contact. In particular, protic organic ionic plastic crystals (POIPCs),<ref name="Jan Fransaer-2015">
{{cite journal
 |author1=Jiangshui Luo |author2=Annemette H. Jensen |author3=Neil R. Brooks |author4=Jeroen Sniekers |author5=Martin Knipper |author6=David Aili |author7=Qingfeng Li |author8=Bram Vanroy |author9=Michael Wübbenhorst |author10=Feng Yan |author11=Luc Van Meervelt |author12=Zhigang Shao |author13=Jianhua Fang |author14=Zheng-Hong Luo |author15=Dirk E. De Vos |author16=Koen Binnemans |author17=Jan Fransaer |s2cid=84176511 |year=2015
 |title=1,2,4-Triazolium perfluorobutanesulfonate as an archetypal pure protic organic ionic plastic crystal electrolyte for all-solid-state fuel cells
 |journal=[[Energy & Environmental Science]]
 |volume=8
 |issue=4 |pages=1276–1291 |doi=10.1039/C4EE02280G
|bibcode=2015EnEnS...8.1276L }}</ref> which are solid [[protic]] organic salts formed by [[proton]] transfer from a [[Brønsted–Lowry acid–base theory|Brønsted acid]] to a Brønsted base and in essence are protic [[ionic liquid]]s in the [[Molten salt|molten state]], have found to be promising solid-state [[proton conductor]]s for [[fuel cell]]s. Examples include [[Triazolium salt#1,4-disubstituted 1,2,4-triazolium salts|1,2,4-triazolium]] [[Nonaflate|perfluorobutanesulfonate]]<ref name="Jan Fransaer-2015" /> and [[Imidazole|imidazolium]] [[methanesulfonate]].<ref>
{{cite journal
 |author1=Jiangshui Luo |author2=Olaf Conrad |author3=Ivo F. J. Vankelecom |s2cid=96622511 |year=2013
 |title=Imidazolium methanesulfonate as a high temperature proton conductor
 |journal=[[Journal of Materials Chemistry A]]
 |volume=1
 |issue=6 |pages=2238–2247 |doi=10.1039/C2TA00713D
|url=https://lirias.kuleuven.be/handle/123456789/392330 |url-access=subscription }}</ref>

== See also ==
* [[Electrochemical machining]]
* [[Elektrolytdatenbank Regensburg]]
* [[Ion transport number]]
* [[ITIES]] (interface between two immiscible electrolyte solutions)
* [[Salt bridge]]
* [[Strong electrolyte]]
* [[Supporting electrolyte]] (background electrolyte)
* [[VTPR]]

== References ==
{{Reflist}}

== External links ==
* {{Commonscat-inline}}
* {{cite journal|doi=10.1063/1.1730863|title=Mayer's Ionic Solution Theory Applied to Electrolyte Mixtures |year=1960 |last1=Friedman |first1=Harold L. |journal=The Journal of Chemical Physics |volume=32 |issue=4 |pages=1134–1149 |bibcode=1960JChPh..32.1134F |doi-access=free }}
* {{cite journal|doi=10.1021/j150612a033|title=Multicomponent diffusion of electrolytes with incomplete dissociation. Diffusion in a buffer solution |year=1981 |last1=Leaist |first1=Derek G. |last2=Lyons |first2=Philip A. |journal=The Journal of Physical Chemistry |volume=85 |issue=12 |pages=1756–1762 }}
* {{cite journal|doi=10.1039/DF9572400171|title=Ion-solvent interaction and the viscosity of strong-electrolyte solutions |year=1957 |last1=Kaminsky |first1=Manfred |journal=Discussions of the Faraday Society |volume=24 |page=171 }}

{{Galvanic cells}}
{{Authority control}}

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