Calcium battery explained

Calcium (ion) batteries are energy storage and delivery technologies (i.e., electro–chemical energy storage) that employ calcium ions (cations), Ca2+, as the active charge carrier.[1] [2] [3] Calcium (ion) batteries remain an active area of research,[4] [5] with studies and work persisting in the discovery and development of electrodes and electrolytes that enable stable, long-term battery operation.[6] Calcium batteries are rapidly emerging as a recognized alternative to Li-ion technology due to their similar performance, significantly greater abundance, and lower cost.[7] [8]

History

Calcium batteries date to the 1960s, used as thermal batteries for military and space applications.[9] The first example of an electrochemical cell was Ca//SOCl2 as a primary cell.[10] Early examination of Ca2+ intercalation hosts proposed transition metal oxides and sulfides.[11] The study of calcium batteries as well as calcium electro-chemistry continued. Research expanded owing to developments in effective Ca-metal redox activity, particularly at room temperature, which had been a longstanding challenge.

Advantages

Calcium batteries are being pursued for their several key advantages:

Abundance: Calcium is highly abundant compared to elements like lithium and zinc, making it more accessible and less prone to supply chain disruptions.

Redox Potential: Calcium’s redox potential is comparable to that of lithium, promising good voltage capabilities for high-performance batteries.

Charge: Calcium ions carry a double positive charge (2+), offering potentially higher energy density than singly charged ions like lithium (1+) and sodium (1+).

Safety: free calcium is stable, non-flammable and less reactive than lithium.

Practicality and Stability: Calcium is a practical choice for manufacturing and stable for long-term use, reflecting its feasibility for widespread commercial applications and chemical stability over time.

Comparison

Material properties

Calcium metal offers high conductivity and high melting temperature (842 °C) relative to other metals. The higher melting temperature can make calcium metal inherently safer in batteries. Calcium is environmentally benign, mitigating concerns over toxicity.

Resource and supply

Calcium batteries are one of many candidates to replace lithium-ion battery technology. It is a multivalent battery. Key advantages are lower cost, earth abundance (41,500 ppm), higher energy density, high capacity and high cell voltage,[12] and potentially higher power density. Calcium is the fifth-most abundant mineral in the Earth's crust, the most abundant alkaline earth metal, and the third-most abundant metal after aluminum (Al) and iron (Fe).[13] The United States is the largest producer (by annual production) of calcium (primarily limestone). Other major producers include Russia and China.

Electrochemistry

Calcium batteries possibly have higher cell voltages than magnesium batteries due to the 0.5 V lower standard reduction potential of the former. Ca2+ ions have the potential for faster reaction kinetics versus magnesium (Mg2+) owing to its less polarizing properties and charge density both in the electrolyte as well as in an intercalation cathode.

Capacity and energy density

Calcium metal anodes have a 2+ oxidation state which could provide greater energy density over monovalent systems (i.e., Li+ and Na+). Calcium has a standard reduction potential of 2.9 V, only 0.17 V greater than that of lithium metal. A calcium metal anode offers higher volumetric capacity and gravimetric capacities (2072 mAh.mL−1 and 1337 mAh.g−1, respectively) than commercial graphite anodes in Li-ion batteries (300–430 mAh mL−1 and 372 mAh g−1).[14] A calcium sulfur (CaS) battery has theoretical energy densities of 3202 Wh/L and 1835 Wh/kg, versus 2800 Wh/L for Li//S.

Comparison to other battery systems

Calcium batteries offer promising performance, safety, and sustainability compared to other prevalent battery technologies, such as lithium, sodium, magnesium, aluminum, potassium, and zinc. Specific advantages of calcium include higher energy density, enhanced safety, greater abundance, and stability, reinforcing its potential as the leading choice for future battery applications.

Components

A calcium battery has yet to be commercialized. Efforts concentrate on developing effective anode and cathode materials, as well as stable electrolytes. Intensive focus has been placed on achieving reliable electrochemistry with a pure calcium metal anode seeking high operating voltages, capacities, and energy densities. However, carbon and metal oxide-based anodes, while featuring lower performance metrics, are also reliable. Cathode research has sought high Ca2+ migration kinetics, high capacity, as well as high operative voltages.

Electrolytes

Calcium salt component

Salts explored in liquid electrolytes include: calcium tetrafluoroborate (Ca(BF4)2, calcium borohydride (Ca(BH4)2, calcium bis(trifluoromethanesulfonimide) (Ca(TFSI)2), calcium perchlorate (Ca(ClO4)2), calcium hexafluorophosphate (Ca(PF6)2), and calcium nitrate (Ca(NO3)2). Calcium nitrate is commonly used in aqueous batteries. Early studies revealed that reversible Ca deposition using simple Ca salts is impossible at room temperature. A Ca salt using a bulky, low-coordinating tetra-hexafluoroisopropoxy borate anion [Ca(B(Ohfip)<sub>4</sub>)<sub>2</sub>] was independently examined by three research groups. It was shown to be active for Ca deposition at room temperature with Coulumbic efficiency up to 80% and anodic stability up to 4.1 V vs Ca.[15] [16] [17] The [Ca(B(Ohfip)<sub>4</sub>)<sub>2</sub>] electrolyte remains the most active electrolyte, but is far below the standard for practical applications.

Liquid

Several electrolyte systems have been examined. Many candidates show low electrochemical stability. Redox reactions on calcium metal in several organic electrolytes avoid Ca deposition by using (Ca(ClO4)2) and Ca(BF4)2 in organic solvents.[18] Water and alkyl carbonate, ionic liquids,[19] mixed cation electrolytes with Li/Ca and Na/Ca (BH4- and PF6- anion), and K/Ca (PF6- anion) have been examined.[20] [21] [22] Salt solvation studies of different solvents were conducted.[23] Theoretical studies on both salts and aprotic solvents show favorable solvation/de-solvation properties.[24] [25]

Polymer

Polymer electrolytes have been examined as a way to combine the functions of battery separator and electrolyte. One of the first samples of a polymer electrolyte was PVA/PVP complexed with CaCl2.[26] Subsequent studies demonstrated polymer electrolytes made from poly(ethylene glycol) diacrylate (PEDGA)[27] and polytetrahydrofuran (PTHF)[28] both with calcium nitrate (Ca(NO3)2), polyethylene oxide,[29] single-ion conducting polymers based on PEG and PTHF backbones and TFSI anions,[30] PEDGA-based gel polymer electrolytes, polyvinyl imidazole,[31] PVDF gel electrolytes,[32] using solvents such as alkyl carbonates and ionic liquids.[33] [34] Most recently, a poly(vinyl imidazole) electrolyte demonstrated one of the highest conductivities for Ca2+ to date.[35]

Solid

Solid electrolytes (i.e., ceramics) have been proposed, but studies remain theoretical.

Reference Electrodes

Suitable reference electrodes are crucial for accurate and comparable electrochemical studies and performance metrics of various anode and cathode systems. Using calcium metal as a reference electrode presents challenges due to its instability, passivation concerns, and voltage drift. Alternatives include Cl/Cl+, activated carbon, and Ag2S electrodes.[36]

One study introduced a silver(I) sulfide (Ag2S) reference electrode for calcium-ion battery research, based on a silver wire coated with silver(I) sulfide crystals. The standard reduction potential of Ag2S relative to the standard hydrogen electrode was determined to vary from −0.291 to −0.477 V, with a linear voltage drift behavior having slopes between −0.28 and −2.45 mV/h.

Anodes

Calcium anodes have focused on using metal anodes, metal oxides, carbons, and metals/semiconductors as alloying compounds.

Examples include vanadium oxide (V2O5),[37] copper-calcium alloying,[38] MgV2O5, graphite,[39] metallic calcium, and silicon anodes.[40] Recent work on plating/stripping calcium was done in ethylene carbonate/propylene carbonate (EC/PC) solutions at elevated temperatures.[41] Calcium metal anodes showed practical plating at room temperature in electrolytes such as tetrahydrofuran (THF) and a binary mixture of ethylene carbonate and propylene carbonate (EC/PC).[42] [43] Aqueous batteries have used calcium vanadate.[44] Graphene-like materials, such as hexa-peri-hexabenzocoronene nanographene, have been considered.[45]

Cathodes

Work on calcium cathodes focused on the experimental and theoretical investigation of intercalation compounds as well as sulfur as a conversion cathode.

Significant progress has been made with employing generally good intercalation materials, as well as ceramics with crystal structures that provide low migration energy barriers for Ca2+ to move through the lattice. Calcium's divalency and large ionic radius necessitates intercalation hosts with relatively open crystal frameworks and milder crystal polarization for better diffusion kinetics. Layered materials, whereby Ca2+ is transported through the van der Waals gap, is another approach to enable faster diffusion.

Calcium metal oxides and sulfides are areas of study. Candidates include calcium manganese oxide,[46] calcium cobalt oxide and titanium disulfide,[47] [48] hexacyanoferrates,[49] [50] or dual carrier batteries,[51] and aqueous batteries.[52] Theoretical work examined the potential of cathodes from different crystal structures such as perovskite (CaMO3),[53] spinel (CaM2O4),[54] [55], post-spinel spinel (CaM2O4),[56] other naturally occurring calcium compounds,[57] metal selenides such as TiSe2,[58] and other calcium lanthanide oxide phases.

Migration energy barriers have also been discussed.

Calcium–sulfur

A primary Ca–S battery was examined.[59] Ca-S batteries using Li as a mediator to make it reversible were studied.[60] The discovery of reliable electrolytes for plating/stripping calcium metal have aided in stable Ca//S battery cycling, however, poly-sulfide dissolution remains an issue.

Calcium–air

A calcium–air (Ca–O2) battery was examined.[61] [62] Unlike Li-O2 batteries, in which lithium can form a superoxide that undergoes easy redox activity, calcium oxidizes only to the chemical stable calcium oxide (CaO), hence suitable catalytic systems are required for reduction of CaO during battery charging. Reliable plating and stripping at the Ca anode is also critical.

In 2024, a team developed a calcium–oxygen (Ca–O2) battery that is rechargeable for 700 cycles at room temperature. This battery utilized a highly reversible two-electron redox reaction, forming calcium peroxide (CaO2) as the discharge product. A durable ionic liquid-based electrolyte facilitated Ca plating–stripping at the Ca metal anode and improved CaO2/O2 redox at the air cathode. The Ca–O2 battery was stable in air and can be made into flexible fibers. These fibers could be woven into textile batteries for next-generation wearable systems.[63]

Calcium-Chlorine

One study introduced a rechargeable Ca/Cl2 battery utilizing a reversible cathode redox reaction between CaCl2 and Cl2, facilitated by lithium difluoro(oxalate)borate as an electrolyte mediator. The Ca/Cl2 battery achieved discharge voltages of 3V, a specific capacity of 1000 mAh.g−1, and a rate capability of 500 mA.g−1. It also demonstrates excellent capacity retention (96.5% after 30 days) and low-temperature capability (down to 0°C).[64]

Performance

Several calcium metal batteries with different cathodes have thus far been examined:

C-rates range from 0.2 to >5 C. Capacities range from 50-250 mAh/g, with operating voltages between 1 and 4 V. Current densities are in the range of 20–500 mA/g, and energy densities of ~250 Wh/kg.

Applications

Owing in the potentially greater weight, calcium batteries have been proposed for use in stationary applications, such as grid storage.

Research

Several groups are dedicated to commercial-grade rechargeable calcium batteries. The include:

Challenges

Calcium batteries show capacity fading and lower energy densities than Li-metal batteries.[68] The solid electrolyte interface (SEI) shows slow migration of Ca2+ ions. Ca metal undergoes dendritic growth at high current rates.[69] The form of the calcium deposits are critical for long-term battery operation. Calcium batteries that provide comparable energy densities of incumbent Li-ion and Li-metal batteries require a pure Ca metal anode. Calcium is significantly harder metal than lithium, complicating manufacture of calcium foils.

Calcium salts generally show strong coordination between the Ca2+ and the anion, consequently requiring strongly coordinating solvents, such as carbonates, in order to produce electrolytes with sufficient salt solubility. This results in slow kinetics. More weakly coordinating salts allow for weakly coordinating solvents to be employed, which shows significantly increased kinetics.

Intercalation hosts require open frameworks and simple migration pathways for ion transport.[70]

Notes and References

  1. Hosein ID . 2021-04-09. The Promise of Calcium Batteries: Open Perspectives and Fair Comparisons. ACS Energy Letters. 6. 4. 1560–1565. 10.1021/acsenergylett.1c00593. free.
  2. Nielson KV, Liu TL . Dawn of Calcium Batteries . Angewandte Chemie . 59 . 9 . 3368–3370 . February 2020 . 31961466 . 10.1002/anie.201913465 . 210842839 .
  3. A Youtube popular science animation explaining Ca batteries - a product of the H2020 project
  4. Arroyo-de Dompablo ME, Ponrouch A, Johansson P, Palacín MR . Achievements, Challenges, and Prospects of Calcium Batteries . Chemical Reviews . 120 . 14 . 6331–6357 . July 2020 . 31661250 . 10.1021/acs.chemrev.9b00339 . free . 10261/199754 . free .
  5. 2021-01-15. Emerging calcium batteries. Journal of Power Sources. en. 482. 228875. 10.1016/j.jpowsour.2020.228875. 0378-7753. Stievano L, de Meatza I, Bitenc J, Cavallo C, Brutti S, Navarra MA . 2021JPS...48228875S. free.
  6. Ji B, He H, Yao W, Tang Y . Recent Advances and Perspectives on Calcium-Ion Storage: Key Materials and Devices . Advanced Materials . 33 . 2 . e2005501 . January 2021 . 33251702 . 10.1002/adma.202005501 . 227237159 .
  7. Web site: Why some researchers think calcium is the future of batteries . 2024-06-11 . Chemical & Engineering News . en.
  8. Web site: Hosein . Ian D. . 2024-05-15 . Why Calcium Batteries Will Win . 2024-06-11 . Medium . en.
  9. Selis SM, Wondowski JP, Justus RF . 1964-01-01. A High‐Rate, High‐Energy Thermal Battery System . Journal of the Electrochemical Society . 111. 1. 6. 10.1149/1.2426065. 1964JElS..111....6S. 1945-7111.
  10. Staniewicz RJ . 1980-04-01. A Study of the Calcium‐Thionyl Chloride Electrochemical System . Journal of the Electrochemical Society. en. 127. 4. 782–789 . 10.1149/1.2129758 . 1980JElS..127..782S . 1945-7111. free.
  11. 1978-01-01. Chemistry of intercalation compounds: Metal guests in chalcogenide hosts . Progress in Solid State Chemistry . 12. 1. 41–99. 10.1016/0079-6786(78)90003-1. 0079-6786. Whittingham MS .
  12. Monti D, Ponrouch A, Araujo RB, Barde F, Johansson P, Palacín MR . Multivalent Batteries-Prospects for High Energy Density: Ca Batteries . English . Frontiers in Chemistry . 7 . 79 . 2019 . 30842941 . 6391315 . 10.3389/fchem.2019.00079 . 2019FrCh....7...79M . free .
  13. Book: Greenwood NN . Chemistry of the Elements . 1997 . Boston, Mass. . Butterworth-Heinemann . 978-0-7506-3365-9 . 2nd .
  14. Muldoon J, Bucur CB, Gregory T . Quest for nonaqueous multivalent secondary batteries: magnesium and beyond . Chemical Reviews . 114 . 23 . 11683–11720 . December 2014 . 25343313 . 10.1021/cr500049y .
  15. Shyamsunder A, Blanc LE, Assoud A, Nazar LF . 2019-09-13 . Reversible Calcium Plating and Stripping at Room Temperature Using a Borate Salt . ACS Energy Letters. en. 4. 9. 2271–2276 . 10.1021/acsenergylett.9b01550 . 202079165. 2380-8195.
  16. Li Z, Fuhr O, Fichtner M, Zhao-Karger Z . 2019-12-04. Towards stable and efficient electrolytes for room-temperature rechargeable calcium batteries. Energy & Environmental Science. en. 12. 12. 3496–3501. 10.1039/C9EE01699F. 1754-5706. free.
  17. Nielson KV, Luo J, Liu TL . Optimizing Calcium Electrolytes by Solvent Manipulation for Calcium Batteries . Batteries & Supercaps . 2020 . 3 . 8 . 766–772 . 10.1002/batt.202000005. 216329867.
  18. Aurbach D, Skaletsky R, Gofer Y . 1991-12-01. The Electrochemical Behavior of Calcium Electrodes in a Few Organic Electrolytes . Journal of the Electrochemical Society. 138. 12. 3536–3545. 1991JElS..138.3536A. 10.1149/1.2085455. 0013-4651.
  19. Biria S, Pathreeker S, Genier FS, Li H, Hosein ID . 2020-03-23. Plating and Stripping Calcium at Room Temperature in an Ionic-Liquid Electrolyte . ACS Applied Energy Materials. en. 3. 3. 2310–2314. 10.1021/acsaem.9b02529. 214030347. 2574-0962.
  20. Jie Y, Tan Y, Li L, Han Y, Xu S, Zhao Z, Cao R, Ren X, Huang F, Lei Z, Tao G, Zhang G, Jiao S . 6 . Electrolyte Solvation Manipulation Enables Unprecedented Room-Temperature Calcium-Metal Batteries . Angewandte Chemie . 59 . 31 . 12689–12693 . July 2020 . 32270534 . 10.1002/anie.202002274 . 215602284 .
  21. Song H, Su J, Wang C . Hybrid Solid Electrolyte Interphases Enabled Ultralong Life Ca-Metal Batteries Working at Room Temperature . Advanced Materials . 33 . 2 . e2006141 . January 2021 . 33215793 . 10.1002/adma.202006141 . 2021AdM....3306141S . 227078025 .
  22. Chando . Paul Alexis . Shellhamer . Jacob Matthew . Wall . Elizabeth . He . Wenlin . Hosein . Ian Dean . 2023-04-10 . Plating and Stripping Calcium Metal in Potassium Hexafluorophosphate Electrolyte toward a Stable Hybrid Solid Electrolyte Interphase . ACS Applied Energy Materials . en . 6 . 7 . 3924–3932 . 10.1021/acsaem.3c00098 . 2574-0962 . 10091900 . 37064409.
  23. Forero-Saboya JD, Marchante E, Araujo RB, Monti D, Johansson P, Ponrouch A . December 2019 . Cation Solvation and Physicochemical Properties of Ca Battery Electrolytes . The Journal of Physical Chemistry C . 123 . 49 . 29524–29532 . 10.1021/acs.jpcc.9b07308 . 6961307 . 31956392.
  24. Shakourian-Fard M, Kamath G, Taimoory SM, Trant JF . 2019-07-05 . Calcium-Ion Batteries: Identifying Ideal Electrolytes for Next-Generation Energy Storage Using Computational Analysis . The Journal of Physical Chemistry C . 123 . 26 . 15885–15896 . 10.1021/acs.jpcc.9b01655 . 1932-7447 . 197216442.
  25. Araujo RB, Thangavel V, Johansson P . 2021-08-01 . Towards novel calcium battery electrolytes by efficient computational screening . Energy Storage Materials . en . 39 . 89–95 . 10.1016/j.ensm.2021.04.015 . 2405-8297 . 234810587 . free.
  26. Vanitha D, Bahadur SA, Nallamuthu N, Shunmuganarayanan A, Manikandan A . Studies on Conducting Polymer Blends: Synthesis and Characterizations of PVA/PVP Doped with CaCl₂ . Journal of Nanoscience and Nanotechnology . 18 . 3 . 1723–1729 . March 2018 . 29448651 . 10.1166/jnn.2018.14215 .
  27. Genier FS, Burdin CV, Biria S, Hosein ID . 2019-02-28. A novel calcium-ion solid polymer electrolyte based on crosslinked poly(ethylene glycol) diacrylate . Journal of Power Sources. en. 414. 302–307. 2019JPS...414..302G. 10.1016/j.jpowsour.2019.01.017. 104435180. 0378-7753. free.
  28. Wang J, Genier FS, Li H, Biria S, Hosein ID . 2019-07-12. A Solid Polymer Electrolyte from Cross-Linked Polytetrahydrofuran for Calcium Ion Conduction . ACS Applied Polymer Materials. en. 1. 7. 1837–1844. 10.1021/acsapm.9b00371. 104749306. 2637-6105.
  29. Martinez-Cisneros CS, Fernandez A, Antonelli C, Levenfeld B, Varez A, Vezzù K, Di Noto V, Sanchez JY . 2020-09-01. Opening the door to liquid-free polymer electrolytes for calcium batteries . Electrochimica Acta. en. 353. 136525. 10.1016/j.electacta.2020.136525. 219746567. 0013-4686. free. 10016/31257. free.
  30. Ford HO, Cui C, Schaefer JL . March 2020. Comparison of Single-Ion Conducting Polymer Gel Electrolytes for Sodium, Potassium, and Calcium Batteries: Influence of Polymer Chemistry, Cation Identity, Charge Density, and Solvent on Conductivity . Batteries . en . 6 . 1 . 11 . 10.3390/batteries6010011 . free.
  31. Pathreeker . Shreyas . Hosein . Ian D. . 2022-10-14 . Vinylimidazole-Based Polymer Electrolytes with Superior Conductivity and Promising Electrochemical Performance for Calcium Batteries . ACS Applied Polymer Materials . en . 4 . 10 . 6803–6811 . 10.1021/acsapm.2c01140 . 2637-6105 . 9578112 . 36277173.
  32. Fluker . Edward C. . Pathreeker . Shreyas . Hosein . Ian D. . 2023-08-24 . Polyvinylidene Fluoride-Based Gel Polymer Electrolytes for Calcium Ion Conduction: A Study of the Influence of Salt Concentration and Drying Temperature on Coordination Environment and Ionic Conductivity . The Journal of Physical Chemistry C . en . 127 . 33 . 16579–16587 . 10.1021/acs.jpcc.3c02342 . 1932-7447 . 10461727 . 37646008.
  33. Biria S, Pathreeker S, Genier FS, Chen FH, Li H, Burdin CV, Hosein ID . Gel Polymer Electrolytes Based on Cross-Linked Poly(ethylene glycol) Diacrylate for Calcium-Ion Conduction . ACS Omega . 6 . 26 . 17095–17102 . July 2021 . 34250366 . 8264931 . 10.1021/acsomega.1c02312 . free .
  34. Biria S, Pathreeker S, Genier FS, Hosein ID . 2020-06-12. A Highly Conductive and Thermally Stable Ionic Liquid Gel Electrolyte for Calcium-Ion Batteries . ACS Applied Polymer Materials. en. 2. 6. 2111–2118. 10.1021/acsapm.9b01223. 219098278. 2637-6105.
  35. Pathreeker S, Hosein ID . Vinylimidazole-Based Polymer Electrolytes with Superior Conductivity and Promising Electrochemical Performance for Calcium Batteries . ACS Applied Polymer Materials . 4 . 10 . 6803–6811 . October 2022 . 36277173 . 9578112 . 10.1021/acsapm.2c01140 .
  36. Shellhamer . Jacob Matthew . Chando . Paul Alexis . Pathreeker . Shreyas . Wang . Xinlu . Hosein . Ian Dean . 2023-10-12 . Unveiling the Potential of Ag 2 S Reference Electrode: Empowering Calcium Electrochemical Reactions . The Journal of Physical Chemistry C . en . 127 . 40 . 19900–19905 . 10.1021/acs.jpcc.3c04580 . 1932-7447. free .
  37. Cabello M, Nacimiento F, Gonzalez JR, Ortiz G, Alcantara R, Lavela P, Perez-Vicente C, Tirado JL . 2016-06-01. Advancing towards a veritable calcium-ion battery: CaCo2O4 positive electrode material . Electrochemistry Communications. en. 67. 59–64. 10.1016/j.elecom.2016.03.016. 1388-2481.
  38. Wang M, Jiang C, Zhang S, Song X, Tang Y, Cheng HM . Reversible calcium alloying enables a practical room-temperature rechargeable calcium-ion battery with a high discharge voltage . Nature Chemistry . 10 . 6 . 667–672 . June 2018 . 29686378 . 10.1038/s41557-018-0045-4 . 19086248 . 2018NatCh..10..667W .
  39. Richard Prabakar SJ, Ikhe AB, Park WB, Chung KC, Park H, Kim KJ, Ahn D, Kwak JS, Sohn KS, Pyo M . 6 . Graphite as a Long-Life Ca2+-Intercalation Anode and its Implementation for Rocking-Chair Type Calcium-Ion Batteries . Advanced Science . 6 . 24 . 1902129 . December 2019 . 31890464 . 6918123 . 10.1002/advs.201902129 .
  40. Ponrouch A, Tchitchekova D, Frontera C, Bardé F, Arroyo-de Dompablo ME, Palacín MR . 2016-05-01. Assessing Si-based anodes for Ca-ion batteries: Electrochemical decalciation of CaSi2 . Electrochemistry Communications. en. 66. 75–78. 10.1016/j.elecom.2016.03.004. 1388-2481. 10261/147984. free.
  41. Ponrouch A, Frontera C, Bardé F, Palacín MR . Towards a calcium-based rechargeable battery . Nature Materials . 15 . 2 . 169–172 . February 2016 . 26501412 . 10.1038/nmat4462 . free . 2016NatMa..15..169P . 10261/148078 .
  42. Wang D, Gao X, Chen Y, Jin L, Kuss C, Bruce PG . Plating and stripping calcium in an organic electrolyte . Nature Materials . 17 . 1 . 16–20 . January 2018 . 29180779 . 10.1038/nmat5036 . 2018NatMa..17...16W . 103355612 .
  43. Biria S, Pathreeker S, Li H, Hosein ID . 2019-11-25. Plating and Stripping of Calcium in an Alkyl Carbonate Electrolyte at Room Temperature . ACS Applied Energy Materials. en. 2. 11. 7738–7743 . 10.1021/acsaem.9b01670 . 208759289. 2574-0962.
  44. Liu L, Wu YC, Rozier P, Taberna PL, Simon P . Ultrafast Synthesis of Calcium Vanadate for Superior Aqueous Calcium-Ion Battery . Research . 2019 . 6585686 . 2019 . 31912041 . 6944483 . 10.34133/2019/6585686 . 2019Resea201985686L .
  45. 2021-07-01. Magnesium and calcium ion batteries based on the hexa-peri-hexabenzocoronene nanographene anode materials . Inorganic Chemistry Communications. en. 129. 108656. 10.1016/j.inoche.2021.108656. 1387-7003. Hassanpour A, Farhami N, Derakhshande M, Nezhad PD, Ebadi A, Ebrahimiasl S . 235542961.
  46. Pathreeker S, Reed S, Chando P, Hosein ID . October 2020 . A study of calcium ion intercalation in perovskite calcium manganese oxide . Journal of Electroanalytical Chemistry. en. 874. 114453. 10.1016/j.jelechem.2020.114453. 1572-6657 . 225409592.
  47. Lee C, Jeong YT, Nogales PM, Song HY, Kim Y, Yin RZ, Jeong SK . January 2019 . Electrochemical intercalation of Ca2+ ions into TiS2 in organic electrolytes at room temperature. Electrochemistry Communications. en. 98. 115–118. 10.1016/j.elecom.2018.12.003. 1388-2481. free.
  48. Tchitchekova DS, Ponrouch A, Verrelli R, Broux T, Frontera C, Sorrentino A, Barde F, Biskup N, Arroyo-de Dompablo ME, Palacin MR . 6 . February 2018 . Electrochemical Intercalation of Calcium and Magnesium in TiS 2 : Fundamental Studies Related to Multivalent Battery Applications . Chemistry of Materials. en. 30. 3. 847–856. 10.1021/acs.chemmater.7b04406. 0897-4756. 10261/344249. free.
  49. Padigi P, Goncher G, Evans D, Solanki R . January 2015 . Potassium barium hexacyanoferrate – A potential cathode material for rechargeable calcium ion batteries . Journal of Power Sources. en. 273. 460–464. 10.1016/j.jpowsour.2014.09.101. 2015JPS...273..460P. 0378-7753.
  50. Tojo T, Sugiura Y, Inada R, Sakurai Y . 2016-07-20. Reversible Calcium Ion Batteries Using a Dehydrated Prussian Blue Analogue Cathode . Electrochimica Acta. en. 207. 22–27. 10.1016/j.electacta.2016.04.159. 0013-4686.
  51. Shiga T, Kondo H, Kato Y, Inoue M . 2015-12-17. Insertion of Calcium Ion into Prussian Blue Analogue in Nonaqueous Solutions and Its Application to a Rechargeable Battery with Dual Carriers . The Journal of Physical Chemistry C. en. 119. 50. 27946–27953. 10.1021/acs.jpcc.5b10245. 1932-7447.
  52. Adil M, Sarkar A, Roy A, Panda MR, Nagendra A, Mitra S . Practical Aqueous Calcium-Ion Battery Full-Cells for Future Stationary Storage . ACS Applied Materials & Interfaces . 12 . 10 . 11489–11503 . March 2020 . 32073827 . 10.1021/acsami.9b20129 . 211214804 .
  53. Arroyo-de Dompablo ME, Krich C, Nava-Avendaño J, Palacín MR, Bardé F . In quest of cathode materials for Ca ion batteries: the CaMO3 perovskites (M = Mo, Cr, Mn, Fe, Co, and Ni) . Physical Chemistry Chemical Physics . 18 . 29 . 19966–19972 . July 2016 . 27398629 . 10.1039/C6CP03381D . free . 2016PCCP...1819966A . 10261/147901 .
  54. Zhao Z, Yao J, Sun B, Zhong S, Lei X, Xu B, Ouyang C . 2018-11-15. First-principles identification of spinel CaCo2O4 as a promising cathode material for Ca-ion batteries . Solid State Ionics. en. 326. 145–149. 10.1016/j.ssi.2018.10.004. 105010988. 0167-2738.
  55. Liu D, Zhu W, Trottier J, Gagnon C, Barray F, Guerfi A, Mauger A, Groult H, Julien CM, Goodenough JB, Zaghib K . 6 . 2013-11-18. Spinel materials for high-voltage cathodes in Li-ion batteries . RSC Advances. en. 4. 1. 154–167. 10.1039/C3RA45706K. 2046-2069. free.
  56. Chando . Paul Alexis . Chen . Sihe . Shellhamer . Jacob Matthew . Wall . Elizabeth . Wang . Xinlu . Schuarca . Robson . Smeu . Manuel . Hosein . Ian Dean . 2023-10-24 . Exploring Calcium Manganese Oxide as a Promising Cathode Material for Calcium-Ion Batteries . Chemistry of Materials . en . 35 . 20 . 8371–8381 . 10.1021/acs.chemmater.3c00659 . 0897-4756 . 10601472 . 37901147.
  57. Torres A, Luque FJ, Tortajada J, Arroyo-de Dompablo ME . Analysis of Minerals as Electrode Materials for Ca-based Rechargeable Batteries . Scientific Reports . 9 . 1 . 9644 . July 2019 . 31273248 . 6609692 . 10.1038/s41598-019-46002-4 . 2019NatSR...9.9644T .
  58. 2019-10-01. TiSe2 cathode for beyond Li-ion batteries . Journal of Power Sources . 436. 226813. 10.1016/j.jpowsour.2019.226813. 0378-7753. Juran TR, Smeu M . 2019JPS...43626813J. 198324987.
  59. See KA, Gerbec JA, Jun YS, Wudl F, Stucky GD, Seshadri R . August 2013. A High Capacity Calcium Primary Cell Based on the Ca-S System . Advanced Energy Materials. en. 3. 8. 1056–1061 . 10.1002/aenm.201300160. 97151846 .
  60. Yu X, Boyer MJ, Hwang GS, Manthiram A . 2019. Toward a Reversible Calcium-Sulfur Battery with a Lithium-Ion Mediation Approach. Advanced Energy Materials . 9 . 14 . 1803794 . 10.1002/aenm.201803794 . 1614-6840. 1598280. free.
  61. Reinsberg P, Bondue CJ, Baltruschat H . 2016-10-06. Calcium–Oxygen Batteries as a Promising Alternative to Sodium–Oxygen Batteries . The Journal of Physical Chemistry C. 120. 39. 22179–22185. 10.1021/acs.jpcc.6b06674. 1932-7447.
  62. Shiga T, Kato Y, Yoko H . 2017-06-27. Coupling of nitroxyl radical as an electrochemical charging catalyst and ionic liquid for calcium plating/stripping toward a rechargeable calcium–oxygen battery . Journal of Materials Chemistry A. en. 5. 25. 13212–13219. 10.1039/C7TA03422A. 2050-7496.
  63. Ye . Lei . Liao . Meng . Zhang . Kun . Zheng . Mengting . Jiang . Yi . Cheng . Xiangran . Wang . Chuang . Xu . Qiuchen . Tang . Chengqiang . Li . Pengzhou . Wen . Yunzhou . Xu . Yifei . Sun . Xuemei . Chen . Peining . Sun . Hao . 2024-02-07 . A rechargeable calcium–oxygen battery that operates at room temperature . Nature . en . 626 . 7998 . 313–318 . 10.1038/s41586-023-06949-x . 1476-4687.
  64. Geng . Shitao . Zhao . Xiaoju . Xu . Qiuchen . Yuan . Bin . Wang . Yan . Liao . Meng . Ye . Lei . Wang . Shuo . Ouyang . Zhaofeng . Wu . Liang . Wang . Yongyang . Ma . Chenyan . Zhao . Xiaojuan . Sun . Hao . 2024-01-31 . A rechargeable Ca/Cl2 battery . Nature Communications . en . 15 . 1 . 944 . 10.1038/s41467-024-45347-3 . 2041-1723. 10831116 .
  65. Gao X, Liu X, Mariani A, Elia GA, Lechner M, Streb C, Passerini S . 2020-08-13. Alkoxy-functionalized ionic liquid electrolytes: understanding ionic coordination of calcium ion speciation for the rational design of calcium electrolytes. Energy & Environmental Science. en. 13. 8. 2559–2569. 10.1039/D0EE00831A. 1754-5706. free.
  66. Black AP, Torres A, Frontera C, Palacín MR, Arroyo-de Dompablo ME . Appraisal of calcium ferrites as cathodes for calcium rechargeable batteries: DFT, synthesis, characterization and electrochemistry of Ca4Fe9O17 . Dalton Transactions . 49 . 8 . 2671–2679 . February 2020 . 32048697 . 10.1039/C9DT04688G . free .
  67. Li Z, Vinayan BP, Diemant T, Behm RJ, Fichtner M, Zhao-Karger Z . Rechargeable Calcium-Sulfur Batteries Enabled by an Efficient Borate-Based Electrolyte . Small . 16 . 39 . e2001806 . October 2020 . 32812367 . 10.1002/smll.202001806 . free .
  68. Palacin M, Black A, Tchitchekova DS, Johansson P, Araujo RB, Aren F, Arroyo-de Dompablo E, Torres A, Tortajada J, Luque J, Wuersig A . 6 . 2020-11-23. Tackling the Development of Rechargeable Calcium Batteries: The CARBAT Project . ECS Meeting Abstracts. en. MA2020-02. 2. 449. 10.1149/MA2020-022449mtgabs. 234584810. 2151-2043.
  69. Pu SD, Gong C, Gao X, Ning Z, Yang S, Marie JJ, Liu B, House RA, Hartley GO, Luo J, Bruce PG . 6 . 2020-07-10. Current-Density-Dependent Electroplating in Ca Electrolytes: From Globules to Dendrites . ACS Energy Letters. 5. 7. 2283–2290. 10.1021/acsenergylett.0c01153. 225648185.
  70. Chando . Paul Alexis . Chen . Sihe . Shellhamer . Jacob Matthew . Wall . Elizabeth . Wang . Xinlu . Schuarca . Robson . Smeu . Manuel . Hosein . Ian Dean . 2023-10-24 . Exploring Calcium Manganese Oxide as a Promising Cathode Material for Calcium-Ion Batteries . Chemistry of Materials . en . 35 . 20 . 8371–8381 . 10.1021/acs.chemmater.3c00659 . 0897-4756 . 10601472 . 37901147.