The critical role of configurational flexibility in facilitating reversible reactive metal deposition from borohydride solutions. Issue 15 (31st March 2020)

• Record Type: Journal Article
• Authors: Hahn, Nathan T.; Self, Julian; Seguin, Trevor J.; Driscoll, Darren M.; Rodriguez, Mark A.; Balasubramanian, Mahalingam; Persson, Kristin A.; Zavadil, Kevin R.
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 15(2020)
• Page Start: 7235
• Page End: 7244
• Publication Date: 2020-03-31
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0ta02502j
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : The size-dependent coordination tendencies of metal dications determine their relative abilities to form associated ionic clusters and thus their relative performance in multivalent battery electrolytes. Abstract : Development of calcium metal batteries has been historically frustrated by a lack of electrolytes capable of supporting reversible calcium electrodeposition. In this paper, we report the study of an electrolyte consisting of Ca(BH4 )2 in tetrahydrofuran (THF) to gain important insight into the role of the liquid solvation environment in facilitating the reversible electrodeposition of this highly reactive, divalent metal. Through interrogation of the Ca 2+ solvation environment and comparison with Mg 2+ analogs, we show that an ability to reversibly electrodeposit metal at reasonable rates is strongly regulated by dication charge density and polarizability. Our results indicate that the greater polarizability of Ca 2+ over Mg 2+ confers greater configurational flexibility, enabling ionic cluster formation via neutral multimer intermediates. Increased concentration of the proposed electroactive species, CaBH4 +, enables rapid and stable delivery of Ca 2+ to the electrode interface. This work helps set the stage for future progress in the development of electrolytes for calcium and other divalent metal batteries.