Abstract:Electrochemical
and analytical techniques were utilized to study
Ca electrodeposition in nonaqueous electrolytes. Linear sweep voltammograms
obtained at Au and Pt ultramicroelectrodes (UMEs) exhibit an inverse
dependence between current density and scan rate, indicative of the
presence of a chemical reaction step in a chemical–electrochemical
(CE) deposition process. However, the magnitude of change in current
density as a function of scan rate is larger at the Au UME than at
the Pt UME. COMSOL simulation reve… Show more
“…Thus, the authors concluded that Ca 2+ is predominantly solvated by THF via the ethereal oxygen and is weakly coordinated, if at all, to BH4 -. [63] Overall, the findings point towards a surface-chemical role of the anion. Interestingly, the conductivities of Ca(BH4)2/THF electrolytes were significantly lower than their carbonate-based counterparts (Fig.…”
Section: Ca(bh4)2 In Thf With Au or Pt Electrodesmentioning
confidence: 90%
“…Recently, Ta et al proposed an explanation for the functional role of BH4in the successful Ca(BH 4 ) 2 /THF system. [63] Linear sweep voltammetry with ultramicroelectrodes was performed on both Au and Pt working electrodes. The authors found that Ca deposition occurs through a chemicalelectrochemical mechanism, in which chemical H abstraction from BH4in the bulk electrolyte (and not THF) and surface H adsorption precedes subsequent reduction of Ca 2+ .…”
Section: Ca(bh4)2 In Thf With Au or Pt Electrodesmentioning
Calcium metal batteries are receiving growing research attention due to significant breakthroughs in recent years that have indicated reversible Ca plating/stripping with attractive Coulombic efficiencies (90-95%), once thought to be out of reach. While the Ca anode is often described as being surface filmcontrolled, the ability to access reversible Ca electrochemistry is highly electrolyte-dependent in general, which affects both interfacial chemistry on plated Ca along with more fundamental Ca 2+ /Ca redox properties. This mini-review describes recent progress towards a reversible Ca anode from the point of view of the most successful electrolyte chemistries identified to date. This includes, centrally, what is currently known about the Ca 2+ solvation environment in these systems. Experimental (physico-chemical and spectroscopy) and computational results are summarized for the two major solvent classescarbonates and ethers-that have yielded promising results so far. Current knowledge gaps and opportunities to improve fundamental understanding of Ca 2+ /Ca redox are also identified.
“…Thus, the authors concluded that Ca 2+ is predominantly solvated by THF via the ethereal oxygen and is weakly coordinated, if at all, to BH4 -. [63] Overall, the findings point towards a surface-chemical role of the anion. Interestingly, the conductivities of Ca(BH4)2/THF electrolytes were significantly lower than their carbonate-based counterparts (Fig.…”
Section: Ca(bh4)2 In Thf With Au or Pt Electrodesmentioning
confidence: 90%
“…Recently, Ta et al proposed an explanation for the functional role of BH4in the successful Ca(BH 4 ) 2 /THF system. [63] Linear sweep voltammetry with ultramicroelectrodes was performed on both Au and Pt working electrodes. The authors found that Ca deposition occurs through a chemicalelectrochemical mechanism, in which chemical H abstraction from BH4in the bulk electrolyte (and not THF) and surface H adsorption precedes subsequent reduction of Ca 2+ .…”
Section: Ca(bh4)2 In Thf With Au or Pt Electrodesmentioning
Calcium metal batteries are receiving growing research attention due to significant breakthroughs in recent years that have indicated reversible Ca plating/stripping with attractive Coulombic efficiencies (90-95%), once thought to be out of reach. While the Ca anode is often described as being surface filmcontrolled, the ability to access reversible Ca electrochemistry is highly electrolyte-dependent in general, which affects both interfacial chemistry on plated Ca along with more fundamental Ca 2+ /Ca redox properties. This mini-review describes recent progress towards a reversible Ca anode from the point of view of the most successful electrolyte chemistries identified to date. This includes, centrally, what is currently known about the Ca 2+ solvation environment in these systems. Experimental (physico-chemical and spectroscopy) and computational results are summarized for the two major solvent classescarbonates and ethers-that have yielded promising results so far. Current knowledge gaps and opportunities to improve fundamental understanding of Ca 2+ /Ca redox are also identified.
“…And for the first time, a Ca(BH 4 ) 2 electrolyte in THF was demonstrated for reversible calcium deposition and stripping at room temperature with low polarization (<0.1 V) and high coulombic efficiencies (≈95 %) by Bruce and Wang et al . and further confirmed by Gewirth et al . However, the reductive nature and insufficient anodic stability (ca.…”
Calcium batteries are a potentially sustainable, high‐energy‐density battery technology beyond Li ion batteries. Now the development of Ca batteries has become possible with a newly invented Ca electrolyte capable of reversible Ca deposition/stripping at room temperature.
“…Except for the self-characters such as electropositivity, ionic radius, and charges etc., it's generally accepted that metal plating/stripping potentials are dependent on the solvation/desolvation properties, which are highly in uenced by the ion concentration, type of solvents, substrates, and temperatures. [7][8][31][32] In the case of Ca-metal, the situations seem more complicated due to anion corrosion and large internal resistance resulted from the extremely insulative passivation layers. [4][5]7 Anyway, we found that the polarization potentials for Ca deposition/dissolution could be largely lowered through the increase of Ca 2+ concentration by adding Ca(BF 4 ) 2 .…”
Section: Voltage Tailorable Cwpdgc Ca-metal Batteriesmentioning
Calcium metal battery as one of the promising alternatives beyond Li-metal technology is challenged by the lack of suitable cathodes with considerable energy performance, and stable Ca anode of long-term stability and lower polorization potentials for Ca-plating/stripping. Here, by recycling cellulose waste paper of wide sources in our daily life, we develop feasible cathodes for Ca-metal batteries of good high-voltage and wide-window-voltage adaptability (0.005-4.9 V vs. Ca/Ca2+), except for considerable energy performance (~517.5 Wh kg-1 at 0.1 A g-1). Meanwhile, through tailorable Ca-plating/stripping potentials (∆V= ~0.65 V) induced by electrolyte modification, proof-of-concept Ca-metal batteries not only delivered enhanced storage capability (101 mAh g-1 vs. 51 mAh g-1 at 0.1 A g-1 in the window voltage of 2.0-4.7 V ) and cycling stability (~77% capacity retention for 100 cycles), but also simutaneously held high output average working voltage of ~3.2V.
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