Proton-assisted calcium-ion storage in aromatic organic molecular crystal with coplanar stacked structure

Abstract

Rechargeable calcium-ion batteries are intriguing alternatives for use as post-lithium-ion batteries. However, the high charge density of divalent Ca2+ establishes a strong electrostatic interaction with the hosting lattice, which results in low-capacity Ca-ion storage. The ionic radius of Ca2+ further leads to sluggish ionic diffusion, hindering high-rate capability performances. Here, we report 5,7,12,14-pentacenetetrone (PT) as an organic crystal electrode active material for aqueous Ca-ion storage. The weak π-π stacked layers of the PT molecules render a flexible and robust structure suitable for Ca-ion storage. In addition, the channels within the PT crystal provide efficient pathways for fast ionic diffusion. The PT anode exhibits large specific capacity (150.5 mAh g-1 at 5 A g-1), high-rate capability (86.1 mAh g-1 at 100 A g-1) and favorable low-temperature performances. A mechanistic study identifies proton-assisted uptake/removal of Ca2+ in PT during cycling. First principle calculations suggest that the Ca ions tend to stay in the interstitial space of the PT channels and are stabilized by carbonyls from adjacent PT molecules. Finally, pairing with a high-voltage positive electrode, a full aqueous Ca-ion cell is assembled and tested.

Bioinspired Catechol‐Grafting PEDOT Cathode for an All‐Polymer Aqueous Proton Battery with High Voltage and Outstanding Rate Capacity

“…A rechargeable aqueous battery with various cationic charge carriers is proposed to meet the above requirements, including monovalent ions (H + , Li + , K + , and Na + ) and multivalent ions (Zn 2+ , Ca 2+ , Mg 2+ , and Al 3+ ). [ 1 , 2 , 3 , 4 ] Although metal‐ion rechargeable batteries possess a high capacity and excellent stability, the ion transport significantly impeded the realization of instantaneous output due to the large ionic radius and strong electrostatic interactions. [ 5 , 6 ] Rechargeable aqueous proton batteries based on the proton uptake/removal mechanism are promising to overcome the ion‐diffusion kinetics limit.…”

A rechargeable aqueous manganese-ion battery based on intercalation chemistry

“…GITT result shows that the diffusion coefficient of Mn 2+ ions in 4-Cl-BQ@rGO composite cathode is ~10 −12 –10 −10 cm 2 s −1 , which is higher than the Li + ion diffusion coefficients in LiFePO 4 and Li 4 Ti 5 O 12 (<10 −12 cm 2 s −1 ) (Fig. 4f ) 49 . Furthermore, it is comparable with the Zn 2+ ion diffusion coefficient in V 5 O 12 and higher than the H + /Zn 2+ ion diffusion coefficient in amorphous MnO 2 54 , 55 .…”

“…The specific energy ( E , Wh kg −1 ) and power ( P , W kg −1 ) of batteries based on active materials were calculated as follows 49 : in which I (A) and V (V) are the current and voltage of the cell, t (s) is the discharge time, and m (g) is the weight of active material. The voltage of the cell was the average discharge voltage, which was at the half of the discharge capacity in discharging process.…”

Marble Waste Sludges as Effective Nanomaterials for Cu (II) Adsorption in Aqueous Media

“…According to the Cu (II) species distribution diagram as a function of pH (Figure 4), the hydrodynamic radius of the aquo-complex [Cu(H 2 O) 6 ] 2+ , the predominant species at pH 6, is 0.069 nm [51] and the solubility product of CuCO 3 is Kps = 2.5 × 10 −10 [52]. The radius of Ca 2+ is 0.099 nm [53].…”

“…According to the Cu (II) species distribution diagram as a function of pH (Figure 4), the hydrodynamic radius of the aquo-complex [Cu(H2O)6] 2+ , the predominant species at pH 6, is 0.069 nm [51] and the solubility product of CuCO3 is Kps = 2.5•10 −10 [52]. The radius of Ca 2+ is 0.099 nm [53]. Hence, Cu (II) adsorption on marble sludges may be produced by: (i) intercalation of the metal cation between CaCO3 layers and (ii) the formation of surface carbonate complexes.…”