Effect of Concentrated Diglyme-Based Electrolytes on the Electrochemical Performance of Potassium-Ion Batteries

Abstract

The effect of salt concentration in diglyme-based electrolytes on cycling performance of promising KVOPO 4 and K 1.69 Mn[Fe(CN) 6 ] 0.85 •0.4H 2 O positive electrodes (cathodes) and a hard carbon negative electrode (anode) for next-generation potassium-ion (K-ion) batteries is investigated. A decrease in free solvent molecule number with increasing electrolyte concentration is found, which results in a better aluminum current collector stability, formation of thinner solid electrolyte interface (SEI) passivation layers, and further inhibition of solvent degradation redox processes occurring at the electrode surface upon cycling. The KVOPO 4 and K 1.69 Mn[Fe(CN) 6 ] 0.85 •0.4H 2 O cathodes exhibit an enhanced specific discharge capacity (54 and 105 mA•h•g −1 , respectively) in K-ion cells at the highest electrolyte concentrations (2 and 2.5 M KPF 6 in diglyme, respectively) at a 0.1 C rate. However, the behavior of the hard carbon anode is noticeably affected by the salt concentration over the first few cycles, a phenomenon tentatively attributed to the SEI layer formation and the presence of irreversible intercalation sites for K + ions in the hard carbon framework. Finally, electrochemical tests on K-ion full cells consisting of the K 1.69 Mn[Fe(CN) 6 ] 0.85 •0.4H 2 O cathode, a hard carbon anode, and an ether-based electrolyte show capacity retention of 86% over 300 cycles at a 0.6 C rate.

Nernstian Li+ intercalation into few-layer graphene and its use for the determination of K+ co-intercalation processes

“…Alkali ion batteries (AIB) based on Li + , and emerging technologies based on K + , are important high-performance rechargeable energy storage devices. [1][2][3] Considerable recent efforts have been devoted to the fabrication of new electrode materials, 4 discovery of energy storage mechanisms, 5 electrochemical reactions at electrodes and interphases, 6,7 and towards improving the cell capacity, stability, and cyclability. 8 Upon AIB cycling, alkali ions are reversibly stored within both anode and cathode in the battery.…”

K‐Ion Storage Enhancement in Sb2O3/Reduced Graphene Oxide Using Ether‐Based Electrolyte

“…Sun's group optimized the concentration of ether‐based electrolyte and found that the high concentration ether‐based electrolyte could effectively stabilize the cycling performance of Bi@C electrode for KIBs . Also, Stevenson's group explored the effect of different concentration ether‐based electrolyte and found that high concentration ether‐based electrolyte could decrease the free solvent molecule, which would restrain the solvent degradation upon cycling . In spite of these works, more material systems cooperated with high concentration ether‐based still need to be explored.…”

“…[26] Li's group employed porous Bi combined with ether-based electrolyte for KIBs, delivering a superior reversible capacity and long cycle life. [30] In spite of these works, more material systems cooperated with high concentration ether-based still need to be explored. [28] Meanwhile, some works involving high concentration ether-based electrolyte have also received attention.…”

Post‐Lithium‐Ion Battery Era: Recent Advances in Rechargeable Potassium‐Ion Batteries

“…Furthermore, reports by Mai et al [178] . and Stevenson et al [179] . also confirmed the unique contribution of ether‐based electrolytes in improving and optimizing the performance of PIBs.…”