Characterisation and modelling of multivalent polymer electrolytes

Ion Transport in Solvent-Free, Crosslinked, Single-Ion Conducting Polymer Electrolytes for Post-Lithium Ion Batteries

“…have faster transport rates in the polyether ionomer than the bare divalent cations Mg 2+ and Ca 2+ . The low ionic conductivity of the hard divalent cations Mg 2+ and Ca 2+ in poly(ethylene oxide) has been documented in other works and is attributed to the divalent cation acting as a crosslinking point, strongly linking adjacent chains [51,52]. The conductivity of the Na and K containing electrolytes is close to that of the lithiated electrolyte at high temperatures, thus, we suggest that these electrolytes be further considered for use in elevated temperature Na and K battery systems.…”

Application of Single-Ion Conducting Gel Polymer Electrolytes in Magnesium Batteries

“…7−11 Because of the higher charge density of Mg 2+ (approximately twice that of Li + ), the magnesium cation exhibits very strong coordination with polar polymers leading to low cation transference numbers and low cation conductivities. 12,13 Many magnesium polymer electrolyte studies have used magnesium triflate or magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI) 2 ), which contains weakly coordinating anions that increase salt dissociation. 9,11,14,15 Computational studies of Mg(TFSI) 2 suggest that the MgTFSI + ion pair is unstable during magnesium electrodeposition, and experimental reports have confirmed that the salt in solution is not chemically stable against magnesium.…”

“…Both gel and solid polymer electrolytes have been researched for use in magnesium metal batteries. − Because of the higher charge density of Mg 2+ (approximately twice that of Li + ), the magnesium cation exhibits very strong coordination with polar polymers leading to low cation transference numbers and low cation conductivities. , Many magnesium polymer electrolyte studies have used magnesium triflate or magnesium bis­(trifluoro­methane­sulfonyl)­imide (Mg­(TFSI) 2 ), which contains weakly coordinating anions that increase salt dissociation. ,,, Computational studies of Mg­(TFSI) 2 suggest that the MgTFSI + ion pair is unstable during magnesium electrodeposition, and experimental reports have confirmed that the salt in solution is not chemically stable against magnesium. , Thus, it is a challenge to enable high Coulombic efficiency magnesium metal deposition and dissolution with electrolytes that employ these salts. Similarly, there are further literature reports on the physical properties of magnesium-based polymer electrolytes containing salts such as Mg­(ClO 4 ) 2 and Mg­(NO 3 ) 2 or plasticizers such as organic carbonates that are commonly used in Li-ion batteries. ,− Although all of these works report total ionic conductivity of the prepared electrolyte, magnesium metal electrodeposition or dissolution is not interrogated beyond symmetric cell cyclic voltammetry. ,− In contrast, reversible electrodeposition/dissolution of magnesium and charge/discharge cycling of a magnesium battery was demonstrated by using a nanocomposite electrolyte of Mg­(BH 4 )-MgO-PEO .…”

Recent advancements in solid electrolytes integrated into all-solid-state 2D and 3D lithium-ion microbatteries

“…120,123 Thus, this parameter is mainly important for polymer electrolytes, where several other species like various anions can be mobile and contribute to the overall conduction. 124 So some earlier studies observed the low cation transference number for polymer electrolytes. 125,126 For solid PEO-based electrolytes, it was shown that the cationic transference number varied between 0.2 and 0.3 with ionic conductivity in the range of 10 À8 -10 À5 S cm À1 .…”