A Novel Li⁺‐Conducting Polymer Membrane Gelled by Fluorine‐Free Electrolyte Solutions for Li‐Ion Batteries

Abstract

Gel polymer electrolytes (GPEs), composed of poly(vinylidene fluoride) (PVdF), a ternary solvent of ethylene carbonate : propyylene carbonate : dimethyl carbonate, and LiBOB, which are characterized by a novel composition with a fluorine-free lithium salt, are here proposed. GPEs were firstly prepared through a solution casting procedure using the ternary carbonate solution as a solvent (named ex situ prepared membranes), and then activated by being immersed in a 0.7 M LiBOB-carbonate solution. Fundamental characterizations, including thermal, spectroscopical, mechanical, and electrochem-ical analyses, were carried out and compared before and after the activation. GPEs, having the same composition, were also prepared by using a novel procedure (named in situ prepared membranes), involving the formation of PVdF membrane and its activation by the LiBOB electrolyte, as well as subsequent electrochemical characterizations, in the same T-shape cell. Thus prepared lithium-ion batteries, employing SnÀ C and LiFePO 4 electrodes, were demonstrated to exhibit a high capacity of 150 mAh g À 1 through the course of cycling.

Aromatic heterocyclic anion based ionic liquids and electrolytes

“…These properties make them the most popular rechargeable batteries for portable gadgets, electric vehicles and aerospace applications. 3,4 They do, however, have serious safety issues due to the electrolytes made up of fluorinated salts dissolved in flammable organic solvents. 5,6 Several attempts have been made to use nonflammable solvents, thermally and electrochemically stable (non-fluorinated) Li-salts, as well as additives to improve safety.…”

The ENEA′s 2019–2021 Three‐Year Research Project on Electrochemical Energy Storage

“…The cell exhibited the capacity of 160 mAh g −1 in the first charge‐discharge cycle, which is corresponding to 94 % of the theoretical specific capacity of LFP and good capacity retention over 10 cycles, with high Coulombic efficiency (>95 %). In following cycles, the cell maintained a good Coulombic efficiency (98.4 % at 40 th cycle) but a slow decay of the full‐cell performances was observed [52] …”

“…This confirmed that the orthoborate anions can form a durable and effective interface layer, allowing prolonged cyclability of high voltage lithium cells. [50] Electrolyte formulations based on ILs and commercial electrolytes (LP30 or LP70) have been developed to produce gel polymer electrolytes [51,52] based on poly(vinylidene fluoride-cohexafluoropropylene) (PVdFÀ HFP), 1 M LiPF 6 in ethylene carbonate/dimethyl carbonate, and 1-butyl-1-methylpyrrolidinium hexafluorophosphate. These gel polymer electrolytes showed improved inherent safety and can be used in high voltage lithium batteries.…”

“…In following cycles, the cell maintained a good Coulombic efficiency (98.4 % at 40 th cycle) but a slow decay of the full-cell performances was observed. [52] Solid electrolytes suitable for working at high voltage have been also developed and characterised. [24,[53][54][55] A perspective on strategies and opportunities, particularly around the development of all-solid-state system configurations, can be found in Ref.…”