University of Pittsburgh researchers have developed novel conducting composite polymer electrolytes (CPEs). These CPEs contain polar halogen groups and incorporate lithium- and sulfur-containing electrolytes with nanometer sized inorganic particles to form a separator. The CPE separators enhance the stability of electrodes and could lead to the production of batteries with improved energy densities. These novel CPEs have the potential to revolutionize the field of high-power Li-ion batteries leading to development of higher-energy battery systems with applications ranging from electric vehicles (EVs) to consumer electronics.
Novel CPE containing polar halogen groups such as poly (vinylidene fluoride – co – hexafluoro propylene) (PVdF – HFP) incorporating LiTFSI salts can form a gel separator between a Li anode and S cathode stabilizing the cathode, improving electrochemical cycling performance, battery safety, and ionic conductivity.
Description
Li-ion batteries are used in many consumer goods from EVs to laptops and medical devices to cell phones and are vital for current global efforts to reduce reliance on fossil fuels. By 2030 some analysts suggest the global market for Li-ion batteries could be over $400bn with Li-ion batteries required to produce around 4.7 TWh of power to meet demand. As global lithium supplies deplete, there is a need to develop higher capacity, efficient Li-ion batteries to meet this demand. Lithium–Sulfur (Li–S) batteries theoretically have an energy density more than twice that of Li-ion batteries but challenges remain in developing stable Li–S batteries. These novel CPE separators can stabilize sulfur electrodes and could lead to the development of higher capacity Li–S batteries with lithium-free cathodes, improving battery energy density while reducing the amount of lithium required and associated costs.
Applications
- High-capacity lithium–sulfur batteries
- Electric vehicles
Advantages
The capacity of current Li-ion batteries is limited by the formation of lithium dendrites on the battery electrodes leading to battery failure and has been associated with safety risks including fires. While sulfur cathodes have presented some promise, the poor capacity of sulfur and dissolution of polysulfide and plating the anode leads to battery failure.
This novel approach replaces the traditionally used liquid organic electrolyte separator with polymer gel electrolyte preventing polysulfide dissolution and improving the stability of the sulfur cathode. This gel separator has improved tolerance to shock, vibration, and mechanical deformation, reducing fire and explosion risk.
Invention Readiness
CPE separators have been produced using electrospun poly(vinylidene fluoride co hexafluoropropylene) (PVdF-HFP), bis(trifluoromethane)sulfonimidelithium salts (LiTFSI), and mesoporous filler nanoparticles. Testing confirmed these polymer membranes have excellent ionic conductivity close to that observed in liquid electrolytes, enhanced electrochemical conductivity, and could prevent polysulfide dissolution with improved safety.
IP Status
https://patents.google.com/patent/WO2019010474A1
