Organic Ionic Plastic crystals novel ionic electrolytes for alkali metal batteries

Prof Patrick C Howlett

Abstract

The electrolyte is one of the key components of an energy storage device required to achieve, for example, high reliability and safety as well as high energy density. There are numerous battery chemistries possible, although lithium-ion has become one of the most common technologies for portable electronics and is making its way increasingly into electric vehicles and stationary storage.

We have found that pyrrolidinium and phosphonium based organic ionic plastic crystals (OIPCs), made entirely of ions, can be applied as attractive, high safety, solid-state electrolytes for lithium batteries.[1] These electrolytes offer attractive stable electrolyte properties and unique interfacial properties, key to the use of high energy density electrodes such as lithium metal. These materials allow flexibility of design and can remove the safety risks associated with leakage and ignition of commonly used volatile liquid electrolytes. They can be classed as fast ion conductors, where one type of ion (i.e., Li+ for lithium batteries) is able to move rapidly against a background of a relatively static matrix.

However, in most cases the ionic conductivity of OIPCs is too low for application in devices at ambient temperatures. In this presentation, the use of nanoscale polymers as additives and mechanical support matrices has been investigated. The obtained composite materials exhibit enhanced mechanical and ion transport properties and improved device performance. Our efforts to understand the OIPC, alkali salt and composite properties for application as new solid state electrolytes will be described.[2-5]

Bio

Professor Patrick Howletts’ research relates to electrochemical devices (e.g., batteries) and surface engineering through the manipulation of electrode interphases using novel materials approaches. The materials focus of Prof Howlett’s research includes ionic liquids, polymer electrolytes, plastic crystal electrolytes as well as their composites and reactive metals such as lithium and sodium. His work also includes the use and development of advanced surface characterisation techniques including synchrotron based sources.
He has published over 160 refereed journal papers and 8 patents, with almost 8000 citations and h-index of 43 (Google Scholar). He is a Chief Investigator within both the ARC Centre of Excellence for Electromaterials Science and within StorEnergy where he is a platform leader.
Prior to commencing his research career he worked in the mining and petrochemical industries. In 1998 he joined the CSIRO doing battery research for 5 years, where he completed his PhD (Monash). Following this he became an ARC Centre of Excellence Research Fellow at Monash University before moving to Deakin in 2010, where he now holds a continuing position focused on energy storage research.

References

1. Jin, L., Howlett, P. C., Pringle, J. M., Janikowski, J., Armand, M., MacFarlane, D. R. & Forsyth, M. An organic ionic plastic crystal electrolyte for rate capability and stability of ambient temperature lithium batteries. Energy Environ. Sci. 7, 3352 (2014).
2. Howlett, P. C., Ponzio, F., Fang, J., Lin, T., Jin, L., Iranipour, N. & Efthimiadis, Thin and Flexible Solid-State Organic Ionic Plastic Crystal-Polymer Nanofibre Composite Electrolytes for Device Applications. Phys. Chem. Chem. Phys. 15, 13784 (2013).
3. Iranipour, N., Gunzelmann, D. J., Seeber, A., Vongsvivut, J., Doherty, C., Ponzio, F., O’Dell, L. A., Hollenkamp, A. F., Forsyth, M., Howlett, P. C., Ionic Transport Through a Composite Structure of N-ethyl-N-methylpyrrolidinium tetrafluoroborate Organic Ionic Plastic Crystals Reinforced with Polymer Nanofibres. J. Mater. Chem. A. 3, 6038 (2015).
4. Zhou, Y.; Wang, X.; Zhu, H.; Armand, M.; Forsyth, M.; Greene, G. W.; Pringle, J. M.; Howlett, P. C. N-Ethyl-N-Methylpyrrolidinium Bis(Fluorosulfonyl)Imide-Electrospun Polyvinylidene Fluoride Composite Electrolytes: Characterization and Lithium Cell Studies. Phys. Chem. Chem. Phys., 19, 2225 (2017).
5. Wang, X.; Zhu, H.; Greene, G. W.; Zhou, Y.; Yoshizawa-Fujita, M.; Miyachi, Y.; Armand, M.; Forsyth, M.; Pringle, J. M.; Howlett, P. C. Organic Ionic Plastic Crystal-Based Composite Electrolyte with Surface Enhanced Ion Transport and Its Use in All-Solid-State Lithium Batteries. Adv. Mater. Technol. 8, 1700046 (2017).