by Binayak Roy, Pavel Cherepanov, Cuong Nguyen, Craig Forsyth, Urbi Pal, Tiago Correia Mendes, Patrick Howlett, Maria Forsyth, Douglas MacFarlane and Mega Kar.
School of chemistry, Monash University,Wellington Road, Clayton, VIC 3800, Australia
Insitutute for Frontier Materials, Deakin University, 221 Burwood Highway, Burwood, VIC
The atmospheric instability and the corrosive tendency of hexafluorophosphate [PF6]− and fluorosulfonylimide [FSI]− based lithium salts, respectively, are among the major impediments towards their application as electrolytes in high voltage lithium batteries. Herein a new class of Li salts is introduced and their electrochemical behavior is explored. The successful synthesis and characterization are reported, including the crystal structure, of lithium 1,1,1,3,3,3-(tetrakis)hexafluoroisopropoxy borate (LiBHfip). The oxidative stability of electrolytes of this salt in an ethylene carbonate:dimethyl carbonate mixture (v/v, 50:50) is found to be 5.0 V versus Li+/Li on various working electrodes, showing substantial improvement over a LiPF6 based electrolyte. Moreover, a high stability of an aluminum substrate is observed at potentials up to 5.8 V versus Li+/Li; in comparison, a LiFSI based electrolyte shows prominent signs of Al corrosion above 4.3 V versus Li+/Li. Cells tested with high voltage layered LiNi0.8Mn0.1Co0.1O2 (NMC811) and spinel LiMn2O4 (LMO) cathodes show stable cycling over 200 cycles with capacity retention of 76% and 90%, respectively. The LMO|Li cell maintains this same low capacity fade rate for 1000 cycles even after the salt has been exposed for 24 h to atmospheric conditions (water content ≈0.57 mass%).
Dr Matt Boot-Handford – On the chemistry of Calix materials for lithium-ion batteries
“We are trying to develop processes technologies materials that look to transition us to a much more sustainable and responsible future”
Matt Boot-Handford manages Calix’s role in a variety of collaborative research programs including: storEnergy: the Australian Research Council funded Training Centre for Future Energy Storage Technologies; POLYSTORAGE: the EU funded training centre developing solid state batteries; and the Calix-led CRC-P for Advanced Hybrid Batteries.