A Novel Ceramic-Polymer Hybrid Electrolyte for Lithium Batteries

Abstract

Lithium (Li) metal is being intensively pursued as a negative electrode due to its high specific capacity. Yet, irreversible Li loss, dendrite formation of plated Li metal, and short circuiting, when being cycled as an electrode in battery cells presently impede its use. Furthermore, the flammability of liquid electrolytes poses a severe safety hazard. Replacement of organic liquids by solid electrolytes could pave the way for using Li metal, simultaneously improving specific energy and battery safety. Significant attention has been paid to ceramic electrolytes due to their high Li-ion conductivity at room temperature and robustness. Nevertheless, processing and manufacturing of the ceramics into sufficiently thin, highly dense, pinhole-free sheets, required for high specific energy and power devices, remains an active challenge. Additionally, the electrolyte must maintain contact with the solid electrodes while simultaneously inhibiting Li dendrites as well as be durable towards electrode volume changes and to external shock. Polymer electrolytes have been developed for a number of years. The advantages include good adhesion and contact to the electrodes. Still, their low conductivity at room temperature, especially in solid polymer electrolytes, along with their limited capability of suppressing Li dendrite formation, are persistent drawbacks.[i] To date, ceramic and polymer electrolytes remain a challenge. Hybrids with particulate ceramics embedded in polymer electrolytes have been investigated to improve the conductivity and mechanical properties. [ii] Our approach is to create continuously ordered hybrid electrolytes, which allows modification of the mechanical properties of the hybrid while retaining a high ionic conductivity through the ceramic phase. The ionic conductivity of the hybrid electrolyte is 1.5 x 10-4S/cm at 25 °C. The results of different ceramic-polymer compositions indicate that the mechanical properties of the hybrids can be adjusted by the presented approach. Electrochemical, mechanical, and microstructural characterizations of the hybrid will be reported. [i] G. M. Stone, S. A. Mullin, A. A. Teran, D. T. Hallinan Jr., A. M. Minor, A. Hexemer, N. P. Balsara, J. Electrochem. Soc., 2012, 159, A222–A227. [ii] Y.-C. Jung, S.-M. Lee, J.-H. Choi, S. S. Jang and D.-W. Kim, J. Electrochem. Soc., 2015, 162, A704–A710.

Architected porous metals in electrochemical energy storage

“…We now have a wide range of methods to fabricate porous metal with different porosity length scales, and with different degrees of ordering or periodicity [5][6][7][8]. While certain metals, their alloys and their physical properties fundamentally limit the range of latticed or porous structures that can be formed, the choice of metal for electrochemical energy storage applications [9][10][11][12] is usually based on surface activity, passivity, electrical conductivity and weightthe length scale of porosity [13], and the types of porous ordering are not always obtainable 'a la carte' for the electrochemical application when open-worked from the bulk metal. We examine the nature of porous metal formation, address some limitation for transition metals and noble metals in foam, lattice or porous form [14] for electrochemical energy storage devices and discuss how the choice of metal and the method of fabrication influence the nature of the porosity and their relative benefit in energy storage devices.…”