Lithium solid electrolytes can potentially address two key limitations of the organic electrolytes used in today’s lithium-ion batteries, namely, their flammability and limited electrochemical stability. However, achieving a Li⁺ conductivity in the solid state comparable to existing liquid electrolytes (>1 mS cm^-1) is particularly challenging. In this work, we reveal a fundamental relationship between anion packing and ionic transport in fast Li-conducting materials and expose the desirable structural attributes of good Li-ion conductors. We find that an underlying body-centred cubic-like anion framework, which allows direct Li hops between adjacent tetrahedral sites, is most desirable for achieving high ionic conductivity, and that indeed this anion arrangement is present in several known fast Li-conducting materials and other fast ion conductors. These findings provide important insight towards the understanding of ionic transport in Li-ion conductors and serve as design principles for future discovery and design of improved electrolytes for Li-ion batteries.

Nature Materials 14, 1026–1031 (2015) doi:10.1038/nmat4369
Received 05 March 2015 Accepted 25 June 2015 Published online 17 August 2015

http://www.nature.com/nmat/journal/v14/n10/full/nmat4369.html