Facile Synthesis of Nanosized Lithium-Ion-Conducting Solid Electrolyte LiAlTi(PO) and Its Mechanical Nanocomposites with LiMnO for Enhanced Cyclic Performance in Lithium Ion Batteries.

Nanoparticles of fast lithium-ion-conducting solid electrolyte LiAlTi(PO) (LATP) are prepared by a modified citric-acid-assisted sol-gel method that involves a two-step heat treatment in which the dry gel is calcined first in argon and then in air. The obtained LATP exhibits smaller particle size (down to 40 nm) with a narrower size distribution and less aggregation than LATP prepared by a conventional sol-gel method because of a polymeric network that preserves during LATP crystallization. It has a high relative density of 97.0% and a high room-temperature conductivity of 5.9 × 10 S cm. The as-prepared superfine LATP is further used to composite with a spinel LiMnO cathode in lithium ion batteries by simple grinding. This noncoating speckled layer over the LiMnO particle surface has a minimal effect on the electronic conductivity of the electrode while offering excellent ionic conductivity. The cycling stability and rate capability of LiMnO are greatly improved at both ambient and elevated temperatures. After 100 cycles at 25 and 55 °C, the capacity retentions are 96.0% and 89.0%, respectively, considerably higher than the values of pristine LiMnO (61.0% at 25 °C; 51.5% at 55 °C) and mechanical LiMnO composite with LATP made by a conventional sol-gel method (85.0% at 25 °C; 71.4% at 55 °C).