Facile Synthesis of Nanosized Lithium-Ion-Conducting Solid Electrolyte Li1.4Al0.4Ti1.6(PO4)3 and Its Mechanical Nanocomposites with LiMn2O4 for Enhanced Cyclic Performance in Lithium Ion Batteries

Nanoparticles of fast lithium-ion-conducting solid electrolyte Li1.4Al0.4Ti1.6(PO4)3 (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 × 10–4 S cm–1. The as-prepared superfine LATP is further used to composite with a spinel LiMn2O4 cathode in lithium ion batteries by simple grinding. This noncoating speckled layer over the LiMn2O4 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 LiMn2O4 are greatly improved at both ambient and el...