%0 Journal Article
%A Saravanan Kuppan
%A Yahong Xu
%A Yijin Liu
%A Guoying Chen
%B Nature Communications
%D 2017
%G eng
%N 1
%R 10.1038/ncomms14309
%T Phase transformation mechanism in lithium manganese nickel oxide revealed by single-crystal hard X-ray microscopy
%V 8
%8 02/2017
%! Nat Commun
%X <p><span>Understanding the reaction pathway and kinetics of solid-state phase transformation is critical in designing advanced electrode materials with better performance and stability. Despite the first-order phase transition with a large lattice mismatch between the involved phases, spinel LiMn</span><span>1.5</span><span>Ni</span><span>0.5</span><span>O</span><span>4</span><span>&nbsp;is capable of fast rate even at large particle size, presenting an enigma yet to be understood. The present study uses advanced two-dimensional and three-dimensional nano-tomography on a series of well-formed Li</span><span><em>x</em></span><span>Mn</span><span>1.5</span><span>Ni</span><span>0.5</span><span>O</span><span>4</span><span>&nbsp;(0≤</span><em>x</em><span>≤1) crystals to visualize the mesoscale phase distribution, as a function of Li content at the sub-particle level. Inhomogeneity along with the coexistence of Li-rich and Li-poor phases are broadly observed on partially delithiated crystals, providing direct evidence for a concurrent nucleation and growth process instead of a shrinking-core or a particle-by-particle process. Superior kinetics of (100) facets at the vertices of truncated octahedral particles promote preferential delithiation, whereas the observation of strain-induced cracking suggests mechanical degradation in the material.</span></p>