understanding the evolution of chemical 
 composition and morphology 
 of battery materials during electrochemical cycling is fundamental 
 to extending battery cycle life and ensuring safety . 
 this is particularly 
 true for the much debated high energy density ( high voltage ) lithium 
 manganese 
 rich cathode material of composition li1 + xm1  xo2 ( m = 
 mn , co , ni ) . in this study 
 we combine full - field transmission x - ray 
 microscopy ( txm ) with x - ray absorption near edge structure ( xanes ) 
 to spatially resolve changes in chemical phase , oxidation state , and 
 morphology within a high voltage cathode having nominal composition 
 li1.2mn0.525ni0.175co0.1o2 . 
 nanoscale microscopy with chemical / elemental sensitivity 
 provides direct quantitative visualization of the cathode , and insights 
 into failure . 
 single - pixel ( 30 nm ) txm xanes revealed changes 
 in mn chemistry with cycling , possibly to a spinel conformation and 
 likely including some mn(ii ) , starting at the particle surface and 
 proceeding inward . 
 morphological analysis of the particles revealed , 
 with high resolution and statistical sampling , that the majority of 
 particles adopted nonspherical shapes after 200 cycles . 
 multiple - energy 
 tomography showed a more homogeneous association of transition metals 
 in the pristine particle , which segregate significantly with cycling . 
 depletion of transition metals at the cathode surface occurs after 
 just one cycle , likely driven by electrochemical reactions at the 
 surface .