fig9

Figure 9. (A) HAADF-STEM images of Li_1.2Mn_0.6Ni_0.2O₂ cathode showing the gradual propagation of the nanovoid-populated zone from the particle surface towards the interior of the particle with increasing cycles^[101]. (i-iii) Represent the HAADF-STEM images of the material after different cycles (5 cycles, 45 cycles, 200 cycles, respectively). (B) Annular dark-field STEM image (i) of an opened pore. Mn (ii) and oxygen (iii) composition extracted from the quantification of the electron energy-loss spectroscopy map^[15]. (C) Charge-discharge curves and phase structural evolution of LRMO during electrochemical cycling^[105]. (D) Mean discharge/charge voltage of the two cells cycled simultaneously (cell 1/2: 22 °C, cycles 1-49; cell 3/4: 25 °C, cycles 1-49; 22 °C, cycles 49-105), with the error bars representing the standard deviation between the two cells^[95]. (E) Contribution towards the discharge capacity from each element at various cycles (left). An illustration of the Fermi level being lifted up as a result of the electronic structure change (right)^[15]. HAADF-STEM: High-angle annular dark-field aberration-corrected scanning transmission electron microscopy.