TY - JOUR JF - ACS Applied Energy Materials ID - discovery10121546 UR - https://doi.org/10.1021/acsaem.0c02010 N1 - This is an open access article published under a Creative Commons Non-Commercial No Derivative Works (CC-BY-NC-ND) Attribution License, which permits copying and redistribution of the article, and creation of adaptations, all for non-commercial purposes. AV - public SN - 2574-0962 N2 - Lithium uptake and release in lithium titanate (LTO) anode materials during a discharge and charge cycle is one of the fundamental processes of a lithium-ion battery (LIB), still not fully understood at the microscopic level. During the discharge cycle, LTO undergoes a phase transformation between Li4Ti5O12 and Li7Ti5O12 states within a cubic crystal lattice. To reveal the details of the microscopic mechanism, it is necessary to track the sequence of phase transformations at different discharge/charge states under operating conditions. Here, we use in situ Bragg coherent diffraction imaging (BCDI) and in situ X-ray diffraction (XRD) experiments to examine the lithium insertion-induced materials phase transformation within a single LTO particle and a bulk battery analogue, respectively. BCDI analysis from (111) Bragg peak shows the two-phase transformation manifesting as a distinct image phase modulation within a single LTO nanoparticle occurring in the middle of the discharge region then subsiding toward the end of the discharge cycle. We observe the biggest phase variation at the two-phase stage, indicating the formation of phase domains of 200 nm in size during the discharge process. We also observe a lattice contraction of >0.2% in a single LTO nanoparticle at the (400) Bragg peak measurement, larger than that in the corresponding bulk material. Our observation of this phase transformation at a single-particle level has implications for the understanding of the microscopic/mesoscale picture of the phase transformation in anode and cathode LIBs materials. SP - 111 VL - 4 Y1 - 2021/01/04/ TI - Imaging the Phase Transformation in Single Particles of the Lithium Titanate Anode for Lithium-Ion Batteries IS - 1 A1 - Assefa, TA A1 - Suzana, AF A1 - Wu, L A1 - Koch, RJ A1 - Li, L A1 - Cha, W A1 - Harder, RJ A1 - Bozin, ES A1 - Wang, F A1 - Robinson, IK KW - coherent diffraction imaging KW - image phase variation KW - displacement field KW - battery material KW - lithium titanate anode EP - 118 ER -