Speaker
Mr
Nkgaphe Tsebesebe
(University of Limpopo)
Description
Li-excess Mn-based materials are potential candidates for the next generation of cathode materials owing to their high discharge capacity (>200 mAh/g). This drives the interest for the intercalation/deintercalation processes using host electrodes with dimensions at the nanoscale, as this is sufficiently quick to deliver the power required from Li-ion batteries. The favorable material Li2MnO3 is known to be electrochemically inactive in the parent bulk form, and can be rendered Li-active by leaching Li from the structure. However the structural configuration and nucleation process of Li2MnO3 have not been documented, particularly during the cycling process. The current study employs the molecular dynamics (MD) DL_POLY code to generate the nanoparticles using amorphization and recrystallization (A&R) technique under microcanonical and canonical ensembles (NVE and NVT), respectively. Nanoparticles were deintercalated to delineate the charging process and investigate new possible Li-Mn-O intermediate phases that may emanate in the Li2MnO3 → LiMnO2 tie-line. The microstructural snapshots depict the formation of intermediate structures due to Li extraction and O loss. Furthermore, XRDs for intermediate structures shows the emergence of new peaks together with the main characteristics’ peaks of the Li2MnO3. Here it is shown that structural complexity evolves during synthesis – specifically, during the nucleation and crystallization process with microstructural features such as grain-boundaries (Li2MnO3, Li1.50MnO2.5 and LiMnO2), dislocations and intrinsic point defects (Li2MnO3). Findings of this work demonstrate how the deintercalation results affect the structural transition of the Li2MnO3 cathode material, and shed valuable details about the intermediate structural transformations that transpire during cycling.
Level for award<br> (Hons, MSc, <br> PhD, N/A)?
Hons
Apply to be<br> considered for a student <br> award (Yes / No)?
Yes
Primary author
Mr
Nkgaphe Tsebesebe
(University of Limpopo)
Co-authors
Mr
Kenneth Kgatwane
(University of Limpopo)
Prof.
Phuti Ngoepe
(University of Limpopo)
Dr
Raesibe Sylvia Ledwaba
(University of Limpopo)
