TAKE FLITE : an integrated communication campaign on promoting creativty among ITE East students

This work seeks to incorporate creativity in the students of the Institute of Technical Education (ITE) through methods best suited to their learning styles.Bachelor of Communication Studie

Typical cathode materials for lithium‐ion and sodium‐ion batteries: From structural design to performance optimization

Abstract Rechargeable lithium‐ion and sodium‐ion batteries (SIB) have dominated the energy storage fields such as electric vehicles and portable electronics due to their high energy density, long cycle life, and environmental friendliness. However, the critical bottleneck hindering the further improvement of their electrochemical performance is the unsatisfactory cathode materials, typically exhibiting inherent drawbacks such as low reversible capacity, initial capacity loss, fast capacity decay, and poor rate performance. These issues are mainly attributed to changes in the internal structure of cathode materials, such as irreversible transformation of particle morphology, evolution of crystal structure, and undesired physicochemical interfacial reactions during the electrochemical process. To address above obstacles, abundant research efforts have been devoted to stabilizing the structural evolution of cathode materials and enhancing their electrochemical performance. Herein, we reviewed the research progress on the cathode materials for lithium‐ion and SIBs. The typical cathodes and their structural characteristics, electrochemical behaviors, reaction mechanisms, and strategies for electrochemical performance optimization were summarized. This review aims to promote the understanding of the structure‐performance relationship in the cathode materials and provide some guidance for the design of advanced cathode materials for lithium‐ion and SIBs from the perspective of crystal structure

Regulating the Electron Distribution of Metal‐Oxygen for Enhanced Oxygen Stability in Li‐rich Layered Cathodes

Abstract Li‐rich Mn‐based layered oxides (LLO) hold great promise as cathode materials for lithium‐ion batteries (LIBs) due to their unique oxygen redox (OR) chemistry, which enables additional capacity. However, the LLOs face challenges related to the instability of their OR process due to the weak transition metal (TM)‐oxygen bond, leading to oxygen loss and irreversible phase transition that results in severe capacity and voltage decay. Herein, a synergistic electronic regulation strategy of surface and interior structures to enhance oxygen stability is proposed. In the interior of the materials, the local electrons around TM and O atoms may be delocalized by surrounding Mo atoms, facilitating the formation of stronger TM─O bonds at high voltages. Besides, on the surface, the highly reactive O atoms with lone pairs of electrons are passivated by additional TM atoms, which provides a more stable TM─O framework. Hence, this strategy stabilizes the oxygen and hinders TM migration, which enhances the reversibility in structural evolution, leading to increased capacity and voltage retention. This work presents an efficient approach to enhance the performance of LLOs through surface‐to‐interior electronic structure modulation, while also contributing to a deeper understanding of their redox reaction

High-Performance Layered Ni-Rich Cathode Materials Enabled by Stress-Resistant Nanosheets

Layered O3-type transition metal oxides are promising cathode candidates for high-energy-density Li-ion batteries. However, the structural instability at the highly delithiated state and low kinetics at the fully lithiated state are arduous challenges to overcome. Here, a facile approach is developed to make secondary particles of Ni-rich materials with nanosheet primary grains. Because the alignment of the primary grains reduces internal stress buildup within the particle during charge–discharge and provides straightforward paths for Li transport, the as-synthesized Ni-rich materials do not undergo cracking upon cycling with higher overall Li+ ion diffusion rates. Specifically, a LiNi0.75Co0.14Mn0.11O2 cathode with nanosheet grains delivers a high reversible capacity of 206 mAh g–1 and shows ultrahigh cycling stability, e.g., 98% capacity retention over 500 cycles in a full cell with a graphite anode

A Li-Rich Layered Oxide Cathode with Negligible Voltage Decay

With high capacity at low cost, Li- and Mn-rich (LMR) layered oxides are a promising class of cathodes for next-generation Li-ion batteries. However, substantial voltage decay during cycling, due to the unstable Li2MnO3 honeycomb structure, is still an obstacle to their practical deployment. Here we report a Co-free LMR Li-ion battery cathode with negligible voltage decay. The material has a composite structure consisting of layered LiTMO2 and various stacked Li2MnO3 components, where transition metal (TM) ions that reside in the Li layers of Li2MnO3 form caps to strengthen the stability of the honeycomb structure. This capped-honeycomb structure is persistent after high-voltage cycling and prevents TM migration and oxygen loss as shown by experimental and computational results. This work demonstrates that the long-standing voltage decay problem in LMRs can be effectively mitigated by internally pinning the honeycomb structure, which opens an avenue to developing next-generation high-energy cathode materials

Quantum Phase Transition of Correlated Iron-Based Superconductivity in LiFe_1-xCo_xAs

The interplay between unconventional Cooper pairing and quantum states associated with atomic scale defects is a frontier of research with many open questions. So far, only a few of the high-temperature superconductors allow this intricate physics to be studied in a widely tunable way. We use scanning tunneling microscopy (STM) to image the electronic impact of Co atoms on the ground state of the LiFe$_{1-x}$Co$_x$As system. We observe that impurities progressively suppress the global superconducting gap and introduce low energy states near the gap edge, with the superconductivity remaining in the strong-coupling limit. Unexpectedly, the fully opened gap evolves into a nodal state before the Cooper pair coherence is fully destroyed. Our systematic theoretical analysis shows that these new observations can be quantitatively understood by the nonmagnetic Born-limit scattering effect in a s$\pm$-wave superconductor, unveiling the driving force of the superconductor to metal quantum phase transition.Comment: 22 pages, 12 figures, includes Supplementary Materials. To appear in Phys. Rev. Let