Junhyeok Kim

Enhancing Interfacial Bonding between Anisotropically Oriented Grains using a Glue-Nanofiller for Advanced Li-ion Battery Cathode

Formation of a glue-nanofiller layer between grains, consisting of a middle-temperature spinel-like Lix CoO2 phase, reinforces the strength of the incoherent interfacial binding between anisotropically oriented grains by enhancing the face-to-face adhesion strength. The cathode treated with the glue-layer exhibits steady cycling performance at both room-temperature and 60 °C. These results represent a step forward in advanced lithium-ion batteries via simple cathode coating.

Controllable Solid Electrolyte Interphase in Nickel-Rich Cathodes by an Electrochemical Rearrangement for Stable Lithium-Ion Batteries

The layered nickel-rich materials have attracted extensive attention as a promising cathode candidate for high-energy density lithium-ion batteries (LIBs). However, they have been suffering from inherent structural and electrochemical degradation including severe capacity loss at high electrode loading density (>3.0 g cm-3 ) and high temperature cycling (>60 °C). In this study, an effective and viable way of creating an artificial solid-electrolyte interphase (SEI) layer on the cathode surface by a simple, one-step approach is reported. It is found that the initial artificial SEI compounds on the cathode surface can electrochemically grow along grain boundaries by reacting with the by-products during battery cycling. The developed nickel-rich cathode demonstrates exceptional capacity retention and structural integrity under industrial electrode fabricating conditions with the electrode loading level of ≈12 mg cm-2 and density of ≈3.3 g cm-3 . This finding could be a breakthrough for the LIB technology, providing a rational approach for the development of advanced cathode materials.

Issues and Challenges Facing Flexible Lithium‐Ion Batteries for Practical Application

With the advent of flexible electronics, lithium-ion batteries have become a key component of high performance energy storage systems. Thus, considerable effort is made to keep up with the development of flexible lithium-ion batteries. To date, many researchers have studied newly designed batteries with flexibility, however, there are several significant challenges that need to be overcome, such as degradation of electrodes under external load, poor battery performance, and complicated cell preparation procedures. In addition, an in-depth understanding of the current challenges for flexible batteries is rarely addressed in a systematical and practical way. Herein, recent progress and current issues of flexible lithium-ion batteries in terms of battery materials and cell designs are reviewed. A critical overview of important issues and challenges for the practical application of flexible lithium-ion batteries is also provided. Finally, the strategies are discussed to overcome current limitations of the practical use of flexible lithium-based batteries, providing a direction for future research.

A highly stabilized nickel-rich cathode material by nanoscale epitaxy control for high-energy lithium-ion batteries

Advanced surface engineering of nickel-rich cathode materials greatly enhances their structural/thermal stability. However, their application into lithium-ion full-cells still faces challenges, such as the unstable solid electrolyte interphase (SEI) layer on the anode. Herein, we reveal that the degradation of battery cycle life is caused by the release of divalent nickel ions from the LiNi0.8Co0.1Mn0.1O2 cathode and the formation of nickel metal particles on the graphite anode surface, deteriorating the anode SEI layer and its structural integrity. On the basis of this finding, we demonstrate a stable lithium-ion battery by modifying the cathode surface by creating a nanostructured stabilizer with an epitaxial structure that enhances the morphological robustness. During cycling, the nickel defects in the cathode are significantly suppressed, preventing nickel ion crossover. In particular, the anode SEI layer maintains a uniform and dense structure, leading to outstanding cycling stability in the full-cell with a capacity retention of ∼86% after 400 cycles at 25 °C.

Li-Ion Battery Cathodes: Enhancing Interfacial Bonding between Anisotropically Oriented Grains Using a Glue-Nanofiller for Advanced Li-Ion Battery Cathode (Adv. Mater. 23/2016)

The formation of a spinel Lix CoO2 layer in a Ni-rich secondary particle for lithium-ion batteries is reported by S. K. Kwak, J. Cho, and co-workers on page 4705, who find that the spinel-like Lix CoO2 layer, between layered primary particles, can enhance the mechanical strength of secondary particles by enhancing the interfacial binding energy among the grains. Moreover, the layer can effectively protect the unstable surface of the primary particles and offers a fast electron-ion pathway, resulting in overall enhancements of stability and kinetics in battery performance.