Publications by authors named "Hyeong Yong Lim"

Ni-rich layered oxides are regarded as key components for realizing post Li-ion batteries (LIBs). However, high-valence Ni, which acts as an oxidant in deeply delithiated states, aggravates the oxidation of the electrolyte at the cathode, causing cell impedance to increase. Additionally, the leaching of transition metal (TM) ions from Ni-rich cathodes by acidic compounds such as Brønsted-acidic HF produced through LiPF hydrolysis aggravates the structural instability of the cathode and renders the electrode-electrolyte interface unstable.

View Article and Find Full Text PDF

Tuning the metal-support interaction of supported metal catalysts has been found to be the most effective approach to modulating electronic structure and improving catalytic performance. But practical understanding of the charge transfer mechanism at the electronic level of catalysis process has remained elusive. Here, it is reported that ruthenium (Ru) nanoparticles can self-accommodate into Fe O and carbon support (Ru-Fe O /C) through the electronic metal-support interaction, resulting in robust catalytic activity toward the alkaline hydrogen evolution reaction (HER).

View Article and Find Full Text PDF

Ni-rich cathodes are the most promising candidates for realizing high-energy-density Li-ion batteries. However, the high-valence Ni ions formed in highly delithiated states are prone to reduction to lower valence states, such as Ni and Ni , which may cause lattice oxygen loss, cation mixing, and Ni ion dissolution. Further, LiPF , a key salt in commercialized electrolytes, undergoes hydrolysis to produce acidic compounds, which accelerate Ni-ion dissolution and the interfacial deterioration of the Ni-rich cathode.

View Article and Find Full Text PDF

Solid electrolyte interphases generated using electrolyte additives are key for anode-electrolyte interactions and for enhancing the lithium-ion battery lifespan. Classical solid electrolyte interphase additives, such as vinylene carbonate and fluoroethylene carbonate, have limited potential for simultaneously achieving a long lifespan and fast chargeability in high-energy-density lithium-ion batteries (LIBs). Here we report a next-generation synthetic additive approach that allows to form a highly stable electrode-electrolyte interface architecture from fluorinated and silylated electrolyte additives; it endures the lithiation-induced volume expansion of Si-embedded anodes and provides ion channels for facile Li-ion transport while protecting the Ni-rich LiNiCoMnO cathodes.

View Article and Find Full Text PDF

Transition metal dichalcogenides (TMDs), due to their fascinating properties, have emerged as potential next-generation semiconducting nanomaterials across diverse fields of applications. When combined with other material systems, precise control of the intrinsic properties of the TMDs plays a vital role in maximizing their performance. Defect-induced atomic doping through introduction of a chalcogen vacancy into the TMDs lattices is known to be a promising strategy for modulating their characteristic properties.

View Article and Find Full Text PDF

The crystalline phase of layered transition metal dichalcogenides (TMDs) directly determines their material property. The most thermodynamically stable phase structures in TMDs are the semiconducting 2H and metastable metallic 1T phases. To overcome the low phase purity and instability of 1T-TMDs, which limits the utilization of their intrinsic properties, various synthesis strategies for 1T-TMDs have been proposed in phase-engineering studies.

View Article and Find Full Text PDF

Developing efficient bifunctional catalysts for overall water splitting that are earth-abundant, cost-effective, and durable is of considerable importance from the practical perspective to mitigate the issues associated with precious metal-based catalysts. Herein, we introduce a heterostructure comprising perovskite oxides (LaSrCoO) and molybdenum diselenide (MoSe) as an electrochemical catalyst for overall water electrolysis. Interestingly, formation of the heterostructure of LaSrCoO and MoSe induces a local phase transition in MoSe, 2 H to 1 T phase, and more electrophilic LaSrCoO with partial oxidation of the Co cation owing to electron transfer from Co to Mo.

View Article and Find Full Text PDF