Hongkyung Lee

Daegu Gyeongbuk Institute of Science and Technology | DGIST · Department of Energy Science & Engineering

Lithium metal anodes have attracted much attention as candidates for high-energy batteries, but there have been few reports of long cycling behaviour, and the degradation mechanism of realistic high-energy Li metal cells remains unclear. Here, we develop a prototypical 300 Wh kg−1 (1.0 Ah) pouch cell by integrating a Li metal anode, a LiNi0.6Mn0.2C...

Inhibiting uneven dendritic Li electroplating is crucial for the safe and stable cycling of Li metal batteries (LMBs). Homogeneous and fast Li⁺ transport towards the Li surface is required for uniform and dendrite‐free deposition. However, the traditional ionic transport of static liquid electrolytes involving electromigration and molecular diffusi...

Ultrathin, large-area Li metal anodes (LMAs) are essential for high-energy Li-metal batteries (LMBs). However, most commercially manufactured LMAs (M-Li) form a native passivation layer (NPL) during manufacturing. Intrinsically non-uniform NPL can initiate sporadic Li dendrite growth and the chemical/structural deterioration of LMAs. This study pre...

With the growing popularity of Li‐ion batteries in large‐scale applications, building a safer battery has become a common goal of the battery community. Although the small errors inside the cells trigger catastrophic failures, tracing them and distinguishing cell failure modes without knowledge of cell anatomy can be challenging using conventional...

Reframing ionic transport and interface chemistry through electrolyte renovation is essential to promote the fast charging of Li-ion batteries, even under extreme conditions. Despite the formation of a less resistive...

The Front Cover depicts the intelligent regulation of the Li+ microenvironment by nanocolloidal electrolytes (NCEs). Nanoparticles in the NCEs can interact with ionic species, providing a surface Li+ diffusion pathway for hybrid ion transport and partly immobilizing the anions, thereby improving selective Li+ transport. Moreover, nanoparticles can...

To recharge lithium‐ion batteries quickly and safely while avoiding capacity loss and safety risks, a novel electrode design that minimizes cell polarization at a higher current is highly desired. This work presents a dual‐layer electrode (DLE) technology via sequential coating of two different anode materials to minimize the overall electrode resi...

Building a lithium–sulfur (Li–S) battery with lean electrolytes is essential to far exceed the energy density of today's Li‐ion. However, earlier electrolyte depletion triggered by Li‐metal anodes (LMAs) causes sluggish Li–S redox kinetics and poor S utilization, resulting in a short cycle lifespan. To retard the electrolyte loss effectively, susta...

Although Li‐metal has been revisited as the most attractive anode in building high‐energy‐density batteries owing to its superiority, such as ultimate theoretical capacity and lowest working voltage, notorious Li dendrite growth has plagued its practical uses. Since dendritic Li electroplating is mostly caused by poor Li⁺ transport and inferior sta...

A Janus separator incorporating an aCSL, an acid-enhanced carbon nanopowder layer, enhances Zn plating uniformity and boosts reversibility, curtailing “dead” Zn and minimizing H 2 O-related side reactions.

Conventional manufacturing process of Li metal anodes employs extrusion-pressing or deposition methods resulting in sheet or film-types, respectively. Considering the demands for high-gravimetric energy density, thinner Li metal is crucial for realizing the desired weight ratio of anode in Li metal batteries (LMBs). However, during the manufacturin...

With the increasing popularity of battery-powered mobility, ensuring the safety and reliability of Li-ion batteries (LIBs) has become critical for manufacturers. Despite advanced manufacturing processes for large-scale Li-ion cells, “latent defects” still unintentionally appear, due to imbalanced battery design, invisible faults, and extreme operat...

Lithium (Li) metal anodes (LMAs) are considered as an ultimate choice for beyond Li-ion batteries because of their high capacity (3860 mAh g –1 ) and low working potential (–3.04 V vs. SHE). However, due to extremely high surface reactivity, uncontrollable dendritic plating, and infinite volume expansion, making Li-metal batteries (LMBs) has long e...

To meet the high-energy-density requirement of Li secondary batteries for EV applications, Li metal is still being re-examined extensively beyond conventional carbon-based anode active materials. However, unlike intercalation mechanism-based anodes, Li metal anodes (LMAs), suffering from significant surface morphology changes during electroplating...

Lithium (Li) metal anodes (LMAs) with high specific capacity (3860 mAh g –1 ) and lowest redox voltage (–3.04 V vs SHE) are considered superlative candidates for high energy batteries. Ultra-thin, large-area LMA is crucial for building Li-metal batteries (LMBs) that can deliver high volumetric and gravimetric energy density in practice. As the char...

Tailoring the Li ⁺ solvating environment and solid-electrolyte interface (SEI) chemistry is crucial for developing long-life lithium (Li) metal batteries. However, it is hard to reinforce at the same time, fully solvating Li ⁺ for fast ionic transport and forming anion-derived SEI, due to both being strongly related. Here, we report a CA-modified S...

Building high-energy-density batteries with Li-metal anodes (LMAs) featuring ultrahigh specific capacity (3860 mAh g ⁻¹ ) and low working voltage (−3.04 V vs. SHE) have been revisited to surpass the energy density limit of current Li-ion batteries. For instance, a successful transition from conventional graphite (372 mAh g –1 ) to ultrathin LMAs ca...

With the growing popularity of Li-ion batteries in electric-powered mobility, securing battery safety has become a common goal of the battery community. Battery failures are commonly caused by small, undetectable defects that can form during manufacturing and operation, ranging from materials to the cell level. Although the small errors inside the...

Tailoring the Li⁺ microenvironment is crucial for achieving fast ionic transfer and a mechanically reinforced solid–electrolyte interphase (SEI), which administers the stable cycling of Li‐metal batteries (LMBs). Apart from traditional salt/solvent compositional tuning, this study presents the simultaneous modulation of Li⁺ transport and SEI chemis...

The energy density of Li-ion batteries (LIBs) can be effectively enhanced by increasing the thickness of a LiNi x Mn y Co 1−x−y O 2 (NMC) electrode and limiting the use of inactive components. However, the deficiency of a binder in thick NMC cathodes causes mechanical failure, such as crack formation and delamination, resulting in performance deter...

Li-metal anode (LMA) is considered promising for overcoming the energy density limit of current Li-ion batteries. However, LMAs in large-scale cells are limited by uneven and excessive anode swelling, owing to the notorious buildup of a highly porous passivation (“dead” Li) layer. To demonstrate the impact of the pressure environment on the LMA swe...

Despite the promises in high‐energy‐density batteries, Li‐metal anodes (LMAs) have suffered from extensive electrolyte decomposition and unlimited volume expansion owing to thick, porous layer buildup during cycling. It mainly originates from a ceaseless reiteration of the formation and collapse of solid‐electrolyte interphase (SEI). This study rev...

Dynamic Ionic Transport In article number 2204052, Hochun Lee, Yong Min Lee, Hongkyung Lee, and co‐workers demonstrate Li dendrite suppression with 1‐μm long, magnetic nanospinbar (NSB) dispersed electrolytes. Spatially distributed NSBs within various electrolytes can generate mesoscale turbulence actuated by an external rotating magnetic field. NS...

Li metal powders (LMPs) are beneficial to fabricating thin and large-area Li electrodes for Li metal batteries (LMBs) owing to slurry coating-based manufacturing and facile impregnation of functional additives. 3D structure of LMP-based composites can alleviate the local current density even at a higher current. However, non-uniform nucleation and...

Enlarging the surface area in the Li metal electrode is practically attractive for increasing long-term cycle life. In this regard, Li metal powders (LMPs) have a larger surface area, which is very beneficial for controlling dendrites and fast charging compared to planar Li metal foil. However, there is the need to increase nucleation sites in LMP...

The Li metal anode has been spotlighted for large-scale battery systems such as electric vehicles (EVs) and energy storage systems (ESSs) because of its high theoretical energy density and lowest potential. However, the Li metal anode still has the several challenging issues like Li dendrite growth and many side reactions. Our strategy to this prob...

Conventional battery recycling has suffered from the risk of explosion during the battery disposal pro-cess and the use of environmental hazard chemicals for recovering precious metals such as Li, Ni, and Co. Thisstudy presents the electrode surface cleaning solutions and optimal electrode structures for cleaning the wastebattery entirely without d...

We developed a thermo-electrochemical model of a 50 Ah pouch-type lithium-ion cell and utilized a cell model to build an 18.5 V/50 Ah module to analyze the thermal behavior under various operating conditions and design cooling systems for optimal operating temperature ranges. Specifically, the heat generated by electrochemical reactions was simulat...

The internal short circuit caused by the Li dendrite is well known to be a major cause for fire or explosion accidents involving state-of-the-art lithium-ion batteries (LIBs). However, post-mortem analysis cannot identify the most probable cause, which is initially embedded in the cell, because the original structure of the cell totally collapses a...

Development of practical lithium (Li) metal batteries (LMBs) remains challenging despite promises of Li metal anodes (LMAs), owing to Li dendrite formation and highly reactive surface nature. Polyolefin separators used in LMBs may undergo severe mechanical and chemical deterioration when contacting with LMAs. To identify the best polyolefin separat...

Inside Back Cover In article number 2101060, Kim, Lee, and co‐workers introduce the Zn‐MnO2 cell incorporating an acid‐treated carbon support layer (aCSL) and it shows stable cycling and rate performances compared to the cell with a common porous separator, owing to the confinement of Mn2+ between cathode and aCSL, revitalization of Mn2+/Mn4+ react...

The microblade cutting method, so-called SAICAS, is widely used to quantify the adhesion of battery composite electrodes at different depths. However, as the electrode thickness or loading increases, the reliability of adhesion values measured by the conventional method is being called into question more frequently. Thus, herein, a few underestimat...

Zn‐MnO2 battery with mild‐acid electrolytes has been considered as a promising alternative to Li‐ion battery for safe and cost‐effective energy storage systems (ESSs), and for full electrification. However, the governing mechanism of MnO2 electrochemistry has not been fully elucidated, hindering further advances in highly reversible MnO2 cathodes....

The safe, stable cycling of Li-metal batteries (LMBs) over wide temperature ranges is crucial for practical applications, even in extreme environments. Although LMB performance has been enhanced using various high-concentration electrolytes (HCEs) with hydrofluoroether dilution, efficient operation over a wide temperature range remains elusive. Thi...

Sodium (Na)-powered rechargeable batteries (NRBs) are promising as sustainable energy storage systems. To overcome an inherent energy density handicap of NRBs, increasing cell voltage is necessary by building a Na metal battery (NMB), which simultaneously features coveted high-voltage stability and efficient Na dendrite protection. Although ionic l...

A comprehensive understanding of the solid–electrolyte interphase (SEI) composition is crucial to developing high-energy batteries based on lithium metal anodes. A particularly contentious issue concerns the presence of LiH in the SEI. Here we report on the use of synchrotron-based X-ray diffraction and pair distribution function analysis to identi...

In article number 2003769, Myung‐Hyun Ryou, Hongkyung Lee, Yong Min Lee, and co‐workers report a LiNO3 pre‐planted lithium metal powder (LN‐LMP) electrode, practically designed for ultra‐thin and wide electrode fabrication. The pre‐planted LiNO3 allows not only chemically induced uniform nitration of the LMP surface but also steady release into the...

Sharks, marine creatures that swim fast and have an antifouling ability, possess dermal denticle structures of micrometer-size. Because the riblet geometries on the denticles reduce the shear stress by inducing the slip of fluid parallel to the stream-wise direction, shark skin has the distinguished features of low drag and antifouling. Although mu...

Making Li metal batteries (LMBs) with thinner Li is necessary to improve the cell energy density in practice. Li metal powders (LMPs) are beneficial for the facile manufacturing of thin Li, flexible cell design, and the 3D control of Li plating/stripping. However, the inhomogeneous surfaces of commercial LMPs limit their practical use in LMBs. Here...

Solid oxides are attractive electrolyte materials for all-solid-state lithium batteries (ASSLBs) owing to their high stability and pure Li-ion conductivity. Nevertheless, the electrochemical performance of ASSLBs employing solid oxide-based electrolytes cannot compete with ASSLBs with sulfide or polymeric electrolytes due to poor interfacial contac...

Due to the highest theoretical capacity, the Li metal anode is considered to be the most ideal anode materials for large-scale batteries, if the problems related to Li dendrite growth can be overcome. Obviously, as most people know well, enlarging the surface area of the Li metal has quite an influence on lower the effective current density to supp...

Lithium (Li) metal has been considered as a very promising anode material for next-generation batteries because of its low electronegativity (-3.04 V), low gravimetric density (0.53 g cc ⁻¹ ) and ultrahigh specific capacity (3860 mAh g ⁻¹ ). The recent simulations forecast that the rechargeable Li metal batteries (LMBs) coupled with the conventiona...

Significance Rechargeable lithium metal batteries are promising next-generation high-energy-density energy storage systems. However, their applications have been greatly impeded by the instabilities of electrolytes toward both highly reductive lithium metal anode and high-voltage cathodes. Here, we use localized high-concentration electrolytes to i...

The lithium–sulfur (Li–S) battery is a promising next-generation energy storage technology because of its high theoretical energy and low cost. Extensive research efforts have been made on new materials and advanced characterization techniques for mechanistic studies. However, it is uncertain how discoveries made on the material level apply to real...

Thin carbon interlayer contributes to the easier Li nucleation, and homogeneous Li distribution. • The carbon interlayer can be enhanced the adhesive strength and prevent galvanic corrosion. • We succeed in quantifying the adhesive strength at the interface for the first time using a SAICAS.: Lithium metal powder Carbon interlayer Thin lithium meta...

In article number 2003132, Hochun Lee and co‐workers design a locally concentrated ionic liquid electrolyte with a non‐solvating, fire‐retardant hydrofluoroether that can resolve the chronic viscosity problems of ionic liquid electrolytes, while further strengthening their intrinsic benefits to establish safe, stable Li metal batteries.

Developing a safe and long-lasting lithium (Li) metal battery is crucial for high-energy applications. However, its poor cycling stability due to Li dendrite formation and excessive Li pulverization is the major hurdle for its practical applications. Here, we present a silica (SiO2) nanoparticle-dispersed colloidal electrolyte (NDCE) and its design...

Ionic liquid (IL) electrolytes with concentrated Li salt can ensure safe, high‐performance Li metal batteries (LMBs) but suffer from high viscosity and poor ionic transport. A locally concentrated IL (LCIL) electrolyte with a non‐solvating, fire‐retardant hydrofluoroether (HFE) is presented. This rationally designed electrolyte employs lithium bis(...

Properties of the solid-electrolyte interphase (SEI) strongly effects the morphology, features and overall performance of the Lithium metal anode (LMA). It is well accepted but least understood that the formation mechanism of SEI is correlated with the electrolyte solvation structure. Here, synchrotron X-ray diffraction (XRD), pair distribution fun...

Although lithium‐metal based batteries (LMBs) offer one the highest energy densities, the issues with Li dendrite growths and the chemical reactivity between Li and electrolytes limit their applications. To enable a stable LMB under the practical conditions of lean electrolyte, thin Li‐metal and high mass loading, we introduce an efficient protecti...

The Cover Feature illustrates the protection of the surface of lithium with a thin layer of MoS2 in order to overcome the practical hurdles of Li‐metal batteries. MoS2 does not only prevent dendrite growth but also minimizes the electrolyte loss under lean conditions. The cell utilizing the MoS2 protection exhibits excellent cycling stability with...

High-energy rechargeable lithium metal batteries have been intensively revisited in recent years. Since more researchers started to use pouch cell as the platform to study the fundamentals at relevant scales, safe testing and handling of lithium metal and high-energy lithium metal batteries have become critical. Cautions and safety procedures are n...

Use of a protective coating on a lithium metal anode (LMA) is an effective approach to enhance its coulombic efficiency and cycling stability. Here, a facile approach to produce uniform silver nanoparticle‐decorated LMA for high‐performance Li metal batteries (LMBs) is reported. This effective treatment can lead to well‐controlled nucleation and th...

Lithium (Li) pulverization and associated large volume expansion during cycling is one of the most critical barriers for the safe operation of Li-metal batteries. Here, we report an approach to minimize the Li pulverization using an electrolyte based on a fluorinated orthoformate solvent. The solid–electrolyte interphase (SEI) formed in this electr...

We present a synergistic strategy to boost the cycling performance of Li-metal batteries. The strategy is based on the combined use of a micro-pattern (MP) on the surface of the Li-metal electrode and an advanced dual-salt electrolyte (DSE) system to more efficiently control undesired Li-metal deposition at higher current density (~3 mA cm⁻²). The...

The development of safe and high-performance lithium (Li) metal anodes has been a challenging issue that has not been addressed for decades. In this study, we have developed a thermally stable polydopamine-treated three-dimensional (3D) carbon fiber-coated separator (P3D-CFS) using an economical and environment-friendly process. P3D-CFS has a condu...

Rechargeable lithium (Li)-metal batteries (LMBs) offer a great opportunity for applications needing high-energy-density battery systems. However, rare progress has been demonstrated so far under practical conditions, including high voltage, high-loading cathode, thin Li anode, and lean electrolyte. Here, in opposition to common wisdom, we report an...

High-voltage (>4.3 V) rechargeable lithium (Li) metal batteries (LMBs) face huge obstacles due to the high reactivity of Li metal with traditional electrolytes. Despite of their good stability with Li metal, conventional ether-based electrolytes are typically used only in <4.0-V LMBs due to their limited oxidation stability. Here we report high-con...

Various electrolytes have been reported to enhance the reversibility of Li-metal electrodes. However, for these electrolytes, concurrent and balanced control of Li-metal and positive electrode interfaces is a critical step toward fabrication of high-performance Li-metal batteries. Here, we report the tuning of Li-metal and lithium cobalt oxide (LCO...

Unexpected Li deposition during plating, which causes low Coulombic efficiency and safety issues, limits the use of Li metal as an anode in commercial secondary batteries. With the recently developed micro-patterned Li metal anodes, dendrite formation during high current Li plating (2.4 mA cm−2) has successfully been reduced, as Li ions are guided...

Fabricating a uniform thin-film Li metal anode on a heterogeneous Cu substrate is a critical step toward high energy density lithium metal batteries. Here, we explore a facet selective lithium (Li) nucleation and growth phenomenon on copper (Cu) substrate and demonstrate that controlling the facet structure can improve the uniformity in electro-dep...

Lithium (Li)-metal batteries have regained broad interest in the battery research community. Although many studies on Li anode have been published in recent years, it is difficult to evaluate and compare these advances for practical applications. A key challenge is a gap between materials and component properties and the achievable large-format cel...

The energy density of conventional Li-ion batteries (LIBs) has eventually reached their theoretical limit. Increasing worldwide efforts have been made towards the next generation of energy storage systems including batteries using Li metal anode in combination with various cathodes, including intercalation compounds (such as NMC) or conversion mate...

Mixed fatty acid-modified aggregators have been developed as potential crude oil sorbents. Cheap pine wood flour was first modified with oleic acid (OA) and further modified with a second fatty acid by a leaving group chemistry, where a surface hydroxyl group is first replaced by p-toluenesulfonyl group and a fatty acid forms a covalent bond on saw...

Interfacial stability is one of the crucial factors for long-term cyclability of lithium (Li) metal batteries (LMBs). While cross-contamination phenomena have been well-studied in Li-ion batteries (LIBs), similar phenomena have rarely been reported in LMBs. Here, we investigated cathode failure triggered by chemical crossover from anode in LMBs. In...

The Cover Feature illustrates two different types of micro‐patterned Li‐metal electrodes. The large‐sized patterns accommodate a deposited Li metal inside the holes, so the dendritic growth of Li metal can be effectively suppressed. However, the Li metal electrode with small‐sized patterns at the surface cannot play a critical role in stabilizing t...

Rechargeable lithium metal batteries are regarded as the ‘‘holy grail’’ of energy storage systems, but their practical applications have long been hindered by poor cyclability and severe safety concerns. In this work, we report a fire-retardant localized high-concentration electrolyte consisting of 1.2 M lithium bis(fluorosulfonyl)imide in a mixture...

Uncontrolled lithium (Li) deposition has hampered the evolution of Li metal electrode‐based Li batteries. In this work, we report the differences of a guided Li deposition with a size change of the square hole micro‐patterns carved on the Li metal surface with two different dimensions using a simple stamping method. Li deposition is preferentially...

We report a carbonate based localized high concentration electrolyte (LHCE) with a fluorinated ether as a diluent for 4-V class lithium metal batteries (LMBs) which enables dendrite-free Li deposition with a high Li Coulombic efficiency (~98.5%) and much better cycling stability for Li metal anode than previously reported dimethyl carbonate-based L...

To enable next-generation high-energy-density lithium (Li)-metal batteries (LMBs), an electrolyte that has simultaneous high Li-metal Coulombic efficiency (CE) and high anodic stability on cathodes is of significant importance. Sulfones are known for strong resistance against oxidation, yet their application in LMBs is restricted because of their p...

The pairing of high‐capacity Li2S cathode (1166 mAh g−1) and lithium‐free anode (LFA) provides an unparalleled potential in developing safe and energy‐dense next‐generation secondary batteries. However, the low utilization of the Li2S cathode and the lack of electrolytes compatible to both electrodes are impeding the development. Here, a novel grap...

Li metal anode is desirable for high energy density batteries because of its high theoretical specific capacity and lowest redox potential. However, its applications have been plagued for decades due to problems such as dendritic Li growth and low Li plating/stripping Coulombic efficiency (CE). The three-dimensional propagation of Li dendrites coul...

Lithium (Li) metal has been considered as a very promising anode material for next-generation batteries because of its low electronegativity (-3.04 V), low gravimetric density (0.53 g cc ⁻¹ ) and ultrahigh specific capacity (3860 mAh g ⁻¹ ). The recent simulations forecast that the rechargeable Li metal batteries (LMBs) coupled with the conventiona...

Carbothermal conversion of Li2SO4 provides a cost-effective strategy to fabricate high-capacity Li2S cathodes, however, most Li2S cathodes derived from Li2SO4 at high temperatures (> 800oC), having high crystallinity and large crystal size, result in a low utilization of Li2S. Here, we report a Li2SO4/poly(vinyl alcohol)-derived Li2S/Carbon nanocom...

Lithium (Li) metal is considered as the "holy grail" anode for high energy density batteries, but its applications in rechargeable Li metal batteries are still hindered by the formation of Li dendrites and low coulombic efficiency for Li plating/stripping. An effective strategy to stabilize Li metal is to embed a Li metal anode in a three-dimension...

Lithium (Li) metal is one of the most promising candidates for the anode in high-energy-density batteries. However, Li dendrite growth induces a significant safety concerns in these batteries. Here, a multifunctional separator through coating a thin electronic conductive film on one side of the conventional polymer separator facing the Li anode is...

Poor proton conduction at low relative humidity (RH) remains a challenge for adopting hydrocarbon (HC) membranes for polymer electrolyte membrane fuel cells (PEMFCs). Here, we report a silica-embedded hydrogel (HG-silica) nanofiller as a water reservoir for improving the performance of the HC membrane under low RH conditions. The incorporation of H...

Formation of soluble polysulfide (PS), which is a key feature of lithium sulfur (Li-S) battery, provides a fast redox kinetic based on liquid-solid mechanism, however, it imposes a critical problem of PS shuttle. Here, we address the dilemma by exploiting a solvent-swollen polymeric single ion conductor (SPSIC) as the electrolyte medium of Li-S bat...