Hyun-Kon Song

Ulsan National Institute of Science and Technology | UNIST · Interdisciplinary School of Green Energy

High‐capacity silicon (Si) materials hold a position at the forefront of advanced lithium‐ion batteries. The inherent potential offers considerable advantages for substantially increasing the energy density in batteries, capable of maximizing the benefit by changing the paradigm from nano‐ to micron‐sized Si particles. Nevertheless, intrinsic struc...

The global energy sector is shifting from fossil-based systems of energy production and consumption to renewable-based ones like wind and solar energy. Hydrogen has emerged as one of the energy carriers for the renewable-based economy, storing electrical energy generated from the renewables and being used as a fuel to generate power. Water electrol...

Safety issues of lithium-ion batteries(LIBs) have caught a priority of concerns as the electric vehicle(EV) market expands dramatically and requires higher energy densities. To be free from a variety of unpredictable situations and environments triggering such a safety issue, materials that provide a mechanism to control the factors causing fire an...

High‐capacity Li‐rich layered oxides using oxygen redox as well as transition metal redox suffer from its structural instability due to lattice oxygen escaped from its structure during oxygen redox and the following electrolyte decomposition by the reactive oxygen species. Herein, we rescued a Li‐rich layered oxide based on 4d transition metal by e...

High‐capacity Li‐rich layered oxides using oxygen redox as well as transition metal redox suffer from its structural instability due to lattice oxygen escaped from its structure during oxygen redox and the following electrolyte decomposition by the reactive oxygen species. Herein, we rescued a Li‐rich layered oxide based on 4d transition metal by e...

Dye-sensitized photorechargeable batteries (DSPBs) have recently gained attention for realizing energy recycling systems under dim light conditions. However, their performance under high storage efficiency (i.e., the capacity charged within a limited time) for practical application remains to be evaluated. Herein, we varied the lithium (Li)-ion con...

A cobalt phthalocyanine having an electron‐poor CoN4 (+δ) in its phthalocyanine moiety was presented as an electrocatalyst for hydrogen peroxide oxidation reaction (HPOR). We suggested that hydrogen peroxide as an electrolysis medium for hydrogen production and therefore as a hydrogen carrier, demonstrating that the electrocatalyst guaranteed high...

Aqueous redox flow batteries (RFBs) have attracted significant attention as energy storage systems by virtue of their inexpensive nature and long‐lasting features. Although all‐vanadium RFBs exhibit long lifetimes, the cost of vanadium resources fluctuates considerably, and is generally expensive. Iron–chromium RFBs take advantage of utilizing a lo...

The electrochemical co-reduction of carbon dioxide (CO 2 ) and nitrate (NO 3 ⁻ ) to urea via C-N bond coupling is a promising alternative to traditional industrial processes that are intensive in energy consumption...

Abundant availability of seawater grants economic and resource‐rich benefits to water electrolysis technology requiring high‐purity water if undesired reactions such as chlorine evolution reaction (CER) competitive to oxygen evolution reaction (OER) are suppressed. Inspired by a conceptual computational work suggesting that OER is kinetically impro...

The continued demand for long-lasting batteries essentially drives us to contribute to a development of high-performance cathode materials, because a cathode material which is one of essential components in Li-ion batteries (LIBs) critically determines an overall energy density of a battery. High-capacity Ni-rich NCM (x > 80%, LiNi x Co y Mn z O 2...

Solid electrolytes are regarded as promising candidates replacing organic liquid electrolyte due to much enhanced safety, which is able to use lithium metal as an anode material for high energy system. Among several solid electroytes, garnet-type solid electrolyte has wide electrochemical window as well as high chemical stability and ionic conducti...

A multifunctional electrolyte additive for lithium oxygen batteries (LOBs) was designed to have (1) a redox-active moiety to mediate decomposition of lithium peroxide (Li2O2 as the final discharge product) during charging and (2) a solvent moiety to solvate and stabilize lithium superoxide (LiO2 as the intermediate discharge product) in electrolyte...

High-capacity LiNi1-x-yCoxMnyO2 (NCM) (x + y ≤ 0.2) is a potential candidate for realizing high-energy-density lithium-ion batteries (LIBs). However, successful application of this cathode requires overcoming the irreversible phase transition (layered-to-spinel/rock-salt), interfacial instability caused by residual lithium compounds, and the electr...

Reversible lithium metal plating and stripping is required for durable operation of lithium metal batteries. Three-dimensional architecture has been employed for accommodating volume change of lithium metal during repeated plating...

Catalyst-support interaction triggering biased electron flows between catalyst and reactant has been studied for electrocatalysis. The interaction was limited to the interfacial region between catalyst and support when nanoparticular catalysts,...

A dendrite‐free and chemically stabilized lithium metal anode is required for extending battery life and for the application of high energy density coupled with various cathode systems. However, uneven Li metal growth and the active surface in nature accelerate electrolyte dissipation and surface corrosion, resulting in poor cycle efficiency and va...

In order to realize electrochemically efficient hydrogen production, various endeavors have been devoted to developing hydrogen evolution reaction (HER) electrocatalysts having zero hydrogen binding energy (ΔGH⁎ = 0) for balancing between adsorption and desorption. This work demonstrated that nitrogen doping improved the HER activity of ruthenium o...

Uniform zinc metal plating has been raised as a critical issue in zinc-based batteries. Randomly localized ions lead to severe zinc dendrite formation in liquid electrolyte due to nonuniform ion flux caused by electroconvective flow. One of the mitigating approaches is to use gel polymer electrolyte to regulate the ion flux for suppressing zinc den...

Aprotic lithium-oxygen batteries (LOBs) have been considered as one of the high-energy-density alternatives to replace currently available lithium ion batteries. Highly reactive superoxide as the discharge intermediate of LOBs triggers side reactions to deteriorate LOB performances. Also, high overpotential is required to oxidize the discharge prod...

Synergistic effects of dual homogeneous catalysts for chemical reactions have been reported. Double activation (chemical transformation process where both catalysts work in concert to activate reactants or intermediates) was often responsible for the synergistic effects of dual catalyst systems. Herein, we demonstrate the extension of the double ac...

Dye-sensitized photorechargeable battery (DSPB) is an all-in-one secondary battery capable of photo-charging without external power and has shown high overall efficiency at indoor lighting. As an electrochemistry of the storage material for DSPBs, the lithium ion insertion into LiMn2O4(LMO) at 3 V (vs. Li/Li+) region was employed due to (1) its red...

Nickel-rich layered oxides (LiNi1-x-yCo x Mn y O2; (1 - x - y) ≥ 0.6), the high-energy-density cathode materials of lithium-ion batteries (LIBs), are seriously unstable at voltages higher than 4.5 V versus Li/Li+ and temperatures higher than 50 °C. Herein, we demonstrated that the failure mechanism of a nickel-rich layered oxide (LiNi0.6Co0.2Mn0.2O...

a redox-active mixed ion and electron conductor (redox-active MIEC) is presented as a binder for lithium titanate anode of LIBs. The redox-active MIEC binder (symbolized by PT*-GmCn) was designed to be (1) electrically conductive along its conjugated thiophene backbone (PT = polythiophene), (2) redox-active from its succinimide moiety (* = redox-ac...

It is demonstrated that the electroactivity of the oxygen reduction reaction (ORR) of Pt depends on the structure of a support. Highly conductive two-dimensional titanium carbide (Ti3C2) was selected as the support for Pt because of the expected strong metal-support interaction (SMSI) between Pt and Ti. To control the edge-to-basal ratio, the numbe...

Reactive oxygen species or superoxide (O 2 ⁻ ) to damage or age biological cells is generated during metabolic pathways using oxygen as an electron acceptor in biological systems. Superoxide dismutase (SOD) protects cells from the superoxide-triggered apoptosis by converting superoxide to oxygen and peroxide. Lithium-oxygen battery (LOB) cells have...

Electrocatalytic oxygen reduction reaction (ORR) in aqueous media proceeds along a pathway having multiple steps in which multiple surface intermediates are involved (* -> *OO -> *OOH -> *O -> *OH where * = active site of catalyst). Proton supplied from media plays a crucial role on the ORR mechanism. Therefore, pH of media affects the kinetics of...

Lithium oxygen batteries (LOBs) have been spotlighted as the next generation of rechargeable batteries due to their high theoretical capacity. One of the key issues of LOBs is how effectively lithium peroxide as the discharge product is removed. (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO) was reported as a charge redox mediator to remove lithiu...

Germanium nanoparticles were synthesized and subjected to study as anode materials for lithium ion batteries and sodium ion batteries. Laser pyrolysis of GeH4 was used to produce germanium nanoparticles and the average diameter of these nanoparticles was easily controlled by regulating sensitizer gas flow rates during the process. 60 and 10 nm diam...

One of the biggest challenges facing the development of comfortable wearable electronics is the fabrication of stretchable power sources, which are inherently safe and can maintain their electrochemical performance under mechanical elongation. Zinc–silver batteries based on water‐based chemistry have been investigated as viable power supply candida...

Although bimetallic materials with various structures have been used as anodes for advanced lithium-ion batteries, structural degradation, caused during electrochemical reactions, leads to a shorter cycle life span. Herein, we propose a rational structural design, carbon-wrapped porous bimetallic nickel-antimony nanosheets ([email protected]) with...

The reversibility of lithium plating/stripping should be guaranteed in lithium metal batteries. Seriously localized lithium growth during plating leads to the dendritic evolution of lithium metal due to the uneven current distribution on the electrically conductive surface. Artificial protective layers covering electrodes (e.g., polymer film on cop...

Lithium metal has been considered as an anode material to improve energy densities of lithium-chemistry-based rechargeable batteries (that is to say, lithium metal batteries or LMBs). Higher capacities and cell voltages are ensured by replacing practically used anode materials such as graphite with lithium metal. However, lithium metal as the LMB a...

Photo-rechargeable batteries (PRBs) benefit from their bifunctionality covering energy harvesting and storage. However, dim-light performances of the PRBs for indoor applications have not been reported. Herein, we present an external-power-free single-structured PRB named a dye-sensitized photorechargeable battery (DSPB) with an outstanding light-t...

In article number 2000563, Sang Kyu Kwak, Hyun‐Kon Song, Nam‐Soon Choi, and co‐workers show that the antioxidant activity of MA‐C60 inhibits the unfavourable reaction between electrolyte solvents and superoxide radicals generated from Li‐rich cathodes, and that MA‐C60 traps water molecules via hydrogen bonding or ionic interactions, leading to the...

High‐capacity Li‐rich layered oxide cathodes along with Si‐incorporated graphite anodes have high reversible capacity, outperforming the electrode materials used in existing commercial products. Hence, they are potential candidates for the development of high‐energy‐density lithium‐ion batteries (LIBs). However, structural degradation induced by lo...

https://www.mrs.org/fall2019/symposium-sessions/symposium-sessions-detail?code=EN03

Although the volume of antimony tremendously expands during the alloying reaction with sodium, it is considered a promising anode material for sodium ion batteries (SIBs). Repeated volume changes along the sodiation/desodiation cycles encourage capacity fading by triggering pulverization accompanying electrolyte decomposition. Additionally, the low...

we demonstrated smart protective web consisted of nanosized beta phase polyvinylidene fluoride (PVDF) fibers with ferroelectricity on copper (Cu) foil to suppress Li dendrite. The beta phase PVDF fiber provides a well-ordered molecular structure, which ensures rapid Li-ion migration along PVDF fiber. That guarantee homogeneous Li-ions flux on the C...

The reversibility of lithium plating/stripping should be guaranteed in lithium metal batteries. Seriously polarized lithium growth during plating leads to the dendritic evolution of lithium metal due to the uneven current distribution on the electrically conductive surface. Artificial protective layers covering electrodes (e.g., polymer film on cop...

Reactive oxygen species or superoxide (O2-) to damage or age biological cells is generated during metabolic pathways using oxygen as an electron acceptor in biological systems. Superoxide dismutase (SOD) protects cells from the superoxide-triggered apoptosis by converting superoxide to oxygen and peroxide. Lithium-oxygen battery (LOB) cells have th...

Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcina...

Gel polymer electrolytes (GPEs), characterized by in situ gelation, are presented. Different from ex situ gelated GPEs, in situ GPEs are formed omnipresent within electrochemical cells, covering the pores of electrode material particles and even the pores of separators. In article number 1804909, Young‐Soo Kim, Hyun‐Kon Song, and co‐workers describ...

In article number 1900570, Seungmin Yoo, Nam‐Soon Choi, Soojin Park and co‐workers demonstrate a seaweed‐extracted biomaterial for use as lithium‐ion battery components. It is utilized as a separator membrane and as a binder for use alongside Mn‐based cathode materials. The resultant full cells demonstrate highly stable cycling performance (84%) ev...

Germanium nanoparticles were synthesized and subjected to a study as anode materials for lithium ion batteries and sodium ion batteries. Laser pyrolysis of GeH4 was used to produce germanium nanoparticles and the average diameter of germanium nanoparticles was easily controlled by regulating sensitizer gas flow rates during the process. 60 and 10 n...

Transition metal ion dissolution due to hydrofluoric acid attack is a long‐standing issue in the Mn‐based spinel cathode materials of lithium‐ion batteries (LIBs). Numerous strategies have been proposed to address this issue, but only a fragmentary solution has been established. In this study, reported is a seaweed‐extracted multitalented material,...

Durability of catalysts for the oxygen reduction reaction (ORR) should be guaranteed for long‐term operation of fuel cells. In article number 1802228, Hu Young Jeong, Hyeon Suk Shin, Hyun‐Kon Song, and co‐workers design a catalyst/support system to confine platinum nanoparticles within holes of graphene for suppressing platinum agglomeration. Spher...

A carbon electrode was designed to guarantee flexibility of symmetric electric double layer capacitors (EDLCs) based on its architecture. Three different dimensional carbon materials were combined to achieve the flexibility without sacrificing high performances: highly capacitive but poorly conductive three-dimensional graphene (3D-Gn∗) as a platfo...

Cost-effective and environmentally friendly seawater-electrolyte-based batteries exhibit high energy density and demonstrate immense potential for use in future energy storage devices; however, lack of high-performance negative and positive electrodes significantly challenges their practical applications. In this study, N-doped and N,S-doped carbon...

A gel polymer electrolyte (GPE) is a liquid electrolyte (LE) entrapped by a small amount of polymer network less than several wt%, which is characterized by properties between those of liquid and solid electrolytes in terms of the ionic conductivity and physical phase. Electrolyte leakage and flammability, demerits of liquid electrolytes, can be mi...

An oxygen reduction reaction (ORR) catalyst/support system is designed to have Pt nanoparticles nanoconfined in a nanodimensionally limited space. Holey crumpled reduced graphene oxide plates (hCR‐rGO) are used as a carbon support for Pt loading. As expected from interparticular Pt‐to‐Pt distance of Pt‐loaded hCR‐rGO longer than that of Pt/C (Pt‐lo...

We present a metal-ion-chelating organogel electrolyte, thermally gelated within cells, to solve the problems triggered by metal dissolution from cathodes of lithium ion batteries. Capacity retentions of high-capacity (> 200 mAh g⁻¹) but unstable cathode materials were significantly improved by the organogel. The organogel mitigated metal depositio...

Partially hydrous RuO2 nanocluster embedded in a carbon matrix (x-RuO2@C with x = hydration degree = 0.27 or [email protected]) is presented as a bifunctional catalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for water splitting. Symmetric water electrolyzers based on 0.27-RuO2@C for both electrodes showed smaller p...

Highly porous thin films and nanostructure arrays are created by a simple process of selective dissolution of a water-soluble material, Sr3Al2O6. Heteroepitaxial nanocomposite films with self-separated phases of a target material and Sr3Al2O6 are first prepared by physical vapor deposition. NiO, ZnO, and Ni1- x Mg x O are used as the target materi...

High-theoretical capacity and low working potential make silicon ideal anode for lithium ion batteries. However, the large volume change of silicon upon lithiation/delithiation poses a critical challenge for stable battery operations. Here, we introduce an unprecedented design, which takes advantage of large deformation and ensures the structural s...

Highly oxygen-evolution-reaction-(OER)-active electrocatalysts often exhibit improved OER durability in the presence of carbon corrosion or oxidation (COR) in literature. The activity-durability coincidence of OER electrocatalysts was theoretically understood by preferential depolarization in galvanostatic situations. At constant-current conditions...

Enhancing the performance of carbon-based anode materials in Li-ion battery (LIB) systems is of considerable interest in terms of next-generation LIB host electrodes, because the unique reversible intercalation–de-intercalation process of such materials ultimately facilitates increases in LIB performance and longevity. This study explored the poten...

In this study, the fabrication of a high-performance electrothermal and anticorrosive transparent heating sticker employing a novel Ni/Ag hybrid microgrid electrode is reported. The proposed sticker not only exhibits an excellent optoelectronic performance (sheet resistance of 4.3 Ω sq⁻¹ at a transmittance of 96%) but also has a uniform heat distri...

Crumply superflexible lithium-ion batteries based on current-collector-free and binder-free nanowire-around-microfiber electrode architectures are presented by Soojin Park, Hyun-Kon Song, and co-workers in article number 1705445. The battery cells, having high loading of active materials, are successfully operated without structural failure and per...

We show that a high energy density can be achieved in a practical manner with freestanding electrodes without using conductive carbon, binders, and current collectors. We made and used a folded graphene composite electrode designed for a high areal capacity anode. The traditional thick graphene composite electrode, such as made by filtering graphen...

A crumply and highly flexible lithium-ion battery is realized by using microfiber mat electrodes in which the microfibers are wound or webbed with conductive nanowires. This electrode architecture guarantees extraordinary mechanical durability without any increase in resistance after folding 1000 times. Its areal energy density is easily controllab...

Stabilizing superoxide (O2-) is one of the key issues of sodium-air batteries because the superoxide-based discharge product (NaO2) is more reversibly oxidized to oxygen when compared with peroxide (O22-) and oxide (O2-). Reversibly outstanding performances of sodium-oxygen batteries have been realized with the superoxide discharge product (NaO2) e...

Ruthenium oxide (RuO2) is the best oxygen evolution reaction (OER) electrocatalyst. Herein, we demonstrated that RuO2 can be also efficiently used as an oxygen reduction reaction (ORR) electrocatalyst, thereby serving as a bifunctional material for rechargeable Zn–air batteries. We found two forms of RuO2 (i.e. hydrous and anhydrous, respectively h...

Delithiation followed by lithiation of Li⁺-occupied (n-type) tetrahedral sites of cubic LiMn2O4 spinel (LMO) at ∼4 V Li\Li+ V Li / Li + (delivering ∼100 mAh gLMO⁻¹) has been used for energy storage by lithium ion batteries (LIBs). In this work, we utilized unoccupied (p-type) octahedral sites of LMO available for lithiation at ∼3 V Li\Li+ V Li / Li...

Antimony metal nanoparticles wrapped with a-few-layer graphene coat ([email protected]) were fabricated from their oxide form (Sb2O3) in a micrometer dimension using a novel two-step ball-milling process. The first mechanochemical process was designed to decrease the particle size of Sb2O3 microparticles for ensuring advantages of nano size and to...

Geometry of carbon supports significantly affected electrochemical durability of Pt/C (platinum electrocatalyst supported by carbon) for oxygen reduction reaction (ORR). Carbon nano-onion (CNO) was used as the support, which is characterized by its nanosize (similar to Pt size) and high curvature. Superior ORR durability was guaranteed by Pt/CNO du...

Cellulose, which is one of the most abundant and renewable natural resources, has been extensively explored as an alternative substance for electrode materials such as activated carbons. Here, we demonstrate a new class of coffee-mediated green activation of cellulose as a new environmentally benign chemical activation strategy and its potential us...

Silicon nanowires (SiNWs) were prepared by chemically etching silicon wafers with silver nanoparticles. Their electrical conductivities and porosities were tuned by adjusting the doping concentration of silicon wafers from which the SiNWs were prepared. Porosity of the SiNWs were proportional to doping concentrations of the mother wafer because the...

In article number 1603045, Guoxiu Wang, Soojin Park, and co-workers develop mesoporous germanium (Ge) particles prepared by a zincothermic reduction at a mild temperature. The mesoporous Ge particles have many advantages including a high surface area and large void spaces for high performance lithium-ion batteries which can operate in a wide temper...

Binder-free and bifunctional electrocatalysts have vital roles in the development of high-performance metal-air batteries. Herein, we synthesized a vanadium oxide (VO2) nanostructure as a novel binder-free and bifunctional electrocatalyst for a rechargeable aqueous sodium-air (Na-air) battery. VO2 nanostructures were grown on reduced graphene oxide...

Porous structured materials have unique architectures and are promising for lithium-ion batteries to enhance performances. In particular, mesoporous materials have many advantages including a high surface area and large void spaces which can increase reactivity and accessibility of lithium ions. This study reports a synthesis of newly developed mes...

Nitrogen-containing electrocatalysts, such as metal–nitrogen–carbon (M–N–C) composites and nitrogen-doped carbons, are known to exhibit high activities for an oxygen reduction reaction (ORR). Moreover, even if the mechanism by which nitrogen improves the activities is not completely understood, a strong electronic interaction between nitrogen and a...

Conversion-reaction-based anode materials for lithium ion batteries (LIBs) such as transition metal oxides have been considered as high-capacity alternatives to graphite. In the conversion reactions, interestingly, microparticles have been known to be superior to nanoparticles in terms of capacity retention along repeated cycles. In this work, a cr...