Jongwoo Lim

The kinetics and uniformity of ion insertion reactions at the solid-liquid interface govern the rate capability and lifetime, respectively, of electrochemical devices such as Li-ion batteries. Using an operando x-ray microscopy platform that maps the dynamics of the Li composition and insertion rate in Li(x)FePO4, we found that nanoscale spatial variations in rate and in composition control the lithiation pathway at the subparticle length scale. Specifically, spatial variations in the insertion

Although it has been qualitatively demonstrated that surface roughness can reduce the thermal conductivity of crystalline Si nanowires (SiNWs), the underlying reasons remain unknown and warrant quantitative studies and analysis. In this work, vapor-liquid-solid (VLS) grown SiNWs were controllably roughened and then thoroughly characterized with transmission electron microscopy to obtain detailed surface profiles. Once the roughness information (root-mean-square, σ, correlation length, L, and pow

The rampant generation of lithium hydroxide and carbonate impurities, commonly known as residual lithium, is a practical obstacle to the mass-scale synthesis and handling of high-nickel (>90 %) layered oxides and their use as high-energy-density cathodes for lithium-ion batteries. Herein, we suggest a simple in situ method to control the residual lithium chemistry of a high-nickel lithium layered oxide, Li(Ni_0.91 Co_0.06 Mn_0.03 )O₂ (NCM9163), with minim

The growth of dendrites on lithium metal electrodes is problematic because it causes irreversible capacity loss and safety hazards. Localised high-concentration electrolytes (LHCEs) can form a mechanically stable solid-electrolyte interphase and prevent uneven growth of lithium metal. However, the optimal physicochemical properties of LHCEs have not been clearly determined which limits the choice to fluorinated non-solvating cosolvents (FNSCs). Also, FNSCs in LHCEs raise environmental concerns,

Block copolymer patterned holey silicon (HS) was successfully integrated into a microdevice for simultaneous measurements of Seebeck coefficient, electrical conductivity, and thermal conductivity of the same HS microribbon. These fully integrated HS microdevices provided excellent platforms for the systematic investigation of thermoelectric transport properties tailored by the dimensions of the periodic hole array, that is, neck and pitch size, and the doping concentrations. Specifically, thermo

During solid-state calcination, with increasing temperature, materials undergo complex phase transitions with heterogeneous solid-state reactions and mass transport. Precise control of the calcination chemistry is therefore crucial for synthesizing state-of-the-art Ni-rich layered oxides (LiNi_1-x-y Co_x Mn_y O₂ , NRNCM) as cathode materials for lithium-ion batteries. Although the battery performance depends on the chemical heterogeneity during NRNCM calc

Systematic control of surface reconstruction during catalysis remains challenging. Particularly, inducing a surface structure reconstruction following the lattice oxygen oxidation mechanism (LOM), which can reduce the overpotential in oxygen evolution reaction (OER) catalysts, has not been extensively investigated. The mechanism of the OER of transition-metal-oxide-based catalysts can be facilitated by manipulating the local coordination structure to modulate the reactivity of lattice oxygen. He

Silicon is an attractive anode material for all-solid-state batteries (ASSBs) because it has a high energy density and is safer than metallic lithium. Conventional silicon powder composite electrodes have significant internal voids and detrimental interfaces that suppress the lithium transport and lifetime. Here, we demonstrate that surface-treated thin silicon wafers could serve as monolithic additive-free, electrolyte-free, and void-free electrodes that can achieve high areal capacity at room

Abstract The electrochemical reduction of carbon dioxide offers a sound and economically viable technology for the electrification and decarbonization of the chemical and fuel industries. In this technology, an electrocatalytic material and renewable energy‐generated electricity drive the conversion of carbon dioxide into high‐value chemicals and carbon‐neutral fuels. Over the past few years, single‐atom catalysts have been intensively studied as they could provide near‐unity atom utilization an

Understanding the cycling rate-dependent kinetics is crucial for managing the performance of batteries in high-power applications. Although high cycling rates may induce reaction heterogeneity and affect battery lifetime and capacity utilization, such phase transformation dynamics are poorly understood and uncontrollable. In this study, synchrotron-based operando X-ray diffraction is performed to monitor the high-current-induced phase transformation kinetics of LiNi_0.6 Co<sub>0.2</sub

First d-block metal-based perovskite oxides (FDMPOs) have garnered significant attention in research for their utilization in the water oxidation reaction due to their low cost, earth abundance, and promising activities. Recently, FDMPOs are being applied in electrocatalysis for the hydrogen evolution reaction (HER) and overall water splitting reaction. Numerous promising FDMPO-based water splitting electrocatalysts have been reported, along with new catalytic mechanisms. Therefore, an in-time s

Stabilised Li-rich and Li-poor surface domains formed during fast lithiation and delithiation, respectively, cause a large overpotential difference between discharging and charging.

Crosstalk, the exchange of chemical species between battery electrodes, significantly accelerates thermal runaway (TR) of lithium-ion batteries. To date, the understanding of their main mechanisms has centered on single-directional crosstalk of oxygen (O₂) gas from the cathode to the anode, underestimating the exothermic reactions during TR. However, the role of multidirectional crosstalk in steering additional exothermic reactions is yet to be elucidated due to the difficulties of co