Geun-gyung Park

Bio: Geun-gyung Park is an academic researcher from Dankook University. The author has contributed to research in topics: Electrode & Overpotential. The author has an hindex of 3, co-authored 3 publications receiving 58 citations.

Enhanced Rate Capability and Cycle Performance of Titanium-Substituted P2-Type Na0.67Fe0.5Mn0.5O2 as a Cathode for Sodium-Ion Batteries.

Abstract: In this study, we developed a doping technology capable of improving the electrochemical performance, including the rate capability and cycling stability, of P2-type Na0.67Fe0.5Mn0.5O2 as a cathode material for sodium-ion batteries. Our approach involved using titanium as a doping element to partly substitute either Fe or Mn in Na0.67Fe0.5Mn0.5O2. The Ti-substituted Na0.67Fe0.5Mn0.5O2 shows superior electrochemical properties compared to the pristine sample. We investigated the changes in the crystal structure, surface chemistry, and particle morphology caused by Ti doping and correlated these changes to the improved performance. The enhanced rate capability and cycling stability were attributed to the enlargement of the NaO2 slab in the crystal structure because of Ti doping. This promoted Na-ion diffusion and prevented the phase transition from the P2 to the OP4/″Z″ structure.

Flexible and wrinkle-free electrode fabricated with polyurethane binder for lithium-ion batteries

Abstract: Flexible and wrinkle-free electrodes for flexible lithium-ion batteries (LIBs) are prepared with a polyurethane (PU) binder by casting a slurry on a glass substrate and detaching the subsequent film after drying. The flexible electrodes do not include a metal-foil current collector that would limit the LIB flexibility. The presence of both soft and hard segments in the PU structure gives the electrodes great flexibility and allows them to be folded without wrinkling or deforming. Adding multi-walled carbon nanotubes (MWNTs) to the electrodes simultaneously enhances the electrochemical properties (discharge capacity, rate capability, and cycling stability) and increases their mechanical strength (tensile strength). The flexible electrodes exhibit excellent electrochemical performance, which may be due to the enhanced electronic conductivity provided by the MWNT network in the electrode. The effects of PU content on the electrochemical performance are also investigated; it is found that a small amount of PU, approximately 11.5 wt%, is sufficient to fabricate the flexible electrode.

Exploring Chemical, Mechanical, and Electrical Functionalities of Binders for Advanced Energy-Storage Devices

Abstract: Tremendous efforts have been devoted to the development of electrode materials, electrolytes, and separators of energy-storage devices to address the fundamental needs of emerging technologies such as electric vehicles, artificial intelligence, and virtual reality. However, binders, as an important component of energy-storage devices, are yet to receive similar attention. Polyvinylidene fluoride (PVDF) has been the dominant binder in the battery industry for decades despite several well-recognized drawbacks, i.e., limited binding strength due to the lack of chemical bonds with electroactive materials, insufficient mechanical properties, and low electronic and lithium-ion conductivities. The limited binding function cannot meet inherent demands of emerging electrode materials with high capacities such as silicon anodes and sulfur cathodes. To address these concerns, in this review we divide the binding between active materials and binders into two major mechanisms: mechanical interlocking and interfacial b...

Reviving lithium cobalt oxide-based lithium secondary batteries-toward a higher energy density

Abstract: By breaking through the energy density limits step-by-step, the use of lithium cobalt oxide-based Li-ion batteries (LCO-based LIBs) has led to the unprecedented success of consumer electronics over the past 27 years. Recently, strong demands for the quick renewal of the properties of electronic products every so often have resulted in smarter, larger screened, more lightweight devices with longer standby times that have pushed the energy density of LCO-based LIBs nearly to their limit. As a result, with the aim of achieving a higher energy density and lifting the upper cut-off voltage of LCO above 4.45 V (vs. Li/Li+), the development of LCO-based all-solid-state lithium batteries (ASSLBs) with a Li metal anode and LCO-based full cells with high-performance anodes have become urgent scientific and technological requirements. This review summarizes the key challenges of synthesizing LCO-based LBs with a higher energy density from the perspectives of structure and interface stability, and gives an account of effective modification strategies in view of the electrodes, liquid electrolytes, binders, separators, solid electrolytes and LCO-based full cells. The improvement mechanisms of these modification strategies and the controversy over them are also analyzed critically. Moreover, some perspectives regarding the remaining challenges for LCO-based LBs towards a higher energy density and possible future research focuses are also presented.

Cable-type supercapacitors of three-dimensional cotton thread based multi-grade nanostructures for wearable energy storage

Abstract: A novel cable-type flexible supercapacitor with excellent performance is fabricated using 3D polypyrrole(PPy)-MnO2 -CNT-cotton thread multi-grade nanostructure-based electrodes. The multiple supercapacitors with a high areal capacitance 1.49 F cm(-2) at a scan rate of 1 mV s(-1) connected in series and in parallel can successfully drive a LED segment display. Such an excellent performance is attributed to the cumulative effect of conducting single-walled carbon nanotubes on cotton thread, active mesoporous flower-like MnO2 nanoplates, and PPy conductive wrapping layer improving the conductivity, and acting as pseudocapacitance material simultaneously.

Particles and Polymer Binder Interaction - A Controlling Factor in Lithium-Ion Electrode Performance

Abstract: Author(s): Liu, G; Zheng, H; Song, X; Battaglia, VS | Abstract: This paper investigates lithium-ion electrode laminates as polymer composites to explain their performance variation due to changes in formulation. There are three essential components in a positive electrode laminate: active material (AM) particles, acetylene black (AB) particles, and the polymer binder. The high filler content and discrete particle sizes make the electrode laminate a very unique polymer composite. This work introduces a physical model in which AB and AM particles compete for polymer binder, which forms fixed layers of polymer on their surfaces. This competition leads to the observed variations in electrode morphology and performance for different electrode formulations. The electronic conductivities of the cathode laminates were measured and compared to an effective conductivity calculation based on the physical model to probe the interaction among the three components to reveal the critical factors controlling electrode conductivity and electrochemical performance. The data and effective conductivity calculation results agree very well with each other. This developed physical model provides a theoretical guideline for optimization of electrode composition for most polymer binder-based Li-ion battery electrodes. © 2012 The Electrochemical Society.