• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3253-3256
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• 2013

Lithium is a highly attractive material for high-energy-concentration batteries, since it has low weight and high potential. Rechargeable lithium-ion batteries (LIBs), which have the extremely high gravimetric and volumetric energy densities, are currently the most preferable power sources for future electric vehicles and various portable electronic devices. In order to improve the efficiency and lifetime, new electrode compounds for lithium intercalation or insertion have been investigated for rechargeable batteries. Solid-state nuclear magnetic resonance (NMR) is a very useful tool to investigate the structural changes in electrode materials in actual working lithium-ion batteries. To detect the in-situ microstructural changes of electrode and electrolyte materials, $^7Li-^{19}F$ double-resonance solid-state NMR probe with a static solenoidal coil for a 600-MHz narrow-bore magnet was designed, constructed, and tested successfully.

• Journal of Electrochemical Science and Technology
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• v.1 no.1
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• pp.1-9
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• 2010

Conducting polymer films grown from various aromatic compounds have been evaluated as overcharge protecting additives for lithium ion rechargeable batteries. The polymer films were grown electrochemically under the conditions similar to those encountered during the overcharging processes of lithium batteries and subsequently characterized by potentiodynamic, electrochemical quartz crystal microbalance, electrochemical impedance spectroscopic, and scanning electron microscopic experiments. Results indicate that bicyclic and polycyclic aromatic hydrocarbons would be poor candidates for inhibitors, while biphenyl, terphenyl, and benzene derivatives displayed excellent performances. Mixed polymer films grown from o-terphenyl and p-xylene show the best performance among the candidates.

• Journal of Electrochemical Science and Technology
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• v.11 no.3
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• pp.195-219
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• 2020

Today, rechargeable lithium-ion batteries are an essential portion of modern daily life. As a promising alternative to traditional energy storage systems, they possess various advantages. This review attempts to provide the reader with an indepth understanding of the working mechanisms, current technological progress, and scientific challenges for a wide variety of lithium-ion battery (LIB) electrode nanomaterials. Electrochemical thermodynamics and kinetics are the two main perspectives underlying our introduction, which aims to provide an informative foundation for the rational design of electrode materials. Moreover, both anode and cathode materials are clarified into several types, using some specific examples to demonstrate both their advantages and shortcomings, and some improvements are suggested as well. In addition, we summarize some recent research progress in the rational design and synthesis of nanostructured anode and cathode materials, together with their corresponding electrochemical performances. Based on all these discussions, potential directions for further development of LIBs are summarized and presented.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.180-186
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• 2018

We report the discovery of Li-rich $Li_{1+x}[(Ni_{0.225}Co_{0.15}Mn_{0.625})_{1-y}V_y]O_2$ as a cathode material for rechargeable lithium-ion batteries in which a small amount of tetravalent vanadium ($V^{4+}$) is selectively and completely incorporated into the manganese sites in the lattice structure. The unwanted oxidation of vanadium to form a $V_2O_5-like$ secondary phase during high-temperature crystallization is prevented by uniformly dispersing the vanadium ions in coprecipitated $[(Ni_{0.225}Co_{0.15}Mn_{0.625})_{1-y}V_y](OH)_2$ particles. Upon doping with $V^{4+}$ ions, the initial discharge capacity (>$275mA\;h\;g^{-1}$), capacity retention, and voltage decay characteristics of the Li-rich layered oxides are improved significantly in comparison with those of the conventional undoped counterpart.

• Journal of the Korean Electrochemical Society
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• v.11 no.4
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• pp.242-255
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• 2008

In lithium-ion batteries(LIB), the development of electrolytes had mainly focused on the characteristics of lithium cobalt oxide($LiCoO_2$) cathode and graphite anode materials since the commercialization in 1991. Various studies on compatibility between electrode and electrolytes had been actively developed on their interface. Since then, as they try to adopt silicon and tin as anode materials and three components(Ni, Mn, Co), spinel, olivine as cathode materials for advanced lithium batteries, conventional electrolyte materials are facing a lot of challenges. In particular, requirements for electrolytes performance become harsh and complicated as safety problems are seriously emphasized. In this report, we summarized the research trend of electrolyte materials for the electrode materials of lithium rechargeable batteries.

• Journal of the Korean Ceramic Society
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• v.55 no.4
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• pp.307-324
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• 2018

Rechargeable lithium-ion batteries (LIBs) have been rapidly expanding from IT based applications to uses in electric vehicles (EVs), smart grids, and energy storage systems (ESSs), all of which require low cost, high energy density and high power density. The increasing demand for LIBs has resulted in increasing price of the lithium source, which is a major obstacle to wider application. To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to LIBs. A lot of transition metal compounds based on conversion-alloying reaction have been extensively investigated to meet the requirement for the anodes with high energy density and long life-time. In-depth understanding the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anode for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.31-35
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• 2007

In this review article, we are going to explain the recent development of lithium secondary batteries for a cellular phone. There are three kinds of rechargeable batteries for cellular phones such as nickel-cadmium, nickel-metal hydride, and lithium ion or lithium ion polymer. The lithium secondary battery is one of the most excellent battery in the point of view of energy density. It means very small and light one among same capacity batteries is the lithium secondary battery. The market volume of lithium secondary batteries increases steeply about 15% annually. The trend of R&D is focused on novel cathode materials including $LiFePO_4$, novel anode materials such as lithium titanate, silicon, and tin, elecrolytes, and safety insurance.

• Korean Journal of Materials Research
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• v.20 no.11
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• pp.592-599
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• 2010

A porous nickel-tin nano-dendritic electrode, for use as the anode in a rechargeable lithium battery, has been prepared by using an electrochemical deposition process. The adjustment of the complexing agent content in the deposition bath enabled the nickel-tin alloys to have specific stoichiometries while the amount of acid, as a dynamic template for micro-porous structure, was limited to a certain amount to prevent its undesirable side reaction with the complexing agent. The ratios of nickel to tin in the electro-deposits were nearly identical to the ratios of nickel ion to tin ion in the deposition bath; the particle changed from spherical to dendritic shape according to the tin content in the deposits. The nickel to tin ratio and the dendritic structure were quite uniform throughout the thickness of the deposits. The resulting nickel-tin alloy was reversibly lithiated and delithiated as an anode in rechargeable lithium battery. Furthermore, the resulting anode showed much more stable cycling performance up to 50 cycles, as compared to that resulting from dense electro-deposit with the same atomic composition and from tin electrodeposit with a similar porous structure. From the results, it is expected that highly-porous nickel-tin alloys presented in this work could provide a promising option for the high performance anode materials for rechargeable lithium batteries.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3190-3194
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• 2010

Mixed electrolytes formed by the combination of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (BMP-TFSI) ionic liquid and standard liquid electrolyte are prepared and characterized. Linear sweep voltammetry measurements demonstrate that these mixed systems exhibit a wide electrochemical stability window, allowing them to be suitable electrolyte for carbonaceous anode-based lithium-ion batteries. Lithium-ion cells composed of graphite anode and $LiCoO_2$ cathode are assembled using the mixed electrolytes, and their cycling performances are evaluated. The cell containing proper content of BMP-TFSI shows good cycling performance comparable to that of a cell assembled with organic electrolyte. The presence of BMP-TFSI in the mixed electrolyte contributes to the reduction of the flammability of electrolyte solution and the improvement of the thermal stability of charged $Li_{1-x}CoO_2$ in the electrolyte solution.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.69-70
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• 2006

In lithium-ion batteries, separator membrane's, main role is to physically isolate a cathode and an anode while maintaining rapid transport of ionic charge carriers during the passage of electric current. As far as battery safety is concerned, the electrical isolation of electrodes is most crucial since unexpected short-circuits across the membrane induces hot spots where thermal runaway may break out. Internal short-circuits are generally believed to occur by protrusions on the electrode surface either by unavoidable deposits of metallic impurities or by dendritic lithium growth during battery operation. Another cause is shrinkage of the separator membrane when exposed to heat. If separator membrane can be engineered to prevent the internal short-circuit, it will not be difficult to improve lithium-ion batteries' safety. Commonly the separators employed in lithium-ion batteries are made of polyethylene (PE) and/or polypropylene (PP). These materials have terrible limitations in preventing the fore-mentioned internal short-circuit between electrodes due to their poor dimensional stability and mechanical strength. In this study we have developed a novel separator membrane that possesses very high thermal and mechanical stability. The cells employing this separator provided noticeable safety improvement in the various abuse tests.