• Journal of Electrochemical Science and Technology
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• 제5권2호
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• pp.37-44
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• 2014

The $Li-O_2$ battery has been attracting much attention recently, due to its very high theoretical capacity compared with Li-ion chemistries. Nevertheless, several studies within the last few years revealed that Li-ion derived electrolytes based on alkyl carbonate solvents, which have been commonly used in the last 27 years, are irreversibly consumed at the $O_2$ electrode. Accordingly, more stable electrolytes are required capable to operate with both the Li metal anode and the $O_2$ cathode. Thus, due to their favorable properties such as non volatility, chemical inertia, and favorable behavior toward the Li metal electrode, ionic liquid-based electrolytes have gathered increasing attention from the scientific community for its application in $Li-O_2$ batteries. However, the scale-up of Li-$O_2$ technology to real application requires solving the mass transport limitation, especially for supplying oxygen to the cathode. Hence, the 'LABOHR' project proposes the introduction of a flooded cathode configuration and the circulation of the electrolyte, which is then used as an oxygen carrier from an external $O_2$ harvesting device to the cathode for freeing the system from diffusion limitation.

• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.78-89
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• 2022

ANODE-free Li-metal batteries (AFLMBs) operating with Li of cathode material have attracted enormous attention due to their exceptional energy density originating from anode-free structure in the confined cell volume. However, uncontrolled dendritic growth of lithium on a copper current collector can limit its practical application as it causes fatal issues for stable cycling such as dead Li formation, unstable solid electrolyte interphase, electrolyte exhaustion, and internal short-circuit. To overcome this limitation, here, we report a novel dual-salt electrolyte comprising of 0.2 M LiPF₆ + 3.8 M lithium bis(fluorosulfonyl)imide in a carbonate/ester co-solvent with 5 wt% fluoroethylene carbonate, 2 wt% vinylene carbonate, and 0.2 wt% LiNO₃ additives. Because the dual-salt electrolyte facilitates uniform/dense Li deposition on the current collector and can form robust/ionic conductive LiF-based SEI layer on the deposited Li, a Li/Li symmetrical cell exhibits improved cycling performance and low polarization for over 200 h operation. Furthermore, the anode-free LiFePO₄/Cu cells in the carbonate electrolyte shows significantly enhanced cycling stability compared to the counterparts consisting of different salt ratios. This study shows an importance of electrolyte design guiding uniform Li deposition and forming stable SEI layer for AFLMBs.

• Corrosion Science and Technology
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• 제22권4호
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• pp.287-296
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• 2023

Li-ion batteries have been gaining increasing importance, driven by the growing utilization of renewable energy and the expansion of electric vehicles. To meet market demands, it is essential to ensure high energy density and battery safety. All-solid-state batteries (ASSBs) have attracted significant attention as a potential solution. Among the advantages, they operate with an ion-conductive solid electrolyte instead of a liquid electrolyte therefore significantly reducing the risk of fire. In addition, by using high-capacity alternative electrode materials, ASSBs offer a promising opportunity to enhance energy density, making them highly desirable in the automotive and secondary battery industries. In ASSBs, Li metal can be used as the anode, providing a high theoretical capacity (3860 mAh/g). However, challenges related to the high interfacial resistance between Li metal and solid electrolytes and those concerning material degradation during charge-discharge cycles need to be addressed for the successful commercialization of ASSBs. This review introduces and discusses the interfacial reactions between Li metal and solid electrolytes, along with research cases aiming to improve these interactions. Additionally, future development directions in this field are explored.

• Journal of Electrochemical Science and Technology
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• 제5권3호
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• pp.87-93
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• 2014

The fluorine-substituted $0.3Li_2MnO_3{\cdot}0.7Li[Mn_{0.60}Ni_{0.25}Co_{0.15}]O_{2-x}F_x$ cathode materials were synthesized by using the transition metal precursor, $LiOH{\cdot}H_2O$ and LiF. This was to facilitate the movement of lithium ions by forming more compact SEI layer and to reduce the dissolution of transition metals. The $0.3Li_2MnO_3{\cdot}0.7Li[Mn_{0.60}Ni_{0.25}Co_{0.15}]O_{2-x}F_x$ cathode material was sphere-shaped and each secondary particle had $10{\sim}15{\mu}m$ in size. The fluorine-substituted cathodes initially delivered low discharge capacity, but it gradually increased until 50th charge-discharge cycles. These results indicated that fluorine substitution gave positive effects on the structural stabilization and resistance reduction in materials.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.202-206
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• 1990

The existing batteries such as lead acid battery and Nicad battery have been at serious issue, because heavy metal such as Pb and Cd give rise to environmental pollution. Therefor, when these material is changed over polymeric electroactive material, we expect environmental pollution will be prevented. We decided to develop 2025 coin type PAn/Li-Al secondary battery for goal of memory back-up battery. This report is concerned with manufacturing of 2025 coin type PAn/Li -Al secondary battery.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.852-856
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• 2011

The lithium ion diffusion coefficients of bare, carbon-coated and Cr-doped $LiFePO_4$ were obtained by fitting the discharge curves of each half cell with Li metal anode. Diffusion losses at discharge curves were acquired with experiment data and fitted to equations. Theoretically fitted equations showed good agreement with experimental results. Moreover, theoretical equations are able to predict lithium diffusion coefficient and discharge curves at various discharge rates. The obtained diffusion coefficients were similar to the true diffusion coefficient of phase transformation electrodes. Lithium ion diffusion is one of main factors that determine voltage drop in a half cell with $LiFePO_4$ cathode and Li metal anode. The high diffusion coefficient of carbon-coated and Cr-doped $LiFePO_4$ resulted in better performance at the discharge process. The performance at high discharge rate was improved much as diffusion coefficient increased.

• 한국전기전자재료학회논문지
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• 제31권5호
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• pp.335-340
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• 2018

Transition metal oxide materials have attracted widespread attention as Li-ion battery electrode materials owing to their high theoretical capacity and good Li storage capability, in addition to various nanostructured materials. Here, we fabricated a CoO Li-ion battery in which Co nanoparticles (NPs) are deposited into a current collector through electrophoretic deposition (EPD) without binding and conductive agents, enabling us to focus on the intrinsic electrochemical properties of CoO during the conversion reaction. Through optimized Co NP synthesis and electrophoretic deposition (EPD), CoO Li-ion battery with 630 mAh/g was fabricated with high cycle stability, which can potentially be used as a test platform for a fundamental understanding of conversion reaction.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.250-255
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• 2019

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes (SPEs) show promise for improving the lithium ion battery safety. However, due to oxidation of the PEO group and corrosion of the Al current collector, PEO-based SPEs have not previously been effective for use in $LiCoO_2$ (LCO) cathode materials at room temperature. In this paper, a semi-interpenetrating polymer network (semi-IPN) PEO-based SPE was applied to examine the performance of a LCO/SPE/Li metal cell at different voltage ranges. The results indicate that the SPE can be applied to LCO-based lithium polymer batteries with high electrochemical performance. By using a carbon-coated aluminum current collector, the Al corrosion was mostly suppressed during cycling, resulting in improvement of the cell cycle stability.

• 전기화학회지
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• 제3권2호
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• pp.115-120
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• 2000

양극 물질로 산화바나듐 박막, 고체전해질로는 LiPON 박막 그리고 음극 물질로는 리튬 금속 박막을 선택하여 $Li/LiPON/V_2O_5/Pt$ 구조의 전고상 박막 전지를 제작하였고 전지 특성을 평가하였다. 산화바나듐 박막은 여러 산소 분압에서 직류 반응성 스퍼터링으로 증착하여 전기화학적 특성을 분석한 결과 $20\%\;O_2/Ar$비에서 가장 우수한 가역 특성을 나타내었다. 직류 반응성 스퍼터링에 의해 산화바나듐 박막을 제작한 후 진공을 그대로 유지한 상태에서 r.f. 반응성 스퍼터링에 의해 LiPON 고체전해질 박막을 증착하였다. 그 후 dry room내에서 진공 열증착법에 의해 리튬 금속 박막을 증착하여 전고상의 박막 전지를 제작하였다. $Li/LiPON/V_2O_5$ 박막 전지를 전압 범위와 전류 밀도를 변화시켜 충방전 시험을 행한 결과 $7{\mu}A/cm^2$의 전류 밀도와 3.6-2.7 V의 전압범위에서 가장 우수한 가역 특성을 나타내었다. $Li/LiPON/V_2O_5$박막 전지로 초시계를 구동 시켰으며 이는 in-situ공정에 의해 제작된 박막 전지가 소자 에너지원으로의 응용 가능성을 보여 주었다.

• 공업화학
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• 제22권1호
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• pp.67-71
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• 2011

$Li/SO_2Cl_2$ 전지의 양극활물질은 $SO_2Cl_2$인데 이 물질은 전해액의 용매이기도 하다. 이를 일컬어 catholyte (cathode와 electrolyte의 합성어)라 칭하는데 전지의 방전이 진행됨에 따라 소진된다. 따라서 전지 제작 시 투입되는 $SO_2Cl_2$의 특성은 전지의 용량을 결정하는 중요 변수이다. 또한, $Li/SO_2Cl_2$ 전지의 transition minimum voltage (TMV)와 전압지연 편차는 전해액과 리튬의 반응에 의하여 형성된 부동화 막과 관련되는데 이 부동화 막은 전해액 내 불순물(수분 또는 중금속 이온)이 있을 경우 이의 성장이 촉진된다. 따라서 전해액을 정제시키는 기술과 이를 평가하는 방법의 정립은 반드시 필요하다. 본 연구에서는 $LiAlCl_4/SO_2Cl_2$전해액을 $AlCl_3$와 LiCl을 이용하여 제조하였고 제조된 전해액을 이온전도도계와 색도계 및 FT-IR을 이용하여 농도와 수분, 금속함량 등을 평가하였다.