Experimental study on flotation of graphite with inorganic electrolytes solution

Wenze Kang,Shufang Ding,Huijian Li,Hong Zhao 한국탄소학회 2023 Carbon Letters Vol.33 No.6

To study the effect of inorganic electrolyte solution on graphite flotation, 19 kinds of inorganic electrolytes, including nitrate, chloride and sulfate were selected as experimental electrolytes. The flotation experiment was carried out on graphite and the contact angle and surface potential of the interaction between inorganic electrolyte solution and graphite were studied. The results show that flotation effect and flotation rate of the three ion valence inorganic electrolytes follow the order: nitrate < chloride < sulfate and univalent < bivalent < trivalent (except Ba(NO3)2 and Pb(NO3)2). When the ion valence are the same, the larger the ion atomic number, the better effect on graphite flotation. Cations in inorganic electrolyte solutions are the main factors affecting mineral flotation. When the cationic type and concentration are the same, different flotation effects are attributed to different anions. For low ion valence inorganic electrolyte solution with weak foaming effect, a certain dose of frother can be added appropriately to improve the flotation effect of graphite. The high ion valence inorganic electrolyte solution has strong foaming effect, and it is not necessary to add a frother. The principle of inorganic electrolyte solution promoting graphite flotation is analyzed from the aspects of liquid phase property, gas–liquid interface property, contact angle and surface potential. It is proved that inorganic electrolyte solution as flotation medium can promote the effective flotation of graphite.

Electrochemical properties of a ceramic-polymer-composite-solid electrolyte for Li-ion batteries

Lee, Seoung Soo,Lim, Young Jun,Kim, Hyun Woo,Kim, Jae-Kwang,Jung, Yeon-Gil,Kim, Youngsik Elsevier 2016 Solid state ionics Vol.284 No.-

<P><B>Abstract</B></P> <P>This study reports on the fabrication of a ceramic-polymer-composite electrolyte with liquid electrolyte, consisting of Li<SUB>1.3</SUB>Ti<SUB>1.7</SUB>Al<SUB>0.3</SUB>(PO<SUB>4</SUB>)<SUB>3</SUB> (LTAPO) ceramic powder, polytetrafluoroethylene (PTFE) polymer and 1M LiPF<SUB>6</SUB> in EC/DMC liquid electrolyte. The morphologies of the LTAPO, LTAPO–PTFE composite membrane, and LTAPO–PTFE–LiPF<SUB>6</SUB>–EC/DMC composite electrolyte were analyzed using a scanning electron microscopy (SEM). The effect of the liquid electrolyte on the ionic conductivity of the prepared ceramic-polymer electrolyte was investigated using electrochemical impedance spectroscopy (EIS). The room temperature ionic conductivities of the LTAPO–PTFE–LiPF<SUB>6</SUB>–EC/DMC composite electrolyte and the LTAPO ceramic electrolyte exhibited 2.94×10<SUP>−4</SUP> S/cm and 8.36×10<SUP>−4</SUP> S/cm, respectively. The first charge capacity of the LTAPO–PTFE–LiPF<SUB>6</SUB>–EC/DMC composite electrolyte cell reached 118mAh/g at 0.06mA/cm<SUP>2</SUP> current density. The electrochemical performance of the ceramic-polymer-composite electrolyte cell was better than that of the ceramic solid electrolyte cell.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Flexible ceramic-polymer composite film was successfully fabricated as an electrolyte. </LI> <LI> The added liquid electrolyte improved the contact of both the LTAPO powder and the electrode/electrolyte. </LI> <LI> The flexible composite electrolyte cell exhibited excellent cycling performance. </LI> </UL> </P>

A high-performance polymer composite electrolyte embedded with ionic liquid for all solid lithium based batteries operating at ambient temperature

You, Duck-Jae,Yin, Zhenxing,Ahn, Yong-keon,Cho, Sanghun,Kim, Hyunjin,Shin, Dalwoo,Yoo, Jeeyoung,Kim, Youn Sang Elsevier 2017 Journal of industrial and engineering chemistry Vol.52 No.-

<P><B>Abstract</B></P> <P>A novel polymer composite electrolyte for lithium-based battery operating at room temperature was introduced. The proposed polymer composite electrolyte consisted of electrolyte using a 3-D cross-linked polymer matrix, which is synthesized with polyethylene glycol (PEG) and 3-glycidoxypropyltrimethoxysilane (GPTMS), and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) as a Li-ion transport medium. The proposed polymer composite electrolyte shows a high ionic conductivity of 35×10<SUP>−2</SUP> mScm<SUP>−1</SUP> and high decomposition temperature of 250°C with a 3-D cross-linked polymer matrix. The EMITFSI mass ratio is 1:0.7 at room temperature. In addition, when polymer composite electrolyte is applied to the solid battery consisting of Li metal as an anode and LiFePO<SUB>4</SUB> as a cathode, it can be operated at room temperature with a high specific capacity of 75.8mAh/g at 0.1C rate. Furthermore, the battery with a structure of Li/polymer composite electrolyte/LiFePO<SUB>4</SUB> also has excellent capacity retention.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Polymer composite electrolytes were composed with the 3-D cross-linked polymer matrix and EMITFSI. </LI> <LI> The suggested polymer composite electrolyte was thermally stable up to 250°C. </LI> <LI> Ionic conductivity was strongly increased by addition of EMITFSI to polymer composite electrolyte. </LI> <LI> Polymer composite electrolyte achieved a high ionic conductivity of 35×10<SUP>−2</SUP> mScm<SUP>−1</SUP> at room temperature. </LI> <LI> The discharge specific capacity of Li/polymer composite electrolyte/LiFePO<SUB>4</SUB> battery was increased to 75.8mAh/g at room temperature. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P> <P>Polymer composite electrolyte embedding ionic liquid to fabricate the high-performance all-solid-state Li-battery operating at room temperature. The proposed electrolyte shows a high ionic conductivity 35×10<SUP>−2</SUP> mScm<SUP>−1</SUP>. When polymer composite electrolyte is applied to the battery, it can be operated at room temperature.</P>

Reversible thixotropic gel electrolytes for safer and shape-versatile lithium-ion batteries

Kim, Ju Young,Shin, Dong Ok,Kim, Se-Hee,Lee, Jun Ho,Kim, Kwang Man,Oh, Jimin,Kim, Jumi,Lee, Myeong Ju,Yang, Yil-Suk,Lee, Sang-Young,Kim, Je Young,Lee, Young-Gi Elsevier 2018 Journal of Power Sources Vol.401 No.-

<P><B>Abstract</B></P> <P>All-solid-state lithium-ion batteries (ASLBs) are receiving considerable attention due to their safety superiority and high energy density (achieved by bipolar configuration). Inorganic solid electrolytes are explored as a key-enabling material of the ASLBs. However, their critical challenges, including grain boundary resistance, interfacial instability with electrode materials and complicated processability, remain yet unresolved. Here, we demonstrate a new class of gel electrolyte with reversible thixotropic transformation and abuse tolerance as an effective and scalable approach to address the aforementioned longstanding issues. The gel electrolyte consists of (fluoropolymer/cellulose derivative) matrix and liquid electrolyte. The reversible thixotropic transformation is realized via sol-gel transition based on Coulombic interaction of the polymer matrix with liquid electrolyte. This unusual rheological feature allows the gel electrolyte to be printed in various forms. In addition, the gel electrolyte shows low crystallinity, thus playing a viable role in delivering high ionic conductivity. Based on understanding of rheological/electrochemical characteristics of the gel electrolyte, we fabricate a form factor-free pouch-type cell assembled with the gel electrolyte using sequential screen-printing process. The resultant cell shows exceptional safety upon exposure to various harsh abuse conditions, along with decent electrochemical performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new class of gel electrolyte with reversible thixotropic property is demonstrated. </LI> <LI> The gel electrolyte consists of (fluoropolymer/cellulose derivatives) and liquid electrolyte. </LI> <LI> A form factor-free pouch-type cell can also be assembled with the gel electrolyte. </LI> </UL> </P>

Poly[(ethylene glycol) diacrylate]-Poly(vinylidene fluoride) 전해질을 이용한 전기 이중층 캐패시터의 전기화학적 특성

양천모 ( Chun Mo Yang ),이중기 ( Joong Kee Lee ),조원일 ( Won Il Cho ),조병원 ( Byung Won Cho ),주재백 ( Jeh Beck Ju ),유관표 ( Kwan Pyo Yoo ),임병오 ( Byung O Rim ) 한국공업화학회 2002 공업화학 Vol.13 No.8

자외선 경화법으로 제조한 PEGDA-PVdF 젤상 고분자 전해질을 전기이중층캐패시터에 적용하였고, 액상 유기 전해질을 이용한 전기이중층캐패시터와 전기화학적 특성을 비교 조사하였다. 자외선 경화법으로 제조된 젤상 고분자 전해질[GPE:poly[(ethylene glycol) diacrylate]-poly(vinylidene fluoride) blend]을 이용한 전기이중층캐패시터의 경우, 비축전용량이 120 F/g으로 액상 유기 전해질 [LOE:1 M LiPF_6/EC:DMC:EMC (1:1:1 volume ratio)]을 이용한 전기이중층캐패시터의 비축전용량인 110 F/g보다 우수하였고, 100회 충방전 후에도 초기 비축전용량대비 92% 이상 유지하는 우수한 싸이클 특성을 나타내었으며 3.7 Ω의 낮은 ESR(equivalent series resistance)을 보여주었다. Cyclic voltammetry 분석 결과에서 보면 액상 유기 전해질과 젤상 고분자 전해질을 이용한 모든 전기이중층캐패시터에서 2.5 V까지 전해질의 분해 없이 전기화학적으로 안정하였고, 산화와 환원과 관련된 전류값 또한 관찰되지 않았다. 젤상 고분자 전해질을 이용한 전기이중층캐패시터의 경우에서 직사각형 모양의 이상적인 전기이중층캐패시터의 특성과 49 ㎂의 낮은 누설 전류값을 나타내었다. 자가방전 특성 결과, 젤상 고분자 전해질을 이용한 전기이중층캐패시터의 경우 2.5 V의 정전압 충전 시 OCV(open circuit voltage) 상태에서 100 h 경과 후 1.76 V의 전압을 유지하고 있어 0.25 V의 액상 유기 전해질을 이용한 전기이중층캐패시터보다 매우 우수함을 확인하였다. Poly[(ethylene glycol) diacrylate] (PEGDA)-poly(vinylidene fluoride) (PVdF) gel polymer was employed as an electrolyte for electric double layer capacitor (EDLC) and compared its electrochemical characteristics with that of liquid organic electrolyte. The used organic electrolyte was 1 mole of lithium hexafluorophosphate (LiPF_6) salt containing in the solvent mixture of ethylene carbonate(EC):dimethyl carbonate(DMC):ethylmethyl carbonate(EMC)(1:1:1 volume ratio). The specific capacitance of EDLC with gel polymer electrolyte showed 120 F/g, which was superior to that of 110 F/g with liquid organic electrolyte. Good cyclability was observed for gel polymer electrolyte of EDLC. The 92% of initial specific capacitance was retained after 100 cycles of charge-discharge runs. Equivalent series resistance of 3.7 Ω of the EDLC with gel polymer electrolyte was lower than that of EDLC with liquid organic electrolyte. The EDLC with gel polymer electrolyte exhibited rectangular cyclic voltammogram of ideal EDLC in operating voltage range of 0∼2.5 V and low leakage current of 49 ㎂. Voltage drop from self-discharge was low for gel polymer electrolyte. The 29.6% of initial voltage decreased for gel polymer electrolyte, but significantly decreased to 99% for liquid organic electrolyte. The good retentivity with gel polymer electrolyte possible comes from the difference in viscosity compared with that of liquid organic electrolyte.

Performance of molten carbonate fuel cell with Li-Na and Li-K carbonate electrolyte at extremely high-temperature condition

이기정,김태균,Samuel Koomson,이충곤 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.10

The cell performance of Li-K and Li-Na carbonate electrolytes was compared using a coin type molten carbonate fuel cell operated at the extremely high temperature of 800oC. It was an acceleration test to compare the performance in a short period. Electrochemical techniques such as steady state polarization (SSP) and impedance from the Nyquist plot were used in the cell performance analysis. The initial performance of both electrolytes was similar, but the performance of the Li-K electrolyte decreased drastically after 180h. The results from SSP showed that the total overpotential of the Li-K electrolyte increased sharply, whereas that of Li-Na electrolyte had a continuous performance up to 340h. The impedance analysis showed that the internal resistance of the Li-K electrolyte increased with time, but that of Li-Na electrolyte remained unchanged. The remaining amount of each electrolyte was determined, and it was observed that the electrolyte loss rate of the Li-K electrolyte was 0.0072g/hr, and that of Li-Na electrolyte was 0.0028g/ hr. This implies that the electrolyte depletion rate of the Li-K electrolyte is about 1.5 times faster than that of the Li-Na electrolyte at the high-temperature condition. Thus, the cell of a Li-Na electrolyte containing MCFC according to the consumption of electrolyte is expected to be longer than one that uses Li-K electrolyte.

Electrolyte effects on undoped and Mo-doped BiVO₄ film for photoelectrochemical water splitting

Das, Pran Krisna,Arunachalam, Maheswari,Seo, Young Jun,Ahn, Kwang-Soon,Ha, Jun-Seok,Kang, Soon Hyung Elsevier 2019 Journal of Electroanalytical Chemistry Vol.842 No.-

<P><B>Abstract</B></P> <P>As the electrolyte in a photoelectrochemical system used for solar water splitting is closely associated with the charge transfer phenomenon, the fundamental study of the electrolyte is an increasingly crucial issue. In this paper, the relation between the photoelectrochemical performance and the variation of electrolyte composition is investigated in depth. Here, the potassium phosphate (KPi) containing different anions (CH<SUB>3</SUB>COO<SUP>−</SUP>, Cl<SUP>−</SUP> and NO<SUB>3</SUB> <SUP>−</SUP>) or cations (NH<SUB>4</SUB> <SUP>+</SUP>, K<SUP>+</SUP> and Na<SUP>+</SUP>) was prepared at the electrolyte with the different pH values of 5, 7, 9, and 11 in order to investigate how anions or cations affect the PEC performance. Herein, we compared the differences in the undoped and Mo-doped BiVO<SUB>4</SUB> films due to the different bulk/surface states, and found different morphological and crystalline features as well as remarkably different PEC performance. At first, the pH in the electrolyte significantly influences the solar water oxidation reaction, revealing that the electrolyte with a high pH grants better PEC activity, because the higher pH solution can provide more hydroxide ions (OH<SUP>−</SUP>) to react with holes to form hydroxyl radicals, which are recognized as important intermediates for PEC water oxidation in the presence of O<SUB>2</SUB>. Further, in the electrolyte containing the different cations, the NH<SUB>4</SUB> <SUP>+</SUP> ions exhibit the enhanced PEC performance, due to its cation size which increases the ionic dissociation and viscosity. By contrast, the anion effect can be negligible in the used electrolyte. From this fundamental research, it can be known that the optimization of electrolyte is quite a vital parameter for advancing the PEC performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electrolyte study in BiVO<SUB>4</SUB> and Mo-doped BiVO<SUB>4</SUB> films in the photoelectrochemical water splitting </LI> <LI> Cation and anion, pH and long-term stability should be investigated to measure the PEC activity. </LI> <LI> Best performance was achieved in the NH<SUB>4</SUB> <SUP>+</SUP> cation in the alkaline solution. </LI> <LI> Faradaic efficiency of Mo-doped BiVO<SUB>4</SUB> film exhibit the higher than that of undoped BiVO<SUB>4</SUB> film. </LI> </UL> </P>

바나듐 레독스 흐름 전지용 전해액으로 클로로황산 첨가에 관한 연구

오용환,이건우,유철휘,황갑진 한국수소및신에너지학회 2016 한국수소 및 신에너지학회논문집 Vol.27 No.2

The electrolyte added the chlorosulfuric acid (HSO3Cl) as an additive was tested for the electrolyte in all-vanadium redox flow battery (VRFB) to increase the thermal stability of electrolyte. The electrolyte property was measured by the CV (cyclic voltammetry) method. The maximum value of a voltage and current density in the electrolyte added HSO3Cl was higher than that in the electrolyte non-added HSO3Cl. The thermal stability of the pentavalent vanadium ion solution, which was tested at 40℃, increased by adding HSO3Cl. The performances of VRFB using the electrolyte added and non-added HSO3Cl were measured during 30 cycles of charge-discharge at the current density of 60 mA/cm 2 . An average energy efficiency of the VRFB was 72.5%, 82.4%, and 81.6% for the electrolyte non-added HSO3Cl, added 0.5 mol of HSO3Cl, and added 1.0 mol of HSO3Cl, respectively. VRFB using the electrolyte added HSO3Cl was showed the higher performance than that using the electrolyte non-added HSO3Cl.

Non-aqueous quasi-solid electrolyte for use in supercapacitors

채지수,권하나,윤원섭,노광철 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.59 No.-

Gel electrolytes have attracted increasing attention for use in supercapacitors. An ideal gel electrolyte usually solves several problems, including electrolyte leakage, corrosion of the liquid electrolyte, and electrolyte packing. In this study, to address these issues, tetraethylammonium tetrafluoroborate in propylene carbonate was integrated into a poly(ethylene glycol) dimethacrylate polymer matrix with azobisisobutyronitrile as a thermal initiator. The specific capacitance of this quasi-solid electrolyte was 22% higher than that of the corresponding liquid-based electrolyte at 1 mA cm−2. Further, a supercapacitor wrapped with the quasi-solid electrolyte exhibited energy and power densities of 39 Wh kg−1 and 2.5 kW kg−1, respectively. Notably, the quasi-solid-electrolyte-based supercapacitor was very stable when cycled at a high current density (5 mA cm−2), with only 31% of its initial capacitance lost after 10,000 cycles. Wrapping the supercapacitor with the non-aqueous quasi-solid electrolyte provided a solidified surface, which reduced contact with moisture and oxygen in the air, thereby solving the evaporation problem encountered with liquid electrolytes.

Non-aqueous quasi-solid electrolyte for use in supercapacitors

Chae, Ji Su,Kwon, Ha-Na,Yoon, Won-Sub,Roh, Kwang Chul Elsevier 2018 Journal of industrial and engineering chemistry Vol.59 No.-

<P><B>Abstract</B></P> <P>Gel electrolytes have attracted increasing attention for use in supercapacitors. An ideal gel electrolyte usually solves several problems, including electrolyte leakage, corrosion of the liquid electrolyte, and electrolyte packing. In this study, to address these issues, tetraethylammonium tetrafluoroborate in propylene carbonate was integrated into a poly(ethylene glycol) dimethacrylate polymer matrix with azobisisobutyronitrile as a thermal initiator. The specific capacitance of this quasi-solid electrolyte was 22% higher than that of the corresponding liquid-based electrolyte at 1mAcm<SUP>−2</SUP>. Further, a supercapacitor wrapped with the quasi-solid electrolyte exhibited energy and power densities of 39Whkg<SUP>−1</SUP> and 2.5kWkg<SUP>−1</SUP>, respectively. Notably, the quasi-solid-electrolyte-based supercapacitor was very stable when cycled at a high current density (5mAcm<SUP>−2</SUP>), with only 31% of its initial capacitance lost after 10,000 cycles. Wrapping the supercapacitor with the non-aqueous quasi-solid electrolyte provided a solidified surface, which reduced contact with moisture and oxygen in the air, thereby solving the evaporation problem encountered with liquid electrolytes.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>