Factors affecting the electrical conductivity of conducting polymers

Pooja,Kumar Anil,Prasher Parteek,Mudila Harish 한국탄소학회 2023 Carbon Letters Vol.33 No.2

Metals had been significantly substituted by synthetic polymers in most of our daily requirements, thus relaxing our life. Out of many applied areas, synthetic polymers especially conducting polymers had shown their marked effect and potential. Batteries, pseudocapacitors, superconductors, etc. are the potential zones where conducting polymers are chiefly employed owing to their appreciable conductivity, cost efficiency, and corrosion inhibition nature. Apart from energy storage devices, these conducting polymers find their potential application in biosensors, lasers, corrosion inhibitors, electrostatic materials, conducting adhesives, electromagnetic interference shielding, and others. These all applications including energy storage are due to astonishing properties like high conductivity, flexibility, tuneability, easy processibility, chemical, thermal and mechanical stability, easy and enhanced charge transportation, lightweight, etc. Conducting polymers are extensively studied for their application in energy storage batteries, for which the material under investigation needs to be electrically conductive. However, the conducting nature of these specific conducting polymers is dependent on numerous factors. This review discussed the effect of certain potential factors such as polymerization techniques temperature, doping, bandgap, extended conjugation, solvent, etc. on the electrical/electrochemical conductivity of these conducting polymers. These all factors with their specific variations are found to have a noticeable consequence on the electrical conductivity of the investigated conducting polymer and hence on the energy storage carried by them. This review could be proved beneficial to the readers, who can judiciously implement the conclusions to their research related to conducting polymers and their composites for generating highly efficient energy storage systems.

전기전도도 측정을 통한 반류수 MLE공정에서 공기공급 제어기술 개발

장신요(Shinyo Chang),신풍식(Pung Shik Shin),정연구(Yeon-Koo Jeong),최영준(Young June Choi) 대한환경공학회 2020 대한환경공학회지 Vol.42 No.3

목적 : 반류수를 대상으로 무산소조에서 전기전도도 측정을 통해 호기조의 공기공급량을 제어할 수 있는 기술을 개발하여 공정성능 향상 및 에너지 사용량 절감을 달성하고자 하였다. 방법 : 전기전도도가 생물학적처리의 운전지표로 활용될 수 있는지를 검증하기 위해 각 공정별 수질인자와 전기전도도의 상관성 분석을 여름철(메탄올 투입), 겨울철, 가을철 시기로 나누어 실험하였다. 기존에 제시된 필요공기량 수식을 간단히 정리하여 경험식을 제시하고, 이를 활용해 전기전도도 범위에 공기공급량을 순차적으로 넣어 조견표를 작성하였다. 성능평가는 암모니아성질소와 총무기질소의 제거효율, SNR과 SDNR, 공기공급량의 변화, 유입수 변화에 대한 공정의 안정성 등을 기준으로 판단하였다. 결과 및 토의 : 계절별로 전기전도도와 각 수질항목의 상관계수가 0.5267 ~ 0.9115 범위로 암모니아성질소, 총무기질소, DOC, 인산염인 순서로 높게 산출되었다. 상관계수 0.5 이상으로 생물학적 처리공정의 운전지표로 전기전도도 가 활용될 수 있음을 알 수 있었다. 전기전도도와 암모니아성질소의 회귀식은 계절별로 재현성이 확보되어 전기전도도를 통해 암모니아성질소를 추정하는 것이 가능할 것으로 판단된다. 호기조 말단 DO가 3.4 mg/L 정도에서 겨울철 질소처리효율이 가장 양호하였다. 호기조 DO는 공기공급량으로 제어할 수 있으며 질소와 상관성이 높은 전기전도도를 직접 측정하여 공기공급량을 제어하고 질소처리효율을 향상시키는 것이 가능함을 알 수 있었다. 전기전도도와 유입유량을 통해 필요공기량을 산정할 수 있는 경험식을 제시하였고, 식 계수를 구한 결과 A", (B" + X") 는 각각 0.0589 (m³-air/h)/(m³/h)/(μS/cm), -77.562 (m³-air/h)/(m³/h)로 나타낼 수 있었다. 겨울철기간 무산소조의 전기전도도 측정값에 따라서 공기공급량을 자동 제어한 결과는 총무기질소 제거효율과 SDNR이 실플랜트 조건보다 각각 8.3%, 0.007 g-N/g-MLSS/d 높게 나타났다. 자동제어한 기간 동안에 공기공급량/유입유량 평균비가 36(m³-air/h)/(m³/h)로 실플랜트 조건보다 공기공급량을 21.7% 감소시킬 수 있었다. 결론 : 전기전도도 기반 MLE공정의 공기공급 제어기술은 질소제거 효율 향상 및 에너지 사용량 절감을 동시에 달성할 수 있을 것으로 판단된다. Objectives : This study aimed to achieve improved process performance and energy saving by developing a technology to control the air supply of an aerobic basin by measuring the conductivity in the anoxic basin. Methods : To verify whether conductivity can be used as an operation indicator of biological treatment, the correlation analysis between water quality factor and conductivity of each process was conducted by dividing into summer (methanol input), winter and autumn periods. An empirical formula was presented by briefly arranging the required air quantity formula, and a quick reference was prepared by putting air supply in the conductivity range sequentially. The performance evaluation was judged based on the removal efficiency of ammonia nitrogen and total inorganic nitrogen, SNR and SDNR, the change of air supply, the stability of the process against inflow change. Results and Discussion : The seasonal correlation coefficients of conductivity and water quality items were calculated in the order of ammonia nitrogen, total inorganic nitrogen, DOC, and phosphate in the range of 0.5267 ~ 0.9115. It was found that the conductivity could be used as an operation indicator of the biological treatment process with a correlation coefficient of 0.5 or more. The regression equations for the conductivity and ammonia nitrogen are secured by season, so it is possible to estimate the ammonia nitrogen through the conductivity. At the end of the aerobic basin DO was 3.4 mg/L, the nitrogen treatment efficiency in winter was the best. The aerobic basin DO can be controlled by the air supply, and it can be seen that it is possible to control the air supply and improve the nitrogen treatment efficiency by directly measuring the conductivity having a high correlation with nitrogen. An empirical formula for estimating the required air volume through conductivity and inflow is presented. A" and (B" + X") are 0.0589 (m³-air/h)/(m³/h)/(μS/cm) and -77.562 (m³-air/h)/(m³/h). The result of automatic control of air supply according to the measured conductivity of anoxic tank during winter season showed that total inorganic nitrogen removal efficiency and SDNR were 8.3% and 0.007 g-N/g-MLSS/d higher than the actual plant conditions, respectively. During the automatic control period, the air supply/inflow average ratio was 36 (m³-air/h)/(m³/h), which could reduce the air supply by 21.7% compared to the actual plant conditions. Conclusions : The air supply can be estimated from the flow rate and conductivity. The air supply control technology of the conductivity-based MLE process will be able to simultaneously improve nitrogen removal efficiency and reduce energy consumption.

탄소섬유 직물 및 전도성 탄소 필러가 고충진 된 열가소성 탄소섬유강화플라스틱의 전도 특성

김성륜 ( Seong Yun Kim ),노예지 ( Ye Ji Noh ),장지운 ( Ji-un Jang ),최성규 ( Seong Kyu Choi ) 한국복합재료학회 2021 Composites research Vol.34 No.5

지구 온난화 억제를 위한 전 세계적인 연비규제에 발맞춘 해결책으로 자동차에 경량구조복합재료를 적용하는 것이 메가트렌드로 인식되고 있다. 본 연구에서는 수리, 폐기 및 재활용 측면에서 유리한 열가소성 탄소섬유강화플라스틱의 적용을 극대화하기 위해 전도특성이 요구되는 부품 대체 이슈에 대응할 수 있는 기술적 접근을 제공하는 것을 목표로 수행되었다. 저점도 중합 가능한 기지재의 특성을 활용하여 전도성 필러를 파우더 믹싱 방법으로 균일하게 혼입하면서도 우수한 함침 특성을 나타내는 열가소성 탄소섬유강화플라스틱 제조방법에 기초하여 카본블랙, 탄소나노튜브, 그래핀 나노플레이틀렛, 흑연, 피치계 탄소섬유 등 다양한 탄소기반 전도성 필러를 최대 함량까지 혼입하여 전기저항 및 열전도도를 비교하여 고찰하였다. 전도성 탄소 필러의 종류나 형태보다는 최대 혼입량이 시편의 전도 특성을 제어하기 위해 가장 중요한 인자임을 확인하였고, 전기전도 특성을 향상시키기 위해서는 1차원 형태의 전도성 탄소필러를 적용하는 것이 유리할 수 있는 반면 열전도 특성을 향상시키기 위해서는 2차원 형태의 전도성 탄소필러를 적용하는 것이 유리 할 수 있다는 실험 결과를 확인하였다. 본 연구의 결과들은 열가소성 탄소섬유강화플라스틱의 전도 특성을 제어하기 위한 최적 구조 설계에 잠재적인 통찰력을 제공할 수 있다. The application of lightweight structural composites to automobiles as a solution in line with global fuel economy regulations to curb global warming is recognized as a megatrend. This study was conducted to provide a technical approach that can respond to the issue of replacing parts that require conductive properties to maximize the application of thermoplastic carbon fiber reinforced plastics (CFRPs), which are advantageous in terms of repair, disposal and recycling. By utilizing the properties of the low-viscosity polymerizable oligomer matrix, it was possible to prepare a thermoplastic CFRP exhibiting excellent impregnation properties while uniformly mixing the conductive filler. Various carbon-based conductive fillers such as carbon black, carbon nanotubes, graphene nanoplatelets, graphite, and pitch-based carbon fibers were filled up to the maximum content, and electrical and thermal conductive properties of the fabricated composites were compared and studied. It was confirmed that the maximum incorporation of filler was the most important factor to control the conductive properties of the composites rather than the type or shape of the conductive carbon filler. Experimental results were observed in which it might be advantageous to apply a one-dimensional conductive carbon filler to improve electrical conductivity, whereas it might be advantageous to apply a two-dimensional conductive carbon filler to improve thermal conductivity. The results of this study can provide potential insight into the optimization of structural design for controlling the conductive properties of thermoplastic CFRPs.

금속입자가 전도성 잉크의 전도도에 미치는 영향

권두효(Doo-Hyo Kwon),정태의(Tae-Eui Jeong),김남수(Nam-soo Kim),한국남(Kenneth N. Han) 한국생산제조학회 2008 한국생산제조학회지 Vol.17 No.2

In this investigation, conductivity of conductive inks was measured. A particular attention has been given to the effect of metal powders with various conductivity on the overall conductivity of the bulk ink. The conductivity of various solutions simulating conductive inks consisting of copper and silver was measured and the results have been discussed in relation to various applications of conductive inks in practice. A conductivity model simulating systems consisting of various materials has been introduced and the results were discussed. Materials of good conductivity are adversely affected by mixing with materials of poor conductivity simply through serial connection. However, parallel connection has rather little effect on the overall conductivity. The practical implication of various mixtures of materials on conductive inks has been discussed.

Conduction Path Formation Characteristics of Solderable Polymer Composite Filled with Low-Melting-Point and High-Melting-Point Alloy Fillers

하민정,김지호,한재구,양진석,김종민,임병승 대한용접·접합학회 2022 대한용접·접합학회지 Vol.40 No.3

In this study, low-melting-point alloy (LMPA) and high-melting-point alloy (HMPA) filler-filled solderable poly- mer composite (LH-SPC) system was proposed to enhance the mechanical and thermal properties of SPC with LMPA fillers. To identify the conduction path formation characteristics of LH-SPC according to the mixing ratio of LMPA and HMPA, four types of LH-SPC with different mixing ratios of LMPA and HMPA fillers (100:0, 80:20, 30:70, and 0:100) were formulated. Furthermore, a chip resistor interconnection test was conducted. The results in- dicated that LH-SPC with only HMPA did not form a conduction path because of the excessively cured polymer composite before melting HMPA. Meanwhile, LH-SPC with LMPA and HMPA fillers showed different conduction path formation mechanisms according to the mixing ratio of LMPA and HMPA fillers. In LH-SPC filled with lower HMPA content than LMPA, the conduction path was formed by the flow, coalescence, and wetting behaviors of molten LMPA containing solid-state HMPA at the melting range of the LMPA filler. On the other hand, in LH-SPC containing higher HMPA content than LMPA, the conduction path was formed by the wetting behavior of the mol- ten HMPA at a lower temperature range than the melting temperature of HMPA because of the decreased melting temperature of HMPA owing to the chemical composition change of HMPA by the diffusion of Bi into HMPA. In this study, low-melting-point alloy (LMPA) and high-melting-point alloy (HMPA) filler-filled solderable polymer composite (LH-SPC) system was proposed to enhance the mechanical and thermal properties of SPC with LMPA fillers. To identify the conduction path formation characteristics of LH-SPC according to the mixing ratio of LMPA and HMPA, four types of LH-SPC with different mixing ratios of LMPA and HMPA fillers (100:0, 80:20, 30:70, and 0:100) were formulated. Furthermore, a chip resistor interconnection test was conducted. The results indicated that LH-SPC with only HMPA did not form a conduction path because of the excessively cured polymer composite before melting HMPA. Meanwhile, LH-SPC with LMPA and HMPA fillers showed different conduction path formation mechanisms according to the mixing ratio of LMPA and HMPA fillers. In LH-SPC filled with lower HMPA content than LMPA, the conduction path was formed by the flow, coalescence, and wetting behaviors of molten LMPA containing solid-state HMPA at the melting range of the LMPA filler. On the other hand, in LH-SPC containing higher HMPA content than LMPA, the conduction path was formed by the wetting behavior of the molten HMPA at a lower temperature range than the melting temperature of HMPA because of the decreased melting temperature of HMPA owing to the chemical composition change of HMPA by the diffusion of Bi into HMPA.

Correlation between Hydraulic Conductivity and Electrical Conductivity for Porous Media

Tae Min Oh,Kyu Won Kim,Gye Chun Cho 한국지반공학회 2013 international journal of geo-engineering Vol.5 No.2

Hydraulic conductivity (permeability) is a very important physical property in geotechnical engineering. Monitoring of the hydraulic conductivity is useful for evaluating the ground condition by nondestructive methods. An electrical conductivity measurement technique can be applied to infer hydraulic conductivity. The goal of this study is theoretically to correlate the hydraulic conductivity and electrical conductivity for porous materials and to verify the developed correlation. The verification process is carried out through experimental tests involving glass beads and Joomunjin standard sand. The test variables are the electrical conductivity of the pore fluid, the porosity, and the particle size. The test results show that the estimated hydraulic conductivity realized by the developed correlation is in good agreement with the measured hydraulic conductivity results. Therefore, this preliminary study provides evidence of the strong possibility of the electrical conductivity being feasible for use to monitor the hydraulic conductivity of porous materials.

Electrical Conduction in $SrZr_{0.95}Y_{0.05}O_{2.975}$ Ceramics

Baek, Hyun-Deok,Noh, Jin-Hyo The Korean Ceramic Society 1999 The Korean journal of ceramics Vol.5 No.3

Partial conductivities contributed by electron holes, oxygen ions, and protons were caluclated in $SrZr_{0.95}Y_{0.05}O_{2.975}$, using the reported formulae derived from the defect chemistry of HTPCs. Required parameters were obtained from the graphical analysis of total conductivity variation against partial pressure of water vapor and oxygen. Predicted overall conductivities showed a reasonable agreement with experimental measurements. The conductivity of the material showed a linear increase with square root of the water vapor pressure. This increase was due to proton conduction in an almost pure ionic conductivity. The calculation of partial conductivities at $800^{\circ}C$ resulted in an almost pure ionic conductivity at $P_{02}=10^{-10}$ atm and a predominant hole conductivity at $P_{02}=10^{-10}$ atm. Pure proton conduction was not expected at this temperature, contrary to the earlier reports. Discussions were made in relation with reported thermodynamic data and defect structure of the material. It was shown that from the total conductivity dependence on water vapor pressure, the pure ionic conductivity at low oxygen partial pressures could be separated into protonic and oxygen ionic conductivity in $ZrO_2$-based HTPCs.

Suppression of bipolar conduction via bandgap engineering for enhanced thermoelectric performance of p-type Bi_0.4Sb_1.6Te₃ alloys

Kim, Hyun-Sik,Lee, Kyu Hyoung,Yoo, Joonyeon,Shin, Weon Ho,Roh, Jong Wook,Hwang, Jae-Yeol,Kim, Sung Wng,Kim, Sang-il Elsevier 2018 Journal of alloys and compounds Vol.741 No.-

<P><B>Abstract</B></P> <P>Substitutional doping is known to be effective when used to enhance the thermoelectric figure of merit <I>zT</I>, and this is generally explained as resulting from a reduction in the thermal conductivity caused by an additional atomic-scale defect structure. However, a comprehensive analysis of the substitutional doping effect on the electrical and thermal properties together has not been undertaken, especially when the bipolar thermal conductivity becomes serious. A previous study by the authors also showed that the <I>zT</I> of Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> thermoelectric alloys was enhanced by indium (In) doping due to the reduction of the total thermal conductivity. Here, we more closely analyze the electrical and thermal transport properties of a series of indium (In)-doped p-type Bi<SUB>0.4</SUB>Sb<SUB>1.6-x</SUB>In<SUB>x</SUB>Te<SUB>3</SUB> (x = 0, 0.003, 0.005, 0.01) using both the single-parabolic-band model and the Debye-Callaway model in an effort to investigate the origin of the observed thermal conductivity reduction more closely. The bipolar contribution to the total thermal conductivity was estimated exclusively based on a two-band model based on a single-parabolic-band model. Furthermore, the lattice thermal conductivity was calculated using the Debye-Callaway model while taking additional In substitutional defects into consideration. The calculations indicated that the significant suppression of bipolar thermal conductivity was achieved as a result of the increased bandgap in Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> caused by In doping. Additional point defects from In doping also reduced the lattice thermal conductivity, but not as much as the bipolar thermal conductivity did. The study suggests that the suppression of bipolar conduction by means of a bandgap modification can be an effective approach for enhancing <I>zT</I> further via a simple In-doping process in Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermal conductivity reduction in In-doped Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> is analyzed. </LI> <LI> Bandgap increase by In doping suppresses bipolar conduction significantly. </LI> <LI> Extra point defects by In doping reduces lattice thermal conductivity. </LI> <LI> The <I>zT</I> enhancement in In-doped Bi<SUB>0.4</SUB>Sb<SUB>1.6</SUB>Te<SUB>3</SUB> is mainly due to bipolar suppression. </LI> </UL> </P>

Temperature dependence and cation effects in the thermal conductivity of glassy and molten alkali borates

Kim, Youngjae,Morita, Kazuki Elsevier 2017 Journal of non-crystalline solids Vol.471 No.-

<P><B>Abstract</B></P> <P>The thermal conductivity of Li<SUB>2</SUB>O-B<SUB>2</SUB>O<SUB>3</SUB>, Na<SUB>2</SUB>O-B<SUB>2</SUB>O<SUB>3</SUB> and K<SUB>2</SUB>O-B<SUB>2</SUB>O<SUB>3</SUB> glass systems was measured as a function of the temperature. As the temperature increases, the thermal conductivity of the glass phase initially increases and then reaches a plateau. Afterwards, in the liquid phases, a further increase in the temperature leads to a decrease in the thermal conductivity. The thermal conduction phenomenon can be better described by considering the glass and molten oxide systems as a one-dimensional continuum. It was found that the temperature corresponding to the highest thermal conductivity lies close to the one-dimensional Debye temperature (<I>Θ</I> <SUB> <I>D</I>1</SUB>). According to phonon gas model, the variables affecting the thermal conductivity were evaluated. Below <I>Θ</I> <SUB> <I>D</I>1</SUB>, the increase in heat capacity with the temperature leads to a corresponding increase in the thermal conductivity. The heat capacity then becomes constant above <I>Θ</I> <SUB> <I>D</I>1</SUB> leading to the observed plateau in the thermal conductivity of the glass phase. After melting the glass, the decrease in thermal conductivity with increasing temperature is due to changes in sound velocity and mean free path. The relative content of 3- and 4-coordinated boron was analyzed by <SUP>11</SUP>B MAS-NMR. The cation effect on the thermal conductivity of alkali borate glasses was evaluated through their ionization potentials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> By phonon gas model, variables determining thermal conductivity in the glassy and molten oxide system were evaluated. </LI> <LI> The glassy and molten oxide system was treated as a conducting medium of one-dimensional continuum. </LI> <LI> In the non-crystalline oxide system, maximum thermal conductivity could be found near one-dimensional Debye temperature. </LI> <LI> Effect of cation on thermal conductivity in the alkali borate system was evaluated through the ionization potential. </LI> </UL> </P>

Electrochemical properties of dual phase neodymium-doped ceria alkali carbonate composite electrolytes in intermediate temperature

Kim, Ji-Tae,Lee, Tae-Hee,Park, Ka-Young,Seo, Yongho,Kim, Ki Buem,Song, Sun-Ju,Park, Byoungnam,Park, Jun-Young Elsevier 2015 Journal of Power Sources Vol.275 No.-

<P><B>Abstract</B></P> <P>Composite electrolyte materials composed of neodymium-doped ceria (Nd<SUB>0.2</SUB>Ce<SUB>0.8</SUB>O<SUB>1.9</SUB>; NDC) and (Li–0.5Na)<SUB>2</SUB>CO<SUB>3</SUB> are investigated to understand the unique behaviors of their multi-ionic conduction. In the intermediate temperature, the NDC-based carbonate composite electrolytes exhibit a much higher conductivity compared to pure NDC. It has been claimed that the oxide ions are transported in the doped-ceria phase via oxygen vacancies and the protons are conducted through the second carbonate phase, thereby resulting in an enhanced ionic conductivity. However, it has not been experimentally demonstrated if the proton conduction within the carbonate phase aided in improving the conductivity of oxygen ions in the composite system. Hence, the primary objective of this work is to cultivate a deeper insight into the conduction property of these composites as an attempt to clarify the ionic transport phenomenon responsible for enhanced conductivity. Electrical conductivities of NDC and NDC/carbonate materials are investigated as a function of oxygen partial pressure and vapor pressure of water to understand transport properties of composite electrolytes. The ionic and electronic transference numbers of composite electrolytes are measured by the oxygen- and hydrogen-concentration cells containing water. The dominant charge carriers are identified quantitatively through the analysis of the partial conductivity of proton, oxygen ions, and electrons (holes). Understanding the transport properties and transference numbers of composite electrolytes can contribute to the development of commercial solid oxide fuel cells, which can be done by reducing the operating temperature using a highly ionic conductive NDC/carbonate composite electrolyte at the intermediate temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Understand the behaviors of multi-ionic conduction of ceria/carbonate electrolyte. </LI> <LI> Conductivities of NDC and NDC/carbonate are investigated as a function of <SUB> a <SUB> O 2 </SUB> </SUB> and <SUB> a <SUB> H 2 </SUB> O </SUB> . </LI> <LI> Transference numbers are measured by the oxygen- and hydrogen-concentration cells. </LI> <LI> Dominant charge carriers are identified by the analysis of partial conductivity. </LI> </UL> </P>