Change In Internal Resistance Research Articles

Diagnostic Analysis and Research on Battery Health Status of Electric Vehicles

With the rapid development of electric vehicles, the attenuation problem of high-specific energy lithium-ion batteries has been paid more and more attention. Its health state is the core parameter of durability management, which is crucial to prolong battery life and improve system reliability. Aiming at the safety and power performance of power battery in the operation of electric vehicles, the kalman filter method was combined with battery charge-discharge curve identification, and the battery health (SOH) diagnosis method based on online testing platform was proposed. The results show that the battery health state can be estimated by the change of internal resistance of the battery model, and the absolute error is not more than 3%, and with the improvement of the model accuracy, the estimation of the battery health state becomes more accurate.

Analysis of Lithium-Ion Cell Deterioration through Parameter Measurement

Deterioration analysis of aged lithium-ion cells is becoming increasingly important as demand for longer life of cells increases for electric vehicles and energy storage systems. In this work, we propose a non-destructive analysis of the degree of deterioration of aged cells by measuring the physicochemical parameters. Low-rate charge-discharge, galvanostatic intermittent titration technique, and electrochemical impedance spectroscopy were used to measure the quasi-equilibrium potential, diffusion coefficient, and exchange current density of the active material in graphite / NCM cell after cycling aging. Loss of active material, loss of lithium inventory, and the internal resistance changes of aged cell were analyzed from differential voltage analysis and capacity variations after aging. Then the measured kinetics and mass transfer related parameters were compared with those of fresh active materials and analyzed as functions of aging conditions. The changes of quasi-equilibrium potential is attributed to the loss of active materials, and decreased kinetic parameters and increased resistances show the formation of inactive phases or byproducts that cause pore structure changes of electrodes.

Self-powered ionic sensors overcoming the limitation of ionic conductors as wearable sensing devices

Ionic hydrogel-based sensors (I-sensors) enable a wide range of wearable applications. However, limited by the signal carriers (i.e., ions) of ionic hydrogels, the I-sensors cannot work stably under commonly used portable direct current (DC) power sources for wearable devices owing to inevitable variation of their chemical compositions. Here, we present a new strategy for designing high-performance self-powered ionic hydrogel-based sensors (SPI-sensors) for wearable applications by simply replacing the metal electrodes of I-sensors with the battery electrodes. The strategy can not only maintain a stable ion concentration within I-sensors due to the insertion/extraction of ions on two battery electrodes during the signal transmission but also endow the sensors with self-powering capacity. The as-prepared SPI-sensors show ultrahigh stability, ultrawide sensing range (~2000%), and high sensitivity, and can recognize an ultrasmall strain of 0.01%, which is superior to the existing I-sensors. This study first demonstrates the feasibility of accurately detecting the full-range human motions based on the internal resistance change of well-designed batteries, paving a new way for practical application of I-sensors.

Nitrogen-Doped Seamless Activated Carbon Electrode with Excellent Durability for Electric Double Layer Capacitor

The electric double layer capacitor (EDLC) using a seamless activated carbon electrode shows an excellent durability against high voltage charging compared to the conventional activated carbon composite electrode. In this study, the authors focused on nitrogen-doping as a surface modification to further improve the electrochemical durability of the seamless electrode. The EDLC using the nitrogen-doped seamless activated carbon electrode achieved the volumetric capacitance of 18 F cm−3 (based on the galvanostatic method, 80 mA g−1, 0–2.5 V, 40 °C) and the capacitance retention of 83% after the float durability test (3.5 V, 70 °C, 100 h) using a typical propylene carbonate electrolyte. The volumetric capacitance is comparable to that (14 F cm−3) of the conventional activated carbon, such as YP50F, and the retention is much higher than that (76%) of the pristine seamless activated carbon. The authors concluded that the extremely excellent durability of the nitrogen-doped seamless activated carbon electrode is due to (i) the stable electric network arising from the binder-less monolithic structure and (ii) nitrogen surface functionalities that suppresses micropore blocking and internal resistance change caused by electrochemical decomposition deposits. (184 words).

Performance of Microbial Reverse-Electrodialysis Cells for Power Generation at Different External Resistance

In this study, the effect of external resistance on the microbial reverse-electrodialysis cell (MRC) performance using organic-rich wastewater as an electron donor was examined. The optimum of external resistance was determined to be 300 Ω. In such condition, the power density of 1.53 ± 0.198 W/m2, substrate removal of 52 ± 2.3%, Coulombic efficiency of 70 ± 2.6%, energy recovery of 3.0 ± 0.4%, and energy efficiency of 53 ± 7.1% were obtained in the MRC. The differences in power density at different external resistances were mainly due to the changes in internal resistance and ion flux efficiency in the MRC. The external resistance affected substrate removal and Coulombic efficiency through the length of batch cycle time, and current density exchanged as well as the Tafel slope. Furthermore, the proper external resistance applied to the reactor created high power production; thus, high energy efficiency and energy recovery were achieved. These results demonstrated that selecting proper external resistance was an essential key for a successful MRC operational.

Study on the performance of proton exchange membrane fuel cell (PEMFC) with dead-ended anode in gravity environment

The accumulation of water on the anode side will have an important impact on the performance of proton exchange membrane fuel cell (PEMFC) with dead-ended anode (DEA). In order to find out the accumulation and distribution characteristics of water in the flow channel and its influence on the performance of PEMFC with DEA, the transparent fuel cell technology and printed circuit board (PCB) segmented measurement technology are used to study the change of water distribution characteristics caused by the placement orientation of the flow channel in gravity environment, and the influence of this change on the performance of PEMFC with DEA is also studied. The experimental results show that the placement orientation of the flow channel has a significant effect on the transient performance of the PEMFC with DEA. When the orientation of the flow channel is changed, not only the accumulated content and distribution state of water in the anode flow channel are significantly affected, but also the working time of the PEMFC with DEA is affected. The change of internal resistance is also one of the important reasons that affect the transient performance of fuel cell, but the accumulation of water in anode flow channel is not the main reason for the performance degradation. In addition, changing the placement orientation of the flow channel will affect the uniformity of the local current density distribution, and when the flow channel is placed in the case of (d), the local current density distribution is the most uniform.

Understanding the different aging trends of usable capacity and mobile Li capacity in Li-ion cells

Abstract While the usable capacity is limited by the internal resistance, the available amount of mobile Li at open circuited voltage (OCV) conditions is not influenced by any change in internal resistance over aging. The difference in the aging trends of usable capacity and available amount of mobile Li at OCV conditions is analyzed. A method is suggested and validated in order to determine the available amount of mobile Li using a standard characterization procedure without constant voltage (CV) step at discharge. By applying the method to calendrical aged cell tests, aging trends for mobile Li and usable capacity are analyzed. Additionally, a model concept is presented, which explains the decrease of internal resistance at the end of discharge and therefore, the different aging trends. Considering lithiation depended over-potentials for anode and cathode and change in electrode balancing due to loss of mobile Li, it can be shown that the internal resistance at end of a constant-current (CC) discharge is decreasing with loss of mobile Li. The model concept is parametrized with half-cell measurements and validated with the previously analyzed calendric aging tests.

Electrochemical Impedance Spectroscopy and Determination of the Internal Resistance as a Way to Estimate Lead-Acid Batteries Condition

Attempts have been made to find the best procedure for the detection of premature battery capacity loss (the so called “PCL”) in AGM-VRLA 48 V batteries operating in telecommunication systems. However, recorded changes in internal resistance and potential did not give clear indications of the beginning of the PCL effect. The obtained correlation between internal resistance and potential derived from used batteries does not show the expected trend in measured parameters. It seems that the application of Electrochemical Impedance Spectroscopy (EIS), which is a faster and non-destructive method, may solve this problem. It is demonstrated that the change in internal resistance (which is an indicator of the state of health (SoH)) can be determined from EIS spectra during continuous operation of 12 V monoblocks in a backup power source of a base transceiver station (BTS).

Precision Differential Thermometers for Studying Thermal Processes at the Northern Caucasus Geophysical Observatory

In order to study the fine structure of temperature fields in the rock strata, precision narrowband temperature sensors have been designed to measure temperature with an accuracy of at least 0.005°C. It is shown that the required sensitivity can be achieved by narrowing the measurement range and application of platinum thermoresistors and 24-bit ADCs for digital signal recording. The developed thermometer uses platinum thermoresistors, which have an almost linear temperature dependence of the change in internal resistance on the external temperature and an excellent long-term stability of their basic characteristics. To reduce the level of self-noise, special technical solutions (low-frequency filtering of both output signals and all supply voltages) are applied. The output differential signals of the thermometer enable its easy connection to a majority of modern digital data acquisition systems. The main methods for calibrating and setting the necessary operating temperature range of sensors are considered. Measurements with the developed sensors in the adit of the Northern Caucasus Geophysical Observatory, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, in the Baksan gorge will ensure unique data on the structure and dynamics of the thermal field near Elbrus volcano. Continuous monitoring is a particularly important task both for obtaining new fundamental knowledge about the structure of magmatic structures and assessing volcanic hazard from the presence of a fluid magmatic melt in the volcano’s interior. This, in turn, will provide new data on the potential hazard of Elbrus’ volcanic center . This research is especially important today in the light of the developing tourist infrastructure both in the Baksan gorge and in the entire Elbrus region.

The Structure Optimization of Lithium-ion Battery Pack Based on Fluid-solid Conjugate Thermodynamic Analysis

To effectively improve the discharging efficiency and the cycle period, the thermodynamic analysis and the heat dissipation structure optimization are conducted on the lithium-iron battery pack. The internal resistance characteristics of the battery are experimented, and the change of internal resistance at different discharge rate and ambient temperature is measured. The three-dimensional thermal effect model of the battery is established, and the simulation analysis of thermoelectric coupling is carried out by using MSMD model in FLUENT. The simulation results are compared with the experimental results to verify the validity of the model. By the Ansys Workbench software, the three dimensional model are established based on the conjugate thermal transfer phenomenon. Based on the fluid-solid conjugate heat transfer mechanism, the influence of the airflow channel spacing and air inlet angle on the temperature distribution of the battery pack is analyzed, thus optimizing the heat dissipation structure. By studying the effect of the air flow rate and its temperature on the temperature distribution of the battery pack, the optimized heat dissipation structure can achieve the best performance.

Experimental Evaluation of the Effect of Cycle Profile on the Durability of Commercial Lithium Ion Power Cells

The effect of the charge/discharge profile on battery durability is a critical factor for the application of batteries and for the design of appropriate battery testing protocols. In this work, commercial high-power prismatic lithium ion cells for hybrid electric vehicles (HEVs) were cycled using a pulse-heavy profile and a simple square-wave profile to investigate the effect of cycle profile on battery durability. The pulse-heavy profile was designed to simulate on-road conditions for a typical HEV, while the simplified square-wave profile was designed to have the same total charge throughput, but with lower peak currents. The 5 Ah batteries were cycled for 100 kAh with periodic performance tests to monitor the state of the batteries. Results indicate that, for the batteries tested, the capacity fade for the two profiles was very similar and was 11±0.5% compared to beginning of life (BOL). The change in internal resistance of the batteries during testing was also monitored and found to increase 21% and 12% compared to BOL for the pulse-heavy and square-wave profiles, respectively. The results suggest that simplified testing protocols using square-wave cycling may provide adequate insight into capacity fade behavior for more complex hybrid vehicle drive cycles.

Influence of operating temperature on Li2ZnTi3O8 anode performance and high-rate charging activity of Li-ion battery

The temperature-dependent performance of a Li2ZnTi3O8 (LZTO) anode and the ultrafast-charging activity of a Li-ion battery were investigated. The LZTO anode operates at different temperatures between − 5 and 55 °C and in this work its sustainability is discussed in terms of storage performance. It delivered a discharge capacity of 181.3 mA h g−1 at 25 °C, which increased to 227.3 mA h g−1 at 40 °C and 131.2 mA h g−1 at − 5 °C. The variation in the discharge capacity with temperature is associated with the reaction kinetics and the change in internal resistance. It showed a capacity retention of 64% and a coulombic efficiency of 98% over 500 cycles. Exhibiting a discharge capacity of 107 mA h g−1, the LZTO anode was sustainable over 100 charge-discharge cycles at an ultra-high charging rate of 10 Ag−1. The reaction kinetics estimated from a cyclic voltammetry analysis at high scan rates revealed a capacitive-type storage mechanism.

Usability Evaluation Method for VRLA Battery Measuring Equipment

This paper presents a method for evaluating the availability of lead-acid battery test equipment and designs the corresponding evaluation mathematical model. International standard IEC60896-2 specifies the lead-acid battery internal resistance level. Because the internal resistance value is usually micro-Ohm level and the lead-acid battery has special electrochemical characteristics, it’s very difficult to measure it. Until now no authority can officially provides the actual resistance value for a given battery. However, the industry has agreed that the internal resistance will gradually increases during the use of the battery and the performance of the battery has close relationship with the change of the internal resistance, so even if the measurement equipment can not measure the absolute actual resistance, but as long as the battery can be measured a small change in internal resistance, it has a high availability. In this paper, we propose a micro-incremental verification method and a mathematical model to facilitate, accurately and quickly verify whether the battery internal resistance test equipment can accurately and stably measure the internal resistance of the battery, and provide technical verification reference for selecting the battery measuring equipment.

(Electrodeposition Division Early Career Investigator Award Address) Magnetocapacitive Carbon Nanocomposites

The global energy supply is transforming from conventional fossil energy to sustainable energy. Sustainable energy species, for example, solar, wind, and hydro energy, are in an unsteady state and fail to provide a stable energy supply. Energy storage units can collect these unsteady state energies and output as stable energy supply. However, current energy storage units face significant challenges to provide both high-energy density and high-power density. To achieve high energy storage performance of electrochemical capacitor, existing research efforts mainly focus on (1) synthesizing new electrode materials to enlarge specific capacitance, and (2) designing asymmetric capacitor configuration and utilizing organic electrolytes to expand the working potential range. Without changing any internal components, we recently observed a significant capacitance enhancement of up to 155% by solely applying a small external magnetic field (0.072 Tesla). The magnetic field induced capacitance change is called magnetocapacitance. In this talk, small magnetic field induced capacitance change on carbon nanocomposites will be discussed. Two processes, conventional- and microwave- annealing, were introduced to manufacture desired electroactive carbon nanocomposites decorated with pseudoactive metal oxide nanostructures (for example, Fe2O3, NiO and Co3O4). Their magnetocapacitances will be measured and compared. The proposed mechanisms will be interpreted by capacitor internal resistance change (solution resistance, charge transfer resistance and leakage resistance), which are based on Magnetohydrodynamics and Magnetoresistance phenomena. These findings will have significant impacts on processes involving proton and electron transfer as used in Li ion battery, fuel cells, electrochemical and biological sensing, and electrocatalytic CO2 reduction. The perspective for future projects will be discussed as well.

Influence of the Electrolyte on the Internal Resistance of Lithium−Sulfur Batteries Studied with an Intermittent Current Interruption Method

AbstractGalvanostatic cycling combined with a modified intermittent current interruption resistance determination method is presented as a fast, accurate, and comparatively simple analytical tool for following internal resistance changes in batteries over long‐term cycling. The technique is demonstrated here to study the influence of electrolyte composition and volume on the internal resistance of lithium−sulfur (Li−S) batteries. This approach is found to be particularly useful for the study of the Li−S system, where resistance changes considerably during charge and discharge as a result of compositional changes to the positive electrode and the electrolyte, but may also be valuable in the study of other battery systems.

(Invited) Sr and Mn Doped LaFeO3 Perovskite Oxide As Active Cathode for High Temperature Electrolysis

Solid oxide electrolysis cells (SOECs) for converting CO2 to more useful chemical species are attracting considerable attention because of their high electrolytic efficiency, offering the possibility of direct conversion of CO2 to CO (CO2 → CO + 1/2O2). In addition, recently, high temperature electrolysis of steam to H2 is also attracing much interest. Heat energy supplied to SOECs can maximize electrolysis efficiency, offering both thermodynamic and kinetic advantages. The generated CO can be used as a fuel gas, converted into syngas via reaction with H2, or to reduce iron oxide to pure iron in the iron-making process. The application of SOECs and related technologies can contribute to a more sustainable economy. For the electrolyte in SOECs, ZrO2 doped with 8 mol% of Y2O3 (YSZ) has always been used because of its chemical stability and mechanical strength. However, an electrolyte for CO2 or H2O electrolysis with lower internal resistance and increased efficiency is highly desirable. LaGaO3-based electrolytes have higher oxide-ion conductivities and transport numbers, which can lead to higher energy conversion efficiency; hence, a doped-LaGaO3 electrolyte (La0.9Sr0.1Ga0.8Mg0.2O3, LSGM) has been tested in this study. For CO2 and H2O electrolysis, another drawbacks is durability since electrode is easily aggregated and deactivated. Although metals, particularly Ni, are widely used as cathodes in CO2 electrolysis cells, we found that a LaFeO3−δ-based perovskite cathode (La0.6Sr0.4Fe0.8Mn0.2O3−δ, LSFM6482) showed the highest activity for CO2 and H2O electrolysis among the examined oxides Among the cells using a La0.6Sr0.4Fe0.9M0.1O3−δ-based oxide cathode (M = Mn, Co, Ni, or Cu) for CO2 electrolysis at 1073K. Mn was the most effective Fe replacement on the B site, and the La0.6Sr0.4Fe0.9Mn0.1O3−δ cathode showed the highest activity and current density for CO2 electrolysis of this set of cathodes. Among the tested dopants, Mn and Co have ionic sizes most similar to Fe and a smaller size mismatch between the host and dopant cations in the perovskite structure, which should suppress dopant segregation and minimize detrimental effects of cation segregation. Overall, among the examined cations, Mn was the best dopant for the B site of the LaFeO3 cathode. A cell consisting of BLC64/LSGM/LSFM6482 exhibited the highest CO2 electrolysis activity (a current density of 0.52 A/cm2 at 1.6 V and 1173 K) of all cathodes investigated in this study and reduced CO2 at a rate of 153 μmol/cm2•min at 1173 K and 1.6 V with negligible carbon formation. In this study, change in internal resistance during electrolysis is also discussed based on impedance measurement.

Electrochemical behavior of zinc particles with silica based coatings as anode material for zinc air batteries with improved discharge capacity

Abstract Silica coatings on zinc particles as anode material for alkaline zinc air batteries are expected to reduce early formation of irreversible ZnO passivation layers during discharge by controlling zinc dissolution and precipitation of supersaturated zincates, Zn(OH)42-. Zinc particles were coated with SiO2 (thickness: 15 nm) by chemical solution deposition and with Zn2SiO4 (thickness: 20 nm) by chemical vapor deposition. These coatings formed a Si(OH)4 gel in aqueous KOH and retarded hydrogen evolution by 40%. By treatment in aqueous KOH and drying afterwards, the silica coatings were changed into ZnO-K2O·SiO2 layers. In this work, the electrochemical performance of such coated zinc particles is investigated by different electrochemical methods in order to gain a deeper understanding of the mechanisms of the coatings, which reduce zinc passivation. In particular, zinc utilization and changes in internal resistance are investigated. Moreover, methods for determination of diffusion coefficients, charge carrier numbers and activation energies for electrochemical oxidation are determined. SiO2-coated zinc particles show improved discharge capacity (CVD-coated zinc: 69% zinc utilization, CSD-coated zinc: 62% zinc utilization) as compared to as-received zinc (57% zinc utilization) at C/20 rate, by reducing supersaturation of zincates. Additionally, KOH-modified SiO2-coated zinc particles enhance rechargeability after 100% depth-of-discharge.

Effects of Boric Acid Tris-(2-oxo-[1,3]dioxolan-4-ylmethyl) Ester as an Additive on the Electrochemical Performance of Graphite Anode

To improve the cycle performance of lithium ion battery (LIB), boric acid tris-(2-oxo-[1,3]dioxolan- 4-ylmethyl) ester (BATE) as a novel electrolyte additive in 1mol•L-1 LiPF6-EC:DMC (1:1 vol., Lithium Battery-grade) electrolyte was investigated. BATE derived from glycerol carbonate, which had the same ring structure as ethylene carbonate (EC). Additionally, the carbonyl group (-C=O) and electron deficient boron atom contained in the BATE molecular structure had been proved to be effective in maintaining the stability of the lithium salt (LiPF6) and increasing the durability of the electrolyte for formation of a solid electrolyte interface (SEI) layer, which plays a critical role in the cycle life of lithium ion battery (LIB). The electrochemical measurements and investigations of the compound BATE as additive were carried out by charge-discharge test, electrochemical impedance spectroscope (EIS), cyclic voltammetry (CV) test and scanning electron microscope (SEM). Results confirmed that BATE decomposed on the graphite anode earlier than electrolyte solvents to form the solid electrolyte interface (SEI) film. BATE could improve cycle stability of the cell significantly, especially when addition of 1.0% BATE, the capacity retention was up to 98.1% after 20 cycles. And the internal resistance change of cell with cycles was decreased after 20 cycles.

Inhibiting Li-Ion Battery Operation at High Temperature Using Responsive Polymers

In recent years, remarkable progress in the development of Li-ion battery technology has led to devices that deliver records in power and energy density. The thermal instability in such batteries, however, creates a major roadblock to implementing these devices in large-format systems to support emerging applications in transportation and energy storage from intermittent sources, such as wind and solar. Efforts to mitigate safety issues pertaining to flammability, reactivity, and thermal runaway typically involve the implementation of low conductivity solid-state materials or irreversible and destructive safety devices, which prove problematic for high-power, large-scale systems. In this presentation, we will discuss a new approach to achieve thermal stability in Li-ion batteries using an electrolyte system that contains a polymer that phase separates from solution above a specific temperature. The phase separation causes the solid polymer to coat the electrode and separator leading to an increase in internal resistance, which prevents the flow of current within a specified voltage range. This approach is advantageous over existing methods because the polymer phase separation is a local process, that is, if hot spots form within the battery, the polymer within that area will phase separate and coat the electrode while the rest of the device continues to operate. Two responsive electrolyte systems will be described: poly(ethylene oxide) (PEO) in ionic liquids (ILs) and poly(benzyl methacrylate) PBMA in ILs. Both systems exhibit Li-ion concentration dependent phase behavior, where ion concentration affects the temperature at which the phase transition occurs and the reversibility of the phase transition. Two distinct differences exist between these electrolyte systems. The PEO-IL system exhibits a change in solution conductivity and charge transfer resistance above the phase transition temperature, while the PBMA-IL system only exhibits an increase in charge transfer resistance, but to a much greater extent. Solution and ion transport resistances are measured using electrochemical impedance spectroscopy (EIS) on stainless steel electrodes to determine changes in solution resistance with increasing temperature, and on porous carbons to measure ion-transport resistances. The influence of ion and polymer concentration on the phase transition temperature will be discussed, along with the extent to which these properties can changed with temperature. Li-ion batteries were fabricated using two electrode configurations, each including a high temperature stable separator (Dreamweaver, International) soaked in the responsive electrolytes. In one setup, lithium titanate (LTO) anodes were used with lithium iron phosphate (LFP) cathodes due to the stability of each material in various ionic liquids. With this cell, we investigated key battery characteristics as a function of temperature using EIS and constant current charge-discharge measurements. With properly formulated electrolytes, we showed that battery operation was inhibited above the phase transition temperature of the electrolyte, which fell in the range of 120-150 °C. Figure 1 shows the discharge characteristics of the LTO-LFP cell at a 4C discharge rate at 60 °C and at 150 °C. Above the phase separation temperature, the internal resistance of the cell increases leading to a rapid decrease in potential as the cell tries to deliver the specified current. Open circuit voltage measurements confirm the change in internal resistance with temperature. In another cell configuration, we investigate the performance of responsive electrolytes with lithium cobalt oxide (LiCoO2) cathodes and graphitic carbon anodes. These batteries represent state-of-the-art cells with high operating voltages and high power capabilities. The performance and stability of responsive electrolytes in these systems will be discussed and compared to LTO-LFP systems, and conventional batteries comprising electrolytes with lithium salt in propylene carbonate. Electrolytes with temperature-responsive polymers provide a new approach to achieve thermal stability in Li-ion batteries. Results presented in this work will provide the foundation for the development of advanced materials that enable large-format and safe lithium batteries capable of delivering high-power. Figure 1

Effect of Solid Electrolyte Distribution in Composite Cathode on Electrochemical Properties of Solid-State Li-Air Batteries

Li-air batteries have increasing attention as energy sources for automotive application due to high theoretical energy density over 3000 Wh/kg which is about 10 times greater than that of Li-ion battery [1-2]. Typical nonaqueous Li-air batteries used organic liquid electrolyte and oxygen from the air in atmosphere as active cathode material. Oxygen can be reduced and oxidized at three phase boundary in electrolyte filled-porous electrode. Excess organic liquid electrolyte may be needed to fill porous electrode and occupy nearly 70% of total weight, which makes the specific energy density of practical Li-air batteries reduced [3].Recently, the studies for solid-state Li-air batteries with solid electrolyte have been reported [4]. Using solid electrolytes such as polymer and inorganic ionic conductors makes it possible to control proper amount in composite cathode and keeps the electrolyte from being squeezed out compared with organic liquid electrolyte. However, lithium ion conductivity of solid electrolyte is lower than that of liquid one and it is difficult to make a good interface between solid electrolyte and carbon in composite cathode. The design and internal structure in composite cathode is important to maintain the performance of solid-state Li-air batteries.In this study, the electrochemical properties and pore structure in various composite cathodes were measured from solid-state Li-air batteries. PEO (polyethylene oxide)-based electrolyte containing LiTFSI (lithium bis(trifluoromethanesulfonyl) imide) was used as a solid electrolyte in composite cathode. The mixture of carbon and PEO was directly coated on LATP (Ohara Inc.) by screen printing method. Solid-state Li-air cell was assembled by stacking Li metal, interlayer, LATP with composite cathode and GDL (gas diffusion layer), respectively.The AC impedance was conducted to get internal resistance in fresh composite cathode at non faradic condition. The activation energy for each resistance components was calculated by fitting the impedance spectra. The activation energy of Rinf (interface resistance between LATP and cathode) is higher than those of Rel (resistance of LATP) and Rion(resistance of Li ion transfer in cathode), which indicates kinetic barrier for Li ion transfer between LATP and solid electrolyte in cathode.We also have studied the change of internal resistance in composite cathode with various carbons and electrolyte composition and will present our investigation.