GS Yuasa (Japan)

The recent main topics in ISO/TC159/SC 4/WG 2 and /WG12, which are in charge of display ergonomics in the International Organization for Standardization (ISO), is ergonomics of head‐mounted displays (HMDs) realizing XR or Cross‐Reality, which has attracted attention in recent years. The paper overviews the major issues related to visual comfortability and Image Safety using HMDs, and reports on the key points for standardization to reduce VR sickness and to maintain comfortable viewing of 3D images.

This paper proposes a power-leveling method in which a lithium-ion battery and a flywheel energy storage are installed in a photovoltaic power generation plant. The proposed method is a division method that focuses on the amplitude component of the compensating power required to level the generated power of photovoltaic power generation. Furthermore, by adding the flywheel state-of-charge automatic adjustment method to the proposed method, the coverage period of the flywheel is improved. The effectiveness of the proposed method is verified on an actual 40kW plant.

For the purpose of making clear the mechanism of interlacing process in a slit-type interlacer, an effect of supplied air pressure on both filaments velocity and its characteristics was studied using a high-speed video camera and particle image velocimetry. Results obtained are as follows: (1) Filaments must produce an opening state of twin spirals to generate tangling parts. It was confirmed that the tangling parts were generated at smaller amount of filaments movement at high supplied air pressure and the opening state became longer time at low supplied air pressure. In addition, filaments in an opening state in left and right regions of the yarn passage need to change their relative positions by crossing the symmetric plane of yarn passage to different region above 300 to 400 filaments. This series of processes produces an interlaced yarn owing to twists accumulated at both ends of opening part. (2) Either fast filament motion or long opening state time can generate tangling parts even when the twin spiral motion of filaments was asymmetric. (3) As the supplied air pressure increased, the position-time-mean angular velocity became large, thus an increment of supplied air pressure was effective to generate tangling parts. (4) In the tangling state, the timeposition-mean of magnitude of velocity increased with increasing supplied air pressure, but the time-position-mean of magnitude of its deviation was almost constant, because filaments formed one bundle. On the other hand, in the opening state, the time-position-mean of magnitude of velocity increased with increasing supplied air pressure from 0.1 MPa to 0.3 MPa, but indicated almost the same value in the supplied air pressures between 0.3 MPa and 0.5 MPa. However, the time-position-mean of deviation of magnitude of velocity was independent of the supplied air pressure. (5) This and our previous studies are available for design guideline of an optimum interlacer.

INTRODUCTION The use of large-size lithium-ion battery has been expanding to not only automotive but also other industrial fields such as AGV, railway, load-leveling, etc. This expansion promotes its various operation conditions and, therefore, requires the way to be able to estimate its life accurately. Many efforts have been devoted to estimate the life even in the several applications. According to the report [1], the battery capacity loss for the estimation is divided into calendar and true cycle capacity loss. The calendar capacity loss is caused by active Li trapping mainly due to SEI growth at negative electrode, of which rate is dependent on SOC level, temperature and time [1-3], whereas the true cycle capacity loss is dependent only on the amount of charge-discharge cycle number in specified DOD range [1]. However, the true cycle capacity loss and its mechanism of large-size battery has not been clarified in the diversified cycle containing high and low frequency of fluctuational SOC. In this study, the factors that affect the true cycle capacity loss with clarification of its mechanism have been investigated in detail, and then updated life estimation algorism based on the result of the investigation has been proposed to enable high-accuracy life estimation of the battery operated even under complicated condition. EXPERIMENTAL The endurance tests for large-size lithium-ion cells were conducted under various conditions of different charge-discharge route (SOC route) in order to clarify the factors that impact the capacity loss. Each amount of the Li trapping at negative electrode, and degradations of the positive and negative electrodes were investigated by discharge profile fitting analysis [4] and post-mortem analysis. RESULTS AND DISCUSSION According to results of the cells tested under various conditions, the capacity loss depends on the SOC route despite of the same accumulative amount of SOC fluctuation and test time. The relation between relative coefficient of true capacity loss and the SOC fluctuational range as controlling the designated value of center SOC at 60% is shown in Fig. 1. The coefficient of the loss drastically increases with expansion of the range, which means that the true cycle capacity loss should be estimated depending on the individual range in the diversified SOC change. Furthermore, post-mortem analysis and discharge profile fitting analysis for the tested cells prove that the total capacity loss of the cell is accelerated mainly by the factors of the range and its center value because the rates of both SEI growth at the negative electrode and degradation of positive electrode are affected by these factors. Therefore, updated model describing true cycling capacity loss has been proposed. Finally, the verification test including high and low frequency of fluctuational SOC under various operating temperature for 550 days was carried out together with estimation of capacity retention by the conventional and the updated model. As a result, the accuracy of battery life estimation even in long-term test with complex patterns is dramatically improved from 31% to within 2% of the actual capacity retention by updated model considering SOC route the cell experienced. REFERENCE H. Yoshida, N. Imamura, T. Inoue, and K. Komada, Electrochemistry, 71, 1018-1024 (2003).H. Ploehn, P. Ramadass, and R. White, J. Electrochem. Soc., 151, A456-A462 (2004).N. Shinha, T. Marks, H. Dahn, A. Smith, J. Burns, D. Coyle, J. Dahn, and J. Dahn, J. Electrochem. Soc., 159, A1672-A1681 (2012).K. Honkura, K. Takahashi, and T. Horiba, J. Power Sources, 196, 10141-10147 (2011). Fig. 1. (a) Relative coefficient of true capacity loss at the same accumulative amount of SOC fluctuation in various SOC fluctuational range. The values are normalized by true capacity loss between 30 and 90% of SOC cycle test (SOC fluctuational range = 60%). (True capacity loss [%]) = (Total capacity loss [%]) - (Calendar capacity loss [%]) (b) Cycling protocols of SOC endurance test shown in Fig. 1 (a). Charge: CC 1.0 CA 4.10 V at 25 ℃. Discharge: CC 1.0 CA 2.75 V at 25 ℃. Figure 1

Spinel LiNi0.5Mn1.5O4 is a promising active material for a positive electrode of lithium ion batteries because it shows extremely high positive working potentials at about 4.7 V vs. Li/Li+. However, conventional electrolyte solutions are thermodynamically unstable at such high potentials. Highly concentrated electrolyte solutions, as well as solvate ionic liquids, offer unique features, including a wide potential window owing to enhanced reductive and oxidative stability. The enhancement of oxidative stability is particularly noted for ether-based concentrated electrolyte solutions. However, ethereal solvents usually cannot tolerate such high potentials. We previously reported that carbonate ester-based concentrated electrolyte solutions showed high oxidative stability at LiNi0.5Mn1.5O4; irreversible capacities due to the oxidative decomposition of PC-based electrolyte solution decreased with increasing the concentration of LiPF6, while the discharge capacities increased. In the present work, we used the highly concentrated LiBF4-based electrolyte solutions to further improve the charge/discharge performance of LiNi0.5Mn1.5O4positive electrodes. When 0.83 mol kg-1 (ca. 1 M) LiPF6 /PC was used, the initial charge capacity (164 mAh g-1) far exceeded the theoretical capacity and the irreversible capacity was very high. As a result, the Coulombic efficiency was very low (72.1 %). These results suggest that irreversible reactions, such as the oxidative decomposition of the electrolyte solution, occurred at high potentials during charging. On the other hand, the use of concentrated 4.45 mol kg-1 electrolyte solution resulted in a decrease in the initial charge capacity to 144 mAh g-1 and the Coulombic efficiency increased to 90.4 % (Fig. 1a). Thus, the initial charge/discharge performance of a LiNi0.5Mn1.5O4 positive electrode was remarkably improved by using highly concentrated electrolyte solutions. However, the polarization in charge/discharge reactions, which was evaluated from the difference between the potentials during charging and discharging, significantly increased with electrolyte concentration, as seen in Fig. 1a. In addition, the discharge capacity rapidly decreased to 112 mAh g-1 at the 50th cycle; the capacity retention (85.6%) was not high. On the other hand, the concentration of electrolyte solution could be further increased with use of LiBF4 as an electrolyte. In the almost saturated 7.25 mol kg-1 LiBF4/PC, charge/discharge capacities in the 1st cycle were close to those obtained for 4.45 mol kg-1 LiPF6/PC, while the polarization in charge/discharge reactions decreased significantly, as shown in Fig. 1b. However, the capacity retention in the first 50 cycles was still low, as is the case in 4.45 mol kg-1 LiPF6/PC. The capacity fading was likely due to the deterioration of the positive composite electrode. To improve the cycle performance, we investigated the effects of conductive additives and a binder, which will be reported in our presentation. Acknowledgement This research is supported by the Super Cluster Program from MEXT and JST. Figure 1

Design and Application of Smart Rectifier for Traction Type BatteriesTraction type batteries are commonly used for forklifts, pallet stackers, conveyors etc. This paper presents a smart charger design for traction batteries. The design criteria is limited with 2.7 V and 5 A so as to charge a single battery cell. However, the design limits can be expanded according to battery capacity and voltage. Firstly, electronic power card has been designed and simulated. Additionally, electronic control card developed. It analyses the measured signals which are current, voltage and temperature. According to the result of the analyzed signals the electronic power card is controlled by digital potentiometer. Then, the simulation results are performed for the selected electronic components, and finally the PCB card has been fabricated. The designed system is tested with an industrial traction battery cell. Furthermore, all the data on the PCB is monitored via MATLAB GUI. The presented system differs from commonly used chargers with regard to software and hardware design.Traksiyoner Tipi Aküler İçin Akıllı Redresör Tasarımı ve UygulamasıTraksiyoner tipi aküler genellikle endüstride forklift gibi mobil ağır iş makinelerinde kullanılmaktadır. Bu çalışmadaki temel hedef, traksiyoner akülere yönelik akıllı bir redresör tasarımıdır. Bu amaçla, traksiyoner aküye ait bir hücrenin şarj edilebilmesi için 2.7 V ve 5 A limitlerine uygun bir redresör tasarlanmıştır. Aküdeki bir hücrenin şarjı esas alınarak yapılan bu çalışma tüm aküye uygun bir redresör tasarım sürecinin temelini oluşturmaktadır. Ana kart ve güç kartına ilişkin elektronik tasarım devresi gerçekleştirilmiş ve simülasyon ortamında performans testleri incelenmiştir. Daha sonra ise sırasıyla PCB kart tasarımı ve komponent montaj işlemleri ile donanım ve yazılımın doğrulama testleri yapılmıştır. Bu tasarımda aküye ilişkin akım-gerilim-sıcaklık parametreleri MATLAB programında tasarlanan bir GUI üzerinden analiz edilmiştir. Tasarlanan sistem, donanım ve yazılım geliştirme bakımından günümüzde yaygın olarak kullanılan redresörlerden şarj karakteristiği yönünden farklılık göstermektedir.