Estimating the State of Health of Lithium-Ion Batteries with a High Discharge Rate through Impedance

Lithium-ion batteries are an attractive power source in many scenarios. In some particular cases, including providing backup power for drones, frequency modulation, and powering electric tools, lithium-ion batteries are required to discharge at a high rate (2~20 C). In this work, we present a method to estimate the state of health (SOH) of lithium-ion batteries with a high discharge rate using the battery’s impedance at three characteristic frequencies. Firstly, a battery model is used to fit the impedance spectrum of twelve LiFePO4 batteries. Secondly, a basic estimation model is built to estimate the SOH of the batteries via the parameters of the battery model. The model is trained using the data of six batteries and is tested on another six. The RMS of relative error of the model is lower than 4.2% at 10 C and lower than 2.8% at 15 C, even when the low-frequency feature of the impedance spectrum is ignored. Thirdly, we adapt the basic model so that the SOH estimation can be performed only using the battery’s impedance at three characteristic frequencies without having to measure the entire impedance spectrum. The RMS of relative error of this adapted model at 10 C and 15 C is 3.11% and 4.25%, respectively.

Aging Characteristics of Lithium Titanate Batteries under Ultrahigh Discharge Rate

The aging characteristics of lithium titanate batteries under ultra-high discharge rate were studied in this paper. The discharge characteristics is highly temperature-dependent under 55C discharge rate. The capacity retention rate is about 73% after 100 cycles of 55C discharge. The in-situ analysis incremental capacity analysis (ICA) was used to analyze the aging mechanism, and it was found that the main reason for the capacity fading was the loss of active material of the positive electrode, which leads to an increase of polarization resistance under 55C discharge rate.

Improved cycling properties of a Li-rich and Mn-based Li1.38Ni0.25Mn0.75O2.38 porous microspherical cathode material via micromorphological control

The as-prepared LMNO-850 with 100–200 nm spherical-like shape primary particles exhibits superior cycling performance even at high discharge rate. The capacity fading in the first 50 cycles may be caused by interfacial side-reactions between electrode and electrolyte.

Comparative Study of Weekly Discharge Rate of Two Solar Batteries Commonly Used in Anambra State

The purpose of this study is to compare the weekly discharge rate of two solar batteries commonly used in Anambra State. The batteries considered were the Indian made battery with specification Luminous, Deep cycle sealed maintenance free batteries solar application, Lum 12V 100Ah 20hr and 3DGP161433 and Chinese made battery with specification Sun-Test std gel battery, 12V-100Ah, 010716w, Cycle use 14.4-15.0V, Stand by use; 13.5-13.8V and Initial current: less than 30A were used to power 2 stand-alone security lights at the Faculty of Physical Sciences, Nnamdi Azikiwe University, Awka. The technical assessment was based on measuring their output voltages bihourly from 19.00 hr to 7.00 hr and estimation of weekly discharge rate of these batteries for a period of two months (eight weeks). From the analysis, the Indian made solar battery has insignificant discharge tendency for the first eight weeks of its use having its discharge rate of -0.034, -0.038, -0.042, -0.037, -0.039, -0.038, -0.039 and -0.036 Volts/hr per week from week one to week eight respectively whereas the Chinese made solar battery has a relatively high discharge rate of Voltage/hr per week within the first eight weeks of its use having its rate at -0.095, -0.213, -0.103, -0.1, -0.104, -0.1, -0.083 and -0.109Volt/hr per week from week one to week eight. Also, while the Indian made battery is observed to be relatively stable, the Chinese made battery was observed to be very erratic and highly susceptible to discharge within the first eight weeks (two months) of its use. Hence, it is concluded that Indian made battery is preferred to that of Chinese made battery for optimal performance of stand-alone PV syste.

The Impact of Transferring Stroke Patients: An Analysis of National Administrative Data

Background: Interhospital transfer is an important but resource-intensive pattern of care. The use for stroke patients is highly dependent upon health system structure. We examined the impact of hospital transfers for stroke care in Canada. Methods: We analyzed hospital administrative data within the Canadian Institute for Health Information (CIHI) Database for the 3 fiscal years 2011/12, 2012/13 and 2013/14. Patients with clinical stroke syndrome (ischemic or hemorrhagic) were identified using International Classification of Diseases. Stroke centers were defined by Heart & Stroke Foundation of Canada stroke report. Results: During the 3-year period,397 patients in Canada (excluding Quebec) were admitted to hospital for clinical stroke syndrome. Median age was 75 (interquartile range [IQR] 64–84) years; 50.6 % were male. Less than 5% (n=4030) of patients were transferred. Patients transferred to stroke centers were younger (p<0.001) and had shorter median length of stay (p<0.001). The highest probability of discharge home was associated with sole care at stroke center (43.8%). Transfer to stroke center from community hospital had the highest probability for discharge to rehabilitation facility (25%) and lowest to either long-term (2.1%) or complex community care (2.0%). Transferred patients had lower mortality at discharge. Conclusion: Younger patients were transferred more frequently to stroke centers; older patients were more likely treated in community hospitals. Sole stroke center care was associated with high discharge rate to home; transfer to a stroke center was associated with high discharge rate to rehabilitation and lower mortality rates.

Nanocomposite multilayer capacitors comprising BaTiO3@TiO2 and poly(vinylidene fluoride-hexafluoropropylene) for dielectric-based energy storage

Multilayer dielectric capacitors were fabricated from nanocomposite precursor comprised of BaTiO 3@ TiO 2 core–shell nanosized particles and poly(vinylidene fluoride–hexafluoropropylene) (P(VDF–HFP)) polymer matrix (20 vol%). The multilayer capacitors showed very high discharge speed and high discharged energy density of around 2.5 J/cm3 at its breakdown field (~ 166 MV/m). The energy density of the nanocomposite multilayer capacitors was substantially higher than the energy density of commercially used power capacitors. Low cost, flexible structure, high discharge rate and energy density suggest that the nanocomposite multilayer capacitors are promising for energy storage applications in many power devices and systems.