Smart and Accurate State-of-Charge Indication in Portable Applications

Accurate State-of-Charge (SoC) and remaining run-time indication for portable devices is important for the user-convenience and to prolong the lifetime of batteries. However, the known methods of SoC indication in portable applications are not accurate enough under all practical conditions. The method presented in this paper aims at designing and testing an SoC indication system capable of predicting the remaining capacity of the battery and the remaining run-time with an accuracy of 1 minute or better under all realistic user conditions, including a wide variety of load currents and a wide temperature range. At the moment Li-ion is the most commonly used battery chemistry in portable applications. Therefore, the focus is on SoC indication for Li-ion batteries. The basis of the proposed algorithm is current measurement and integration during charge and discharge state and voltage measurement during equilibrium state. Experimental results show the effectiveness of the presented novel approach for improving the accuracy of the SoC indication

A Real-Time evaluation system for a state-of-charge indication algorithm

The known methods of State-of-Charge (SoC) indication in portable applications are not accurate enough under all practical conditions. This paper describes a real- time evaluation LabVIEW system for an SoC algorithm, that calculates the SoC in [%] and also the remaining run-time available under the valid discharge conditions. With the described system the accuracy of the SoC algorithm and its validity can be determined. The final goal of the SoC algorithm is to predict the remaining capacity of the battery and the remaining run-time with an accuracy of 1 minute or better under all realistic user conditions, including a wide variety of load currents and a wide temperature range. The basis of the SoC algorithm is current measurement and integration during charge and discharge state and voltage measurement during equilibrium state. Experimental results show the testing ability of the real-time evaluation system and the effectiveness of the novel approach for improving the accuracy of the SoC indication

Apparatus and method for determination of the state-of-charge of a battery when the battery is not in equilibrium

The invention relates to a method and an apparatus, like a charger for determining the state-of-charge of a battery which has been charged or discharged and which has not reached its equilibrium state, the method comprising the steps of determining the EMF of the battery by extrapolation of the battery voltage sampled during relaxation after the charge or the discharge process, wherein the extrapolation is based on a model using only variables sampled during the relaxation process and deriving the state-of-charge from the EMF of the battery by using a predetermined relation between the EMF and the state-of- charge. This method is a voltage-prediction method without the need to store parameters beforehand.; Instead, the voltage relaxation end value is determined based on the measured first part of a voltage relaxation curve and mathematical optimisation/fitting of a function to this measured part of the relaxation curve

The electrochemistry of carbon nanotubes : I, aqueous electrolyte

The energy storage potentials of many different carbon nanotube (CNT) materials are investigated electrochemically. The electrochemical response of all the investigated materials is rather featureless during charging and discharging and does not show any phase transitions or clear redox responses. The maximum discharge capacity, ~130 mAh/g, is measured for an as-produced single-walled carbon nanotube material. Measurements indicate that the electrochemical activity of the matrix material, used to manufacture composite electrodes, should also not be ignored. Highly pure CNTs yield a substantially lower response, indicating that the CNTs itself can only account for a small part hereof. The measured response of CNT materials is related to a number of processes, including the irreversible oxidation of carbonaceous material, the reversible oxidation/reduction of residual metal catalyst or carbonaceous impurities, and an electrostatic charging component. Steady-state impedance measurements, cross-correlated with cyclic voltammetry, show that (dis)charging of the electrical double layer can be directly linked to this electrostatic charging component. Characterization of highly pure CNT materials shows that more than 90% of the total charge was stored in this way. Only about 25% of the total amount of charge could be explained in this way for the as-produced materials. Based on the overall results it is highly unlikely that a significant amount of hydrogen can be stored in CNT material and that the exact amount of charge that can be reversibly stored in CNT material heavily depends on its morphology and the level of purity

Hydrogen storage material, electrochemically active material, electrochemical cell and electronic equipment

The invention relates to a hydrogen storage material comprising an alloy of magnesium. The invention further relates to an electrochemically active material and an electrochemical cell provided with at least one electrode comprising such a hydrogen storage material. Also, the invention relates to electronic equipment comprising such an electrochemical cell

Remote plasma atomic layer deposition of thin films of electrochemically active LiCoO2

One of the remaining challenges in the field of portable electronics is the miniaturization of lithium-ion batteries without decreasing their storage capacity. To tackle this challenge and to effectively integrate battery technology in even a wider variety of applications, it is essential to produce high quality thin films for all-solid-state batteries. A remote plasma ALD process for the positive electrode material LiCoO2 was developed using the combination of CoCp2 as the cobalt precursor, LiOtBu as the lithium precursor and O2 plasma as the oxidant source. The thin films were deposited at a temperature of 325 °C with a virtually linear growth rate of 0.06 nm/cycle. After annealing the samples at 700 °C for 6 minutes the high temperature phase LiCoO2 was obtained, as demonstrated by XRD and Raman spectroscopy measurements. Electrochemical charge/discharge cycling showed good electrochemical activity with a promising storage capacity

Hydrogen storage material, electrochemically active material, electrochemical cell and electronic equipment

The invention relates to a hydrogen storage material comprising an alloy of magnesium. The invention further relates to an electrochemically active material and an electrochemical cell provided with at least one electrode comprising such a hydrogen storage material. Also, the invention relates to electronic equipment comprising such an electrochemical cell