Dl Dmitry Danilov

Modeling Battery Behavior for Accurate State-of-Charge Indication

Li-ion is the most commonly used battery chemistry in portable applications nowadays. Accurate state-of-charge (SOC) and remaining run-time indication for portable devices is important for the users convenience and to prolong the lifetime of batteries. A new SOC indication system, combining the electromotive force (EMF) measurement during equilibrium and current measurement and integration during charge and discharge, has been developed and implemented in a laboratory setup. During discharge, apart from simple Coulomb counting, the effect of the overpotential is also considered. Mathematical models describing the EMF and the overpotential functions for a Li-ion battery have been developed. These models include a variety of parameters whose values depend on the determination method and experimental conditions. In this paper the battery measurement and modeling efforts are described. The method of implementing the battery model in an SOC indication system is also described. The aim is an SOC determination within 1% inaccuracy or better under all realistic user conditions, including a wide variety of load currents and a wide temperature range. The achieved results show the effectiveness of our novel approach for improving the accuracy of the SOC indication.

Honeycomb-structured silicon: remarkable morphological changes induced by electrochemical (de)lithiation.

Arrays of silicon honeycombs are evaluated as a negative electrode material for lithium-ion microbatteries. The morphological changes of the structure are investigated by means of scanning electron microscopy (SEM) and it is revealed that the honeycomb structure can reversibly withstand huge mechanical deformations. Free-standing structures are envisioned to serve advanced future applications, such as switchable sieves and microelectromechanical systems.

Adaptive Battery Management Systems for the new generation of Electrical Vehicles

Proper functioning of rechargeable batteries is of crucial importance for any electrical vehicle, especially for Plugin Electrical Vehicles (PEV). Modern Battery Management Systems (BMS) provide a driver for a number of important indications, such as remaining operation time, remaining charge and power. Therefore, BMS is a key element of PEV. However, the performance of the batteries deteriorates during the cycle life, in particular the capacity fades and impedance grows, leading to a decrease in battery power. BMS may decrease these negative effects without creating inconvenience for the end-user. A number of advanced battery charging algorithms were developed in the recent decade. These algorithms can significantly improve the performance of PEV facilitating their mass production.

From battery modeling to Battery Management

The principles of rechargeable battery operation form the basis of the electronic network models developed for Nickel-based aqueous battery systems, including Nickel Metal Hydride (NiMH), and non-aqueous battery systems, such as the well-known Li-ion. These electronic network models are based on fundamental physical and (electro)chemical processes, occurring during battery operation and also during over(dis)charging in the case of the aqueous battery systems. This enabled us to visualize the various reaction pathways, including conventional and pulse (dis)charge behavior but also, for example, the self-discharge performance.

On the estimation of a large sparse Bayesian system: The Snaer program

The Snaer program calculates the posterior mean and variance of variables on some of which we have data (with precisions), on some we have prior information (with precisions), and on some prior indicator ratios (with precisions) are available. The variables must satisfy a number of exact restrictions. The system is both large and sparse. Two aspects of the statistical and computational development are a practical procedure for solving a linear integer system, and a stable linearization routine for ratios. The numerical method for solving large sparse linear least-squares estimation problems is tested and found to perform well, even when the nxk design matrix is large (nk=O(10^8)).

Voltage and temperature dynamic simulations for advanced Battery Management Systems

Successful introduction of Plug-in Electrical Vehicles (PEV) increases the requirements for advanced on-board Battery Management Systems (BMS) significantly. Modern BMS provides the driver for a number of important indications, such as remaining operation time, adaptive State-of-Charge and State-of-Health. The core of an advanced BMS is a mathematical model for the battery (pack). However, the high complexity and the large amount of computing power necessary for a proper implementation of such models creates a barrier for their introduction to automotive applications. In the present paper a simple dynamic model, describing the behavior of the battery voltage is therefore proposed. The approach is experimentally validated for 18650-type of Li-ion cells.

Equilibrium kinetics of chemisorption processes

A new approach to describe the equilibrium kinetics of chemisorption is proposed. The description of the system is based on first-principles chemical reaction kinetics and statistical thermodynamics. The rate constants are described by using a novel way of activation energy characterization. General expressions for equilibrium gas pressure isotherms and forward/backward reaction rates are obtained as a function of surface coverage. A strong influence of attraction and repulsion interaction energies between the adsorbed species on the equilibrium kinetics is found.

Modeling of electrochemical hydrogen storage in metal hydride electrodes

Nowadays, modern civilization faces the hazardous global warming, which is a result of consumption of traditional fossil fuels. To decrease CO2 emission, sharp improvements in energy generation technologies are required. Modern society urgently needs more sustainable energy. It is commonly accepted that electricity storage systems are the key element of energy efficient technologies, and hydrogen is considered as one of the most important future energy carriers. High energy density rechargeable nickel metal hydride NiMH batteries, which are based on the principles of electrochemical hydrogen storage, play an important role in modern industrial, automotive, and portable electronics sectors. These batteries are relatively cheap, ecologically friendly, and have advantages over other types of batteries especially in transportation and automotive applications. To control the operation of hybrid electrical vehicles HEVs nowadays and plug-in electrical vehicles PEVs in the future, a new effective generation of battery management systems BMSs is required. 1-5

Battery Technologies for Transportation Applications

More than a fifth of the greenhouse emissions produced worldwide come from the transport sector. Several initiatives have been developed over the last few decades, aiming at improving vehicles’ energy conversion efficiency and improve mileage per liter of fuel. Most recently, electric vehicles have been brought back into the market as real competitors of conventional vehicles. Electric vehicle technology offers higher conversion efficiencies, reduced greenhouse emissions, low noise, etc. There are, however, several challenges to overcome, for instance: improving batteries’ energy density to increase the driving range, fast recharging, and initial cost. These issues are addressed on this chapter by looking in depth into both conventional and non-conventional storage technologies in different transportation applications.