Recent progress in theoretical and computational investigations of Li-ion battery materials and electrolytes

There is an increasing worldwide demand for high energy density batteries. In recent years, rechargeable Li-ion batteries have become important power sources, and their performance gains are driving the adoption of electrical vehicles (EV) as viable alternatives to combustion engines. The exploration of new Li-ion battery materials is an important focus of materials scientists and computational physicists and chemists throughout the world. The practical applications of Li-ion batteries and emerging alternatives may not be limited to portable electronic devices and circumventing hurdles that include range anxiety and safety among others, to their widespread adoption in EV applications in the future requires new electrode materials and a fuller understanding of how the materials and the electrolyte chemistries behave. Since this field is advancing rapidly and attracting an increasing number of researchers, it is crucial to summarise the current progress and the key scientific challenges related to Li-ion batteries from theoretical point of view. Computational prediction of ideal compounds is the focus of several large consortia, and a leading methodology in designing materials and electrolytes optimized for function, including those for Li-ion batteries. In this Perspective, we review the key aspects of Li-ion batteries from theoretical perspectives: the working principles of Li-ion batteries, the cathodes, anodes, and electrolyte solutions that are the current state of the art, and future research directions for advanced Li-ion batteries based on computational materials and electrolyte design

A novel high-fidelity unscented particle filtering method for the accurate state of charge estimation of lithium-ion batteries.

Power Li-ion batteries are one of the core "three powers" systems of new energy vehicles, and its accurate batteries modeling and state prediction have become the core technology of the scientific and technological progress in the industry. This paper takes the ternary Li-ion batteries as the research subject. Aiming at the mathematical expressions of different structural features, innovatively construct a second-order Thevenin equivalent circuit model with autoregressive effect. This model can characterize the internal reaction mechanism of Li-ion batteries and fit the complex electrochemical reactions inside the battery. An improved particle filter model, namely a new high-fidelity unscented particle filter method, is designed and established. By introducing a suitable suggested density function, the model can accurately calculate the mean and variance, solve the particle degradation problem, and find out the Li-ion batteries state of charge, which is suitable for complex charging and discharging conditions. By further improving the theoretical analysis and combining with experiments under different working conditions, this method studies the Li-ion batteries state of charge. The test results show that the average absolute error of the improved equivalent circuit model is reduced by 0.00457 V, and the error rate is stably kept within 1%, which has the ability to describe Li-ion batteries well. When using the high-fidelity unscented particle filter algorithm to estimate the state of charge of the lithium battery, the robustness of the system is improved, the following effect is better, and the estimation error is controlled within 1.5%, which brings good practical value to the power Li-ion batteries

Lithium Storage in Nanoporous Complex Oxide 12CaO•7Al2O3 (C12A7)

Porous materials have generated a great deal of interest for use in energy storage technologies, as their architectures have high surface areas due to their porous nature. They are promising candidates for use in many fields such as gas storage, metal storage, gas separation, sensing and magnetism. Novel porous materials which are non-toxic, cheap and have high storage capacities are actively considered for the storage of Li ions in Li-ion batteries. In this study, we employed density functional theory simulations to examine the encapsulation of lithium in both stoichiometric and electride forms of C12A7. This study shows that in both forms of C12A7, Li atoms are thermodynamically stable when compared with isolated gas-phase atoms. Lithium encapsulation through the stoichiometric form (C12A7:O2−) turns its insulating nature metallic and introduces Li+ ions in the lattice. The resulting compound may be of interest as an electrode material for use in Li-ion batteries, as it possesses a metallic character and consists of Li+ ions. The electride form (C12A7:e−) retains its metallic character upon encapsulation, but the concentration of electrons increases in the lattice along with the formation of Li+ ions. The promising features of this material can be tested by performing intercalation experiments in order to determine its applicability in Li-ion batteries

Recent progress on nanostructured 4 v cathode materials for Li-ion batteries for mobile electronics

Mobile electronics have developed so rapidly that battery technology has hardly been able to keep pace. The increasing desire for lighter and thinner Li-ion batteries with higher capacities is a continuing and constant goal for in research. Achieving higher energy densities, which is mainly dependent on cathode materials, has become a critical issue in the development of new Li-ion batteries. In this review, we will outline the progress on nanostructured 4 V cathode materials of Li-ion batteries for mobile electronics, covering LiCoO2, LiNixCoyMn1-x-yO 2, LiMn2O4, LiNi0.5Mn 1.5O4 and Li-rich layered oxide materials. We aim to provide some scientific insights into the development of superior cathode materials by discussing the advantages of nanostructure, surface-coating, and other key properties.open2

DEVELOPMENT OF TINB2O7 ANODE FOR LITHIUM ION BATTERY ANODES

I have received 1200 dollars research scholarship.With an increase in gasoline price and greenhouse gas emissions, hybrid electrical vehicles (HEV) and pure electric vehicles (EV) have been commercialized in auto market. Li-ion batteries have become the dominant power source for the EV applications because of many advantages such as high energy densities, less pollution, stable performance and long cycle life. However, the market for HEVs and EVs need to overcome many technical issues. For example, energy densities and cycle life of Li-ion batteries need to be improved at low temperature for electrical vehicle applications. TiNb2O7 (TNO) electrode-based battery can be a good choice in order to improve the energy densities and cycle life. The original anode-based batteries are Li4Ti5O12 (LTO) anode-based batteries. I have made a comparison between TNO anode and LTO anode for Li-ion batteries. The energy densities of TNO anode-based batteries are around 350Wh/L and the energy densities of LTO anode-based batteries are around 177Wh/L. It means that TNO anode-based batteries have a higher energy density than LTO anode-based batteries. In addition, TNO anode batteries have a longer cycle life and shorter charging time than LTO anode batteries. The purpose of this research is to identify whether the TNO anodes-based batteries have the advantage of high energy and power densities for Li-ion batteries application. First, I need to identify whether the TNO anode can be run in normal cycling battery by doing half-cell test. I have done the half-cell test which consist of TNO anode and metallic Li as a counter electrode. The voltage profile obtained from half-cell test fits well with TNO electrode. In addition, cycle life tendency corresponding to high-density TNO composite electrode which indicate the TNO electrode can be used in normal cycling battery. In the future research study, I will identify the important parameters that lead to poor performance in the low-temperature condition and demonstrate the performance of TiNb2O7 anodes-based batteries has been improved in the low temperature condition.College of Engineering Research OfficeNo embargoAcademic Major: Mechanical Engineerin

Electrochemical Lithium Harvesting from Waste Li-ion Batteries

poster abstractThis study demonstrates the feasibility of using water and the contents of waste Li-ion batteries for the electrodes in a Li-liquid battery system. Li metal was collected electrochemically from a waste Li-ion battery containing Li-ion source materials from the battery’s anode, cathode, and electrolyte, thereby recycling the Li contained in the waste battery at the room temperature. The harvested Li metal in the battery system was discharged to produce the electricity by using water as the cathode. The discharge voltage of the water showed 2.7 V at 0.1 mA/cm2 versus Li metal harvested from waste Li-ion batteries, compared to 2.8 V versus fresh Li metal at the same current rate. Since the electrodes for this proposed battery system are water and the contents of waste Li-ion batteries, the cost of the battery decreases, which is an attractive strategy for a large size energy storage application. The new design of a battery cell is accompanied in this research. The cell design has two anodes and one cathode which allow it to charge and discharge simultaneously. Thus far, the designs for the cell have been finalized, and will soon be machined so that testing may follow. This drives toward the hopes that an actual battery will be made which can directly harvest the Li metal from a waste Li-ion battery and gain energy immediately. This research will hopefully introduce a new, higher-energy-potential battery while using waste Li-ion batteries which will drastically reduce the cost of Li-ion batteries

Hollow Nanostructured Anode Materials for Li-Ion Batteries

Hollow nanostructured anode materials lie at the heart of research relating to Li-ion batteries, which require high capacity, high rate capability, and high safety. The higher capacity and higher rate capability for hollow nanostructured anode materials than that for the bulk counterparts can be attributed to their higher surface area, shorter path length for Li+ transport, and more freedom for volume change, which can reduce the overpotential and allow better reaction kinetics at the electrode surface. In this article, we review recent research activities on hollow nanostructured anode materials for Li-ion batteries, including carbon materials, metals, metal oxides, and their hybrid materials. The major goal of this review is to highlight some recent progresses in using these hollow nanomaterials as anode materials to develop Li-ion batteries with high capacity, high rate capability, and excellent cycling stability

Failure Detection for Over-Discharged Li-Ion Batteries

poster abstractLi-ion batteries are high density, slow loss of charge when not in use and no memory effect. Vast research on Li-ion batteries has been focusing on increasing the energy density, durability, and cost. Due to its advantages it has been widely used in consumer electronics and electric vehicles. Apart from its advantages, safety is a major concern for Li-ion batteries. The Li-ion safety issues have been widely publicized due to devastating incidents with laptop and cell phone batteries. Despite of much research towards the safety of Li-ion battery, it remains as a major concern related to Li-Ion batteries. A failure of Li-ion battery may result in thermal runaway. Li-ion battery failure may be due to overcharge, over-discharge, short circuits, particles poisoning, mechanical or thermal damage [1, 2]. Short circuit, overcharge, and over-discharge are the most common electrical abuses a battery suffers. This poster presents preliminary results for the failure signatures of over-discharged Li-ion batteries, and proposes a rule-based method and a probabilistic method for failure detection. The two methods Rule-based method and Probabilistic method are verified using experimental results for a Li-ion battery. The proposed methods were successfully implemented in a real-time system for failure detection and early warning

REDUCING INTERFACIAL RESISTANCE OF LI-ION BATTERIES THROUGH ATOMIC LAYER DEPOSITION

The attention to solid state batteries are increasing as electrical vehicles start to dominate automobile industry. Solid-state batteries (SSBs) are type of Li-ion batteries that have solid medium. They are regarded as the next-generation energy storage device for electric vehicles because they can potentially solve the problems of conventional Li-ion batteries. In conventional Li-ion batteries, when delivered in high energy densities, they had extremely high possibility for inflammation due to the presence of flammable liquid organic electrolytes. Also, though the use of Li metal anode may significantly increase energy density, likelihood of short circuiting the cell due to the growth of Li dendrites prevents the commercialization of Li-ion batteries with Li anodes. Thus, in order to provide safer and higher energy batteries, SSBs with nonflammable and mechanically robust SSEs which may suppress Li dendrite growth came up as an alternative solution. However, there are new challenges that need to be overcome for SSBs. Not only are they more expensive than conventional Li-ion batteries, but due to solid-characteristic of the electrolyte, SSBs have critical flaw of high resistance at the SSE-electrode interfaces. The performance of SSBs in high temperature environment may be safer, but the thick SSE membrane and low active loading with the electrodes do not show better performance when compared to the liquid electrolyte cells. To enhance the battery performance, the interfacial resistance in SSBs needs to be reduced. Therefore, the focus of our lab is to come up with a novel coating method that has the least interfacial resistance. This new study will utilize the atomic layer deposition (ALD) technique to coat metal oxides on electrodes and enhance the battery performance, as previous research by many scientists has already proven that metal oxide coatings are effective at reducing the interfacial resistance in SSBs.Undergraduat

Cathode chemistries and electrode parameters affecting the fast charging performance of li-ion batteries

Li-ion battery fast-charging technology plays an important role in popularizing electric vehicles (EV), which critically need a charging process that is as simple and quick as pumping fuel for conventional internal combustion engine vehicles. To ensure stable and safe fast charging of Li-ion battery, understanding the electrochemical and thermal behaviors of battery electrodes under high rate charges is crucial, since it provides insight into the limiting factors that restrict the battery from acquiring energy at high rates. In this work, charging simulations are performed on Li-ion batteries that use the LiCoO2 (LCO), LiMn2O4 (LMO), and LiFePO4 (LFP) as the cathodes. An electrochemical-thermal coupling model is first developed and experimentally validated on a 2.6Ah LCO based Li-ion battery and is then adjusted to study the LMO and LFP based batteries. LCO, LMO, and LFP based Li-ion batteries exhibited different thermal responses during charges due to their different entropy profiles, and results show that the entropy change of the LCO battery plays a positive role in alleviating its temperature rise during charges. Among the batteries, the LFP battery is difficult to be charged at high rates due to the charge transfer limitation caused by the low electrical conductivity of the LFP cathode, which, however, can be improved through doping or adding conductive additives. A parametric study is also performed by considering different electrode thicknesses and secondary particle sizes. It reveals that the concentration polarization at the electrode and particle levels can be weaken by using thin electrodes and small solid particles, respectively. These changes are helpful to mitigate the diffusion limitation and improve the performance of Li-ion batteries during high rate charges, but careful consideration should be taken when applying these changes since they can reduce the energy density of the batteries