Li-ion batteries have transformed portable electronics and will play a key role in the electrification of transport. However, the highest energy storage possible for Li-ion batteries is insufficient for the long-term needs of society, for example, extended-range electric vehicles. To go beyond the horizon of Li-ion batteries is a formidable challenge; there are few options. Here we consider two: Li-air (O(2)) and Li-S. The energy that can be stored in Li-air (based on aqueous or non-aqueous electrolytes) and Li-S cells is compared with Li-ion; the operation of the cells is discussed, as are the significant hurdles that will have to be overcome if such batteries are to succeed. Fundamental scientific advances in understanding the reactions occurring in the cells as well as new materials are key to overcoming these obstacles. The potential benefits of Li-air and Li-S justify the continued research effort that will be needed.

Li-O2 and Li-S batteries with high energy storage.

Li-ion battery technology has become very important in recent years as these batteries show great promise as power sources that can lead us to the electric vehicle (EV) revolution. The development of new materials for Li-ion batteries is the focus of research in prominent groups in the field of materials science throughout the world. Li-ion batteries can be considered to be the most impressive success story of modern electrochemistry in the last two decades. They power most of today's portable devices, and seem to overcome the psychological barriers against the use of such high energy density devices on a larger scale for more demanding applications, such as EV. Since this field is advancing rapidly and attracting an increasing number of researchers, it is important to provide current and timely updates of this constantly changing technology. In this review, we describe the key aspects of Li-ion batteries: the basic science behind their operation, the most relevant components, anodes, cathodes, electrolyte solutions, as well as important future directions for R&D of advanced Li-ion batteries for demanding use, such as EV and load-leveling applications.

Challenges in the development of advanced Li-ion batteries: a review

In the previous paper Ralph Brodd and Martin Winter described the different kinds of batteries and fuel cells. In this paper I will describe lithium batteries in more detail, building an overall foundation for the papers that follow which describe specific components in some depth and usually with an emphasis on the materials behavior. The lithium battery industry is undergoing rapid expansion, now representing the largest segment of the portable battery industry and dominating the computer, cell phone, and camera power source industry. However, the present secondary batteries use expensive components, which are not in sufficient supply to allow the industry to grow at the same rate in the next decade. Moreover, the safety of the system is questionable for the large-scale batteries needed for hybrid electric vehicles (HEV). Another battery need is for a high-power system that can be used for power tools, where only the environmentally hazardous Ni/ Cd battery presently meets the requirements. A battery is a transducer that converts chemical energy into electrical energy and vice versa. It contains an anode, a cathode, and an electrolyte. The anode, in the case of a lithium battery, is the source of lithium ions. The cathode is the sink for the lithium ions and is chosen to optimize a number of parameters, discussed below. The electrolyte provides for the separation of ionic transport and electronic transport, and in a perfect battery the lithium ion transport number will be unity in the electrolyte. The cell potential is determined by the difference between the chemical potential of the lithium in the anode and cathode, ∆G ) -EF. As noted above, the lithium ions flow through the electrolyte whereas the electrons generated from the reaction, Li ) Li+ + e-, go through the external circuit to do work. Thus, the electrode system must allow for the flow of both lithium ions and electrons. That is, it must be both a good ionic conductor and an electronic conductor. As discussed below, many electrochemically active materials are not good electronic conductors, so it is necessary to add an electronically conductive material such as carbon * To whom correspondence should be addressed. Phone and fax: (607) 777-4623. E-mail: stanwhit@binghamton.edu. 4271 Chem. Rev. 2004, 104, 4271−4301

http://www.chemie.uni-regensburg.de/Anorganische_Chemie/Vortrag/StudentenWS06-07/Vortrag_Amereller.pdf

Lithium Batteries and Cathode Materials

Energy storage using batteries offers a solution to the intermittent nature of energy production from renewable sources; however, such technology must be sustainable. This Review discusses battery development from a sustainability perspective, considering the energy and environmental costs of state-of-the-art Li-ion batteries and the design of new systems beyond Li-ion. Images: batteries, car, globe: © iStock/Thinkstock.

Towards greener and more sustainable batteries for electrical energy storage

The Li-S battery has been under intense scrutiny for over two decades, as it offers the possibility of high gravimetric capacities and theoretical energy densities ranging up to a factor of five beyond conventional Li-ion systems. Herein, we report the feasibility to approach such capacities by creating highly ordered interwoven composites. The conductive mesoporous carbon framework precisely constrains sulphur nanofiller growth within its channels and generates essential electrical contact to the insulating sulphur. The structure provides access to Li+ ingress/egress for reactivity with the sulphur, and we speculate that the kinetic inhibition to diffusion within the framework and the sorption properties of the carbon aid in trapping the polysulphides formed during redox. Polymer modification of the carbon surface further provides a chemical gradient that retards diffusion of these large anions out of the electrode, thus facilitating more complete reaction. Reversible capacities up to 1,320 mA h g(-1) are attained. The assembly process is simple and broadly applicable, conceptually providing new opportunities for materials scientists for tailored design that can be extended to many different electrode materials.

http://dns2.asia.edu.tw/~ysho/YSHO-English/1000%20WC/PDF/Nat%20Mat8,%20500.pdf

A highly ordered nanostructured carbon–sulphur cathode for lithium–sulphur batteries

This work reports a quantitative analysis of the shuttle phenomenon in Li/S rechargeable batteries. The work encompasses theoretical models of the charge process, charge and discharge capacity, overcharge protection, thermal effects, self-discharge, and a comparison of simulated and experimental data. The work focused on the features of polysulfide chemistry and polysulfide interaction with the Li anode, a quantitative description of these phenomena, and their application to the development of a high-energy rechargeable battery. The objective is to present experimental evidence that self-discharge, charge-discharge efficiency, charge profile, and overcharge protection are all facets of the same phenomenon.

https://iopscience.iop.org/article/10.1149/1.1806394/pdf

Polysulfide Shuttle Study in the Li/S Battery System

A mathematical model is presented for a complete lithium-sulfur cell. The model includes various electrochemical and chemical (precipitation) reactions, multicomponent transport phenomena in the electrolyte, and the charge transfer within and between solid and liquid phases. A change in the porosity of the porous cathode and separator due to precipitation reactions is also included in the model. The model is used to explain the physical reasons for the two-stage discharge profiles that are typically obtained for lithium-sulfur cells.

/pdf/a-mathematical-model-for-a-lithium-sulfur-cell-psjstue3me.pdf

A Mathematical Model for a Lithium-Sulfur Cell

Li/S fundamental chemistry and application to high-performance rechargeable batteries

The primary mechanisms limiting lithium sulfur (Li-S) cell cycle life and thermal stability are discussed. Two major cycle life limiting mechanisms are identified: development of rough surface morphology on the metallic lithium anode with cycling; and depletion of lithium and electrolyte components through chemical reaction. The approach taken here to mitigate these problems, by employing physical protection, including multi-functional membrane assemblies and non-isotropic pressure is presented. Sulfur utilization of 92%, at C/5 discharge rates, increased cycle life and elimination of thermal runaway in 300 mAh Li-S cells was achieved.

https://iopscience.iop.org/article/10.1149/1.3414001/pdf

High Energy Rechargeable Li-S Cells for EV Application: Status, Remaining Problems, and Solutions

This paper relates to development of a new generation of Li/S rechargeable batteries with energy density exceeding 180 Wh/kg and rate capability comparable with aqueous systems. The cells demonstrate 5 C discharge rate at −40°C. Retained energy and capacity at −40°C exceeded 60 and 80%, respectively. At room temperature cells generate specific power up to 750 W/kg. Cells are inherently protected from overcharge at low and room temperatures by internal chemistry and can sustain 30 times overcharge. It was shown that at −40°C sulfur cathode discharge includes at least five steps, in contrast to the known two steps at room temperature. Thermal effects related to different charge-discharge steps were analyzed. Cell thermal model including Ohm and Arrhenius parts of polarization allowed simulation Ragone plots and capacity over a wide range of currents and temperatures. © 2003 The Electrochemical Society. All rights reserved.

https://iopscience.iop.org/article/10.1149/1.1545452/pdf

Yuriy V. Mikhaylik

Papers

Polysulfide Shuttle Study in the Li/S Battery System

A Mathematical Model for a Lithium-Sulfur Cell

Li/S fundamental chemistry and application to high-performance rechargeable batteries

High Energy Rechargeable Li-S Cells for EV Application: Status, Remaining Problems, and Solutions

Low Temperature Performance of Li/S Batteries