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

Over the past 30 years, significant commercial and academic progress has been made on Li-based battery technologies. From the early Li-metal anode iterations to the current commercial Li-ion batteries (LIBs), the story of the Li-based battery is full of breakthroughs and back tracing steps. This review will discuss the main roles of material science in the development of LIBs. As LIB research progresses and the materials of interest change, different emphases on the different subdisciplines of material science are placed. Early works on LIBs focus more on solid state physics whereas near the end of the 20th century, researchers began to focus more on the morphological aspects (surface coating, porosity, size, and shape) of electrode materials. While it is easy to point out which specific cathode and anode materials are currently good candidates for the next-generation of batteries, it is difficult to explain exactly why those are chosen. In this review, for the reader a complete developmental story of LIB should be clearly drawn, along with an explanation of the reasons responsible for the various technological shifts. The review will end with a statement of caution for the current modern battery research along with a brief discussion on beyond lithium-ion battery chemistries.

30 Years of Lithium-Ion Batteries.

The escalating and unpredictable cost of oil, the concentration of major oil resources in the hands of a few politically sensitive nations, and the long-term impact of CO2 emissions on global climate constitute a major challenge for the 21st century. They also constitute a major incentive to harness alternative sources of energy and means of vehicle propulsion. Today's lithium-ion batteries, although suitable for small-scale devices, do not yet have sufficient energy or life for use in vehicles that would match the performance of internal combustion vehicles. Energy densities 2 and 5 times greater are required to meet the performance goals of a future generation of plug-in hybrid-electric vehicles (PHEVs) with a 40–80 mile all-electric range, and all-electric vehicles (EVs) with a 300–400 mile range, respectively. Major advances have been made in lithium-battery technology over the past two decades by the discovery of new materials and designs through intuitive approaches, experimental and predictive reasoning, and meticulous control of surface structures and chemical reactions. Further improvements in energy density of factors of two to three may yet be achievable for current day lithium-ion systems; factors of five or more may be possible for lithium–oxygen systems, ultimately leading to our ability to confine extremely high potential energy in a small volume without compromising safety, but only if daunting technological barriers can be overcome.

Electrical energy storage for transportation—approaching the limits of, and going beyond, lithium-ion batteries

A strategy used to design high capacity (>200 mAh g−1), Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries is discussed. The advantages of the Li2MnO3 component and its influence on the structural stability and electrochemical properties of these layered xLi2MnO3·(1 −
				x)LiMO2 electrodes are highlighted. Structural, chemical, electrochemical and thermal properties of xLi2MnO3·(1 −
				x)LiMO2 electrodes are considered in the context of other commercially exploited electrode systems, such as LiCoO2, LiNi0.8Co0.15Al0.05O2, Li1+xMn2−xO4 and LiFePO4.

Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrodes for lithium-ion batteries

The significance of the Li2MnO3 component in ‘composite’ xLi2MnO3 · (1 − x)LiMn0.5Ni0.5O2 electrodes

Layered xLiMO2.(1 - x)Li2M'O3 electrodes for lithium batteries: a study of 0.95LiMn0.5Ni0.5O2.0.05Li2TiO3

The effect of tetravalent titanium substitution in LiNi1−xTixO2 (0.025⩽x⩽0.2) system

Significance of the Tetrahedral A Site on the Electrochemical Performance of Substituted Li1.05 M 0.05Mn1.90 O 4 Spinel Electrodes ( M = Li , Mg , Zn , Al ) in Lithium Cells

Layered LiNi{sub 0.95}Ti{sub 0.05}O{sub 2} cathodes were prepared by solid-state reaction and characterized by various techniques. X-ray diffraction shows that the samples have highly ordered and phase-pure layered compounds after heating at 750{sup o}C in an O{sub 2} atmosphere. Scanning electron microscopy and particle size distribution analysis reveal that the LiNi{sub 0.95}Ti{sub 0.05}O{sub 2} material has spherical morphology with particle size of about 12 {mu}m. The LiNi{sub 0.95}Ti{sub 0.05}O{sub 2} electrodes exhibited large capacity and excellent electrochemical behavior. X-ray photoelectron spectroscopy confirms the existence of tetravalent titanium as a substituent. Indications are that the structural integrity of the LiNi{sub 1-x}Ti{sub x}O{sub 2} materials was preserved because the Ti{sup 4+} ions prevented impurity Ni{sup 2+} migration into the lithium sites. Hybrid pulse power characterization testing shows the area specific impedance of 22 {Omega}cm{sup 2}, indicating that the materials could provide more than enough power to level the load on the main engine of the hybrid electric vehicle. Aging tests also show stable impedance values as a function of time (days) at 55{sup o}C, which indicates that the battery based on this material could exhibit long calendar life.

J.-S. Kim

Papers

The significance of the Li2MnO3 component in ‘composite’ xLi2MnO3 · (1 − x)LiMn0.5Ni0.5O2 electrodes

Layered xLiMO2.(1 - x)Li2M'O3 electrodes for lithium batteries: a study of 0.95LiMn0.5Ni0.5O2.0.05Li2TiO3

The effect of tetravalent titanium substitution in LiNi1−xTixO2 (0.025⩽x⩽0.2) system

Significance of the Tetrahedral A Site on the Electrochemical Performance of Substituted Li1.05 M 0.05Mn1.90 O 4 Spinel Electrodes ( M = Li , Mg , Zn , Al ) in Lithium Cells

Material characterization and electrochemical study on LiNi{sub 0.95}Ti{sub 0.05}O{sub 2} materials.