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

The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Electrolytes and interphases in Li-ion batteries and beyond.

The status of room-temperature potassium-ion batteries is reviewed in light of recent concerns regarding the rising cost of lithium and the fact that room-temperature sodium-ion batteries have yet to be commercialised thus far. Initial reports of potassium-ion cells appear promising given the infancy of the research area. This review presents not only an overview of the current potassium-ion battery literature, but also attempts to provide context by describing previous developments in lithium-ion and sodium-ion batteries and the electrochemical reaction mechanisms discovered thus far. Perspectives and directions on the techniques available to characterize newly developed battery materials are also provided based on our experience and knowledge from the literature. It is hoped that through this review, the potential of potassium-ion batteries as a competitive energy-storage technology will be realised, and the accessibility and available knowledge of the techniques required to develop the technology will be made apparent.

An Initial Review of the Status of Electrode Materials for Potassium-Ion Batteries

Understanding reactions at the electrode/electrolyte interface (EEI) is essential to developing strategies to enhance cycle life and safety of lithium batteries. Despite research in the past four decades, there is still limited understanding by what means different components are formed at the EEI and how they influence EEI layer properties. We review findings used to establish the well-known mosaic structure model for the EEI (often referred to as solid electrolyte interphase or SEI) on negative electrodes including lithium, graphite, tin, and silicon. Much less understanding exists for EEI layers for positive electrodes. High-capacity Li-rich layered oxides yLi2–xMnO3·(1–y)Li1–xMO2, which can generate highly reactive species toward the electrolyte via oxygen anion redox, highlight the critical need to understand reactions with the electrolyte and EEI layers for advanced positive electrodes. Recent advances in in situ characterization of well-defined electrode surfaces can provide mechanistic insights an...

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Electrode–Electrolyte Interface in Li-Ion Batteries: Current Understanding and New Insights

This study investigates the organic components of the solid electrolyte interphase (SEI) on the carbonaceous anodic electrode in LiCoO 2 batteries using solid-state nuclear magnetic resonance (NMR) techniques. The electrolyte solvents, ethylene carbonate and diethyl carbonate, were enriched on the carbonyl carbon prior to cell assembly and conditioning in an attempt to trace the breakdown pathways of these components. A strong signal was seen, demonstrating that the carbonyl carbons of both electrolytes survive in some reasonable quantity as insoluble breakdown products on the rinsed electrode surface. This confirms that the fate of these carbons as consumed in the formation of CO 2 is either not unique, or not as final product. Furthermore the central carbonyl carbon survives, not as an intact carbonyl species, but instead in the form of compounds in which the carbon-oxygen double bond has been disrupted. Formation of this class of species is likely initiated by a nucleophilic attack on the carbonyl carbon by one or more radical, alkoxy, carbanion or fluorine-containing ionic species formed from solvent and/or salt breakdown. These results suggest a new family of electrolyte breakdown products, predominantly consisting of binary, tertiary and/or quaternary ether-type compounds (i.e., orthocarbonates and orthoesters), as well as fluorine-containing alkoxy compounds.

https://iopscience.iop.org/article/10.1149/1.3559551/pdf

13C Solid State NMR Suggests Unusual Breakdown Products in SEI Formation on Lithium Ion Electrodes

With the intent of improving the performance of Li-ion cells over a wide operating temperature range, we have investigated the use of co-solvents to improve the properties of electrolyte formulations. In the current study, we have focused upon evaluating promising electrolytes which have been incorporated into large capacity (7 Ah) prototype Li-ion cells, fabricated by Yardney Technical Products, Inc. The electrolytes selected for performance evaluation include the use of a number of esters as co-solvents, including methyl propionate (MP), ethyl propionate (EP), ethyl butyrate (EB), propyl butyrate (PB), and 2,2,2-trifluoroethyl butyrate (TFEB). The performance of the prototype cells containing the ester-based electrolytes was compared with an extensive data base generated on cells containing previously developed all carbonate-based electrolytes. A number of performance tests were performed, including determining (i) the discharge rate capacity over a wide range of temperatures, (ii) the charge characteristics, (iii) the cycle life characteristics under various conditions, and (iv) the impedance characteristics.

https://iopscience.iop.org/article/10.1149/1.3393863/pdf

Performance Demonstration of MCMB-LiNiCoO2 Cells Containing Electrolytes Designed for Wide Operating Temperature Range

Solid electrolyte interphase (SEI) formation in lithium ion cells prepared with advanced electrolytes is investigated by solid state multinuclear (7Li, 19F, 31P) magnetic resonance (NMR) measurements of electrode materials harvested from cycled cells subjected to an accelerated aging protocol. The electrolyte composition is varied to include the addition of fluorinated carbonates and triphenyl phosphate (TPP, a flame retardant). In addition to species associated with LiPF6 decomposition, cathode NMR spectra are characterized by the presence of compounds originating from the TPP additive. Substantial amounts of LiF are observed in the anodes as well as compounds originating from the fluorinated carbonates.

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Kiah Smith

Papers

13C Solid State NMR Suggests Unusual Breakdown Products in SEI Formation on Lithium Ion Electrodes

Performance Demonstration of MCMB-LiNiCoO2 Cells Containing Electrolytes Designed for Wide Operating Temperature Range

Solid State Multinuclear Magnetic Resonance Investigation of Electrolyte Decomposition Products on Lithium Ion Electrodes