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.

Energy density is the main property of rechargeable batteries that has driven the entire technology forward in past decades. Lithium-ion batteries (LIBs) now surpass other, previously competitive battery types (for example, lead–acid and nickel metal hydride) but still require extensive further improvement to, in particular, extend the operation hours of mobile IT devices and the driving mileages of all-electric vehicles. In this Review, we present a critical overview of a wide range of post-LIB materials and systems that could have a pivotal role in meeting such demands. We divide battery systems into two categories: near-term and long-term technologies. To provide a realistic and balanced perspective, we describe the operating principles and remaining issues of each post-LIB technology, and also evaluate these materials under commercial cell configurations. Post-lithium-ion batteries are reviewed with a focus on their operating principles, advantages and the challenges that they face. The volumetric energy density of each battery is examined using a commercial pouch-cell configuration to evaluate its practical significance and identify appropriate research directions.

Promise and reality of post-lithium-ion batteries with high energy densities

Energy production and storage technologies have attracted a great deal of attention for day-to-day applications. In recent decades, advances in lithium-ion battery (LIB) technology have improved living conditions around the globe. LIBs are used in most mobile electronic devices as well as in zero-emission electronic vehicles. However, there are increasing concerns regarding load leveling of renewable energy sources and the smart grid as well as the sustainability of lithium sources due to their limited availability and consequent expected price increase. Therefore, whether LIBs alone can satisfy the rising demand for small- and/or mid-to-large-format energy storage applications remains unclear. To mitigate these issues, recent research has focused on alternative energy storage systems. Sodium-ion batteries (SIBs) are considered as the best candidate power sources because sodium is widely available and exhibits similar chemistry to that of LIBs; therefore, SIBs are promising next-generation alternatives. Recently, sodiated layer transition metal oxides, phosphates and organic compounds have been introduced as cathode materials for SIBs. Simultaneously, recent developments have been facilitated by the use of select carbonaceous materials, transition metal oxides (or sulfides), and intermetallic and organic compounds as anodes for SIBs. Apart from electrode materials, suitable electrolytes, additives, and binders are equally important for the development of practical SIBs. Despite developments in electrode materials and other components, there remain several challenges, including cell design and electrode balancing, in the application of sodium ion cells. In this article, we summarize and discuss current research on materials and propose future directions for SIBs. This will provide important insights into scientific and practical issues in the development of SIBs.

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Sodium-ion batteries: present and future

Amid burgeoning environmental concerns, electrochemical energy storage has rapidly gained momentum. Among the contenders in the ‘beyond lithium’ energy storage arena, the lithium–sulfur (Li–S) battery has emerged as particularly promising, owing to its potential to reversibly store considerable electrical energy at low cost. Whether or not Li–S energy storage will be able to fulfil this potential depends on simultaneously solving many aspects of its underlying conversion chemistry. Here, we review recent developments in tackling the dissolution of polysulfides — a fundamental problem in Li–S batteries — focusing on both experimental and computational approaches to tailor the chemical interactions between the sulfur host materials and polysulfides. We also discuss smart cathode architectures enabled by recent materials engineering, especially for high areal sulfur loading, as well as innovative electrolyte design to control the solubility of polysulfides. Key factors that allow long-life and high-loading Li–S batteries are summarized. Li–S batteries are a low-cost and high-energy storage system but their full potential is yet to be realized. This Review surveys recent advances in understanding polysulfide chemistry at the positive electrode and the electrolyte and discusses approaches towards long-life and high-loading batteries.

Advances in lithium-sulfur batteries based on multifunctional cathodes and electrolytes

Owing to high specific energy, low cost, and environmental friendliness, lithium–sulfur (Li–S) batteries hold great promise to meet the increasing demand for advanced energy storage beyond portable electronics, and to mitigate environmental problems. However, the application of Li–S batteries is challenged by several obstacles, including their short life and low sulfur utilization, which become more serious when sulfur loading is increased to the practically accepted level above 3–5 mg cm−2. More and more efforts have been made recently to overcome the barriers toward commercially viable Li–S batteries with a high sulfur loading. This review highlights the recent progress in high-sulfur-loading Li–S batteries enabled by hierarchical design principles at multiscale. Particularly, basic insights into the interfacial reactions, strategies for mesoscale assembly, unique architectures, and configurational innovation in the cathode, anode, and separator are under specific concerns. Hierarchy in the multiscale design is proposed to guide the future development of high-sulfur-loading Li–S batteries.

Review on High-Loading and High-Energy Lithium–Sulfur Batteries

In the present work, the extent and the role of oxygen release during the first charge of lithiumand manganese-rich Li1.17[Ni0.22Co0.12Mn0.66]0.83O2 (also referred to as HE-NCM) was investigated with on-line electrochemical mass spectrometry (OEMS). HE-NCM shows a unique voltage plateau at around 4.5 V in the first charge, which is often attributed to a decomposition reaction of the Li-rich component Li2MnO3. For this so-called “activation”, it has been hypothesized that the electrochemically inactive Li2MnO3 would convert into MnO2 while lattice oxide ions are oxidized and released as O2 (or even CO2) from the host structure. However, qualitative and quantitative examination of the O2 and CO2 evolution during the first charge shows that the onset of both reactions is above the 4.5 V voltage plateau and that the amount of released oxygen is an order of magnitude too low to be consistent with the commonly assumed Li2MnO3 activation. Instead, the amount of released oxygen can be correlated to a structural rearrangement of the active material which occurs at the end of the first charge. In this process, oxygen depletion from the HE-NCM host structure leads to the formation of a spinel-like phase. This phase transformation is restricted to the near-surface region of the HE-NCM particles due to the poor mobility of oxide ions within the bulk. From the evolved amount of O2 and CO2, the thickness of the spinel-like surface layer was estimated to be on the order of ≈2–3 nm, in excellent agreement with previously reported (S)TEM data. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.1001702jes] All rights reserved.

https://iopscience.iop.org/article/10.1149/2.1001702jes/pdf

The Role of Oxygen Release from Li- and Mn-Rich Layered Oxides during the First Cycles Investigated by On-Line Electrochemical Mass Spectrometry

https://iopscience.iop.org/article/10.1149/2.0981606jes/pdf

Decomposition of LiPF6 in High Energy Lithium-Ion Batteries Studied with Online Electrochemical Mass Spectrometry

The electrochemical behavior of Na-ion and Li-ion full cells was investigated, using hard carbon as the anode material, and NaNi0.5Mn0.5O2 and LiNi0.5Mn0.5O2 as the cathodes. A detailed description of the structure, phase transition, electrochemical behavior and kinetics of the NaNi0.5Mn0.5O2 cathodes is presented, including interesting comparison with their lithium analogue. The critical effect of the hard carbon anodes pretreatment in the total capacity and stability of full cells is clearly demonstrated. Using impedance spectroscopy in three electrodes cells, we show that the full cell impedance is dominated by the contribution of the cathode side. We discuss possible reasons for capacity fading of these systems, its connection to the cathode structure and relevant surface phenomena.

Comparison between Na-Ion and Li-Ion Cells: Understanding the Critical Role of the Cathodes Stability and the Anodes Pretreatment on the Cells Behavior.

The development of a successful Li-O2 battery depends to a large extent on the discovery of electrolyte solutions that remain chemically stable through the reduction and oxidation reactions that occur during cell operations. The influence of the electrolyte anions on the behavior of Li-O2 cells was thought to be negligible. However, it has recently been suggested that specific anions can have a dramatic effect on the chemistry of a Li-O2 cell. In the present paper, we describe how LiNO3 in polyether solvents can improve both oxygen reduction (ORR) and oxygen evolution (OER) reactions. In particular, the nitrate anion can enhance the ORR by enabling a mechanism that involves solubilized species like superoxide radicals, which allows for the formation of submicronic Li2O2 particles. Such phenomena were also observed in Li-O2 cells with high donor number solvents, such as dimethyl sulfoxide dimethylformamide (DMF) and dimethylacetamide (DMA). Nevertheless, their instability toward oxygen reduction, lithium m...

Catalytic Behavior of Lithium Nitrate in Li-O2 Cells.

We present the results of our in situ X-ray diffraction (XRD) and Raman spectroscopy measurements for the first Li-ion extraction/insertion (charge/discharge) processes of nickel-rich Li1+x(NiyCozMnz)wO2 (0.005<x<0.03; y:z=8:1, w is nearly 1) electrodes in Li cells. These cells were of a special design that provide in situ (at-work) measurements during electrochemical polarization and can be used for regular cycling tests of practical Li-battery electrodes. By using XRD measurements, it was established that, upon Li+ extraction, these cathode materials demonstrate structural transformations of the hexagonal phase (space group R-3m) H1 to another hexagonal phase H2 (with a lower Li-ion content in the lattice) and to domains comprising both of these two phases, coexisting at potentials E≈4.2–4.3 V. The above phases differ by the a and c lattice constants, which is in agreement with literature results. Evolution of the lattice constants with the electrode potential upon charge/discharge is shown to be in correlation with the differential capacity dQ/dE versus E plots and with some Raman parameters calculated from complementary in situ studies of these cathode materials by Raman spectroscopy.

Frederick Chesneau

Papers

The Role of Oxygen Release from Li- and Mn-Rich Layered Oxides during the First Cycles Investigated by On-Line Electrochemical Mass Spectrometry

Decomposition of LiPF6 in High Energy Lithium-Ion Batteries Studied with Online Electrochemical Mass Spectrometry

Comparison between Na-Ion and Li-Ion Cells: Understanding the Critical Role of the Cathodes Stability and the Anodes Pretreatment on the Cells Behavior.

Catalytic Behavior of Lithium Nitrate in Li-O2 Cells.

Li+‐Ion Extraction/Insertion of Ni‐Rich Li1+x(NiyCozMnz)wO2 (0.005<x<0.03; y:z=8:1, w≈1) Electrodes: In Situ XRD and Raman Spectroscopy Study