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Martin Winter - One of the best experts on this subject based on the ideXlab platform.

  • in situ7li nmr analysis of Lithium metal surface Deposits with varying electrolyte compositions and concentrations
    Physical Chemistry Chemical Physics, 2019
    Co-Authors: Verena Kupers, Martin Winter, Martin Kolek, Peter Bieker, Gunther Brunklaus
    Abstract:

    A major challenge of Lithium metal electrodes, in theory a suitable choice for rechargeable high energy density batteries, comprises non-homogeneous Lithium deposition and the growth of reactive high surface area Lithium, which eventually yields active material losses and safety risks. While it is hard to fully avoid inhomogeneous Deposits, the achievable morphology of the occurring Lithium Deposits critically determines the long-term cycling behaviour of the cells. In this work, we focus on a combined scanning electron microscopy (SEM) and 7Li nuclear magnetic resonance spectroscopy (7Li-NMR) study to unravel the impact of the choice of conducting salts (LiPF6 and LiTFSI), solvents (EC : DEC, 3 : 7, DME : DOL, 1 : 1), as well as their respective concentrations (1 M, 3 M) on the electrodeposition process, demonstrating that Lithium deposition morphologies may be controlled to a large extent by proper choice of cycling conditions and electrolyte constituents. In addition, the applicability of 7Li-NMR spectroscopy to assess the resulting morphology is discussed. It was found, that Lithium deposition analysis based on the 7Li chemical shift and intensity should be used carefully, as various morphologies can lead to similar results. Still, our case study reveals that the combination of SEM and NMR data is rather advantageous and offers complementary insights that may provide pathways for the future design of tailored electrolytes.

  • correlation of aging and thermal stability of commercial 18650 type Lithium ion batteries
    Journal of Power Sources, 2017
    Co-Authors: Markus Börner, Martin Winter, Alex Friesen, Martin Grutzke, Yannick Philipp Stenzel, Gunther Brunklaus, Jan Haetge, Sascha Nowak, Falko M Schappacher
    Abstract:

    Abstract Established safety of Lithium ion batteries is key for the vast diversity of applications. The influence of aging on the thermal stability of individual cell components and complete cells is of particular interest. Commercial 18650-type Lithium ion batteries based on LiNi 0.5 Co 0.2 Mn 0.3 O 2 /C are investigated after cycling at different temperatures. The variations in the electrochemical performance are mainly attributed to aging effects on the anode side considering the formation of an effective solid-electrolyte interphase (SEI) during cycling at 45 °C and a thick decomposition layer on the anode surface at 20 °C. The thermal stability of the anodes is investigated including the analysis of the evolving gases which confirmed the severe degradation of the electrolyte and active material during cycling at 20 °C. In addition, the presence of metallic Lithium Deposits could strongly affect the thermal stability. Thermal safety tests using quasi-adiabatic conditions show variations in the cells response to elevated temperatures according to the state-of-charge, i.e. a reduced reactivity in the discharged state. Furthermore, it is revealed that the onset of exothermic reactions correlates with the thermal stability of the SEI, while the thermal runaway is mainly attributed to the decomposition of the cathode and the subsequent reactions with the electrolyte.

  • Influence of Lithium-cyclo-difluoromethane-1,1-bis(sulfonyl)imide as electrolyte additive on the reversibility of Lithium metal batteries
    Journal of Applied Electrochemistry, 2016
    Co-Authors: Patrick Murmann, Markus Börner, Isidora Cekic-laskovic, Martin Winter
    Abstract:

    Electrolyte solutions containing Lithium-cyclo-difluoromethane-1,1-bis(sulfonyl)imide (LiDMSI) as an additive were specifically designed for measurements in Lithium plating-stripping model experiments on copper electrodes. LiDMSI was implemented into two different electrolyte solutions. The first electrolyte setup consisted of a 1 M solution of LiTFSI in PC as an electrolyte which is known to show a comparably limited performance for reversible Li deposition. The second setup was comprised 1 M LiAsF_6 in 1,3-dioxolane as the base electrolyte which depicts a well-tested performance for Lithium deposition–dissolution. The addition of LiDMSI yielded significantly improved results in regard to Coulombic efficiencies and cycling stability in both electrolyte compositions. Furthermore, it negated the formation of high surface area, e.g., dendritic Lithium, which depicts the main source for the limited safety of rechargeable Lithium metal batteries. In the case of the PC-based electrolyte system, the LiDMSI-containing electrolyte illustrates a slightly lowered over-potential on the copper substrate, while for the dioxolane-based setup the over-potentials were almost completely equal. In order to compare the morphologies of the Lithium Deposits, SEM images were utilized. Graphical Abstract

Lijun Wan - One of the best experts on this subject based on the ideXlab platform.

Yi Cui - One of the best experts on this subject based on the ideXlab platform.

  • Carbonate-hosted clay-type Lithium deposit and its prospecting significance
    Chinese Science Bulletin, 2019
    Co-Authors: Hanjie Wen, Yi Cui, Chongguang Luo, Kunyue Ling, Jihua Yang
    Abstract:

    In recent years, the clay-type Lithium resources have attracted increasing attention due to their large scale, stable distribution, low cost of mining and utilization. Comparing with the traditional pegmatite-type and brine-type Lithium Deposits, it has become an important direction of exploration of new type Lithium resources. The clay-type Lithium resources reported have genetic relationship to volcanic materials. Through systematic research and review, this paper first proposed the genetic concept of “carbonate-hosted clay-type Lithium deposit”, which was related to carbonate weathering-sedimentation. Li-rich clay rocks found at present mainly include the Jiujialu formation (C1 jj ) of lower carboniferous in Guizhou Province and Daoshitou formation (P1 d ) of the lower Permian in central Yunnan Province. Although the different formation ages of the two sets of Li-rich strata in this study, their lithology is relatively similar to the section upward, including: (1) Aluminized clay rocks, local iron bearing; (2) compact aluminaceous clay rocks; (3) bean oolitic aluminaceous clay rocks; (4) loose soil-like clay rocks, among which the dense aluminaceous clay rocks and pisolitic aluminaceous clay rocks are the most favorable lithology for Lithium enrichment. The results of XRD analysis show that the major minerals of clay rocks are hydralite, bomberite, montmorillonite, illite, kaolinite, anatase, rutile, zircon and pyrite. According to the analysis of more than 1000 samples from more than 30 profiles, it is shown that most of the samples from two sets of Li-rich strata have reached the comprehensive utilization index of Lithium in bauxite (Li2O ≥500 μg/g), and the average Li2O content in the clay rocks is about 0.3%, and the highest is 1.1%. The detailed micro-analysis using Tof-SIMS technique has shown that Lithium was mainly distributed in clay minerals, and mainly occurred in amorphous clay minerals identified as montmorillonite. The trace and major elements suggest that the weathering of underlying carbonate rocks provides a source of Li-rich clay rocks. Detailed field observations in combination with trace element geochemical analysis (such as high Lithium samples of Sr/Ba ratio is generally less than 0.5, MgO/Al2O3 ratio less than 1, Rb/K ratio is less than 0.003, Ni/Co ratio greater than 5), indicate that oxygen-poor and low-energy coastal marshes, lagoons and limited and closed ancient bay (basin) in the transitional environment may be ideal places for Li enrichment to form high-grade Deposits. Therefore, the main geological and geochemical characteristics of this new type can be summarized as: (1) The ore-forming material is derived from the underlying carbonate formation; (2) Lithium mainly exists in the smectite phase by adsorption; (3) the sedimentary environment plays an important role in the enrichment of Lithium, the limnic basin in coastal plain was an ideal place for Lithium accumulation; (4) in addition to Li, there may be Ga and REE enrichment occurring in this type clay. According to this new metallogenic model, it has obtained 340000 tons of Lithium oxide resources in Dianzhong basin by geological exploration, reaching a super-large class deposit. Due to the numerous regions with similar ore-forming conditions of these type Lithium resources, it can be expected that “carbonate-hosted clay-type Lithium deposit” will become an important source of Lithium resources in China.

  • fast galvanic Lithium corrosion involving a kirkendall type mechanism
    Nature Chemistry, 2019
    Co-Authors: Dingchang Lin, Allen Pei, Jin Xie, Yi Cui, Yayuan Liu, Yanbin Li, Yuzhang Li, William Huang
    Abstract:

    Developing a viable metallic Lithium anode is a prerequisite for next-generation batteries. However, the low redox potential of Lithium metal renders it prone to corrosion, which must be thoroughly understood for it to be used in practical energy-storage devices. Here we report a previously overlooked mechanism by which Lithium Deposits can corrode on a copper surface. Voids are observed in the corroded Deposits and a Kirkendall-type mechanism is validated through electrochemical analysis. Although it is a long-held view that Lithium corrosion in electrolytes involves direct charge-transfer through the Lithium–electrolyte interphase, the corrosion observed here is found to be governed by a galvanic process between Lithium and the copper substrate—a pathway largely neglected by previous battery corrosion studies. The observations are further rationalized by detailed analyses of the solid–electrolyte interphase formed on copper and Lithium, where the disparities in electrolyte reduction kinetics on the two surfaces can account for the fast galvanic process. Developing a stable metallic Lithium anode is necessary for next-generation batteries; however, Lithium is prone to corrosion, a process that must be better understood if practical devices are to be created. A Kirkendall-type mechanism of Lithium corrosion has now been observed. The corrosion is fast and is governed by a galvanic process.

  • Effects of Polymer Coatings on Electrodeposited Lithium Metal
    2018
    Co-Authors: Jeffrey Lopez, Allen Pei, Yi Cui, Ging-ji Nathan Wang, Zhenan Bao
    Abstract:

    The electrodeposition of Lithium metal is a key process in next-generation, high energy density storage devices. However, the high reactivity of the Lithium metal causes short cycling lifetimes and dendrite growth that can pose a serious safety issue. Recently, a number of approaches have been pursued to stabilize the Lithium metal–electrolyte interface, including soft polymeric coatings that have shown the ability to enable high-rate and high-capacity Lithium metal cycling, but a clear understanding of how to design and modify these coatings has not yet been established. In this work, we studied the effects of several polymers with systematically varied chemical and mechanical properties as coatings on the Lithium metal anode. By examining the early stages of Lithium metal deposition, we determine that the morphology of the Lithium particles is strongly influenced by the chemistry of the polymer coating. We have identified polymer dielectric constant and surface energy as two key descriptors of the Lithium deposit size. Low surface energy polymers were found to promote larger Deposits with smaller surface areas. This may be explained by a reduced interaction between the coating and the Lithium surface and thus an increase in the interfacial energy. On the other hand, high dielectric constant polymers were found to increase the exchange current and gave larger Lithium Deposits due to the decreased overpotentials at a fixed current density. We also observed that the thickness of the polymer coating should be optimized for each individual polymer. Furthermore, polymer reactivity was found to strongly influence the Coulombic efficiency. Overall, this work offers new fundamental insights into Lithium electrodeposition processes and provides direction for the design of new polymer coatings to better stabilize the Lithium metal anode

  • Strong texturing of Lithium metal in batteries.
    Proceedings of the National Academy of Sciences of the United States of America, 2017
    Co-Authors: Feifei Shi, Allen Pei, Arturas Vailionis, Jin Xie, Bofei Liu, Jie Zhao, Yongji Gong, Yi Cui
    Abstract:

    Lithium, with its high theoretical specific capacity and lowest electrochemical potential, has been recognized as the ultimate negative electrode material for next-generation Lithium-based high-energy-density batteries. However, a key challenge that has yet to be overcome is the inferior reversibility of Li plating and stripping, typically thought to be related to the uncontrollable morphology evolution of the Li anode during cycling. Here we show that Li-metal texturing (preferential crystallographic orientation) occurs during electrochemical deposition, which governs the morphological change of the Li anode. X-ray diffraction pole-figure analysis demonstrates that the texture of Li Deposits is primarily dependent on the type of additive or cross-over molecule from the cathode side. With adsorbed additives, like LiNO3 and polysulfide, the Lithium Deposits are strongly textured, with Li (110) planes parallel to the substrate, and thus exhibit uniform, rounded morphology. A growth diagram of Lithium Deposits is given to connect various texture and morphology scenarios for different battery electrolytes. This understanding of Lithium electrocrystallization from the crystallographic point of view provides significant insight for future Lithium anode materials design in high-energy-density batteries.

Yang Shi - One of the best experts on this subject based on the ideXlab platform.

Michal Swietoslawski - One of the best experts on this subject based on the ideXlab platform.

  • Uniform Lithium electrodeposition for stable Lithium-metal batteries
    Nano Energy, 2020
    Co-Authors: Yang Yang, Marian Stan Cristian, Jun Wang, Xu Hou, Bo Yan, Tong Zhang, Elie Paillard, Michal Swietoslawski
    Abstract:

    Abstract A Lithium-metal composite is proposed, which includes a carbon-nitrogen modified stainless steel mesh (CNSSM) favoring homogeneous Lithium-metal nucleation and growth of fresh and dense Lithium Deposits when employed as anode for Lithium-metal batteries. This novel approach is able to overcome the usual drawbacks linked to the preexisting passivation layer at the surface of Lithium. Instead, a favorable interphase with low resistivity is formed with the electrolyte, and the CNSSM modified Lithium-metal composite (CNSSM-Li) results in low-voltage hysteresis (±24 mV) and allows stable and dendrite-free Lithium electrodeposition. The performance of Lithium-metal batteries demonstrates the outstanding capabilities of the novel CNSSM-Li electrode in promoting cell energy density and cycling stability. In addition, advanced X-ray nano-tomography is employed to characterize the composition and morphology changes of this electrode upon plating.