AABC Europe 2015 - LLIBTA Symposium: Large Lithium Ion Battery Technology and Application - Session 2

Advanced Battery Chemistries for Automotive and Utility Energy Storage

This session reviewed the recent developments and future prospects of new chemistries as well as advanced cathodes, anodes, and electrolytes that promise to deliver better performance at equal or lower cost, or equal performance at lower cost, than the current technologies, and thus to provide enhanced value.

Session Chairman:

Martin Winter is the scientific director of the MEET Battery Research Center at Muenster University. MEET stands for Münster Electrochemical Energy Technology and the director of the Helmholtz Institute Muenster (HI MS) “Ionics in Energy Storage”. Prof. Winter has been the spokesperson of the Innovation Alliance LIB 2015 of the German Federal Ministry of Education and Research. Today he is an associate of the National Platform E-Mobility (NPE) and he is the head of the research council of the Battery Forum Germany. For his scientific achievements Martin Winter has been awarded amongst others with the Battery Technology Award of the Electrochemical Society and the Research Award as well as the Technology Award of the International Battery Materials Association and as Fellow of The Electrochemical Society.

1. Li-Ion and Beyond: Recent Advances
   Jean-Marie Tarascon, Professor of Chemistry, Collège de France
   

   With the ingress of renewable energies we are entering a new era of sustainable energy harvesting which conspires to make electrical storage more important than ever for the years to come. Batteries, by converting chemical energy into electricity, appear as an attractive option. Therefore, our success towards this transition depends on our ability to develop battery systems (Li-ion or others) that could store electricity reliably and in a sustainable way at both large scale and low cost. This calls for transformational changes enabling the design of new insertion materials together with the emergence of new concepts while keeping aware of sustainability issues. Within this context some of the recent directions and advances dealing with the Li-ion technology or other technologies beyond Li will be reviewed and discussed. Special attention will be given to electrodes cumulating both cationic and anionic redox processes and to other battery technologies such as the Na-ion for instance.
2. Lithium-Ion Battery with Highly-Concentrated Electrolytes
   Atsuo Yamada, Professor, Department of Chemical System Engineering, University of Tokyo
   

   We introduce a “salt-superconcentrating” strategy as a simple yet effective method of expanding a graphite negative electrode reaction in a wide variety of organic solvents. This can break the battery-performance limitation based on an EC-based electrolyte to open up a way to advanced lithium-ion batteries. As a typical example, unusual reductive stability as well as very fast graphite intercalation provided by a superconcentrated AN electrolyte will be demonstrated. The origin of the remarkable properties were analyzed with spectroscopic analyses and first-principle density functional theory based molecular dynamics (DFT-MD) simulations.

   • Narrow electrolyte option severely limited by EC
   • Modified local coordination structure in superconcentrated electrolyte
   • Enhanced stability and kinetics
   • Anion-based SEI: experimental&computational evidences
   • Paradigm shift: diverse slat-solvent combination for new functional electrolytes
3. Towards High-Voltage Cathodes Using New Electrolyte Approaches
   Martin Winter, Chair, Applied Material Science for Energy Conversion and Storage, MEET Battery Research Center, Institute of Physical Chemistry, University of Muenster
   

   A higher energy and power of a lithium ion battery can be achieved with cathode materials operating at a higher voltage.^{[1, 2]}
   LiNi_xMn_yCo_zO₂ (NMC, with x + y + z  = 1) with its most prominent protagonist LiNi_1/3Mn_1/3Co_1/3O₂ ("1/3-NMC") is regarded as one of the most competitive cathode materials due to the combination of decent capacity, lesser thermal and electrochemical instability in the charged state and lower cost compared to the well-known LiCoO₂. Using 4.3 V vs. Li/Li⁺ as upper cut-off potential, 1/3-NMC delivers a specific charge of ca. 150 mAh g^-1 (at low C-rates) and shows stable cycling performance at an average discharge potential of 3.86 V vs. Li/Li⁺ (= ca. 3.7 V cell voltage vs. graphite).^[1] With increasing the cut-off potential from 4.3 to 4.6 V vs. Li/Li⁺, almost linear growth of the specific charge of ca. 190 mAh g^-1 at a slightly higher potential of 3.95 V vs. Li/Li⁺ can be obtained.^[3]
   However, cycling at 4.6 V vs. Li/Li⁺ inevitably results in a rapid capacity decay. Various failure mechanisms have been discussed in literature so far, including: oxidative decomposition of the conventional carbonate/LiPF₆ electrolyte,^[4] increase of the overall battery impedance,^[5] increased transition metal dissolution of the active material in the electrolyte due to manganese disproportional reaction and acidic attack by HF,^{[4, 6]} oxygen release from the host structure,^{[7, 8]} or irreversible phase changes.^[8]
   In order to solve the problems associated with instabilities at the cathode/electrolyte interface, two approaches are intensively discussed in literature. On the one hand, there is the design of an electrolyte, which is thermodynamically stable vs. oxidation at the operation potential of the cathode. On the other hand, the addition of small amounts of film-forming electrolyte additives or the application of surface coatings and modifications of the cathode/electrolyte interface, lead to kinetic stability.^[9] Here we report on novel approaches for new classes of electrolyte additives that improve the cycling stability of 1/3 NMC (used as model material for other high voltage cathode materials) at elevated cathode potentials, i.e., metal cation additives and novel HF scavengers.

    

   Acknowledgements
   Parts of this work have been supported by BMW group.

   References:

   • ^[1] R. Wagner; N. Preschitschek; S. Passerini; J. Leker; M. Winter, Journal of Applied Electrochemistry 2013, 43, 481.
   • ^[2] A. Kraytsberg; Y. Ein-Eli, Advanced Energy Materials 2012, 2, 922.
   • ^[3] H. Zheng; Q. Sun; G. Liu; X. Song; V. S. Battaglia, Journal of Power Sources 2012, 207, 134.
   • ^[4] P. Niehoff; M. Winter, Langmuir 2013, 29, 15813.
   • ^[5] J. Zhou; P. H. L. Notten, Journal of Power Sources 2008, 177, 553.
   • ^[6] D. R. Gallus; R. Schmitz; R. Wagner; B. Hoffmann; S. Nowak; I. Cekic-Laskovic; R. W. Schmitz; M. Winter, Electrochimica Acta 2014, 134, 393.
   • ^[7] F. La Mantia; F. Rosciano; N. Tran; P. Novák, Journal of the Electrochemical Society 2009, 156, A823.
   • ^[8] J. Choi; A. Manthiram, Journal of the Electrochemical Society 2005, 152, A1714.
   • ^[9] K. Xu, Chemical Reviews 2004, 104, 4303.
4. Beyond Li-Ion Battery Technologies: The Challenge of Li-Sulfur Batteries
   Doron Aurbach, Professor of Chemistry, Director of the Nano Cleantech Center, Bar-Ilan Institute of Nanotechnology and Advanced Materials (BINA)
   

   In this presentation we review first in brief the limitation of advanced Li ion batteries, and explain the impetus to develop new high energy density battery technologies. The use of high capacity sulfur cathodes for Li batteries can take us further in terms of energy density. We start with simple Li-sulfur battery systems, describing their failure mechanisms and their delicate surface chemistry aspects. After understanding the limitations of these systems based on spectroscopic (FTIR, XPS, Raman) and microscopic (SEM, HRTEM, AFM) studies (in conjunction with electrochemical tools), we describe our efforts to develop stable, long cycle-life systems. There are ‘magic’ solutions for Li-sulfur systems based on ethereal solvents or some ionic liquids. Excellent, long life sulfur cathodes are prepared by encapsulation of sulfur in activated carbon matrices. The structure of these matrices and the encapsulation method used play an important role. It is also possible to fabricate effective composite sulfur electrodes starting with Li2S by using red-ox mediators in solutions. Finally, once we are pleased with the sulfur side, we face the real problem with is the negative electrodes. Li metal is irrelevant for practical rechargeable ling life batteries. We discuss a possible use of Li-silicon anodes, thus pushing the SLS concept (Si-Li-S batteries).