Conversion/alloy active materials, such as ZnO, are one of the most promising candidates to replace graphite anodes in lithium-ion batteries. Besides a high specific capacity (q ZnO = 987 mAh g–1), ZnO offers a high lithium-ion diffusion and fast reaction kinetics, leading to a high-rate capability, which is required for the intended fast charging of battery electric vehicles. However, lithium-ion storage in ZnO is accompanied by the formation of lithium-rich solid electrolyte interphase (SEI) layers, immense volume expansion, and a large voltage hysteresis. Nonetheless, ZnO is appealing as an anode material for lithium-ion batteries and is investigated intensively. Surprisingly, the conclusions reported on the reaction mechanism are contradictory and the formation and composition of the SEI are addressed in only a few works. In this work, we investigate lithiation, delithiation, and SEI formation with ZnO in ether-based electrolytes for the first time reported in the literature. The combination of operando and ex situ experiments (cyclic voltammetry, X-ray photoelectron spectroscopy, X-ray diffraction, coupled gas chromatography and mass spectrometry, differential electrochemical mass spectrometry, and scanning electron microscopy) clarifies the misunderstanding of the reaction mechanism. We evidence that the conversion and alloy reaction take place simultaneously inside the bulk of the electrode. Furthermore, we show that a two-layered SEI is formed on the surface. The SEI is decomposed reversibly upon cycling. In the end, we address the issue of the volume expansion and associated capacity fading by incorporating ZnO into a mesoporous carbon network. This approach reduces the capacity fading and yields cells with a specific capacity of above 500 mAh g–1 after 150 cycles.

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Dossier ‘Urk’: the role of aviation in relations between the Netherlands and the People’s Republic of China, 1949-96In the study of the history of international relations much of the focus has been on the high politics of alliances. Trading interests, generally regarded as belonging to the realm of low politics, have received less attention, although they were often significant. Aviation serves here as an example. As symbols of national prestige, airlines have played an important role in bilateral relations. An exchange of landing rights symbolizes a good relationship between countries. When disputes between countries arise, air transport is one of the first fields to suffer. Although the Netherlands recognized the People’s Republic of China in 1950, political differences ensured that a bilateral air transport agreement was not reached until 1979. It was not ratified, however. When The Hague approved the delivery of two submarines to the Taiwanese navy in 1980, Beijing regarded this as an unfriendly act. In the years that followed, Dutch airlines began services to Taiwan, under a private contract. This became a new obstacle to normal relations with the People’s Republic. Beijing regarded the Dutch air services to Taiwan as an infringement of Chinese sovereignty. Only after years of diplomatic skirmishes and the removal of all symbols of nationality from the aircraft used on the route to Taipeh was a bilateral air transport agreement with the People’s Republic signed in 1996. This shows that aviation played a more important role in bilateral relations than is generally assumed.

Mechanical modifications or harmful side reactions are undesirable ageing effects that can occur during cycling. These phenomena have a negative impact on cell performance and consequently limit cycling stability. The focus here is on investigations of ageing processes such as volume changes and electrolyte decomposition during cycling. Thickness measurements as well as gas analytical studies of Li-C half cells with a carbonate-based electrolyte are presented. Graphite and Hard Carbon, respectively, were used as carbon materials. The electrolyte applied consists of 1M LiPF6 in EC:DMC (1:1, wt). All investigations were carried out using specially developed multifunctional test setups and accordingly modified test cells. Application-oriented analysis such as gas analysis, thickness measurements or both combined are suitable methods to define operating parameter, to benchmark and to identify decomposition reactions.In-operando electrochemical dilatometry was conducted to check whether an irreversible increase in thickness occurred. On the corresponding cell configurations, the dilatation was recorded over the entire electrode stack as well as of the separate working electrode only.Furthermore, in-operando MS could be used to detect gaseous substances produced by (electro)chemical processes as a function of the state of charge. With the GC-MS, a post-mortem analysis could be performed to identify the individual substances qualitatively. Results of the different half cells are shown and can be compared with each other. A detailed relationship can be demonstrated between the change in thickness and the potential curve. Moreover, any emerging Li-plating is clearly detectable. Among others, carbon dioxide, ethane as well as ethene were identified as degradation products of the carbonate-based electrolyte and are formed during the charging process. In addition, possible correlations between gas evolution and thickness changes can be shown. These analytical studies make an important contribution to get a more detailed insight into ageing processes that take place. The possible combination of in-operando dilatometry with in-operando mass spectrometry opens up new interesting perspectives to analyse cell performance. Finally, the shown results lead to a better understanding and help to develop appropriate countermeasures in order to reduce the negative effects and thus to ensure a higher cycling stability. This work is supported by the Fraunhofer and Max Planck cooperation program (Germany) in the project “ClusterBatt” with Fraunhofer Institute for Material and Beam Technology IWS, Dresden and Max Planck Institute of Colloids and Interfaces MPIKG, Potsdam. Figure 1

Low-cost cell chemistries like metal-oxygen batteries are an essential component of future energy storage systems. Due to its very high theoretical energy density the system lithium-oxygen (Li-O2) is an interesting candidate.Gas analytical studies of Li-O2 cells with ether-based electrolytes are presented. The electrolytes used consist of 1M LiTFSI in DEGDME respectively TEGDME. The focus is on investigations of non-linear ageing processes such as electrolyte decomposition during cycling. All measurements were carried out using specially developed multifunctional test setups and accordingly modified test cells. Li-O2 measurements at different O2-flow rates were examined by GC-MS and in-operando MS.Next-generation battery systems typically suffer from severe gassing, which causes a loss of electrolyte and finally the cell to dry out. Consequently, the cycling stability is strongly limited. Gas analysis is a suitable method to identify decomposition and ageing reactions, to benchmark and to define operating parameters. With the GC-MS, a post-mortem analysis could be performed to identify the individual substances qualitatively. In addition, in-operando MS could be used to detect gaseous substances produced by (electro)chemical processes as a function of the state of charge.As major results, the cyclic formation of several degradation products can be demonstrated. CO2, hydrogen as well as methanol, methyl formate, methylal and 1,3-dioxolane were identified as characteristic decomposition products of DEGDME. Furthermore, the presence of many other oxygenated organic compounds can be detected, making it possible to trace the stepwise degradation of DEGDME as a function of the state of charge.These analytical studies make an important contribution to the understanding of the reaction mechanism and ageing reactions in Li-O2 cells with ether-based electrolyte. As a consequence, the shown results help to develop appropriate countermeasures in order to reduce the negative effects mentioned above and thus to ensure a higher cycling stability.This work is funded by the German Federal Ministry of Education and Research (BMBF) in the project “Osaban” (03XP0227B) which is part of the German-Japanese battery cooperation program. The project partners are University of Kyoto (Japan) and Justus-Liebig-University Gießen (Germany). Figure 1