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Das Verhalten von Batteriezellen bei Beschädigung ist von hoher Bedeutung für die Einschätzung der Sicherheit bei Transport, Lagerung sowie Verwendung. Die Auswirkungen bei Schädigung hängen natürlich von der Art der Zelle, jedoch auch vom Ladezustand und der Schädigungsmethode ab.
Im Vortrag werden die Schädigungsversuche von Einzelzellen sowie Propagationsversuche an der BAM für verschieden Ladezustände präsentiert. Des Weiteren werden die aktuellen Vorgaben/Empfehlungen bezüglich der Lagerung von Lithium-Batterien kurz dargestellt. Darüber hinaus werden die neusten Entwicklung bezüglich der Vorgaben für den Transports von Natrium-Ionen-Batterien vorgestellt und diskutiert.
Porous carbons are promising anode materials for next generation lithium batteries due to their large lithium storage capacities. However, their highsloping capacity during lithiation and delithiation as well as capacity fading due to intense formation of solid electrolyte interphase (SEI) limit their gravimetric and volumetric energy densities. Herein we compare a microporous carbide-derived carbon material (MPC) as promising future anode for all solid-state batteries with a commercial high-performance hard carbon anode. The MPC obtains high and reversible lithiation capacities of 1000 mAh g−1carbon in half-cells exhibiting an extended plateau region near 0 V vs. Li/Li+ preferable for full-cell application. The well-defined microporosity of the MPC with a specific surface area of >1500 m2 g−1 combines well with the argyrodite-type electrolyte (Li6PS5Cl) suppressing extensive SEI formation to deliver high coulombic efficiencies. Preliminary full-cell measurements vs. nickel-rich NMC-cathodes (LiNi0.9Co0.05Mn0.05O2) provide a considerably improved average potential of 3.76 V leading to a projected energy density as high as 449 Wh kg−1 and reversible cycling for more than 60 cycles. 7Li Nuclear Magnetic Resonance spectroscopy was combined with ex-situ Small Angle X-ray Scattering to elucidate the storage mechanism of lithium inside the carbon matrix. The formation of extended quasi-metallic lithium clusters after electrochemical lithiation was revealed.
Das Verhalten von Batteriezellen bei Beschädigung ist von hoher Bedeutung für die Einschätzung der Sicherheit bei Transport, Lagerung sowie Verwendung. Vor allem im Zusammenhang mit dem exponentiell wachsenden Sektor der Lithium-Batterien kam es in der Vergangenheit immer wieder zu kritischen Vorfällen. Hierbei haben Lithium-Metall-Batterien, welche elementares Lithium enthalten, den Ruf besonders gefährlich zu sein. Um dieses Thema bewerten zu können, werden im Vortrag die Unterschiede zwischen Lithium-Ionen- und Lithium-Metall-Batterien erläutert und experimentelle Studien des Verhaltens von aktuellen Systemen bei Schädigung verglichen. Darüber hinaus wird auf die Eigenschaften sowie das Sicherheitsverhalten von zukünftigen Lithium- bzw. Natrium-Batterien eingegangen.
Lithium ion batteries (LIBs) are omnipresent in our daily lives. LIBs power our laptops and mobile phones, are the energy storage of choice for the electrification of vehicles, and play a vital role in the layout of the storage devices needed for the balancing of the grid.
Research groups all over the world work on the improvement of LIBs, e.g., an increase in energy density and cycle-life as well as a decrease in costs. In recent years, investigations concerning the LIB’s safety continuously gain importance, especially, pushed by incidents with electric vehicles. They are multiple levels at which safety measures can be implemented, i.e., material, cell, battery and system level. Accordingly, the behaviour of LIBs under abuse/misuse conditions are often investigated on those levels.
Here, we focus on the safety on cell level. Generally, the abuse/misuse leads to an increase in heat in the cell at worst triggering a chain of exothermic reactions. Hence, the cell’s temperature rapidly increases leading to the so-called thermal runaway (TR) possibly accompanied by flames and/or explosion of the cell. Herein, different hazardous features during the TR of different commercial cells are analysed such as temperature, flames, projectiles and toxic gases. In order to gain further insights on the parameters influencing the TR, different type of initiation modes, e.g., external heating, overcharging, nail penetration and external short circuiting are utilized. Moreover, the state of charges (SOCs) are varied to differ the amount of electrical energy present in the cells.
Next to the characteristic of the TR of a single cell, the investigation of the propagation of the TR from one cell to another is an important parameter, as a battery is usually composed of multiple cells. Due to the close packaging of the single cells, the TR of one cell is often able to initiate the TR of the surrounding cells, finally, causing the TR of the whole battery. Herein, the propagation ability is studied depending on the cell type and SOC. Finally, the results will be used to formulate (cell specific) conditions for a safe transport of LIBs. Moreover, the gained knowledge can support the development of advanced measures to increase the safety on cell level in the future.
Hard carbon is the material of choice for sodium ion battery anodes. Capacities comparable to those of lithium/graphite can be reached, but the understanding of the underlying sodium storage mechanisms remains fragmentary. A two‐step process is commonly observed, where sodium first adsorbs to polar sites of the carbon (“sloping region”) and subsequently fills small voids in the material (“plateau region”). To study the impact of nitrogen functionalities and pore geometry on sodium storage, a systematic series of nitrogen‐doped hard carbons is synthesized. The nitrogen content is found to contribute to sloping capacity by binding sodium ions at edges and defects, whereas higher plateau capacities are found for materials with less nitrogen content and more extensive graphene layers, suggesting the formation of 2D sodium structures stabilized by graphene‐like pore walls. In fact, up to 84% of the plateau capacity is measured at potentials less than 0 V versus metallic Na, that is, quasimetallic sodium can be stabilized in such structure motifs. Finally, gas physisorption measurements are related to charge discharge data to identify the energy storage relevant pore architectures. Interestingly, these are pores inaccessible to probe gases and electrolytes, suggesting a new view on such “closed pores” required for efficient sodium storage.