![]() The role of the thermal insulation layer is to provide the thermal connection between the heating sleeve and the sample. The inside wall of the heating sleeve is thermally insulated. A Li-ion battery with the dimensions 18650 (cylindrical geometry with d = 18 mm and l = 65 mm) can be fitted into the centre of the heating sleeve. The sample holder consists of a metal structure, which houses a heating sleeve and the thermocouples. (b) The reactor is the main component of the test stand.Ī removable sample holder is placed inside the reactor. 1 (a) The reactor and its principal elements. The whole structure is hosted inside a fume hood to prevent any escaping of gases and electrolyte vapours.įig. The pressure inside the reactor is recorded by a pressure transmitter. The reactor has gas feedthroughs that connect it to an inert gas flask, to a gas sampling station and to a cold trap with an attached vacuum pump. The main component of the test rig is a heatable reactor with electric feedthroughs for the temperature measurement and the inner sample heating. 2 Experimental 2.1 Brief description of the test rig To carry out unrestricted thermal-runaway experiments, a custom-designed test stand was built ( Fig. To further assess the hazard potential of the released gases, samples were taken and analysed with a gas chromatography system. Particular attention was given to (1) the dynamics of the thermal responses of the cells, (2) the maximum temperatures reached, (3) the amount of gases produced and (4) to the production rates of the gases. This work investigated the thermal stability of three types of commercially available Li-ion batteries for consumer electronics. Such experiments were undertaken with commercial Li-ion batteries produced for consumer electronics 3–11 and with Li-ion batteries fabricated in the laboratory. 4 To quantify possible hazards of exothermic Li-ion battery over-temperature reactions, tests with complete batteries should be performed. 2ĭuring thermal runaway, temperatures as high as 900 ☌ can be reached, 3 and the battery can release a significant amount of burnable and (if inhaled in high concentrations) toxic gas. This catastrophic self-accelerated degradation of the Li-ion battery is called thermal runaway. The reactions lead to a further temperature increase, which in turn accelerates the reaction kinetics. At a critical temperature, a chain of exothermic reactions can be triggered. Abuse conditions such as overcharge, over-discharge and internal short-circuits can lead to battery temperatures far beyond the manufacturer ratings. However, there are concerns regarding the safety of Li-ion batteries. Li-ion batteries have a high specific energy and favourable ageing characteristics compared to NiMH and lead acid batteries. They are also gaining traction as a power source in electrified vehicles. 1 As of 2013, Li-ion batteries are in wide use for portable electronics, such as cell phones and notebook computers. 1 Introduction Li-ion batteries have been commercially available since 1991. The active cathode materials of the three tested cell types were (a) LiFePO 4, (b) Li(Ni 0.45Mn 0.45Co 0.10)O 2 and (c) a blend of LiCoO 2 and Li(Ni 0.50Mn 0.25Co 0.25)O 2. This work investigated the influence of different cathode-material chemistry on the safety of commercial graphite-based 18650 cells. The safety of Li-ion batteries is determined by their composition, size, energy content, design and quality. The main gas components were quantified with gas-chromatography. Cell temperatures up to 850 ☌ and a gas release of up to 0.27 mol were measured. The Li-ion batteries were deliberately driven into thermal runaway by overheating under controlled conditions. In this work we demonstrate the thermal runaway characteristics of three types of commercially available Li-ion batteries with the format 18650. Therefore, it is important to understand the potential risks involved with these devices. Li-ion batteries play an ever-increasing role in our daily life.
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