{"id":15811,"date":"2021-11-16T14:07:30","date_gmt":"2021-11-16T14:07:30","guid":{"rendered":"https:\/\/www.innovationnewsnetwork.com\/?p=15811"},"modified":"2021-11-16T14:07:30","modified_gmt":"2021-11-16T14:07:30","slug":"examining-lithium-ion-battery-safety-and-how-it-can-be-enhanced","status":"publish","type":"post","link":"https:\/\/www.innovationnewsnetwork.com\/examining-lithium-ion-battery-safety-and-how-it-can-be-enhanced\/15811\/","title":{"rendered":"Examining lithium-ion battery safety and how it can be enhanced"},"content":{"rendered":"

Dr Carlos Ziebert, Head of IAM-AWP\u2019s Calorimeter Center, KIT, answers frequently asked questions regarding battery safety and explains how it can be improved by battery calorimetry.<\/h2>\n
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Fig. 2: Burning mobile phone due to a defective charger \u00a9 Stock\/Aleksandr Pykhteev<\/figcaption><\/figure>\n

Everyone is familiar with the pictures of burning mobile phones, notebooks or even electric vehicles, such as e-bikes, electric cars and buses (as well as house fires) from the media (see Fig. 1 and 2). Many of these events can be traced back to a critical failure of lithium-ion batteries (LIBs), which are their power source. This has led to a more or less factual discussion in recent years, which ultimately led to uncertainty among (potential) customers worldwide. These customers have developed reservations about the use of \u2018equipment\u2019 that uses LIBs.<\/p>\n

It is clear that safety issues have a significant influence on consumers\u2019 willingness to adopt new technologies. It is well known that in comparison to other battery types such as nickel-metal hydride or lead-acid batteries, LIBs have the advantages of a high speci\ufb01c energy, long cycle life, and low self-discharge rates. However, battery accidents have raised concerns and have hindered the rapid market penetration of electric vehicles<\/a>, for example. Therefore, it is helpful to ask and answer several important questions.<\/p>\n

What causes a thermal runaway in a battery?<\/h3>\n

A safety risk arises when a permissible upper limit for the temperature of a cell is exceeded. If this is the case, exothermic reactions occur, resulting in an increase in temperature, which in turn triggers further reactions. If the dissipated heat is too low or the heat supply is too great, a heating-reaction cycle is created, characterised by the term \u2018thermal runaway\u2019.<\/p>\n

The literature does not clearly define the temperature rates from which one can speak of a thermal runaway. Our measurements show that the cell usually goes into thermal runaway from temperature rates of 10-60 K min-1. The fact that the chemical energy is about eight times that of the electrically stored energy illustrates the risk of such an uncontrolled release of this energy. The causes and effects of thermal runaway can be very diverse and complex (Fig. 3). A thermal runaway is preceded by an unusually high-temperature rise that requires a trigger.<\/p>\n

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Fig. 3: Causes and effects of thermal runaway in lithium-ion cells during normal use, abuse or accidents<\/figcaption><\/figure>\n

The causes can be internal as well as external:<\/p>\n