Safety Aspects of Li-Ion Batteries

Even though the mechanism of thermal runaway is initiated by the anode in combination with the electrolyte [2], the rapid temperature rise in the cell, which dominates the overall heat generated during this process, is produced by the cathode reacting with the electrolyte [3, 4]. Therefore, it is of utmost importance to find a more structurally stable cathode in order to use lithium batteries at their fullest potential [5]. 

Lithium ion cells have historically used lithium metal oxides as cathode materials due to their high capacity for lithium intercalation, and suitable chemical and physical properties required for Li-ion electrodes. Layered materials with LiM02 structure, where M = Co, Ni, Mn, or a combination of these metals, have been the most extensively used and investigated cathodes. These types of cathodes show excellent performance, but suffer from higher cost, toxicity (LiCo02), and thermal instability (LiNi02). hi order to avoid these problems, another hthium metal oxide material with spinel stracture LiMn204 has been proposed to substitute the layered materials. This oxide is inexpensive and environmentally friendly, but has 

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In general, ensuring a safe product begins at cell level and ends with the user. The IEEE 1625 and 1725 standards committees have recently focused on conveying the concept that Li-ion battery-pack safety is a function of the entirety of the cell, pack, system design and manufacture [8,9]. A system-level approach thus becomes very essential in addressing the safety of Li-ion batteries. System-level safety includes the combination of cell, battery pack, host device, power supply or adapter end user/environment, and each of these aspects has a role to play in ensuring pack safety. 

SAFETY ASPECTS OF THE LI-ION BATTERY AND THE ADVANTAGES OF USE OF IONIC LIQUIDS... 

While additives meant to improve the SEl certainly constitute a major portion of the additive research for Li-ion batteries, many other additives aim to improve different aspects of the Li-ion batteries, such as the safety characteristics, ionic conductivity of the electrolyte, and high/low temperature performance of the electrolyte. For example, researchers have developed redox shuttle and overcharge shutdown additives to protect the battery from overcharge and the resulting thermal mnaway, flame retardant additives to reduce the flammability of the electrolyte, and anion receptors to enhance the ionic conductivity and increase the lithium transference number. These additives may not be critical to the cell performance, but may be very important and possibly necessary in commercial batteries. 

Several representative battery chemistries are discussed below. Each section covers a commercially important cell chemistry, briefly describing the relevant aspects of the materials used and the safety response. A more detailed discussion is presented for li-ion batteries since they are a relatively new chemistry and because of their commercial importance. 

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