Energy Dependencies in Li-Ion Cells and Their Influence on the Safety of Electric Motor Vehicles and Other Large Battery Packs

Abstract

For this work, the specific heat value of a Li-ion cell was determined experimentally as if it were a homogeneous body. The heat absorbed in the cell was compared with the amount of energy contained in the charged cell. It was found that a fully charged cell poses a risk of spontaneous combustion in the event of the release of electrical energy. On the basis of literature research, the combustion process of a lithium cell has been described. The formula was derived for the value of the state of charge that does not pose a risk of self-ignition. In view of the existing threats, the currently used protection against cell damage and tests to demonstrate the safety of cells were analyzed. It has been indicated that currently used battery management systems do not guarantee the safety in a state of developing thermal runaway process. A new active way of protecting cells in a battery has been proposed, consisting in sectoral discharge of cells. The use of this solution would be important for the improvement of fire safety in the automotive industry as well as in mining and in the construction of energy storage.

Lessons from the Electric Vehicle Crashworthiness Leading to Battery Fire

“…For the case of occupant protection against vehicle structure, deformation pressure on EV makers is exercised through advanced safety programs, termed as New Car Assessment Program (NCAP). The NCAPs and other regulations consider to test the vehicle as a whole [5]. A series of crash tests are usually performed to mimic the most common road incidents such as frontal impact, side impact, and rear-end crashes.…”

“…Currently, the strict environmental constraints have made the transport sector focus on the clean technologies to reduce emissions in the environment [1]. In this context, electric vehicles (EVs) have emerged as a promising solution to reduce the tank-to-wheel emissions in the road transport [2] as they offer a zero emission in the driving mode [3][4][5]. Besides, EVs have higher tank-to-wheel efficiency of about 60% to 80% compared to 20% to 35% [6] of conventional vehicles and lower recharge cost as electricity is cheaper than petrol/diesel fuels.…”

The Dependence of the Burning Process and Ignition Temperature of a Lithium Cell on Its State of Charge

“…The main disadvantages are a long safe charging time and low resistance to irregularities in the charging process [ 3 , 4 ], which may result in self-ignition or even explosion [ 5 , 6 ]. In the currently produced lithium cells, if the limit parameters are exceeded, a dangerous process of thermal runaway may develop [ 7 , 8 ]. In the papers [ 9 , 10 , 11 ], the course of the thermal runaway process for a fully charged cell was considered.…”

Design and additive manufacturing of brushless electric motor components

“…To combat both: pollution and the consumption of the limited fossil fuel resources, but also due to the increased reliability and efficiency of electric motors, recently, internal combustion engines have begun to be replaced, increasingly more, with electric motors. The largest share of the implementation of this solution is indisputably held by the automotive industry [1].…”