First, the variety of batteries. In various power batteries, lithium-ion batteries have the highest specific energy, chemical side reactions heat, the most likely to cause an increase in air pressure in the battery, the heavy explosion, the light electrolyte leakage is easy to burn. Metal hydride/nickel batteries and lead-acid battery electrolytes are alkaline and acidic aqueous solutions, there is a risk of corrosion when leaking, but the combustion, the explosion is much lower, but not absolutely no problem.
Second, the level of battery design. Lithium-ion battery cathode materials such as lithium ferrous phosphate, safety is higher than other cathode materials, but problems can occur, most of the accidents that have occurred in recent years are lithium ferrous phosphate as the cathode battery; negative electrode with hard carbon, safety can be better than the graphite class; electrolyte, diaphragm selection are likely to improve the safety of the battery. But these technologies are often at the expense of the battery's specific energy and specific power, which should be considered. The NiMH battery bus fire in Zibo, Shandong Province in April this year may be due to the attempt to pursue high power and replace the hydrogen storage alloy in the negative electrode with too much-activated carbon, resulting in an excess of active material in the positive electrode, leading to the accumulation of hydrogen gas in the battery. Lead-acid batteries also undergo water electrolysis into hydrogen and oxygen when overcharged, and this problem has been better solved.
I. Variety of batteries. Among various kinds of power batteries, lithium-ion batteries have the highest specific energy and large heat release from chemical side reactions, which are most likely to cause an increase in air pressure inside the battery, which can lead to an explosion in heavy cases, and electrolyte leakage and easy combustion in light cases. Metal hydride/nickel batteries and lead-acid battery electrolytes are alkaline and acidic aqueous solutions, there is a risk of corrosion when leaking, but the combustion, the explosion is much lower, but not absolutely no problem.
Second, the level of battery design. Lithium-ion battery cathode materials such as lithium ferrous phosphate, safety is higher than other cathode materials, but problems can occur, most of the accidents that have occurred in recent years are lithium ferrous phosphate as the cathode battery; negative electrode with hard carbon, safety can be better than the graphite class; electrolyte, diaphragm selection are likely to improve the safety of the battery. But these technologies are often at the expense of the battery's specific energy and specific power, which should be considered. The NiMH battery bus fire in Zibo, Shandong Province in April this year may be due to the attempt to pursue high power and replace the hydrogen storage alloy in the negative electrode with too much-activated carbon, resulting in an excess of active material in the positive electrode, leading to the accumulation of hydrogen gas in the battery. Lead-acid batteries also undergo water electrolysis into hydrogen and oxygen when they are overcharged, and this problem has been better solved.
Third, the quality of the battery. Some manufacturers do not test the battery trial out of the long-term full test, even the failure rate of the single battery parameters can not be counted on the eager delivery of the vehicle demonstration, the safety of the battery pack from what to talk about? The same lithium-ion batteries with lithium iron phosphate as the positive electrode, some manufacturers produce more accidents, some less, and some do not occur at all; the same factory, improve the production process, strengthen quality control, the probability of battery accidents significantly reduced. All these fully illustrate the important role of improving product quality to improve safety. In addition, the quality of the battery monomer is also shown in the life, capacity, internal resistance, and self-discharge rate of consistency, they are also closely related to safety.
Fourth, the total capacity of the battery. The total capacity of the battery is the product of the number of cells of the battery and the capacity of every single cell. It goes without saying that this is a fundamental factor proportional to the probability of an accident. Overloading batteries in pursuit of range and a top speed of electric vehicles not only wastes energy and materials, price rises while the market is small, and the heat in charging and discharging is more difficult to dissipate, but also increases the probability of accidents. This is the traditional car experts "fuel car inertia thinking", regardless of the current level of battery blindly pursuing high indicators and the misrepresentation of the serious safety risks.
Fifth, the length of time used. Can also be used to charge and discharge times or driving mileage to express this factor. After continuous use of the battery pack, the capacity of each individual decreases, and the degree of internal resistance increases differently, and the longer the use of these differences, the probability of problems increases.
Sixth, the effectiveness of security measures. The management system is to ensure the normal operation of the battery pack of effective components, management system failure may have serious consequences. Battery pressure relief mechanism (safety valve, etc.) can effectively prevent the battery from exploding, the higher its reliability, the lower the probability of an explosion. However, the electrolyte or gas released from the pressure relief mechanism still has the risk of combustion after meeting with air, which may be the reason why the flexible packaging and plastic case batteries do not explode but will burn.
Seven, the use of rational. Do not act according to the characteristics of the battery pack, the consequences are serious. At present, the use of battery packs exists fast charging, fully charged, discharged, overload, and other problems. Overcharging and over-discharging will not only damage the life of the battery but also increase the risk of accidents. Even full charging and discharging at nominal capacity should not be encouraged. Excessive load and speed are required to use excessive current, the battery temperature will rise steeply, such as the absence or failure of overcurrent protection mechanism, will likely trigger the occurrence of safety accidents.
VIII. Other factors. For example, the regulation power and adaptability of electric vehicles to various unexpected factors (such as severe impact, accident hazards), etc.
