There has been an increase in the number of reported events involving lithium battery explosions. Let's talk about the causes of lithium battery failure. Even if you aren't familiar with lithium batteries since you aren't in the battery industry, you can't avoid them if you're just a regular person living on Earth. Lithium batteries are ubiquitous in modern life, powering everything from electric vehicles to computer motherboards. However, lithium batteries may inform you that they frequently trigger certain safety accidents. The fire and explosion created by lithium batteries is the most remarkable.
The Lithium-Ion Battery Operating Principle. A lithium-ion battery has several primary parts, including an electrolyte, a separator, a positive electrode, and a negative electrode. Insulators sit between the layers of positive and negative electrodes, which are tightly rolled together. Electrodes, both positive and negative, are submerged in the electrolyte. Below, we'll look at how cylindrical and prismatic batteries use lithium-ion structures with positive and negative electrodes made from distinct lithium intercalation compounds. Metal oxides, metal sulfides, and transition metal oxides are the most common types of cathode materials. Transition metal oxides are widely employed as cathode materials in commercial lithium-ion batteries. Inorganic non-metal materials, metals, metal-non-metal composites, and metal oxides are some of the most common types of anode materials. Electrodes are made by coating conductive materials with lithium iron phosphate anode and cathode materials; the electrode materials themselves define the battery's voltage and capacity. Electrolyte is a crucial component of lithium-ion batteries because it facilitates the flow of current during the charging and discharging processes.
A polyolefin separator is used to keep the positive and negative materials from coming into contact with one another in the electrolyte, which would cause a short circuit. Secondary lithium-ion batteries are those in which the concentration of lithium-ions is low. Li is transferred from the positive to the negative electrode via the electrolyte during charging. Lithium is abundant at the negative electrode and scarce at the positive. As a negative electrode, carbon receives the electrical compensatory charge from an external circuit. Lithium ions are introduced and removed between the layered carbon material and the layered structure oxide during normal charge and discharge, causing merely a change in the material's layer spacing and not compromising the crystal structure.
Do the frequent reports of fires and explosions in electric vehicles caused by lithium batteries prove that lithium batteries are unsafe? Submarines using lithium battery technology for conventional power in the military have no issues. But rather than fixate on the technology itself, we should investigate the causes of the electric vehicle fires.
Damage to the lithium battery's flammable layers of positive and negative electrodes, electrolytes, diaphragm, and other thin sheets can cause an explosion.
Lithium fires and spontaneous combustion are caused by the battery's temperature management. The phrase "thermal control" refers to the battery's ability to prevent the battery from exploding by preventing the internal short circuit that causes the battery's internal temperature to rise by thousands of degrees, the flammable electrolyte to boil and be ejected, and the battery to burn upon contact with air.
There are now three primary causes of short circuits, and they are mechanical, electrochemical, and temperature-related.
Extrusion, external impact, or needle damage to a battery can puncture the diaphragm, cause structural damage to the battery, or crack the shell, all of which can result in an electrode short circuit or electrode exposure, direct connection of the positive and negative electrode plates, or an internal short circuit, all of which can cause the battery to overheat and cause serious damage.
A key contributor to electrochemical loss of control is subpar battery quality. A major cause of spontaneous combustion in electric vehicles nowadays is either the aging of the lithium battery or the unqualification of the battery itself, both of which are the result of an internal short circuit. As soon as the warning indications of spontaneous combustion are recognized, the situation is usually irreversible.
The inside negative copper plate of the aging battery has trash and burrs adhering to it that are excessive. Copper metal pieces and burrs are introduced into the electrolyte during the charging and discharging processes and can readily puncture the diaphragm, leading to an internal short circuit. Because of this, companies making products for resale should avoid using recycled batteries.
The "villains" of electrochemical regulation in electric vehicles are overcharging and high-current fast charging.
Lithium ions on the surface of the negative form like branches when the battery is overcharged, and when the branches reach a certain length, they poke the diaphragm, causing a short circuit. This happens when an electric car is charged with an improper charging pile, charging pile, charging pile may output lithium battery unbearable current.
Additionally, the battery will produce a great deal of heat during the charging process due to the battery resistance. The lithium battery's safety mechanism can monitor voltage and prevent overcharging to some degree. Overcharging a lithium-ion battery for too long at too high of a voltage can result in a dendritic short circuit, which in turn raises the lithium battery's internal temperature and pressure, the battery drum pack failing, and an internal short circuit.
The fact that lithium batteries are so sensitive to high temperatures is a major contributor to the problem. High-temperature charging and discharging of lithium-ion batteries can lead to a number of problems, including diaphragm melting, chain reactions leading to combustion and explosion, and extensive short circuiting due to the release of oxygen. Battery fires are common in the summer due to improper charging in the hot sun without proper heat dissipation. Since battery deflagration can be devastating, manufacturers have developed a wide variety of safeguards to prevent it. Lithium batteries, which contain volatile liquid electrolytes, have been largely replaced by lithium-ion polymer batteries ever since the Samsung NOTE7 exploded.
Through our lithium battery distribution companies, we've found that merchants carrying such brands typically stock Samsung, LG, and other name-brand cells known for their reliability and longevity. The core components of a lithium battery are the electric cells and the BMS. The BMS system is responsible for shutting off the circuit when the battery is operating abnormally, and the cell is constructed with a safety valve to assure safety. Overcharge and discharge protection tests, as well as vibration and drop testing, will be performed on the lithium battery shell before it leaves the factory.
A good lithium battery with 48 volts can set you back more than $250, and batteries that cost too much may not have the essential safety guarantee.
Only two methods exist for gaining knowledge about ultra-cheap batteries. The first is to cut down on production expenses, and the second is to make use of raw materials and recycled batteries. The inexpensive price of the battery is due to the fact that it can be disassembled, reprocessed, and reused numerous times. In addition, there is a significant financial outlay necessary to meet the stringent environmental and machinery standards associated with lithium battery manufacture. It is feasible to make lithium battery without such equipment and atmosphere, but the quality or safety of the lithium battery production cannot be assured, albeit the cost is minimal.
Short circuits are the leading cause of lithium battery-related mishaps.
In common parlance, a short circuit occurs when the battery's positive and negative electrodes are connected in a channel with very low resistance.
Inside the battery, a massive amount of current and heat will be produced.
Even lithium batteries with airtight encapsulation will be severely harmed by the excess heat produced and electrical energy released.
The internal pressure of the battery will suddenly grow due to the generation of a given amount of pressure. Furthermore, the shell will eventually rupture and burn due to the highly reactive chemical characteristics of lithium ions.
When we overload a lithium-ion battery, the negative electrode cannot absorb any more lithium ions due to the battery's unique chemical features. Lithium ions also cause the phenomena of dendritic lithium by combining with lithium metal on the negative electrode's surface. Lithium dendrites can cause a short circuit in a battery if they reach a specific size and then puncture the diaphragm. Dentrite lithium will also corrode the protective layer. At some point, a safety incident will also be triggered by an internal short circuit.
Therefore, we need take great care to prevent short circuits and overcharges when using lithium batteries in our daily life. In most modern electronic devices, however, the charging circuit includes a safeguard IC that prevents the lithium battery from being overcharged. When the lithium battery has been charged to capacity, the protective circuit will immediately turn off the charging process.
But it's still not a good idea to leave your phone or other gadget plugged into the charger while it's on.
After all, nobody wants to risk their phone, other electronic gadgets, or even their own safety on a microchip meant only to safeguard charging.
Piercing lithium batteries is just as reckless as short-circuiting or overcharging them. Lithium ions inside the battery directly react chemically with oxygen in the air, causing the battery to burn violently if penetrated by a hard item.
It is quite risky to pierce our lithium battery once it has swelled, as this will happen ineluctably.
We frequently encounter attention-grabbing garbage can signs for lithium batteries and other electrical devices that contain lithium batteries. If lithium batteries are thrown away carelessly, they will pollute the environment and increase the risk of fires and other accidents at landfills.
Explosions and combustion are also possible outcomes of exposing lithium batteries to high temperatures or fire. In hot weather or when left in the car in the sun for an extended period of time, the lithium battery will be subjected to temperatures above its optimal storing range.
Therefore, we should aim to avoid prolonged use in high-temperature situations when operating equipment powered by lithium-ion batteries.
When lithium batteries are directly roasted by fire, they explode and burn for a long period, but they also experience a dramatic increase in internal pressure, often known as swelling.
If the internal pressure of our mobile phone batteries or other lithium-ion batteries begins to rise, we should immediately disconnect the power source and stop the swelling.
The electrolytr will break down if the charging voltage rises beyond 5V, which can happen if the protective circuit or the detecting cabinet are malfunctioning. Reactions inside the battery can get rather heated. The pressure inside the battery will eventually produce an explosion.
In the extremely unlikely event that either the protection circuit or the detection cabinet fails, the charging current will be too high, the lithium ions will arrive too late to be embedded, lithium metal will form on the electrode sheet's surface, penetrate the diaphragm, and cause an explosion when the positive and negative electrodes are directly shorted.
Lithium ions can't be incorporated into the cathode if the protective circuit or the detecting cabinet are malfunctioning. Additionally, lithium will be precipitated out as a thin film on the electrode sheet by the lithium ions. When that happens, the diaphragm will be pierced. Explosion due to electrical short.
Because of technical limitations in the welding equipment, ultrasonic energy is delivered to the battery cell during ultrasonic welding of the plastic case. The power of the ultrasonic waves is enormous. When the battery's internal diaphragm melts, the positive and negative electrodes short directly, leading to an explosion.
If the current during spot welding is too high, a major internal short circuit could result in an explosion. Spot welding also involves a direct connection between the positive electrode connecting piece and the negative electrode, which might result in an explosion if either electrode is accidentally shorted out.
It is simple for copper from the negative electrode to dissolve and deposit on the diaphragm when the battery is subjected to overcharging or overdischarging at a C-rate of 3C. Because of this, the circuit will short out and blow up.
Have no fear. This sort of thing doesn't usually happen in the real world.
Vibrations and drops can dislodge the battery's internal pole component, resulting in a direct catastrophic short and explosion.
As soon as the lithium battery cell is overcharged to a voltage of more than 4.2V, negative consequences will start to show up. The threat level increases as the overcharge voltage rises. When the voltage of a lithium battery cell rises above 4.2V, less than half of the original number of lithium atoms in the cathode material remain.
The storage cell usually fails at this point, permanently reducing the battery's capacity. If charging proceeds, lithium metal will be deposited on the surface of the negative electrode, even though the storage cell is already full with lithium atoms. From the negative electrode's surface, in the direction from which the lithium ions originate, dendritic crystals of lithium atoms will develop.
These lithium metal crystals will puncture the diaphragm and create a short circuit between the battery's positive and negative terminals. In some cases, a short circuit will cause the battery to explode first. Because the electrolyte and other materials will split during the overcharge process, releasing gas that will cause the battery shell or pressure valve to bulge and shatter. It also lets oxygen in, which triggers an explosion once it combines with the lithium atoms that have gathered on the surface of the negative electrode.
This means that the maximum voltage allowed when charging lithium batteries must be determined in advance. In order to simultaneously consider battery life, capacity, and security. Maximum charging voltage should not exceed 4.2V. When the lithium battery is depleted, there must also be a lower voltage restriction. When the voltage in the cell drops below 2.4V, material breakdown will commence.
The longer the battery is left on, the lower the voltage will get due to self-discharge. That's why you shouldn't charge it to more than 2.4V. When a lithium-ion battery is depleted from 3.0V to 2.4V, just roughly 3% of the battery's total capacity is used up in the process. The optimal discharge cut-off voltage is 3.0V.
The current limit is also important for charging and discharging procedures. If the current is too strong, the lithium ions won't have time to reach the storage cell, thus they'll instead accumulate there.
Lithium atoms will crystallize on the surface once these ions have acquired electrons, a process analogous to overcharging that can be harmful. If the battery case cracks, the battery will detonate. Consequently, at least the maximum charging voltage, minimum discharge voltage, and maximum current must all be present in a lithium-ion battery protection system.
Lithium battery packs typically include a protection board in addition to the lithium battery cells. These are the three main safeguards offered by this board. Despite the protection board's three layers of safety, lithium battery explosions are nevertheless a common occurrence in many parts of the world.
1. high degrees of polarization inside;
2. The pole takes in water and undergoes an electrochemical reaction. The reaction produces gas, which causes the battery to expand.
3. The effectiveness and efficiency of the electrolyte;
4. The injected volume of liquid is insufficient to suit the needs of the procedure;
5. When air leaks are identified, laser welding's poor sealing performance in the assembly process becomes apparent.
6. Micro-short circuits are easily initiated by dust and pole piece dust.
7. It's tough to go inside the shell because the positive and negative electrode components are thicker than the process range.
8. The issue of liquid injection sealing, the air bulge caused by the steel ball's subpar sealing ability;
9. The shell's incoming material has a thick shell wall, and this thickness is changed by the shell's deformation;
10. The high outside air temperature is mostly responsible for the blast.
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