The back cover of the phone suddenly tilted up while using it.After riding the electric bike for several years, the battery casing began to deform.Even the battery pack of new energy vehicles may experience local swelling.Many people's first reaction when they see this scene is:Did the battery explode from chargingIn fact, what really makes the battery "fat up" is not just a simple charge, but the fact that a large amount of gas may have already been generated inside the battery.The question is: Where do these gases come from? Why do some batteries last for several years without any issues, while others quickly start to swell?More importantly, can the swollen battery still be used?1. Why does gas produce inside the batteryUnder normal circumstances, during the charging and discharging process of lithium-ion batteries, lithium ions move back and forth between the positive and negative electrodes without producing a large amount of gas inside the battery.But if there is an abnormal side reaction inside the battery, the situation is different.For example, if the electrolyte decomposes under high temperature, overcharging, or unstable material surfaces, it may produce gases.Especially during the initial use of the battery, a layer of SEI film will form on the negative electrode surface.If this layer of film is unstable, side reactions may continue to occur, consuming electrolyte and continuously producing gas.As the gas increases, the internal pressure of the battery keeps rising, which may eventually manifest as bulging.2. High temperature is the catalyst for battery bulgingMany people are unaware that temperature has a significant impact on the internal reactions of batteries.After the temperature rises, processes such as electrolyte decomposition and material side reactions will accelerate.It can be understood as:The higher the temperature, the easier it is for many "undesirable reactions" to occur inside the battery.Therefore, batteries that are exposed to high temperatures for a long time are more prone to problems such as capacity decay, increased internal resistance, and gas production.This is also why new energy vehicle batteries require complex thermal management systems.3. Overcharging can also cause the battery to become increasingly 'fat'If the battery is in an overcharged state for a long time, both positive and negative electrode materials may exhibit abnormal reactions.Especially when the battery is close to full charge and continues to be forcefully charged, internal side reactions may significantly increase.In severe cases, not only may gas production occur, but more dangerous problems such as lithium evolution and internal short circuits may also occur.So:Sometimes bulging is just an "external manifestation" of battery problems, and the real danger may occur internally.4. After bulging, can it still be usedNot recommended.If it is found that the lithium battery in a mobile phone, electric vehicle, or other device has visibly bulged, it indicates that there is an abnormality inside the battery cell.At this point, do not continue to squeeze, needle or disassemble the battery, and do not attempt to eliminate the bulge through "discharge".For batteries with obvious deformation, heating, or odor, they should be stopped from use and professionally disposed of according to local regulations.In conclusionThe battery is bulging, it just looks like the outer shell has become 'fat'.But inside this shell, a series of complex electrochemical reactions may be occurring.High temperature, overcharging, material side reactions, unstable SEI film, and manufacturing defects may all be the reasons behind bulging.

In recent years, new energy vehicles have rapidly become popular, but occasional spontaneous combustion incidents have also attracted public attention.Many people wonder: why do new energy vehicles still catch fire without engines and fuel?In fact, most new energy vehicle fire accidents are related to thermal runaway of the power battery.1.What is battery thermal runawayDuring normal operation, a large number of electrochemical reactions occur inside the power battery.But when the battery is subjected to abnormal stimuli, such as:Internal short circuit, overcharge and overdischarge, high temperature environment, mechanical collisionMay cause a rapid increase in internal temperature of the battery.When the temperature exceeds a certain range, continuous side reactions will occur inside the battery, releasing a large amount of heat and ultimately forming an uncontrollable heating process, which is called thermal runaway.2. Why did the battery suddenly catch fireThe interior of a lithium battery includes a positive electrode, a negative electrode, an electrolyte, and a separator.When an internal short circuit occurs, the positive and negative poles come into direct contact, generating a large amount of heat.As the temperature increases:Firstly, the SEI film begins to decompose;Subsequently, the electrolyte undergoes a violent reaction;After further heating, the positive electrode material may release oxygen;Ultimately, a large amount of heat and combustible gases are rapidly released, triggering combustion.This is also why lithium battery fires often have the characteristics of suddenness and rapid diffusion.3. What situations can easily lead to thermal runawayThe battery is impactedWhen a new energy vehicle experiences a serious collision, the battery pack may be compressed, causing damage to the internal structure and triggering a short circuit.Therefore, battery packs usually require the design of anti-collision protection structures.Long term high temperature useHigh temperatures can accelerate internal side reactions in batteries.If the cooling system is insufficient and the battery temperature continues to rise, it will increase the risk of thermal runaway.Battery agingAs the number of cycles increases, there will be:SEI film repeatedly generates and destroys;Damage to electrode structure;Internal resistance increases.Aging batteries are more prone to local heating problems.Unreasonable fast chargingDuring fast charging, a large amount of lithium ions need to be quickly embedded into the negative electrode.If the charging conditions are not suitable, lithium deposition may occur, forming lithium dendrites and increasing the risk of short circuits.4. How to prevent spontaneous combustion of new energy vehiclesAt present, power batteries mainly improve safety through various ways:The Battery Management System (BMS) monitors voltage, temperature, and current in real-time;Thermal management system controls battery temperature;Optimization of battery cell structure to improve heat resistance;Use more stable positive electrode materials.For example, lithium iron phosphate batteries have certain advantages in terms of safety due to their stable structure and high thermal decomposition temperature.In conclusionThe spontaneous combustion of new energy vehicles is not due to the fact that the battery will definitely burn, but rather the result of thermal runaway of the battery in extreme situations.The safety of power batteries is the result of the combined action of materials, cell design, battery management systems, and manufacturing processes.In the future, with the development of solid-state batteries, new materials, and intelligent monitoring technology, the safety level of new energy vehicles will continue to improve, making electric vehicles a more reliable mode of transportation.

In recent years, with the rapid development of the new energy vehicle and energy storage industries, the price fluctuations and supply issues of lithium resources have garnered increasing attention. Against this backdrop, sodium-ion batteries have gradually entered the public spotlight. Many people are now questioning: Will sodium-ion batteries replace lithium batteries? The answer may not be a simple "replacement," but rather a long-term coexistence of both technologies in the future.1. Why are sodium-ion batteries receiving attentionSodium-ion batteries operate on a principle similar to lithium-ion batteries, both utilizing the migration of metal ions between the positive and negative electrodes for charging and discharging. The key difference lies in the fact that lithium batteries rely on lithium ions, whereas sodium batteries depend on sodium ions. Sodium is abundant in the Earth's crust and has more stable pricing. Therefore, the primary advantages of sodium batteries are their abundant resources and lower costs.2. What are the advantages of sodium batteriesFirstly, the cost advantage is obvious. Sodium resources are abundant and do not rely on scarce elements such as lithium and cobalt, which is beneficial for reducing battery manufacturing costs. Secondly, it has good low-temperature performance.Some sodium ion battery systems can still maintain good charge and discharge capabilities in low-temperature environments. In addition, sodium batteries can use aluminum foil as the positive and negative electrode current collectors, reducing the use of copper foil and helping to further reduce costs.3. Why can't sodium batteries completely replace lithium batteriesThe biggest issue is energy density. Due to the larger mass and radius of sodium ions compared to lithium ions, there is relatively less energy that can be stored in the same volume. At present, the energy density of sodium ion batteries is usually lower than that of mainstream lithium batteries. This means that for new energy vehicles pursuing long endurance, lithium batteries still have significant advantages. In addition, the sodium battery industry chain and manufacturing process are still in the development stage and need further improvement.4. How will the two be divided in the futureWhat is more likely to happen in the future is the use of lithium batteries in high-energy demand scenarios and sodium batteries in low-cost application scenarios. For example, lithium batteries are suitable for high range new energy vehicles, high-end electronic devices, and weight sensitive applications. Sodium batteries are suitable for large-scale energy storage, low-speed vehicles, and backup power sources for base stations. Both will have advantages in different application fields.In conclusionThe emergence of sodium ion batteries is not simply to replace lithium batteries, but to provide another option for the new energy industry. Lithium batteries have a mature industrial chain and higher energy density, and will continue to occupy an important position in the long term in the future; Sodium batteries have shown great potential in energy storage and other fields due to their resource and cost advantages. The future battery market is likely to not be dominated by lithium over sodium, but rather by the joint development of multiple technological routes. Choosing the right battery for the right scenario is the true direction of new energy development.

In recent years, "solid-state batteries" have frequently appeared on the hot search list.Higher energy density, safer, longer battery life... Various promotions give people a feeling that solid-state batteries are about to be fully popularized.However, in reality, there are still limited solid-state batteries that can be installed on a large scale and produced stably.So someone asked: Is solid-state battery a scam?The answer is clear: it is not a scam, but there is indeed a "concept first" promotion in some parts of the market.1.What is a solid-state batteryTraditional lithium batteries use liquid electrolytes, and lithium ions rely on the electrolyte to move between the positive and negative electrodes.Solid state batteries attempt to use solid electrolytes instead of traditional liquid electrolytes.Its core value lies in the opportunity to improve battery safety and further match high-energy density electrode materials by changing the electrolyte system.But 'solid-state' does not mean 'automatic doubling of performance'.2. Why do everyone think it's powerfulThe biggest attraction mainly comes from two aspects.Firstly, the potential for safety.Solid electrolytes typically have better heat resistance, which can reduce the risks of leakage, volatilization, and combustion caused by traditional liquid electrolytes.Secondly, the potential for energy density.If solid electrolytes are successfully combined with lithium metal negative electrodes and other systems, there is a chance to reduce the weight of ineffective materials and improve the overall energy density of the battery.Please note that there is a keyword here:'Potential'.Being able to do it in the laboratory does not mean it can be mass-produced immediately.3. Where is the real difficultyThe biggest challenge for solid-state batteries is actually "moving from the laboratory to the factory".The contact between solids is not as easy as that between liquids.During battery charging and discharging, the electrode undergoes volume changes, and cracks, detachment, and increased interface impedance may occur between the solid electrolyte and the electrode.In addition, it is necessary to address issues such as material stability, manufacturing processes, yield rates, costs, and large-scale production.So, a high-performance solid-state battery in a laboratory is a completely different concept from being able to stably produce hundreds of thousands or even millions of battery cells.4. Why is it easy to have a sense of fraud in the marketThe problem often lies not in the technology itself, but in the way it is promoted.The term 'solid-state battery' is sometimes used in a generalized manner.Semi solid, quasi solid, solid-liquid mixed systems, and truly all solid state batteries are not exactly the same technological route.If you only see the word 'solid-state', it is easy to misunderstand that it has completely replaced liquid batteries.In conclusionSolid state batteries are not a sc am.It is a real and rapidly developing next-generation battery technology.But it is not a "magic technology" that has completely matured and is about to fully replace lithium-ion batteries.What is truly worth paying attention to is not the word "solid-state" in corporate advertising, but the type of electrolyte, actual energy density, cycle life, fast charging performance, cost, and mass production progress.Only by understanding these indicators can we distinguish between "technological breakthroughs" and "conceptual hype".Technology is worth looking forward to, but don't mistake 'what may be possible in the future' for 'what has already been achieved now'.

When it comes to batteries, many people's impression is of a hard 'battery cell'.But what if the battery could bend, fold, or even be sewn into clothes like paper, and still supply power normally?This is the flexible metal ion battery that has received much attention in recent years.It can not only store energy, but also adapt to complex deformations such as bending, stretching, and twisting, and is considered an important energy solution for wearable and flexible electronics.1. What is a flexible metal ion batteryFlexible metal ion batteries refer to secondary batteries that can maintain normal charging and discharging performance even when bent, curled, or deformed to a certain extent.The "metal ions" here not only include lithium ions, but also various battery systems such as sodium ions, zinc ions, potassium ions, etc.Compared with traditional batteries, its biggest feature is not higher capacity, but better mechanical flexibility.2. Why can it bendThe metal current collector, separator, and packaging materials in ordinary lithium batteries are relatively hard and easily damaged by repeated bending.And flexible batteries will use more flexible materials, such as:Flexible current collectorUltra thin electrode materialGel polymer electrolyteFlexible packaging filmThese materials work together to maintain stable electron and ion transport channels during the bending process of the battery.3. What are the advantages of flexible batteriesThe biggest advantage is adapting to complex deformations.For example, it can still work normally after bending, is lighter in weight, thinner in thickness, and easier to integrate with flexible electronic devicesTherefore, it is particularly suitable for application scenarios that require fitting to the human body or curved surfaces for installation.4. What are the main applications in which fieldsAt present, flexible metal ion batteries are mainly aimed at emerging electronic products, such as:Wearable devices such as smart bracelets and smartwatchesFlexible displayelectronic skinSmart ClothingMedical monitoring equipmentflexible sensorWith the development of flexible electronic technology, the demand for flexible energy storage devices is also constantly increasing.5. Why hasn't it been widely popularized yetAlthough research progress is fast, there are still many challenges in achieving industrialization.For example:The electrode material is prone to cracking after repeated bendingIt is difficult to balance the conductivity and mechanical strength of flexible current collectorsThe ionic conductivity of gel electrolyte still has room for improvementThe reliability after long-term cycling needs further verificationIn addition, the manufacturing process of flexible batteries is more complex and the cost is relatively high compared to traditional batteries.6. What is the future development directionThe current research focuses mainly on several aspects:Developing highly flexible electrode materialsBuilding a stable flexible electrolyte systemImprove cycle life and energy densityOptimize scalable production processesIn the future, flexible batteries should not only be "bendable", but also achieve the unity of "high capacity, long life, and high safety".In conclusionFlexible metal ion batteries are not simply "softening" traditional batteries, but the result of joint innovation in material design, structural design, and manufacturing processes. With the rapid development of industries such as wearable devices, flexible displays, and smart healthcare, the importance of flexible batteries will continue to increase. Perhaps in the near future, our clothes, watches, and even electronic skins will be continuously powered by these freely bendable batteries.

When using mobile phones, electric vehicles, or energy storage devices in daily life, we often hear two words:Overcharging and overdischarging.Many people know that they can damage batteries, but they do not understand the reasons behind it.In fact, the stable operation of lithium batteries relies on strict voltage range control. Once it exceeds this range, the internal structure of the battery may undergo irreversible changes.1. What is overcharging of lithium batteriesThe so-called overcharging refers to:After the battery has reached a fully charged state, it continues to charge.Under normal circumstances, lithium ions will detach from the positive electrode during charging, migrate through the electrolyte to the negative electrode, and embed into the negative electrode material.But when the negative electrode is close to saturation, continuing to input lithium ions will result in a situation of "nowhere to place".At this point, metal lithium may precipitate on the negative electrode surface; Continuous decomposition of electrolyte; The SEI film is constantly damaged and rebuilt; This is the main problem caused by overcharging.2. Why is overcharging dangerousFirstly, overcharging accelerates battery aging.Due to the increase in side reactions, a large amount of active lithium will be consumed, resulting in a decrease in the amount of recyclable lithium, manifested as:Capacity reductionInternal resistance increasesShortened cycle lifeSecondly, overcharging may pose safety risks.When there is severe overcharging, the positive electrode material may undergo structural changes and even release oxygen; At the same time, lithium precipitated from the negative electrode may form a dendritic structure.If lithium dendrites pierce the diaphragm, it may cause an internal short circuit and lead to uncontrolled heat generation.3. What is lithium battery over dischargeOverdischarging is the opposite of overcharging.It refers to:The battery level is already too low, but it continues to discharge.During the discharge process, lithium ions will detach from the negative electrode and return to the positive electrode.When the battery voltage drops to a low state, both the negative and positive electrode materials will undergo adverse changes.4. What are the impacts of excessive dischargeFirstly, the negative electrode structure may be damaged.Taking graphite negative electrode as an example, excessive lithium removal will change the material structure and reduce the subsequent lithium storage capacity.Secondly, copper current collectors may dissolve.When the battery voltage is too low, the negative electrode potential increases, and the copper foil may oxidize and dissolve to form copper ions.When recharging, these copper ions may deposit on the negative electrode, forming metallic copper particles and increasing the risk of short circuits.In addition, excessive discharge can also lead to:Permanent decrease in battery capacityInternal resistance increasesCycle performance deteriorates5. Why do batteries not easily overcharge or dischargeModern lithium batteries are typically equipped with a Battery Management System (BMS).It will monitor in real-time:voltageelectric currenttemperatureState of Charge (SOC)When the voltage reaches the upper or lower limit, the system will automatically stop charging or discharging.This is also why regular battery products generally do not easily experience severe overcharging or overdischarging.6. How to use lithium batteries correctlyTo extend battery life, please note:Avoid long-term charging to 100%Avoid frequent use until completely out of batteryAvoid high current charging in low-temperature environmentsUse legitimate charging equipmentFor ordinary users, keeping the battery level within a reasonable range is more beneficial for lifespan than frequently pursuing full and full charging.In conclusionThe overcharging and overdischarging of lithium batteries are essentially breakthroughs in the working boundary of the battery.Overcharging can easily lead to lithium deposition and increased side reactions;Overdischarge may cause structural damage and dissolution of the current collector.How long a battery can last depends not only on the material itself, but also on the way it is used.Only by understanding the principles of overcharging and overdischarging can we truly achieve scientific use of electricity and enable lithium batteries to perform for a longer period of time.