Dongguan Everwin Tech Co., Limited Company News

"Lithium battery" is a type of battery that uses lithium metal or lithium alloy as the anode material and uses a non-aqueous electrolyte solution. In 1912, the lithium metal battery was first proposed and studied by Gilbert N. Lewis. In the 70s of the 20th century, M.S. Whittingham proposed and began to research lithium-ion batteries. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal have very high environmental requirements. Therefore, lithium batteries have not been applied for a long time. With the development of science and technology, lithium batteries have now become the mainstream. Lithium batteries can be broadly divided into two categories: lithium metal batteries and lithium-ion batteries. Lithium-ion batteries do not contain lithium in a metallic state and are rechargeable. The fifth-generation product of rechargeable batteries, lithium metal batteries, was born in 1996, and its safety, specific capacity, self-discharge rate and performance-to-price ratio are all better than those of lithium-ion batteries. Due to its own high technical requirements, only a few companies in a few countries are now producing such lithium metal batteries. Lithium-ion batteries can only be charged and discharged 500 times?I believe that the vast majority of consumers have heard that the life of lithium batteries is "500 times", 500 times of charge and discharge, more than this number of times, the battery will "end of life", many friends in order to be able to extend the life of the battery, every time the battery is completely exhausted before charging, so that the life of the battery really has a prolonging effect? The answer is no. The life of a lithium battery is "500 times", which refers not to the number of charges, but to a cycle of charge and discharge.A charging cycle means that all the battery power is used from full to empty, and then from empty to full, which is not the same as a single charge. For example, a lithium battery uses only half of its power on the first day, and then fully charges it. If it is still the case the next day, that is, it will be charged half of it, and a total of two charges will be charged, which can only be counted as one charging cycle, not two. As a result, it can often take several recharges to complete a cycle. With each completed charge cycle, the battery capacity decreases a little. However, this reduction in power is very small, and high-quality batteries will still retain 80% of their original capacity after multiple cycles, and many lithium-powered products are still in use after two or three years. Of course, lithium batteries still need to be replaced after the end of their life.The so-called 500 times means that the manufacturer has achieved about 625 rechargeable times at a constant discharge depth (such as 80%), reaching 500 charging cycles.(80%*625=500)And due to the various effects of real life, especially the depth of discharge when charging is not constant, so "500 charge cycles" can only be used as a reference battery life. Correct statement: The life of lithium battery is related to the number of completion of the charging cycle, and there is no direct relationship with the number of charging times.Simple understanding, for example, a piece of lithium battery uses only half of the charge on the first day and then fully charges it again. If it is still the case the next day, that is, it will be charged half of it, and a total of two charges will be charged, which can only be counted as one charging cycle, not two. As a result, it can often take several recharges to complete a cycle. With each completed charge cycle, the charge decreases a little. However, the reduction is very small, and high-quality batteries will still retain 80% of the original power after multiple cycles, and many lithium-powered products are still in use as usual after two or three years, which is the reason. Of course, the lithium battery still needs to be replaced in the end when it reaches its life. The life of lithium battery is generally 300~500 charging cycles. Assuming that the amount of electricity provided by a complete discharge is Q, if the reduction of power after each charge cycle is not considered, the lithium battery can provide or supplement a total of 300Q-500Q of power during its lifetime. From this, we know that if you charge 1/2 each time, you can charge 600-1000 times; If you charge 1/3 each time, you can charge 900~1500 times. And so on, if it is charged randomly, the number of times is indefinite. In short, no matter how it is charged, a total of 300Q~500Q of electricity is replenished, which is constant. Therefore, we can also understand it this way: the life of lithium battery is related to the total charging power of the battery, and has nothing to do with the number of charges. There is little difference between deep and shallow charging and shallow charging on the life of lithium batteries. In fact, shallow discharge and shallow charging are more beneficial for lithium batteries, and only when the power module of the product is calibrated for lithium batteries, there is a need for deep discharge and deep charging. Therefore, the use of lithium battery powered products do not have to stick to the process, everything is convenient, charge at any time, do not have to worry about affecting the life.If the lithium battery is used in an environment higher than the specified operating temperature, i.e. above 35°C, the battery will continue to decrease, that is, the battery will not be powered for as long as usual. If you have to charge the device at such temperatures, the damage to the battery will be even greater. Even storing batteries in a hot environment will inevitably cause corresponding damage to the quality of the battery. Therefore, keeping it at a suitable operating temperature as much as possible is a good way to extend the life of the lithium battery. If you use lithium batteries in a low temperature environment, that is, below 4 °C, you will also find that the battery life is reduced, and the original lithium battery of some mobile phones cannot even be charged in a low temperature environment. But don't worry too much, this is only a temporary situation, unlike use in a high-temperature environment, once the temperature rises, the molecules in the battery are heated and immediately return to their previous power.In order to maximize the efficiency of lithium-ion batteries, it is necessary to use them frequently, so that the electrons in the lithium battery are always in a flowing state. If you don't use lithium battery often, please remember to complete a charging cycle for lithium battery every month and do a power calibration, that is, deep discharge and deep charge once.The formal name is "charge and discharge cycle", not equal to "charge times", the cycle refers to the battery from full charge to use up, this is a cycle, if your battery from a full state, used a tenth of the power, and then full again, this is a tenth of a cycle, so that 10 times, is basically a cycle. Again, from a full charge, half of it is used and then it is fully charged, and then it is half of it and then it is fully charged, which is also a cycle, at which point you are charged twice. Therefore, the cycle only depends on the "cumulative amount of power released from the battery", and is not directly related to the "number of charges". How to maintain the battery of your mobile phone:1. Each time it is fully charged, it can reduce the number of charging times and improve the battery life.2. You don't need to completely discharge the battery, usually the power is less than 10% and you need to charge it.3. Use the original charger to charge, do not use the universal charger to charge.4. Do not use your phone during charging.5. Don't overcharge, stop charging after the battery is full. According to the experimental results, the life of lithium batteries is constantly attenuated with the increase of charging times, and the general charging times of lithium batteries are 2000-3000 times. Cycle is use, we are using the battery, we are concerned about the time of use, in order to measure the performance of how long the rechargeable battery can be used, the definition of the number of cycles is specified. Actual user use is ever-changing, because the test with different conditions is not comparable, and the definition of cycle life must be standardized in order to be compared.Lithium battery cycle life test conditions and requirements stipulated in the national standard: under the condition of ambient temperature of 20 °C ± 5 °C, charge at 1C, when the battery terminal voltage reaches the charging limit voltage of 4.2V, change to constant voltage charging, until the charging current is less than or equal to 1/20C, stop charging, put on hold for 0.5h~1h, and then discharge at 1C current to the termination voltage of 2.75V, after the discharge is over, set aside for 0.5h~1h, and then carry out the next charge-discharge cycle until the discharge time is less than 36min for two consecutive times , it is considered to be at the end of life, and the number of cycles must be greater than 300 times.

"KC" certification is a national unified certification mark implemented by the Korean National Standards Committee, and lithium batteries are included in the KC certification catalog as a compulsory certification product. Ⅰ.Scope of KC certification for battery products 1. Single battery: carrying;2. Battery: single cell straight parallel assembly manufacturing;3. Lithium single batteries with navigation functions or batteries that have nothing to do with the energy density per volume are applicable objects;4. Single batteries and batteries used in portable medical devices, barcode and credit card readers and other products are applicable;5. Portable machines: MP3, electronic dictionary, PMP, laptop, digital camera, etc.;6. Breakdown of portable products: batteries used in mobile products also belong to the certification object;7. Non-certification objects: vehicle drive, industrial, medical. Ⅱ.Lithium battery to do KC certification precautions 1. Models cannot be applied for in the same institution.2. KC certificate does not accept any changes involving the basic model, if you need to change the certificate:A.Only the series models can be consideredB. You can only cancel the original certificate and reapply3. It is recommended that lithium battery products do not directly apply for KC certification, but can apply for CB certification first, and then use CB certification to convert to KC certification, which has the following benefits:A. The fees are comparatively cheaper. The cost of KC directly is more expensive, and it is necessary to send samples to South Korea for testing, which increases the courier fee and the difficulty of certification. By doing CB first, and then using CB to apply for KC certification, the cost is relatively cheaper, and there is no need to send samples to Korea.B. The cycle is comparatively shorter. To do KC certification directly, you need to send samples to South Korea for testing, and the sample plus test cycle basically takes more than 3 months, while through CB to apply for KC, CB certification cycle is 3-4 weeks, and it only takes a few weeks to transfer to KC, and KC certification can be done in more than a month, which is more efficient. Ⅲ.Updates to the KC 62133-02 (2020) regulation for the certification requirements for coin cell batteries On January 4, 2021, KATS clarified the requirements for rechargeable button batteries to apply for KC safety certification in South Korea. Batteries with pouch shape and thickness smaller than diameter fall within the scope of KC 62133-02 (2020).

What is Energy Density?Energydensity refers to the amount of energy stored in a certain unit of space or mass of matter. The energy density of a battery is the amount of electricity emitted by the average unit volume or mass of the battery. The energy density of a battery is generally divided into two dimensions: weight energy density and volume energy density.Battery weight energy density = battery capacity × discharge platform/weight, the basic unit is Wh/kg (watt-hours/kg)Battery volume energy density = battery capacity ×discharge platform/volume, the basic unit is Wh/L (watt-hours/liter)The greater the energy density of a battery, the more power can be stored per unit volume or weight.What is Monomer Energy Density? The energy density of a battery often refers to two different concepts, one is the energy density of a single cell, and the other is the energy density of a battery system.A battery cell is the smallest unit of a battery system. M cells form a module, and N modules form a battery pack, which is the basic structure of automotive power batteries.The energy density of a single cell, as the name suggests, is the energy density at the level of a single cell.According to the "Made in China 2025", the development plan of power batteries has been clarified: in 2020, the energy density of batteries will reach 300Wh/kg; In 2025, the energy density of the battery will reach 400Wh/kg; In 2030, the energy density of batteries will reach 500Wh/kg. This refers to the energy density at the level of a single cell. What is System Energy Density? System energy density refers to the weight or volume of the entire battery system after the combination of monomers to the weight or volume of the entire battery system. Because the battery system contains the battery management system, thermal management system, high and low voltage circuits, etc., which occupy part of the weight and internal space of the battery system, the energy density of the battery system is lower than that of the single body.System energy density = battery system power / battery system weight OR battery system volumeWhat exactly limits the energy density of lithium batteries?The chemistry behind the battery is the main reason.Generally speaking, the four parts of a lithium battery are very critical: the positive electrode, the negative electrode, the electrolyte, and the diaphragm. The positive and negative electrodes are the places where the chemical reaction takes place, which is equivalent to the second pulse of Ren Du, and its important position can be seen. We all know that the energy density of a battery pack system with ternary lithium as the cathode is higher than that of a battery pack system with lithium iron phosphate as the cathode. Why is that?The existing anode materials of lithium-ion batteries are mainly graphite, and the theoretical gram capacity of graphite is 372mAh/g. The theoretical gram capacity of lithium iron phosphate, the cathode material, is only 160mAh/g, while the ternary material nickel-cobalt-manganese (NCM) is about 200mAh/g.According to the barrel theory, the water level is determined by the shortest point of the barrel, and the lower limit of energy density of lithium-ion batteries depends on the cathode material.The voltage platform of lithium iron phosphate is 3.2V, and the ternary index is 3.7V, compared with the two phases, the energy density is high: a difference of 16%.Of course, in addition to the chemical system, the level of the production process such as compaction density, foil thickness, etc., will also affect the energy density. Generally speaking, the larger the compaction density, the higher the capacity of the battery in a limited space, so the compaction density of the main material is also regarded as one of the reference indicators of the energy density of the battery.In the fourth episode of "Great Power Heavy Equipment II", CATL uses 6-micron copper foil to improve the energy density by using advanced technology.If you can stick to each line, read it all the way to this point. Congratulations, your understanding of batteries has gone up to the next level. How can we increase energy density?The adoption of new material system, the fine adjustment of lithium battery structure, and the improvement of manufacturing capacity are the three stages for R&D engineers to "dance with long sleeves". Below, we will explain from the two dimensions of monomer and system.——The energy density of monomers mainly depends on the breakthrough of the chemical system1. Increase the size of the batteryBattery manufacturers can achieve the effect of power expansion by increasing the size of the original battery. The most familiar example is that Tesla, the well-known electric vehicle company that pioneered the use of Panasonic 18650 batteries, will replace it with a new 21700 battery.However, the "fattening" or "growing" of the battery cell is only a symptom, not a cure. The method of drawing wages from the bottom of the kettle is to find the key technology to improve the energy density from the positive and negative electrode materials and electrolyte components that make up the battery cell.2. Chemical system reformAs mentioned earlier, the energy density of a battery is limited by the positive and negative electrodes of the battery. Since the energy density of the current anode material is much greater than that of the cathode, it is necessary to continuously upgrade the cathode material to improve the energy density. High nickel cathodeTernary materials generally refer to the large family of nickel-cobalt-manganese oxides, and we can change the performance of batteries by changing the ratio of nickel, cobalt, and manganese.In the figure silicon carbon anodeThe specific capacity of silicon-based anode materials can reach 4200mAh/g, which is much higher than the theoretical specific capacity of graphite anode of 372mAh/g, so it has become a strong substitute for graphite anode.At present, the use of silicon-carbon composite materials to improve the energy density of batteries has been recognized as one of the development directions of lithium-ion battery anode materials in the industry. Tesla's Model 3 uses a silicon carbon anode.In the future, if you want to go one step further - break through the 350Wh/kg threshold of single cells, industry peers may need to focus on lithium metal anode battery systems, but this also means the change and improvement of the entire battery manufacturing process. It can be seen that the proportion of nickel is getting higher and higher, and the proportion of cobalt is getting lower and lower. The higher the nickel content, the higher the specific capacity of the cell. In addition, due to the scarcity of cobalt resources, increasing the proportion of nickel will reduce the amount of cobalt used.3. System energy density: improve the grouping efficiency of the battery packThe group of battery packs tests the ability of the battery "siege lions" to arrange the single cells and modules, and it is necessary to maximize the use of every inch of space on the premise of safety.

In the parallel connection of lithium batteries, it is critical to ensure the consistency of battery parameters, including capacity, open-circuit voltage, and internal resistance. Only if these parameters are close can the batteries be paralleled, and for safety reasons, additional protection plates are required. In the case of multiple cells in parallel, if one of the cells has a lower capacity while the other parameters are the same, this poses some potential problems. During the charging process, if the batteries connected in parallel are not equipped with a protection board, a charger with a limited voltage of 4.2V must be used to prevent the lithium battery from overcharging and causing explosion. Even if a protection plate is installed, the battery with low capacity will be fully charged first, and long-term overcharge will lead to an increase in the internal electrolyte and the occurrence of side reactions, which will lead to battery leakage. Batteries with low capacity can also be over-discharged during discharge, which not only reduces battery life, but also poses a risk of leakage. Therefore, batteries that have been in a state of overcharge and overdischarge for a long time have great safety risks, and may even cause explosions or fires. Considering that your battery comes from the power bank disassembly, the parameters may be inconsistent, and you are not sure whether a protective board is installed, it is strongly recommended not to assemble and use it by yourself, so as not to cause potential safety hazards.

Lithium-ion batteries are complex electrochemical and mechanical systems that are the subject of dozens of international safety standards. In this FAQ, we'll discuss the critical environmental aspects of LIB safety, review common safety standards for lithium-ion batteries, and consider the use of custom battery test chambers to keep testers safe. Many LIBs are safety concerns because these devices are voltage and temperature sensitive, and the battery is specified to operate in a temperature range of -30 to 55°C.At temperatures above 55°C (to about 80°C), the battery exhibits better rate capability due to faster electrochemical reactions and rapid ion migration of the electrolyte and electrodes. In this case, the side reactions become severe, resulting in rapid volume decay. At temperatures above 80°C, the battery begins to be damaged, and anything above 130°C can cause the components of the battery to melt and potentially cause a fire. Low temperatures can cause poor battery performance and can cause damage, but they are generally not a safety hazard. However, overcharging (too high voltage) can lead to cathodic decomposition and oxidation of the electrolyte, which is a safety concern. Overdischarge (too low voltage) can cause the solid electrolyte interface (SEI) on the anode to decompose and may cause oxidation of the copper foil, further damaging the battery. In addition to voltage and temperature-related operational and environmental issues, mechanical damage can lead to safety issues with the LIB. In light of these concerns, the security standards for LIBs are equally extensive.The five common safety standards for lithium-ion batteries are:　　 1,IEC62133　　 IEC62133 is a safety test standard for lithium-ion batteries and batteries, and is a safety requirement for testing secondary batteries and batteries containing alkaline or non-acidic electrolytes. It is used to test LIBs used in portable electronics and other applications. IEC 62133 addresses chemical and electrical hazards and mechanical issues such as vibration and shock that can threaten consumers and the environment.　 2,UN/DOT38.3 UN/DOT38.3 (also known as T1-T8 testing and UN ST/SG/AC.10/11/Rev. 5) covers all LIBs, lithium metal batteries, and transport safety testing of batteries. The test standard consists of eight tests (T1 – T8), all of which focus on specific transport hazards. UN/DOT 38.3 is a self-certification standard that does not require independent third-party testing, but the use of third-party testing laboratories is common to reduce the risk of litigation in the event of an accident.　　 3,IEC62619 IEC62619 covers the safety standards for secondary lithium batteries and battery packs, specifying the requirements for the safe application of LIBs in electronic and other industrial applications. The IEC 62619 standard test requirements apply to both stationary and power applications.Stationary applications include telecommunications, uninterruptible power supplies (UPS), electric energy storage systems, utility switches, emergency power supplies, and similar applications. Power applications include forklifts, golf carts, automated guided vehicles (AGVs), railways, and ships – excluding road vehicles. 4,UL1642 UL1642 is the UL standard for the safety of lithium batteries, specifying the standard requirements for primary and secondary lithium batteries used as a power source in electronic products.UL1642 covers: 1.Technician-replaceable lithium batteries containing 5.0 grams (0.18 ounces) or less of metallic lithium. Batteries containing more than 5.0 grams of lithium will be judged on their compliance with the requirements (if applicable) and will be subject to additional tests and inspections to determine whether the battery can be used for its intended use.2. User-replaceable lithium batteries, each electrochemical cell contains no more than 4.0 grams (0.13 ounces) of lithium metal, and no more than 1.0 grams (0.04 ounces) of lithium metal. Batteries over 4.0 grams or batteries over 1.0 grams of lithium require further inspection and testing to determine if the battery or battery can be used for its intended use. 5,UL2580x UL2580x is the UL standard for electric vehicle battery safety and consists of several tests, including: High-current battery short-circuit: Runs on a fully charged sample. The sample is shorted using a total circuit resistance of ≤ 20mΩ. Spark ignition detects the presence of flammable concentrations of gases in the sample and shows no signs of explosion or fire. In addition, steam is not vented to the outside through designated vents or systems. There will be no cracked housing or observable signs of electrolyte leakage. If the LIB is still operational after a short-circuit test, it will be charged and discharged in accordance with the manufacturer's specifications. Short-circuit tests can be performed on sub-assemblies rather than the entire energy storage assembly (EESA).　　 Battery Extrusion: Run on a fully charged sample and simulate the impact of a vehicle crash on EESA integrity. Like the short-circuit test, spark ignition detects the presence of a flammable concentration of gas within a sample and there are no signs of explosion or fire. No toxic gases are released.　　 Cell extrusion (vertical): Runs on a fully charged sample. The force applied in the extrusion test must be limited to 1000 times the weight of the battery. Like the crush test, spark ignition detects the presence of a flammable concentration of gas within the sample and there are no signs of explosion or fire. No toxic gases are released.　　

Everwin Tech Co., Limited was established in 2009 and is a professional battery manufacturer specializing in reserach design and producing power solutions for all kinds of market . EWT Battery provide ODM, OEM battery solutions for medical, solar lighting, smart metering low speed vehicle and solar power storage system for cusstomer all over the world. Our products are widely used in various fields such as electric bicycles, electric motorcycles, electric scooters, electric forklifts, outdoor and home energy storage, electric tools, wireless vacuum cleaners, smart homes, security, medical and other fields. We provide a full range of intelligent manufacturing and services, including project evaluation, scheme design, battery pack structure design, battery pack production, as well as product inspection and after-sales service, aiming to efficiently provide customers with the most competitive lithium battery solutions.