Lithium-ion batteries have high energy density, long cycle life and good charge and discharge performance. However, when a lithium-ion battery has an internal short circuit, it means that an abnormal conductive path has appeared between the positive and negative electrodes inside the battery.Under normal circumstances, lithium ions are orderly embedded and extracted between the positive and negative electrodes through the electrolyte during the charge and discharge process, and the diaphragm can effectively prevent the direct conduction of electrons between the positive and negative electrodes. However, when an internal short circuit occurs, the insulation between the positive and negative electrodes is destroyed, and electrons can bypass the normal circuit path and flow directly from the positive electrode to the negative electrode, forming a low-resistance short circuit. This abnormal current path will lead to a series of serious consequences and is one of the important reasons for battery failure.Common causes of short circuit in lithium-ion batteries(1) Manufacturing defectsMetal impurities: During the manufacturing process of lithium-ion batteries, if the cleanliness of the production environment is not well controlled or the raw materials contain metal impurities, these metal impurities may be mixed into the battery. When the metal impurity particles penetrate the diaphragm and contact the positive and negative electrodes, a conductive path will be formed between the positive and negative electrodes, causing an internal short circuit.Electrode burrs: During the manufacturing process of the electrode, if the operation is improper or the equipment is not accurate enough, tiny burrs may be generated on the edge of the electrode. These burrs may gradually penetrate the diaphragm as the battery is used, causing an internal short circuit.(2) Damage during useMechanical stress: In the daily use of lithium-ion batteries, they are inevitably subject to various mechanical stresses. For example, if a mobile phone is accidentally dropped or an electric car is driven on a bumpy road, the battery may be impacted or squeezed. When the battery is subjected to large mechanical stress, the internal electrodes, diaphragms and other structures may be deformed or damaged. For example, the diaphragm may rupture, resulting in direct contact between the positive and negative electrodes, thereby causing an internal short circuit.Temperature influence: Temperature has an important influence on the performance and safety of lithium-ion batteries. When the battery is in a high temperature environment, the chemical reaction rate inside the battery will accelerate, which may lead to problems such as electrolyte decomposition. Under extremely high temperature conditions, the performance of the diaphragm will decrease, and it may even melt, causing the isolation between the positive and negative electrodes to fail and causing an internal short circuit. On the contrary, under low temperature conditions, the internal resistance of the battery will increase and the migration rate of lithium ions will slow down, which may also cause excessive local current inside the battery and cause an internal short circuit.(3) Battery agingAs the number of charge and discharge cycles of lithium-ion batteries increases, the battery will gradually age. During the aging process, a series of complex physical and chemical changes will occur inside the battery. For example, a thicker SEI film will gradually form on the surface of the negative electrode. The growth of this film may reduce the activity of the negative electrode material and may also produce some cracks. When these cracks expand to a certain extent, the contact between the negative electrode and the electrolyte may deteriorate, thereby causing local current concentration and leading to internal short circuits. In addition, as the number of cycles increases, the crystal structure of the positive electrode material may also change, resulting in a decrease in the stability of the material, which may also indirectly increase the risk of internal short circuits.Impact of short circuit in lithium-ion batteries(1) Battery capacity decayInternal short circuits can cause self-discharge inside the battery, where a large amount of electrical energy is consumed in vain and cannot be output to the outside for use by the device. Similarly, after an internal short circuit occurs in a lithium-ion battery, its actual available capacity will gradually decrease, and the device's endurance will also be greatly reduced.(2) Increased battery internal resistanceWhen an internal short circuit occurs, the current distribution inside the battery becomes uneven, and high current density appears in local areas. The increase in battery internal resistance will not only increase the energy loss of the battery during charging and discharging, reduce the battery's energy conversion efficiency, but also cause the battery to heat up during charging and discharging. If the battery is in a high internal resistance state for a long time, its life will be further shortened, accelerating the battery's failure process.(3) Increased risk of thermal runawayThermal runaway is one of the most serious consequences of an internal short circuit in a lithium-ion battery. When an internal short circuit occurs, a large amount of electrical energy is converted into heat energy in a short period of time, causing the temperature inside the battery to rise sharply. As the temperature rises, the chemical reaction inside the battery will further intensify, generating more heat, forming a vicious cycle. If this heat cannot be dissipated in a timely and effective manner, when the temperature reaches a certain threshold, the battery will experience thermal runaway. In the thermal runaway state, the battery may smoke, catch fire or even explode, posing a great threat to personal safety and property safety.Therefore, in order to prevent short circuits in lithium-ion batteries, manufacturers need to optimize the manufacturing process; users also need to strengthen management of use; regular inspection and maintenanceBosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack

The battery capacity of portable energy storage products is usually in the range of 500Wh-3000Wh, and the power of the supporting solar panels is between 40W-200W.The battery capacity of household energy storage products is usually in the range of 3000Wh-6000Wh, and the power of the supporting solar panels is between 200-500W.1. Portable energy storage refers to small devices with built-in lithium-ion batteries, which can also be used as "Outdoor Power Supply"Portable energy storage power supply with a capacity of less than 500Wh:①Entry-level style for outdoor travel, suitable for suburban picnics, outdoor entertainment needs, etc., mainly for powering small-power electrical equipment such as TVs, small refrigerators, electric fans, etc.②Take 300Wh products as an example, it can support 16 mobile phone charging, 3 laptop charging, 5+ hours of car refrigerator, and 3+ hours of TV operation③The capacity is small and the average price is low④Small weight, light volume, easy to carryPortable energy storage power supply with a capacity of 500-1000Wh:①Outdoor travel demand model, suitable for camping, cycling, fishing, sports, outdoor entertainment needs, etc., mainly used for outdoor and home emergency electricity②Take 600Wh products as an example, it can support 6 hours of small refrigerator operation, 1.5+ hours of 330W rice cooker charging, 7 times of laptop charging, and 30+ times of camera charging③Moderate capacity and moderate average unit price④Small weight, light volume, easy to carryPortable energy storage power supply with a capacity of <3000Wh:①Long-distance travel demand model, suitable for outdoor activities such as long-distance self-driving, mainly used for outdoor long-distance activities and household emergency electricity, and can power more than 95% of household appliances②Take 1200Wh product as an example, it can support projector working for 9 hours, TV working for 15 hours, 50W car refrigerator working for 25 hours③Large capacity, high average unit price④Moderate weight and volume2. Household energy storage power source refers to a small household energy storage device with a capacity of 3-6 kWh, equipped with solar panels to achieve self-generation, self-storage and self-use energy storage systemEnergy storage power supply with a capacity of about 3000Wh:①A replacement product for generators, providing sufficient power for home and outdoor activities, suitable for long-distance outdoor activities and emergency rescue applications, making it an ideal choice for various power demand scenarios②Can be used for 110W TV to work for 25 hours, 120W refrigerator to work for 24 hours, mobile phone charging 100+ times, 900W electric oven to work for 2+ hours③Large capacity, high average unit price④Heavy weight and large volumeEnergy storage power supply with a capacity of more than 5000wh-6000Wh:①Small household energy storage equipment, suitable for RV travel, long-distance outdoor travel, household power backup power supply, emergency power supply and other application scenarios②Take 5000Wh product as an example, it can provide 520W refrigerator to work for 10 hours, 100W projector to work for 25 hours, 900W air conditioner to work for 4.5 hours, 1400 water pump to work for 3.5 hours③High capacity, high average unit price④Heavier weight and larger volumeBosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack

The Battery Management System (BMS) is the core control system of the battery pack, responsible for monitoring, protecting and optimizing battery performance to ensure its safe, reliable and efficient operation.Core functions of BMSThe main functions of BMS can be divided into the following categories:1. Battery status monitoringVoltage monitoring: Real-time monitoring of the voltage of each battery cell and the entire battery pack, accurately obtaining voltage data, so as to promptly detect voltage abnormalities, such as overvoltage, undervoltage, etc., and provide basic information for the safe use and performance evaluation of the battery.Current monitoring: Accurately measure the current size and direction during the battery charging and discharging process, understand the battery charging and discharging status and energy flow, and then calculate the battery charging and discharging capacity, providing an important basis for estimating the remaining battery capacity.Temperature monitoring: Real-time monitoring of the temperature at different locations of the battery pack. Since the battery will generate heat during the charging and discharging process, too high or too low temperature will affect the performance and life of the battery, and even cause safety problems, so accurate temperature monitoring is the key to ensuring battery safety and performance.2. Battery status evaluationSOC estimation: Based on the battery's voltage, current, temperature and other parameters, multiple algorithms such as ampere-hour integration method, open circuit voltage method, neural network method, etc. are used to estimate the remaining battery capacity in real time, so that users can clearly understand the available battery capacity, so as to reasonably arrange the use of equipment.State of Health (SOH) Assessment: By analyzing the battery's charge and discharge history data, internal resistance changes, capacity attenuation, etc., the battery's health status is assessed, the remaining service life of the battery is predicted, and a reference is provided for battery replacement and maintenance, which helps to improve the reliability and stability of the equipment.3. Charge and discharge managementCharging control: During the charging process, the charging current and voltage are accurately controlled according to the battery status and charging requirements to ensure that the battery can be charged in a safe and efficient manner, prevent overcharging, undercharging, and overheating, and extend the battery life. For example, the constant current-constant voltage charging mode is adopted. At the beginning of charging, the battery is charged with a constant current. When the battery voltage reaches a certain value, it is switched to constant voltage charging until the charging is completed.Discharge control: Monitor the battery's discharge process to prevent the battery from over-discharging. When the battery voltage or power reaches the set lower limit, the discharge circuit is cut off in time to protect the battery from irreversible damage. At the same time, according to the load requirements, the battery's output power is reasonably allocated to ensure that the battery can provide stable power under different working conditions.4. Battery safety protectionOvervoltage protection: When the voltage of a battery pack or a single cell exceeds the safety threshold, the BMS will quickly take measures, such as cutting off the charging circuit or limiting the charging voltage, to prevent the battery from bulging, burning or even exploding due to overvoltage.Overcurrent protection: Once it is detected that the battery charge and discharge current exceeds the maximum allowed value, the BMS will immediately cut off the circuit to prevent the battery and other equipment from being damaged by overcurrent, and also prevent overheating and fire risks caused by excessive current.Overheat protection: When the battery temperature is too high, the BMS will start the heat dissipation mechanism, such as turning on the fan or stopping the charge and discharge operation, to reduce the battery temperature and prevent the battery from accelerating aging or safety hazards due to high temperature. In addition, the battery can be heated in a low temperature environment to ensure that the battery works within a suitable temperature range.Short circuit protection: When a short circuit occurs inside or outside the battery pack, the BMS can quickly detect and cut off the circuit to prevent the short circuit current from causing serious damage to the battery and equipment, and ensure personal and equipment safety. 5.Balance management: Due to the differences in manufacturing process, initial capacity, self-discharge rate, etc. among the cells in the battery pack, inconsistencies are prone to occur during the charging and discharging process, resulting in a decrease in the overall performance of the battery pack. BMS uses active or passive balancing technology to balance the cells in the battery pack, so that each cell can be charged and discharged in a nearly identical state, thereby improving the overall capacity and service life of the battery pack. 6.Communication function: BMS communicates with external devices through specific communication protocols (such as CAN, RS485, etc.), transmits battery status information (such as voltage, current, temperature, SOC, SOH, etc.) to the control system or user interface of the device, and receives control commands from the outside to achieve remote monitoring and management of the battery, so that users can understand the battery's operating status in a timely manner and perform corresponding operations and adjustments.Bosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack

Generally, thermal runaway of lithium batteries is caused by three types of abuse, namely mechanical abuse, electrical abuse, and thermal abuse.Among them, mechanical abuse refers to the battery being subjected to external forces such as collision, extrusion, and puncture;Electrical abuse refers to the battery being subjected to internal and external short circuits, overcharge, and discharge;Thermal abuse refers to the battery being subjected to external heating.In fact, these three types of abuse are not completely independent, but are chain-related. The relationship between the three types of abuse is shown in the figure.As can be seen from the figure, mechanical abuse will first lead to electrical abuse, and then electrical abuse will lead to thermal abuse, and finally trigger thermal runaway.The reason why mechanical abuse leads to electrical abuse is that external force causes the internal diaphragm of the lithium battery to rupture, causing the positive electrode to connect with the negative electrode, thereby causing an internal short circuit, which is a case of electrical abuse.The reason why electrical abuse leads to thermal abuse is that once a short circuit occurs inside the lithium battery, a large amount of heat will be released, and chemical reactions under higher temperature conditions will be triggered, which will further release heat, which is equivalent to the external heat source constantly heating the battery, that is, thermal abuse.Once the heat inside the battery accumulates to a certain extent, thermal runaway will break out.Bosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack

1. Definition and calculation logic of surface densitySurface density is a core parameter in the design of lithium-ion battery pole piece, which is defined as the mass of active material per unit surface area of the electrode (unit: mg/cm²).The calculation formula is: Surface density = compaction density (g/cm³) * pole piece thickness (μm)/1000The surface density directly determines the content of active materials per unit area of the pole piece and is a regulatory lever for energy density (battery life) and rate performance (charging speed).2. The impact of surface density on battery life: the "amplifier" of energy densityHigh surface density improves battery life. The higher the surface density, the more active materials the positive electrode can accommodate per unit surface area, and the energy density increases accordingly.The cost of battery life: internal resistance and thermal runaway risk. High surface density leads to increased thickness of the pole piece, longer lithium ion diffusion path, increased internal resistance and increased heat generation, which may cause thermal runaway.3. The impact of surface density on charging speed: the "double-edged sword" of fast charging performanceLow surface density optimizes fast charging capability. When the surface density decreases, the pole piece becomes thinner, the lithium ion diffusion path is shortened, the polarization effect is weakened, and the internal resistance is reduced, which is more suitable for fast charging scenarios.Hidden dangers of extreme low surface density: Too low surface density will increase the difficulty of coating process, reduce mechanical strength (easy to break), and require more pole piece layers to be stacked, which will increase costs and safety risks.Theoretically, the smaller the surface density, the more conducive it is to improving rate performance. However, the surface density design also has a lower limit. In addition, the battery has not only rate requirements, but also capacity requirements. Simply reducing the surface density will inevitably increase the number of layers of the pole piece, and the increase in the number of layers also increases the risk.The balance rule of R&D engineers: How to design the optimal surface density?Application scenario priority, material and process coordination, dynamic test verificationBosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack

On April 19, the world's first humanoid robot half marathon was held in Beijing. On the 21.0975-kilometer track, 20 robot teams from universities, research institutes, and enterprises participated in the first "human-robot co-run".The 180cm tall and 52kg"Tiangong Robot Ultra" won the championship by running at a constant speed of 7 to 8 kilometers in 2 hours and 40 minutes.Batteries are not only the power source of robots, but also directly affect their endurance, performance and application scenarios.This competition not only ignited the public's enthusiasm for smart manufacturing, but also made the application of lithium battery technology in the field of robotics a focus.Core application requirements of batteries in the robotics field①High energy density and lightweightHigh energy density allows the robot to have a longer battery life and continue to drive without slowing down.Lightweight structure can match the structural limitations of humanoid robots or service robots and reduce load②High safety design and environmental adaptabilityStable output, through overcharge and overdischarge protection, thermal runaway protection (such as high temperature resistance of lithium iron phosphate battery), to avoid power outage or overheating during operation.③High power output and fast charging or quick replacement capabilitiesThe battery of "Tiangong Robot Ultra" was replaced 3 times during the whole process, and the robot was not replaced. The first battery replacement took 1 minute and 50 seconds to complete.④Long cycle life and intelligent managementMarathon is not only a race, but also a microcosm of future intelligent manufacturing applications. From automatic food delivery robots, intelligent logistics vehicles, to inspection unmanned vehicles, special service robots... they all rely on the support of high-performance lithium batteries.Bosa EnergyBosa Energy with 150GWH capacity and over 400,000 electric bus/utility vehicle application experience we are listing first 5 in China power battery industry. We cooperate with Yutong/Geely/Damiler etc.We are also offering Container ESS systems and delivered 6GWh in 2024(=75,000 Model3 with 80kWh battery). In local market, we are offering OEM service for Changan, CALB, National grid, Ping Gao Electric , Xuji electronics, Ruineng electronics, they are our main Container ESS suppliers in China Market.We are the most professional supplier of marine lithium batteries in China, and our export volume of marine batteries consistently ranks among the top three in China; We are also the top 1 exporter of lithium battery modules in China, specializing in providing various lithium battery module solutions.For excellent quality and performance our products are popular in more than 30 countries in the world. We also have established warehouse in Germany and Netherlands to provide safety stock timely delivery for our customers.l Customized and Flexiblel High Delivery capacityl Wide Applicationsl Rich experience on Lithium battery pack