lithium ion battery cells 18650

Compared with lead-acid batteries, lithium ion battery cells 18650 have unparalleled technical advantages

As the "last barrier" of the data center power supply system, new battery technology is triggering a huge new energy revolution. According to Uptime's global data center survey data in 2017, 10% of data centers have adopted lithium-ion batteries (hereinafter referred to as lithium ion battery cells 18650) as energy storage devices for UPS power supplies. Schneider Electric, a global leader in digital transformation in energy efficiency management and automation, predicts that the average annual growth rate of lithium ion battery cells 18650 for UPS will exceed 100% in the next three years.

Compared with lead-acid batteries, lithium ion battery cells 18650 have unparalleled technical advantages: the energy density is several times that of lead-acid batteries, which reduces the space occupied by lithium ion battery cells 18650 by more than 60%; the weight is reduced by more than 70%; the ability to adapt to high temperatures is stronger; it can be quickly recharged after discharge, and the number of cycles is 4 times that of lead-acid batteries; the long life design of 10-15 years and the high number of cycles make lithium ion battery cells 18650 unnecessary to be replaced within the 10-year life cycle of UPS, reducing maintenance and replacement costs, and ultimately helping users reduce TCO and obtain the greatest commercial value.

In China, the trend of UPS switching to lithium ion battery cells 18650 will be even faster. As a global leader in data center infrastructure solutions and services, Schneider Electric has found through precise market positioning and investigation that, in addition to the purchase price factor, Chinese customers' current focus on UPS lithium ion battery cells 18650 is mainly on safety. As the largest energy storage component in the data center, the safety of lithium ion battery cells 18650 depends largely on the following four points. Schneider Electric reminds users to focus on the following when selecting:

1. High-quality battery cell production and quality control

At present, the world's top lithium battery manufacturers have adopted advanced automated production lines. Only through high-quality production process control can the high quality and high consistency of the battery cells be guaranteed. After the production of lithium ion battery cells 18650 is completed, multiple batteries need to be connected in series and parallel to form a battery module (commonly known as Module). In this process, the positive and negative terminals of the battery need to be connected. Large manufacturers usually use laser welding machines to weld the terminals to reduce contact resistance and ensure the reliability of terminal connection. Small manufacturers generally use manual bolt and nut crimping, which is difficult to ensure the reliable connection of the terminals, which may bring hidden dangers to long-term operation in the future.

Due to the strict quality control of lithium ion battery cells 18650 and the fact that their cycle life has been greatly improved compared to lead-acid batteries, many big brands of lithium ion battery cells 18650 can provide a 10-year warranty in the data center field.

2. Perfect BMS design

BMS (battery management system) is the core technology for the safety of the entire lithium battery system. When any battery faults such as overvoltage charging, overcurrent discharge, battery short circuit, etc. occur, the BMS can quickly cut off the fault current to prevent the risk of thermal runaway of the battery. Schneider Electric believes that lithium battery BMS should not only monitor the voltage, current, temperature and other conditions of each battery cell in real time and provide battery health trend analysis, but more importantly, it can actively balance the charging and discharging of the battery cells, and ultimately improve the consistency of each battery cell, avoiding the failure of the entire battery group due to the short board effect of the wooden barrel. At present, international first-line lithium battery manufacturers all design and produce BMS by themselves to ensure the performance matching and charging and discharging safety of their own battery cells and BMS.

3. Chemical materials of lithium ion battery cells 18650

For data center UPS, due to its application characteristics such as short-term high current discharge, high discharge power, and long-term backup floating charge, lithium iron phosphate, lithium manganese oxide, and NCM ternary lithium technology are more suitable.

The Chinese market is mainly ternary lithium and lithium iron phosphate. Although there are endless debates between the two on energy density and safety, it is undeniable that these debates are only limited to one aspect of the theoretical performance of lithium battery positive electrode materials. Schneider Electric believes that the safety of lithium battery systems requires comprehensive consideration of many factors such as negative electrode materials, electrolytes, diaphragm materials, battery shell packaging, battery module grouping, BMS, fuse protection, DC circuit breakers, production and manufacturing process levels, and quality control. Problems caused by lithium battery positive electrode materials account for less than 10% of all lithium battery system problems. Schneider Electric recommends that users should make a comprehensive trade-off between the safety, energy density, and cost of UPS lithium ion battery cells 18650, and choose lithium battery systems from large brand companies to obtain reliable quality assurance.

4. Compatibility test of lithium battery and UPS

Unlike lead-acid batteries, lithium ion battery cells 18650 have their own BMS. They are intelligent batteries with self-control capabilities and can communicate with the UPS host. When the lithium battery is fully charged, it will automatically disconnect from the UPS charger. Traditional UPS software design may think that this is a battery failure and issue an alarm. More importantly, the charging and discharging voltage, current, and cut-off voltage of lithium ion battery cells 18650 of different materials are different. For example, the rated voltage of lithium iron phosphate batteries is 3.2V, while that of ternary lithium is 3.8V. Therefore, before using lithium ion battery cells 18650, UPS needs to conduct strict matching tests with them, and the UPS firmware needs to be updated for this lithium battery.

It is worth mentioning that the UPS launched by Schneider Electric in recent years have already been compatible with lithium ion battery cells 18650. The high-rate lithium ion battery cells 18650 used by UPS can be charged and discharged with high current for a short time. Correspondingly, the UPS charger design also needs to adapt to this change. Schneider Electric's new Galaxy V series UPS charging power can reach 40% of the UPS's rated output power (traditional ones are only 10-15%). Such a powerful charger can theoretically quickly charge the lithium battery in 30 minutes to 1 hour.

As lithium battery technology matures and its cost becomes increasingly optimized, data center UPS will quickly complete the transition from lead-acid batteries to lithium ion battery cells 18650. Since the world's first lithium battery data center was put into use in 2012, Schneider Electric has always been a leader in promoting the application of lithium battery technology in the data center field. With its strong brand and technological innovation power, it has always been at the forefront of this data center new energy technology reform and led the entire industry to move forward.

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