Summary :
Lithium-ion is among the most well-known rechargeable batteries technology that provides energy for consumer-oriented applications. Its energy density is perfect and does not have a remarkable memory effect; the slow loss of charge when in standby mode and its low weight make Li-ion batteries ideal for storing energy for various electric vehicles, mainly to supply a substitute for the heavy lead acid batteries. To ensure the cycle’s longevity, the susceptible lithium cells must be protected from excessive temperatures and overcurrents caused by short circuits of the terminals, excessive charging, or switching circuit malfunctions. In this post, we’d like to outline lithium-ion technology with an introduction to a top manufacturer, EVE Battery’s range of products, and the potential circuit protection solutions available from TE Circuit Protection.
Lithium-ion structures from EVE Battery
EVE Energy Co., Ltd was established in 2001 and is a specialist in high-energy lithium batteries. EVE is the biggest supplier of primary lithium cells in China. In 2010 EVE significantly increased its investments in the manufacture of rechargeable (often known as secondary) lithium-ion batteries. The latest state-of-the-art automated production lines were installed. This will enable EVE to make significant contributions to energy storage using lithium-ion. This includes the polymer lithium-ion cell, prismatic Li-ion Cylindrical Li-ion cell, and power batteries.
Both cylindrical and prismatic models are utilized in the realm that includes mobile phones (phone laptop) as well as Backup power sources (UPS) and electric bikes and power tools. Space-efficient Prismatic cells because of their layers. There are only some universal designs. If the design’s housing permits a few millimeters more within the final product, the designer creates an entirely new package to maximize capacity. Large volumes warrant customizing.
The prismatic cell can provide capacities of between 20 and 30Ah and is commonly employed in electric powertrains for electric and hybrid automobiles. The prismatic cell enhances space utilization and permits a flexible design but could be more efficient in thermal management. It also has shorter life cycles as compared to the popular cylindrical methods.
Polymer Li-ion batteries can be more adaptable due to their flexible appearance Manufacturers can design their designs for devices like MP3 players and Bluetooth apps, GPS, and E-book readers. LiPo batteries are made up of several identical secondary cells arranged in parallel to boost the discharge current capacity and are typically; they are sold in series packs that increase the voltage available to all users.
All Li-Ion cells grow in high levels charged by state (SOC). If the cell isn’t contained, there is a possibility of delamination and reducing the cycle’s durability and life. The cylindrical cells offer protection, whereas pure polymer cells aren’t sealed. To attain high-performance ratings, batteries made of polymer cells should have an external casing that is strong enough to maintain its shape. The overcharging of a Li-poly battery could result in a fire or explosion. While the battery is charging, the load must be removed when the voltage is reduced to around 3.0 V/cell, or the battery cannot take a complete charge and cannot hold the voltage at a load. Li-poly batteries must be protected with circuitry that stops over-charging and deep discharge. Compared to lithium-ion batteries, the Li-poly battery has disadvantages in terms of life cycle degradation.
Although Li-Ion batteries are protected by manufacturers exceptionally well, several incidents involving lithium-ion batteries have been reported; therefore, there are questions about their general safety. A few of these incidents have been linked to overheating, which could cause an explosion or fire. There are a variety of standards that were developed to guide manufacturers to ensure safe construction. They are built on the consensus of consumer advocacy associations and the insurance industry’s needs.
These international norms of these associations are currently being used to determine some security aspects of lithium primary and secondary batteries:
- Underwriters Laboratories (UL)
- Institute of Electrical and Electronics Engineers (IEEE)
- National Electrical Manufacturers Association
- International Electrotechnical Commission (IEC)
- United Nations (UN)
- Japanese Standards Association
- Battery Safety Organisation
Protection of circuits for Lithium cells
The distinctive electric characteristics and the thin, flat shape make TE Circuit Protection Polyswitch PPTC annular disc devices an ideal solution for lithium-cell applications. In normal conditions, the PolySwitch is a series component in the circuit, has a low resistance, and does not affect the course’s performance because the conductive particles within the polymer create a conductive low-resistance system. As a result of an overtemperature, the device goes and increases the resistance rapidly and decreases the current until it reaches a limit that is transported in the battery. The heating may result from caused by the rise in temperature of the surrounding cell or through resistance II 2R the heating of an overcurrent state. This PolySwitch PPTC annular disc latch will change to a high resistance state in the event of a fault, then automatically resets when the responsibility is eliminated, allowing the battery to regain regular operating condition.
Battery packs that can be recharged and utilized in digital cameras or other handheld devices are prone to overtemperature and overcurrent caused by abrupt running or external shorting. These problems can increase your battery’s temperature and cause damage to the cells or even smoking. A battery that is not protected is typically capable of delivering as much as 100A power when it is shorted using materials with low resistance, and the power loss by the battery’s internal resistance can cause massive overheating. This could lead to cell loss and smoke in the case of a crisis. In the event of an object that is resistant to shorting, the temperature in the battery’s exterior can be as high as a few hundred degrees, which can ignite nearby flammable material. Another common issue is overcharging the battery. The most common cause is an uncontrollable event, typically due to a charger’s fault – it does not stop providing power to the battery even after it has been fully charged. The problem with excessive charging can occur if a lousy charger is utilized and an overvoltage or current circumstance causes a battery cell to overcharge when a typical fault occurs during an overcharge that causes cell temperatures to rise because the high voltage within the fully charged cell causes chemical destruction in the structure of its internal. When using the PolySwitch system, increasing temperature aids the device’s ability to turn off even when operating on a lower current. Typically, the Li-ion pack has an active primary Undervoltage, overvoltage, and safety circuit for overcurrent protection, and PolySwitch is a good choice for an additional level of security.
A PolySwitch MXP, VTP, VLR, or VTP Strap device should be used for Li-ION and Li-Polymer-based packs due to their specific design in contrast to SMD devices that are welded to the cell’s body, which aids in transferring heat from the cell overheated onto the PolySwitch device to speed up thermal amplification.
PolySwitch devices are typically used to replace bimetal and thermal fuse protectors. Bimetals can be heavy and expensive and could be more latching-friendly. They have a fast response, excellent capability to handle current, and meager resistance at the point of contact. With the rising demand for Polymer lithium-ion batteries, these cells tend to be susceptible to increased discharge rates, high pulse currents, and higher charge currents. The high winds cause batteries to run at greater temperatures, which can pose the risk of causing damage. There are currently only a few protection options on the market that provide low temperatures for thermal cut-off and high current hold ratings in a small size. The most advanced version of the TE Circuit Protection’s MHP ( Metal Hybrid PPTC) device, named the MHP-TA ( Thermal Activation) series, combines a PPTC and a bimetallic circuit breaker parallel.
The PPTC is a heater that keeps bimetal latched when a fault occurs, and it can interrupt current when it detects high temperatures in the cell. This can help protect cells from overheating, which could cause fatal damage.
The MHP-TA product line comprises two devices built around different capacity levels to carry current. The instruments with low-current power provide approximately 6A of hold at temperatures up to 25°C, while high-current devices provide about 15A. With two capacity levels in compact packaging (L: 5.8mm x W: 3.85mm x H: 1.15mm), The MHP-TA device tackles the problem of satisfying the requirements for high hold-current ratings. Also, it provides an affordable and space-saving solution for overtemperature battery protection for the most modern generation of consumer electronics.
Endrich provides ready-to-use primary Li-Ion cells in various forms, from cylindrical AA to AAA via CRX button, super-pulse caps, and secondary rechargeable cells and batteries. Additionally, Endrich is at your assistance with circuit protection suggestions to protect batteries.