A Comparative Testing Study of Commercial 18650-Format Lithium-Ion Battery Cells

Abstract

Demand for portable electronic and electrical devices has led to considerable growth in production of lithium-ion battery cells and the number of manufacturers thereof. However, due to lack of supplied information or independent verification, it is frequently difficult to compare cells based on available data. In this study, we conduct a comparative testing study on five types of 18650-format lithium-ion cells from three different commercial manufacturers, ranging from budget to high-performance cells. Key insights gathered in the comparison were that the tested budget cells frequently offer less than 20% of their rated capacity, that the budget cells degrade at a significantly higher proportional rate than other cells, and that certain high-performance cells exceed the size dimensions of the 18650-format by over 3%. Electrochemical impedance spectroscopy testing showed the budget cells to have internal impedances several times higher than other cells, leading to notably increased heat generation and a significantly reduced cell efficiency. Differential capacity analysis found this high internal resistance to notably impede lithium intercalation processes. The presented methodology is intended as a base framework for conducting subsequent comparative testing studies for Li-ion cells. A strong demand for portable electronic and electrical devices in recent years has led to a corresponding demand for high-performance batteries. Due to the large amount of energy that can be stored per unit of weight and volume, lithium-ion (Li-ion) batteries have become the battery of choice for many small devices such as mobile phones, laptop computers and power tools. Increasingly these cells are also being used for much larger applications including electric bicycles, electric cars and stationary energy storage in domestic or commercial settings.Li-ion battery cells first became commercially available in 1991. Today, there are many different cell manufacturers that offer a wide variety of battery cells to both corporate and personal customers. Unfortunately however, reliable information on the physical dimensions and electrical characteristics can be difficult to obtain for many cells. High-end suppliers commonly provide data sheets that contain technical product information including factors such as size, weight, capacity, voltage profile and cycle life, as well as some limited measurement data to support these numbers. Low-cost products are frequently supplied only with a nominal capacity rating, without any measurement data. Where available, the ratings are typically based on in-house testing without independent verification. As private or small commercial consumers rarely have both the specific equipment and know-how required to accurately test cells, there is a risk that manufacturers may inflate ratings in order to make their products appear more competitive. This adds further complexity to the already difficult task of choosing cells for commercial or personal applications. As a result, there is scope for academic researc...

18650 lityum-iyon ve 6HR61 nikel-metal hidrit tekrar şarj edilebilir pillerinin elektrokimyasal empedans analizi

“…Li-iyon pilleri elektrikli araçlar ile evsel ve ticari ortamlardaki sabit enerji depolama sistemleri gibi çok çeşitli alanlarda giderek artan uygulamalara sahiptir. Li-iyon pili ilk olarak 1991 yılında ticari olarak kullanılmaya başlanmıştır [13]. [13,20].…”

“…Li-iyon pili ilk olarak 1991 yılında ticari olarak kullanılmaya başlanmıştır [13]. [13,20]. Li-iyon pilleri dikkate alındığında 18650 pilinin geniş kullanım alanı bu pil ile yapılan çalışmaları ilgi çekici hale getirmiş ve arttırmıştır [13].…”

“…[13,20]. Li-iyon pilleri dikkate alındığında 18650 pilinin geniş kullanım alanı bu pil ile yapılan çalışmaları ilgi çekici hale getirmiş ve arttırmıştır [13]. Bu nedenle 18650 Li-iyon pili ile yapılacak çalışmalar enerji depolama alanında büyük öneme sahiptir.…”

“…Böylece empedans verilerinin yorumlanabilmesinin önü de açılmıştır. Ayrıca, modele dayalı empedans analizi ile farklı pil koşullarında batarya performansının ve pil kapasitesinin azalmasına neden olan mekanizmaların daha iyi anlaşılması amaçlanmaktadır [13,18,19]. Bununla birlikte bir eşdeğer devre modelinin tanımlanması şarj/deşarj süreçleri boyunca bataryada meydana gelen fiziksel olayları anlamak ve fayda durumunu değerlendirmek için kullanılacak yöntemlerin belirlenmesi için de önem taşımaktadır [21].…”

Second-Life Batteries on a Gas Turbine Power Plant to Provide Area Regulation Services

“…Some age slightly faster or slower than others. Most of the aging studies in literature use commercial 18650-format Li-ion cells, which have a relevant deviation regarding aging [22]. However, EV batteries use improved cells with temperature and balancing control devices that reduce this deviation.…”