In this era where people can't leave their mobile phones, power banks have become a must-have artifact for people to travel. As the core component of power banks, the quality and performance of the battery cell directly determine the quality of the power bank. Faced with all kinds of power banks on the market, which battery cell is the best? Today, let's take a deep look.
A review of common battery cell types
18650 lithium-ion battery cell: the "main force" with mature technology
The 18650 lithium-ion battery cell is named for its standard cylindrical appearance with a diameter of 18mm and a height of 65mm. It looks like an enlarged version of the No. 5 battery. It is a "veteran" in the field of power bank batteries, with a long history of development and extremely mature production technology. This means that its performance is stable and the product consistency is good. In terms of cost control, the 18650 lithium-ion battery cell has the advantages of high standardization and large-scale production. At the same capacity, the price of the power bank equipped with it is often more affordable. Moreover, the capacity of a single battery cell can be achieved at a high level, and the energy density is good. However, its cylindrical design limits the appearance innovation of power banks to a certain extent, making it difficult to create extremely thin or unique styles. In terms of safety, although qualified batteries produced by regular large manufacturers have undergone rigorous safety tests and are equipped with protection circuits, due to the use of metal shells and liquid electrolytes, once the production quality is poor, or they suffer from extreme physical damage such as severe impacts and punctures, there is a risk of short circuits, leakage, or even fire and explosion in theory. Compared with some other batteries, the safety is slightly inferior.
Lithium polymer batteries: flexible and changeable "newcomers"
Lithium polymer batteries are usually in the shape of flat soft packs, with no fixed standard for size, and can be flexibly customized according to product design requirements. Safety is one of its outstanding advantages. Gel or solid electrolytes are mostly used inside, which greatly reduces the risk of leakage; even in extreme conditions, generally only bulging occurs, rather than violent explosions, and the safety factor is relatively higher. The flexibility of shape allows the design of power banks to be more creative, and it is easy to create thin, small or unique products. Many ultra-thin power banks benefit from lithium polymer batteries. In terms of volume energy density, lithium polymer batteries can sometimes achieve higher capacity at the same volume. However, its production process requirements are quite high, and the degree of customization is also high, resulting in a generally higher cost than 18650 lithium-ion batteries. There is also a view that under the same number of charge and discharge cycles, the life of some lithium polymer batteries may be slightly shorter than that of high-quality 18650 lithium-ion batteries, but this is affected by many factors and is not absolute.
Brief description of other battery types
In addition to the above two mainstream batteries, there are some relatively niche batteries on the market that are used in power banks. For example, lithium iron phosphate batteries are known for their high safety, wide sources of raw materials, low self-discharge, and long life. They are a type of solid-state lithium battery. However, their energy density is relatively low. When achieving the same capacity, the weight and volume of power banks are often larger, which to a certain extent limits their wide application in the field of power banks that pursue light and portable power banks. In addition, there are lead-acid battery cells, which are one of the early battery technologies with low cost, but are heavy, low energy density, and short service life. They are rarely seen in power banks.
Comparison of battery cell performance in all aspects
Safety
From a safety perspective, lithium polymer batteries undoubtedly have the upper hand. Its solid or gel electrolyte and soft-pack shell design greatly reduce the probability of serious safety accidents such as leakage, fire, and explosion. Although the 18650 lithium-ion battery has a protection circuit, the characteristics of the liquid electrolyte and the metal shell make it relatively risky when facing extreme situations. Of course, as long as the power bank is purchased through formal channels and meets safety standards, no matter which battery cell is used, the safety in daily use can be basically guaranteed.
Energy density
Energy density determines how much electrical energy the battery cell stores per unit volume or weight. Lithium polymer batteries perform well in terms of volume energy density and can provide higher capacity in a limited space, which is very attractive to users who pursue small, portable and large-capacity power banks. The energy density of 18650 lithium-ion batteries is also not inferior, and the capacity of a single battery cell is high. By combining multiple batteries reasonably, it can also bring considerable total capacity to the power bank.
Cost
Cost is one of the important factors that affect consumer choice. Due to standardized production and large-scale manufacturing, the cost of 18650 lithium-ion batteries is relatively low, making power banks equipped with such batteries more competitive in price and more acceptable to the public. Lithium polymer batteries have a complex production process, a high degree of customization, and a high cost, which makes the price of power banks using them generally more expensive.
Service life
The service life of a battery is usually measured by the number of charge and discharge cycles. Generally speaking, high-quality 18650 lithium-ion batteries perform well in charge and discharge cycle life and can meet the user's use needs for a long time. For lithium polymer batteries, although some people believe that their life is slightly shorter under the same conditions, with the continuous advancement of technology, high-quality lithium polymer batteries also have excellent performance in service life, and the gap between the two is gradually narrowing.
How to choose a suitable battery
When choosing a power bank battery, you cannot simply determine which battery is absolutely the best, but you must consider many factors comprehensively. If you pursue the ultimate lightness, portability and safety, and are not very sensitive to price, a power bank with lithium polymer batteries is undoubtedly the best choice. It can easily adapt to various stylish and compact designs, reducing the burden on travel while ensuring safety. If you have a limited budget, pay more attention to cost-effectiveness, and have no special requirements for the appearance of the power bank, then a power bank with 18650 lithium-ion batteries can meet your basic charging needs at an affordable price. No matter which battery power bank you choose, you must pay attention to the brand and quality. Give priority to products that have passed the national 3C certification or meet national safety standards such as GB 31241. These qualified products usually have multiple safety protection measures such as overcharge, over-discharge, overcurrent, short circuit, and temperature protection built in, making your use process more secure.
The choice of power bank batteries should be determined based on personal actual needs, budget, and emphasis on various aspects of performance. Only by understanding the characteristics of different batteries can you accurately pick out the one that suits you best among many power bank products and escort the battery life of your mobile device.