Lithium ion and lithium polymer batteries: their differences

长兴新能源 2021-07-09 16:20 Industry

Lithium ion batteries have always been the preferred power for smartphones and various other portable devices. However, most smart phones now usually use lithium polymer batteries, which are gradually replacing lithium-ion batteries as the mainstream. However, what causes this trend? What are the differences between lithium-ion batteries and lithium polymer batteries, and what are their advantages and disadvantages? What should we know.
Before making clear their differences, advantages and disadvantages, we should first understand their working principles. Lithium ion battery is the main force of the industry. The development of this technology started as early as 1912, but it was not popularized until 1991 when it was adopted by Sony. Since then, lithium-ion batteries have powered small devices such as portable cameras, music players and smartphones.
Part of the reason why lithium-ion batteries are so successful is that they have a very high energy density, unlike previous battery technologies, which have a "memory effect" (that is, batteries become more difficult to charge over time), and their production costs are relatively low.
Lithium ion battery consists of two positive and negative electrodes separated by liquid chemical electrolyte such as ethylene carbonate or diethyl carbonate. The chemical composition of the battery limits its rectangular shape. The capacity of lithium-ion battery will decrease with the charging cycle, and even discharge when not in use, which is not ideal. To make matters worse, the chemical electrolyte becomes unstable at extreme temperatures or if punctured, leading to "thermal runaway" and fire. However, this situation is very rare, because the electronic controller usually adjusts the charging and discharging power to prevent the battery from overheating.
Lithium polymer battery technology is more advanced than lithium ion battery. It didn't appear until the 1970s, and it hasn't been installed in smartphones in recent years. For example, Samsung only switched to lithium polymer in the galaxy S20 series, while other manufacturers used the technology earlier. And Samsung has used lithium ion back in the galaxy note 20 series.
Lithium polymer technology also uses positive and negative electrodes, but uses dry solid, porous chemical or gel electrolyte rather than liquid. As a result, polymer batteries offer a lower profile, more flexible and robust design, and have a lower chance of thermal runaway due to electrolyte leakage. In short, they are safer.
One of the main disadvantages of this technology is that the manufacturing cost is obviously high. The life cycle of lithium polymer is also shorter, and the energy stored in the battery is less than that of lithium-ion battery of the same size. These batteries also still need to rely on the protection circuit, so that the voltage is also within a safe range of operation.
Both types of batteries have their advantages and disadvantages. Generally speaking, lithium-ion batteries have the largest capacity and lower price. The disadvantage of lithium-ion battery is that it will gradually self discharge, but for the mobile phone that has been turned on, this is not too important, and the possibility of safety problems is very small, but not zero.
In contrast, lithium polymer batteries are safer. This is particularly important in the era of rapid development of fast charging technology. This kind of battery also has a low degree of self discharge, so it won't lose a lot of power when you don't use it. However, it also leads to higher price, shorter life and lower capacity density. Although the lightweight characteristics of lithium polymer battery make the overall energy density of the battery better.
In general, lithium polymer is widely used in high-end and mid end devices due to its superior safety, shape versatility and weight attributes. Lithium polymer batteries are gradually replacing lithium-ion batteries in smart phone industry.
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