What is a lithium polymer battery? What is the correct way to use them?

Lithium polymer batteries (Li-polymer, also known as lithium polymer batteries).

Compared to previous batteries, it is a chemically based battery with high energy, miniaturisation and light weight. In terms of shape, Li-polymer batteries are ultra-thin and can be made in a variety of shapes and capacities to suit the needs of some products. This type of battery, in theory, can have a minimum thickness of 0.5 mm.

The three elements of a typical battery are: the positive electrode, the negative electrode and the electrolyte. A lithium polymer battery is a battery system in which at least one or more of the three elements is made of a polymer material. In lithium polymer battery systems, the majority of polymer materials are used in the cathode and electrolyte. The cathode is made from a conductive polymer or inorganic compound normally used in lithium ion batteries, the cathode is often made from lithium metal or lithium-carbon interlayer compounds, and the electrolyte is made from a solid or gel polymer electrolyte, or an organic electrolyte. Lithium polymers are more reliable and stable because there is no excess electrolyte in them.

1. How to charge a new battery

In the use of lithium batteries, it should be noted that after a period of time, the battery enters a dormant state, when the capacity is lower than normal, and the use time is shortened. However, lithium batteries are easy to activate, as long as 3-5 times after the normal charge and discharge cycle can activate the battery to restore the normal capacity. Due to the characteristics of the lithium battery itself, it has almost no memory effect. Therefore the new lithium battery in the user's mobile phone does not require special methods or equipment during the activation process. Not only is this theoretically true, but in my own practice, the "natural activation" method of charging in the standard way from the beginning is the best.

There is a lot of talk about the "activation" of lithium batteries: the charge time must exceed 12 hours and be repeated three times in order to activate the battery. This statement that "the first three charges should be over 12 hours" is clearly a carry-over from nickel batteries (e.g. NiCd and NiMH). Therefore, it can be argued that this statement was misrepresented from the beginning. The charge and discharge characteristics of lithium and nickel batteries are very different and I can tell you very clearly that all the serious official technical sources I have consulted emphasise that overcharging and overdischarging can be very damaging to lithium batteries, especially liquid lithium ion batteries. It is therefore best to charge them at standard times and in standard ways, and especially not for longer than 12 hours. Usually, the charging method described in the manual of a mobile phone is the standard charging method for that phone.

There is no such thing as a "trickle" charge that lasts for 10 hours or so with a nickel charger. In other words, if you leave your Li-ion battery on the charger after it has been fully charged, it will still be charged for nothing. None of us can guarantee that the characteristics of the battery's charge/discharge protection circuitry will never change and that the quality of the battery will never fail, so your battery will be on the edge of danger for a long time. This is another reason why we are against long charging.

In addition, on some phones, if you do not remove the charger after charging for a certain period of time, the system will not only not stop charging, but will also start a discharge-charge cycle. Perhaps the manufacturers of this practice have their own agenda, but it is clearly detrimental to the battery and the life of the phone/charger. At the same time, long charging takes a long time and often needs to be done at night, when, given the state of our power grid, the voltage is higher and more volatile in many places. As already mentioned, Li-ion battery is very delicate.

It is much less resistant to fluctuations than nickel in terms of charging and discharging, so this poses an additional danger.

Another aspect that must not be overlooked is that lithium batteries are also not suitable for over-discharging, which is also detrimental to lithium batteries. This leads to the following question.