What Is The Difference Between A Lithium-ion Battery And An 18650 Battery? How To Tell The Difference Between Them?

- Dec 21, 2019-

1. Different sizes. Although the 18650 and No. 5 batteries look similar, the sizes of the two are actually different. The 18650 is much larger than the No. 5 battery in both length and diameter.

2. The voltage is different. The voltage of lithium battery is generally around 3.5 ~ 4.0V, the most common is 3.7V; while the voltage of No. 5 battery is 1.5V (non-rechargeable) or 1.2V (rechargeable).

3. Its working principle (internal chemical reaction process) is different.

4.18650 is a rechargeable battery. Most of the ordinary No. 5 batteries are disposable batteries, and very few can be charged.

1. The voltage is different and the capacity is different. The former can be charged, and the latter cannot be charged.

2. Analysis from the shape: These two types of batteries are cylindrical batteries, but the specifications of the shapes are different. The specifications of the 18650 lithium battery are 18 mm in diameter and 65 mm in length; the rule for the 5th battery (in fact, the scientific name of the 5th battery is 14500 battery) is 14mm in diameter and 50mm in length.

3. Analysis by type: 18650 lithium batteries can be divided into 18650 lithium-ion batteries, 18650 lithium iron phosphate lithium batteries, and 18650 nickel-metal hydride batteries; while No. 5 batteries include nickel-metal hydride rechargeable batteries, nickel-cadmium rechargeable batteries, and alkaline zinc. Manganese batteries (referred to as alkaline batteries), ordinary acid zinc manganese batteries (referred to as ordinary batteries), etc.

The so-called polymer lithium battery refers to a lithium ion battery using a polymer as an electrolyte, and is specifically divided into two types of semi-polymer and full polymer. Semi-polymer refers to coating a layer of polymer (usually PVDF) on the separator to make the cell's adhesion stronger, the battery can be made harder, and its electrolyte is still a liquid electrolyte. The all-polymer means that a polymer is used to form a gel network inside the cell, and then an electrolyte is injected to form an electrolyte. Although all polymer batteries still use liquid electrolyte, the amount used is much less, which greatly improves the safety performance of lithium-ion batteries. As far as I know, only SONY is currently mass-producing all-polymer lithium-ion batteries.

From another aspect, the polymer battery refers to a lithium-ion battery using an aluminum-plastic packaging film as an outer packaging, also known as a soft-pack battery. This packaging film consists of three layers, namely a PP layer, an Al layer, and a nylon layer. Since PP and nylon are polymers, this type of cell is called a polymer battery.

1.Lower price

The international price of 18650 is about 1USD / pcs, which is about 3RMB / Ah if calculated based on 2Ah. The price of polymer lithium batteries is 4RMB / Ah for low-end cottage factories, 5 ~ 7RMB / Ah for middle-end factories, and 7RMB / Ah or higher for high-end ones. People like ATL and Lishen can usually sell for about 10RMB / Ah, and you are still unwilling to pick it up when you are young.

2.Cannot be customized

SONY has always wanted to make lithium-ion batteries like alkaline batteries. There are certain industry standards, just like No. 5 batteries and No. 7 batteries, which are basically the same in the world. However, because the great advantage of lithium-ion batteries is that they can be designed in accordance with customer needs, there can be no unified standard. So far, the lithium-ion battery industry has basically only a standard model of 18650. Requirements are designed.

3. Poor security

We know that under extreme conditions (such as overcharge, high temperature, etc.), a lithium ion battery will undergo a violent chemical reaction inside the battery, generating a large amount of gas. The 18650 battery uses a metal casing with a certain strength. When the internal air pressure reaches a certain level, the steel casing will rupture and explode, causing a terrible security accident.

This is why rooms testing 18650 batteries must generally be protected by layers, and no one can enter during the test. Polymer batteries do not have this problem. Even in extreme cases, because of the low strength of the packaging film, as long as the air pressure is slightly higher, it will rupture without explosion. The worst case is combustion. So in terms of safety, polymer batteries are better than 18650 batteries.

4.Low energy density

The general 18650 battery capacity can be about 2200mAh, so the energy density is about 500Wh / L, and the energy density of polymer batteries can be close to 600Wh / L at the current stage of mass production.

But polymer batteries also have their own disadvantages. The main reason is that the cost is high. Because it can be designed according to customer needs, the R & D costs must be included. In addition, the shape and variety of various shapes lead to various non-standard fixtures in the manufacturing process, which also increases the cost accordingly. The polymer battery itself has poor versatility, which is also brought by flexible design. Often, it is necessary to design a new one for customers for the difference of 1mm.

Application of 18650 lithium battery

The application of lithium secondary batteries in the energy battery industry benefits from its superior performance. With the continuous development of lithium secondary battery technology, it has been widely used in our daily life; rechargeable batteries that have been used many times have become more and more popular with consumers. Pay attention to the energy battery industry and fully understand the battery so that we can do it for me. At present, 18650 lithium batteries have certain applications in the following areas.

1. Energy storage

Mainly used in base station power supply, clean energy storage, grid power storage, home optical storage system, etc.

2.Power category

Mainly refers to electric vehicles, electric bicycles, new energy vehicles, etc.


Mobile phones, tablets, laptops, electric toys, MP3 / MP4, headphones, power banks, aircraft models, mobile power, etc.

Lithium polymer batteries are all-solid-state or lithium-ion batteries with too much electrolyte. Generally, aluminum-plastic composite film is used as the packaging material. Currently only two of the world are true lithium polymer batteries. One is SONY from Japan and the other is ATL from China

Lithium battery generally refers to an aluminum case battery, the electrolyte is liquid, and the outer packaging material is an aluminum case.

1. No battery leakage problem. The battery does not contain liquid electrolyte and uses colloidal solids.

2. Can be made into a thin battery: with a capacity of 3.6V400mAh, its thickness can be as thin as 0.5mm.

3. The battery can be designed into various shapes.

4. The battery can be bent and deformed: The polymer battery can be bent up to about 90 °.

5. Can be made into a single high voltage: a battery with liquid electrolyte can only get a high voltage by connecting several batteries in series, and a polymer battery can be made into multiple layers in a single unit to achieve high voltage because it has no liquid.

6. Capacity will be doubled compared to the same size lithium-ion battery.