Which Lithium Polymer or Lithium Ion Battery is Better?

Lithium Polymer Battery is a lithium-ion battery upgrade product. Compared with popular lithium-ion batteries, it has the advantages of large capacity, small size (thin) and safety (does not explode). However, because it takes some time to replace the entire industrial chain, its cost is still relatively high, and it is only used in high-end digital products (ultra-thin notebook computers, etc.).

It can be predicted that in the next 5-10 years lithium polymer batteries will replace the existing lithium-ion batteries! In fact, the penetration rate of lithium polymer batteries has reached a certain level in countries such as Japan and South Korea, which are more developed in the electronic products industry, but China is still relatively backward in this regard, let us wait and see! In the near future, mobile phones with lithium polymer batteries will become cheaper, and I must replace this safer mobile phone (battery)!

Li-polymer battery (Li-polymer, also known as polymer Lithium Battery) : It has many obvious advantages such as high energy density, miniaturisation, ultra-thin, lightweight, high safety and low cost, and is a new type of battery. In terms of shape, lithium polymer batteries have ultra-thin characteristics and can be made into batteries of any shape and capacity to meet the needs of various products. The minimum thickness of this type of battery can be as low as 0.5mm. Compared with lithium-ion batteries, the characteristics of lithium-polymer batteries are as follows:

1. No battery leakage problem, the battery does not contain liquid electrolyte, the use of colloidal solid.

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

3. Batteries can be designed in a variety of shapes.

4. The battery can be bent and deformed: the maximum bending of the polymer battery is about 90°.

5. Can be made into a single high voltage: the liquid electrolyte battery can only be a few batteries in series to get a high voltage, and the polymer battery because it has no liquid itself, can be made into a multi-layer combination in a single to achieve high voltage.

6. The capacity will be twice that of lithium-ion batteries of the same size.

Li-polymer battery (Li-polymer, also known as polymer lithium battery) : relative to the previous battery, it is a chemical battery with high energy, miniaturization and lightweight.

In terms of shape, lithium polymer batteries have ultra-thin characteristics, which can be used to meet the needs of some products to make batteries of different shapes and capacities. The theoretical minimum thickness of this type of battery can reach 0.5mm.

The three elements of the general battery: positive, negative and electrolyte. The so-called lithium polymer battery refers to a battery system in which at least one or more of the three elements use polymer materials. In lithium polymer battery systems, polymer materials are mostly used in the positive electrode and electrolyte. The positive electrode material uses conductive polymer or inorganic compounds used in general lithium-ion batteries, the negative electrode often uses lithium metal or lithium carbon interlayer compounds, and the electrolyte is a solid or colloidal polymer electrolyte, or an organic electrolyte. Because there is no excess electrolyte in the lithium polymer, it is more reliable and stable.

Lithium polymer battery uses file alloy as the positive electrode, uses high molecular conductive materials, polyacetylene, polyaniline or polyp-phenol as the negative electrode, and organic solvent as the electrolyte. The specific energy of lithium polyaniline battery can reach 350W.h/kg, but the specific power is only 50-60W/kg, the use temperature is -40-70 degrees, and the service life is about 330 times.

Compared with lithium-ion batteries, the characteristics of lithium polymer batteries are as follows:

1. Relatively, the problem of battery leakage is improved, but it is not completely improved.

2. Can be made into thin battery: with a capacity of 3.6V250mAh, its thickness can be as thin as 0.5mm.

3. Batteries can be designed in a variety of shapes.

4. Can be made into a single high voltage: the liquid electrolyte battery can only be a few batteries in series to get a high voltage, and the polymer battery because it has no liquid itself, can be made into a multi-layer combination in a single to achieve high voltage.

5. Discharge capacity, theoretically 10% higher than the same size lithium-ion battery.

Li-polymer battery (Li-polymer, also known as polymer lithium-ion battery), has a variety of advantages such as high energy, miniaturisation, ultra-thin, light weight and high safety. Based on such advantages, lithium polymer batteries can be made into batteries of any shape and capacity to meet the needs of various products; and it uses aluminium-plastic packaging, internal problems can be immediately displayed through the outer packaging, even if there is a safety risk, it will not explode, only bulge. In polymer batteries, the electrolyte plays the dual role of diaphragm and electrolyte: on the one hand, like a diaphragm, it separates the positive and negative electrode materials so that there is no self-discharge and short-circuit inside the battery; on the other hand, like an electrolyte, it conducts lithium ions between the positive and negative electrodes. The polymer electrolyte not only has good electrical conductivity, but also has the characteristics of light weight, good elasticity, easy film formation, etc., which also meets the development trend of chemical power supply with light weight, safety, high efficiency and environmental protection.

All lithium-ion batteries, whether before or over the years, including: polymer lithium-ion batteries, Lithium Iron Phosphate Batteries, etc., are very afraid of internal short circuit, external short circuit and overcharging of the battery.

Because the chemical properties of lithium are very active, it is easy to burn, when the battery is discharged and charged, the battery will continue to heat up, the gas generated during the activation process expands, the internal pressure of the battery increases, and the pressure reaches a certain degree, such as the shell is scarred, it will break, causing leakage, fire and even explosion.

In order to alleviate the danger of lithium-ion batteries, technicians have added ingredients that can inhibit the activity of lithium (such as cobalt, manganese, iron, etc.), but these cannot fundamentally change the risk of lithium-ion batteries.

When the ordinary lithium-ion battery is overcharged, short-circuited, etc., it may heat up inside the battery, decompose the positive electrode material and oxidise the negative electrode and electrolyte material, which will cause gas expansion and increase the internal pressure of the battery, and explosion may occur when the pressure reaches a certain level. The polymer lithium-ion battery because of the use of colloidal electrolyte, will not produce a large amount of gas due to liquid boiling, thus eliminating the possibility of violent explosion.

At present, most of the domestic polymer batteries are only soft pack batteries, using aluminium-plastic film as the shell, but the electrolyte has not changed. This battery can also be thin, its low-temperature discharge characteristics are better than polymer batteries, and the material energy density is basically the same as liquid Lithium Batteries and ordinary polymer batteries, but because of the use of aluminium-plastic film, it is lighter than ordinary liquid lithium batteries. In terms of safety, when the liquid is close to boiling, the aluminium-plastic film of the soft-pack battery will naturally bulge or break, and it will not explode.

It should be noted that the new battery may still burn or expand and rupture, and safety is not foolproof.

Therefore, we must be careful when using different types of lithium-ion batteries.

At present, there are two types of lithium-ion batteries (LIB) and lithium-polymer batteries (PLIB). Among them, the liquid lithium-ion battery refers to the secondary battery with Li+ compounds embedded as positive and negative electrodes. Lithium compounds LiCoO2, LiNiO2 or LiMn2O4 are used in the positive electrode and Li-carbon interlayer compound LixC6 is used in the negative electrode. The typical battery system is as follows:

(-)C|LiPF6-EC+DEC|LiCoO2(+)

Positive reaction: LiCoO2=Li1-xCoO2+xLi++xe-

Negative reaction: 6C+xLi++xe-=LixC6

Total battery reaction: LiCoO2+6C=Li1-xCoO2+LixC6

The principle of lithium polymer batteries is the same as liquid lithium, the main difference is that the electrolyte is different from liquid lithium. The main structure of the battery consists of three elements: positive electrode, negative electrode and electrolyte. The so-called lithium polymer battery means that at least one or more of these three main structures use polymer materials as the main battery system. In the developed lithium-polymer battery system, polymer materials are mainly used for the positive electrode and the electrolyte. Anode materials include conductive polymers or inorganic compounds commonly used in lithium-ion batteries. Electrolytes can be solid or colloidal polymer electrolytes or organic electrolytes. Conventional lithium-ion technology uses liquid or colloidal electrolytes, requiring strong secondary packaging to hold the combustible active ingredients, which adds weight. It also limits size flexibility.

The new generation of lithium polymer batteries can theoretically be achieved in shape, shape diversification, improve the flexibility of battery design, so that it can meet product needs, and make some shapes and capacity of the battery, which provides a high degree of design flexibility and adaptability for application equipment developers in power solutions to maximise the optimisation of their product performance. At the same time, the unit energy of lithium polymer batteries is 10% higher than that of general purpose lithium-ion batteries. Their capacity, cycle life and other aspects are significantly improved over lithium-ion batteries.