1.
Overview of Lithium Polymer Batteries
Polymer lithium batteries generally refer to polymer lithium ion batteries.
According to the different electrolyte materials used in lithium-ion batteries, lithium-ion batteries are divided into liquid lithium-ion batteries (LiquifiedLithium-IonBattery, referred to as LIB) and polymer lithium-ion batteries (polymerLithium-IonBattery, referred to as pLB) or plastic lithium-ion batteries (plasTIcLithiumIonBatteries) , referred to as pLB).
The positive and negative materials used in polymer lithium-ion batteries are the same as liquid lithium ions.
The positive materials are divided into lithium cobalt oxide, lithium manganate, ternary materials and lithium iron phosphate materials.
The negative electrode is graphite, and the working principle of the battery is also basic.
Consistent.
The main difference between them is the difference in the electrolyte.
Liquid lithium-ion batteries use liquid electrolytes, while polymer lithium-ion batteries use solid polymer electrolytes instead.
This polymer can be "dry" or "colloidal" Yes, polymer gel electrolytes are mostly used at present.
Lithium polymer battery classification:
solid:
The solid polymer electrolyte lithium ion battery electrolyte is a mixture of polymer and salt.
This battery has high ionic conductivity at room temperature and can be used at room temperature.
gel:
Gel polymer electrolyte lithium ion battery is to add plasticizer and other additives to solid polymer electrolyte, so as to improve ionic conductivity, so that the battery can be used at room temperature.
polymer:
Since the liquid electrolyte is replaced by a solid electrolyte, compared with the liquid lithium ion battery, the polymer lithium ion battery has the advantages of thinning, arbitrary area and arbitrary shape.
Therefore, the aluminum-plastic composite film can be used to manufacture the battery shell, thereby It can improve the specific capacity of the entire battery; polymer lithium-ion batteries can also use polymers as positive electrode materials, and its mass specific energy will be more than 20% higher than the current liquid lithium-ion batteries.
Polymer Lithium-Ion Battery has the characteristics of miniaturization, thinning and light weight.
Therefore, the market share of polymer batteries will gradually increase.Lithium Battery Pack
The principle of polymer lithium battery:
There are two types of lithium-ion batteries: liquid lithium-ion batteries (LIB) and polymer lithium-ion batteries (pLB).
Among them, the liquid lithium ion battery refers to a secondary battery in which the Li+ intercalation compound is the positive and negative electrodes.
The positive electrode adopts lithium compound LiCoO2, LiNiO2 or LiMn2O4, and the negative electrode adopts lithium carbon interlayer compound LixC6.
The typical battery system is:
The principle of polymer lithium-ion battery is the same as that of liquid lithium, the main difference is that the electrolyte is different from liquid lithium.
The main structure of the battery includes three elements: positive electrode, negative electrode and electrolyte.
The so-called polymer lithium-ion battery means that at least one or more of the three main structures use polymer materials as the main battery system.
In the currently developed polymer lithium-ion battery systems, polymer materials are mainly used in positive electrodes and electrolytes.
The positive electrode material includes conductive polymers or inorganic compounds commonly used in lithium-ion batteries.
The electrolyte can use solid or colloidal polymer electrolytes, or organic electrolytes.
Generally, lithium-ion technology uses liquid or colloidal electrolytes.
Therefore, it is necessary to Rugged secondary packaging to contain flammable active ingredients adds weight and additionally limits dimensional flexibility.
The new generation of polymer lithium-ion batteries can be thinned in shape (ATL battery can be as thin as 0.
5 mm, which is equivalent to the thickness of a card), arbitrary area and arbitrary shape, which greatly improves the battery design.
Flexibility, so that it can be made into batteries of any shape and capacity according to product requirements, providing equipment developers with some design flexibility and adaptability in power solutions to maximize the performance of their products.
At the same time, the unit energy of the polymer lithium-ion battery is 20% higher than that of the current general lithium-ion battery, and its capacity and environmental performance are improved compared to the lithium-ion battery.
Advantages and disadvantages of polymer lithium battery: Advantages:
1.
The working voltage of the single battery is as high as 3.
6v~3.
8v, which is much higher than the 1.
2V voltage of nickel-metal hydride and nickel-cadmium batteries.
2.
High capacity density, its capacity density is 1.
5~2.
5 times that of nickel-metal hydride batteries or nickel-cadmium batteries, or higher.
3.
The self-discharge is small, and its capacity loss is also small after being placed for a long time.
4.
Long service life, the cycle life of normal use can reach more than 500 times.
5.
No memory effect, no need to empty the remaining power before charging, easy to use.
6.
Good safety performance
The polymer lithium battery adopts aluminum-plastic flexible packaging in structure, which is different from the metal shell of the liquid battery.
In the event of a safety hazard, the liquid battery is easy to explode, while the polymer battery will only bulge at most.
7.
Small thickness, can be made thinner
Ultra-thin, the battery can fit into a credit card.
Ordinary liquid lithium batteries use the method of customizing the casing first, and then plugging the positive and negative materials.
There is a technical bottleneck when the thickness is less than 3.
6mm.
The polymer battery does not have this problem, and the thickness can be less than 1mm, which is in line with the current demand for mobile phones.
8.
Light weight
Batteries with polymer electrolytes do not require a metal case as a protective outer packaging.
The weight of the polymer battery is 40% lighter than that of the steel case lithium battery with the same capacity specification, and 20% lighter than that of the aluminum case battery.
9.
Large capacity
The capacity of polymer batteries is 10-15% higher than that of steel-shell batteries of the same size and 5-10% higher than that of aluminum-shell batteries, making them the first choice for color screen mobile phones and MMS mobile phones.
Polymer batteries.
10.
Small internal resistance
The internal resistance of the polymer battery is smaller than that of the general liquid battery.
At present, the internal resistance of the domestic polymer battery can even be below 35mΩ, which greatly reduces the self-consumption of the battery and prolongs the standby time of the mobile phone.
level with international standards.
This polymer lithium battery that supports large discharge current is an ideal choice for remote control models, and has become the most promising product to replace nickel-metal hydride batteries.
11.
Shape can be customized
Manufacturers are not limited to a standard form factor and can be economically made to the right size.
Polymer batteries can increase or decrease the thickness of the battery cells according to the needs of customers, and develop new battery cell models.
The price is cheap and the mold opening cycle is short.
Some can even be tailored according to the shape of the mobile phone to make full use of the battery shell space and improve the battery capacity.
12.
Good discharge characteristics
Polymer batteries use colloidal electrolytes, which have smoother discharge characteristics and higher discharge platforms than liquid electrolytes.
13.
The design of the protection board is simple
Due to the use of polymer materials, the cells will not fire or explode, and the cells themselves have sufficient safety.
Therefore, the protection circuit design of polymer batteries can consider omitting pTC and fuses, thereby saving battery costs.LiFePO4 Battery Cell
shortcoming:
1.
The cost of the battery is high, and the purification of the electrolyte system is difficult.
2.
It is necessary to protect the circuit control.
Overcharging or overdischarging will destroy the reversibility of the chemical substances inside the battery, which will seriously affect the life of the battery.
2.
Overview of lithium iron phosphate battery
Lithium iron phosphate battery refers to a lithium ion battery using lithium iron phosphate as a positive electrode material.
The cathode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganate, lithium nickel oxide, ternary materials, lithium iron phosphate, etc.
Among them, lithium cobalt oxide is the cathode material used in the vast majority of lithium-ion batteries.More details