What is a high rate battery?

What is a high rate battery?

A high-rate battery generally refers to a lithium battery, and a lithium-ion battery is a high-charge battery that relies on lithium ions to move between a positive electrode and a negative electrode to operate. During charge and discharge, Li+ is embedded and deintercalated between the two electrodes: when charging the battery, Li+ is deintercalated from the positive electrode, embedded in the negative electrode via the electrolyte, and the negative electrode is in a lithium-rich state; A battery containing a lithium element as a electrode is generally used. It is the representative of modern high-performance batteries.

Lithium batteries are classified into high-rate batteries and lithium-ion batteries. At present, mobile phones and notebook computers use lithium-ion batteries, which are commonly referred to as high-rate batteries, and true high-rate batteries are rarely used in everyday electronic products because of their high risk.

Lithium-ion batteries have high energy density and high uniform output voltage. Self-discharge is small, good battery, less than 2% per month (recoverable). There is no memory effect. The operating temperature range is -20 ° C ~ 60 ° C. The regenerative function is excellent, the battery can be charged and discharged quickly, the charging efficiency is up to 100%, and the output power is large. Long lasting. It does not contain toxic or hazardous substances and is called a green battery.

Charging

It is an important step in the repeated use of the battery. The charging process of the lithium ion battery is divided into two stages: a constant current fast charging phase and a constant voltage current decreasing phase. During the constant current fast charging phase, the battery voltage is gradually increased to the standard voltage of the battery, and then the constant voltage is turned under the control chip, the voltage is no longer raised to ensure that the battery is not overcharged, and the current is gradually reduced to the rise of the battery power. Set the value and finish charging. The power statistics chip can calculate the battery power by recording the discharge curve. After the lithium ion battery is used for many times, the discharge curve will change. Although the lithium ion battery does not have a memory effect, improper charging and discharging will seriously affect the battery function.

Pay attention to matters

Excessive charging and discharging of lithium-ion batteries can cause permanent damage to the positive and negative electrodes. Excessive discharge causes the negative carbon sheet structure to collapse, and the collapse causes lithium ions to be inserted during charging; excessive charging causes excessive lithium ions to be embedded in the negative carbon structure, which causes the lithium ions in the sector to be released again. The charging amount is the charging current multiplied by the charging time. When the charging control voltage is constant, the charging current is larger (the charging speed is faster), and the charging amount is smaller. The battery charging speed is too fast and the termination voltage control point is improper, which also causes the battery capacity to be insufficient. The battery electrode active material does not fully react and stops charging. This phenomenon of insufficient charging is aggravated by the increase in the number of cycles.

Discharge

For the first charge and discharge, if the time is long (usually 3 - 4 hours is enough), then the electrode can reach the highest oxidation state (enough power) as much as possible, and the discharge (or use) is forced to Set the voltage, or until the automatic shutdown, such as the ability to activate the battery capacity. However, in the ordinary use of the lithium ion battery, it is not necessary to operate, and it can be charged at any time according to needs, and it is not necessary to be fully charged when charging, and it is not necessary to discharge first. For the first time charging and discharging, it is only necessary to perform 1 to 2 consecutive times every 3 to 4 months.

For electric vehicles and hybrid vehicles, the core technology lies in batteries. Compared with other types of batteries, power lithium-ion batteries have the disadvantages of high price and poor safety performance, but they have important energy and long cycle life. Advantages, therefore have a broader development prospect. The technical development of power lithium-ion batteries is also changing with each passing day. Both the capacity and the structure have been improved. Experts say that no matter which technical route the battery manufacturer adopts, it should meet the requirements of high safety, wide temperature difference, and charge and discharge functionality. Strong, high rate discharge and other conditions.

Battery capacity involves technology and cost Lithium-ion batteries can be divided into small batteries and large batteries according to their size. Small batteries are usually used in 3C electronic products. The related technologies and industries have developed very maturely, and the overall profit is decreasing. More than 85% of current lithium-ion battery products are small batteries.

Large batteries are also commonly known as power batteries. There are also two types of small power batteries and large power batteries. The former is mainly used for electric tools and electric bicycles, and the latter is used in electric vehicles and energy storage. At present, three types of electric vehicles, namely, pure electric (EV), plug-in hybrid (PHEV) and hybrid (HEV), are in a period of rapid development, which has attracted much attention from the industry. As the core of the future automotive industry, the development of the power lithium-ion battery industry has received unprecedented attention and has been raised to a strategic height by major countries. Yang Rukun, president of Shenzhen Jiyang Automation Technology Co., Ltd., said that small batteries cannot be compared with large batteries in terms of product profit or development scale. Although the current power lithium-ion battery industry is still small, electric vehicles Mass production has brought important development opportunities to the power lithium-ion battery industry. According to estimates by industry authorities, in recent years, the market for power lithium-ion batteries will exceed the scale of the global mobile phone lithium-ion battery market. This change will trigger a new round of investment in related manufacturing equipment and plants, and at the same time, new power lithium Major manufacturers in the ion battery industry will make technology competition in related fields more intense.

At present, whether to adopt a single-capacity large-capacity battery technology solution or a small-capacity battery parallel technology solution has always been a matter of debate in the industry. In the end, which technical route is adopted, the key is to look at the result of the battery pack, depending on whether it is in volume, weight, Product quality, performance, price, ease of installation and other aspects of competitiveness [1].

Lithium battery coated with carbon foil

First, the material description [2]

The carbon coated aluminum foil is a composite slurry mainly composed of conductive carbon and a high-purity electronic aluminum foil, which is produced by a transfer coating process.

Second, the scope of application

Power type lithium battery with fine particle active material

Lithium iron phosphate

The positive electrode is a fine particle ternary/lithium manganate

Used for supercapacitor, lithium primary battery (lithium, lithium manganese, lithium iron, button, etc.) instead of etched aluminum foil

Third, the performance of the battery / capacitor

Suppress battery polarization, reduce thermal effects, and improve rate performance;

Reduce the internal resistance of the battery and significantly reduce the dynamic internal resistance increase during the cycle;

Improve consistency and increase battery cycle life;

Improve the adhesion of the active material to the current collector, and reduce the manufacturing cost of the pole piece;

Protecting the current collector from corrosion by the electrolyte;

Improve the high and low temperature performance of lithium iron phosphate battery and improve the processing performance of lithium iron phosphate and lithium titanate materials.

Fourth, the recommended parameters

The corresponding coated active material D50 is preferably not more than 4 to 5 μm, the compaction density is not more than 2.25 g/cm, and the specific surface area is in the range of 13 to 18 m 2 /g.

Five, the precautions in use

1. Storage requirements: In the environment where the temperature is 25±5°C and the humidity is not more than 50%, the erosion of aluminum foil by air and water vapor should be avoided during transportation;

2. This product is divided into two types, A and B. The key characteristics of each product are: A is black in appearance, the thickness of conventional coating is 4~8μm on both sides, the conductivity is more prominent; the appearance of B is light gray, regular The coating thickness is 2~3μm on both sides, the coating area can be welded in less layers, and the coating machine can recognize the jump gap;

3.B (grey) coated carbon foil can be directly ultrasonically welded in the coating area, only suitable for coiled battery welding tabs (up to 2-3 layers of pole pieces), but the ultrasonic power and time need to be fine-tuned;

4. The heat dissipation of the carbon layer is worse than that of the aluminum foil, so it is necessary to finely adjust the belt speed and the baking temperature when coating;

5. It has a big improvement on comprehensive performance of lithium batteries and capacitors, but it cannot be used as a major factor to change some aspects of battery performance, such as battery energy density, high and low temperature performance, high voltage and so on.

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