What is the difference between soft pack lithium battery and lithium battery pack and aluminum shell lithium battery?

July 25, 2020

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"Lithium battery" is a kind of battery made of lithium metal or lithium alloy as harmful material and using a non-aqueous electrolyte solution.

Lithium metal battery was first proposed and researched by Gilbert. Lewis, in 1912.

In the 1970s, M.S. Whittingham came up with and began working on lithium-ion batteries.

Due to its very active chemical properties, lithium metal has high environmental requirements for processing, preservation, and use.

So lithium batteries have not been used for a long time.


With the development of science and technology, lithium battery has become the mainstream now.


Lithium batteries can be broadly divided into two categories: lithium metal batteries and lithium-ion batteries.

Lithium-ion batteries do not contain metallic lithium and are rechargeable.

Lithium-metal battery, the fifth generation of rechargeable batteries, was born in 1996. Its safety, specific capacity, self-discharge rate, and performance-price ratio are superior to the lithium-ion battery.

Companies in only a handful of countries are producing lithium-metal batteries because of their high-tech requirements.


Lithium-ion battery structure


The lithium-ion battery is the replacement product of metal lithium battery emerged several years ago. The main components of the cell are anode and cathode, electrolyte, diaphragm, and case.


Positive electrode -- a carbon electrode that can absorb and store lithium ions. When discharging, lithium becomes lithium ions, leaving the battery anode and reaching the cathode of a lithium-ion battery.


Negative electrode -- Materials are embeddable lithium compounds with potential as close as possible to lithium. Various carbon materials include natural graphite, synthetic graphite, carbon fiber, mesophase carbon, and metal oxides.


Electrolyte -- a mixed solvent system with alkyl carbonates such as LiPF6 ethylene carbonate, propylene carbonate, and low viscosity diethyl carbonate.


Diaphragm -- using polyene microporous membranes such as PE, PP, or their composite membrane, especially PP/PE/PP three-layer membrane, has a low melting point and a high puncture resistance playing a heat insurance role.


Housing -- steel or aluminum material, cover body assembly has the function of explosion-proof power off.


The basic concept of lithium battery in soft package and lithium battery package and aluminum case

The soft pack lithium battery is a battery with a polymer shell covered by a liquid lithium-ion battery packaged by the aluminum-plastic composite film. The mechanical strength of the soft pack lithium battery is not high. In case of safety accidents such as internal short circuit, the battery is easy to puff up and exhaust, reducing the risk of explosion.


Lithium battery pack: "lithium battery" is a kind of battery made of lithium metal or lithium alloy as harmful material, using a non-aqueous electrolyte solution.

Lithium battery packs can be roughly divided into two categories: lithium metal batteries and lithium-ion batteries.

The lithium battery pack is mainly composed of anode and cathode, electrolyte, diaphragm, and shell.


Lithium battery in aluminum case:


Lithium battery aluminum shell is a kind of battery shell made of aluminum alloy material.

They are mainly used in square lithium batteries, lithium battery pack aluminum packaging reason for its lightweight, and safer than steel case.
The aluminum-clad lithium battery is the mainstream of liquid lithium battery, which is used in almost all fields of lithium battery.


What is the difference between the lithium battery pack and lithium battery pack?

Application field


Softpack lithium batteries are mainly used in mobile Internet, mobile power, and digital products such as smartphones, laptops, video cameras, etc.


Lithium-ion battery packs are widely used in small machine rooms, weak current rooms and other sub-systems, new energy outdoor stations, communication base stations, indoor and outdoor non-air conditioning stations, radio and television stations, military, petroleum and meteorological stations and other uncrewed stations.


Structural features


The most significant difference between the critical materials used in soft-pack lithium batteries lies in the soft-pack material (aluminum-plastic composite film), which is the most vital and technically challenging material in soft-pack lithium batteries.

Flexible packaging materials are usually divided into three layers, namely the outer resistance layer (generally nylon BOPA or PET formed by the outer protective layer), the permeability layer (intermediate layer of aluminum foil), and the inner layer (multi-functional high barrier layer).

Lithium battery pack: The lithium battery is assembled as a lithium battery pack with a higher energy ratio, longer life, and service life.

The lithium battery pack is mainly composed of anode and cathode, electrolyte, and diaphragm.


Energy ratio and weight


The weight of a soft-coated lithium battery is 40% lighter than that of steel-clad lithium battery of the same capacity, and 20% lighter than that of the aluminum battery.

The steel shell battery capacity of the same size is 10 ~ 15% higher, 5 ~ 10% higher than aluminum shell battery.


The lithium battery pack's energy density is 3~4 times that of lead-acid battery, 2.5 times that of nickel-cadmium battery, and 1.8 times that of Ni-MH battery. Therefore, with the same battery capacity, lithium battery will be smaller and lighter than lead-acid, nickel-cadmium, and ni-MH battery.


Lithium battery design round horn of square horn and two kinds of aluminum shell, aluminum material for aluminum manganese alloy commonly, it contains the main alloy elements Mn, Cu, Mg, Si, and Fe, etc., the five kinds of aluminum alloy in lithium battery pack shell plays a different role, such as Cu and Mg is to improve the strength and hardness, Mn to improve the corrosion resistance, Si can enhance the effect of magnesium-aluminum alloy heat treatment, Fe can improve the high-temperature strength.

Lightweight and safety, as well as the resulting performance advantages, make lithium battery aluminum case become the mainstream of the case. Lithium battery aluminum case is still evolving towards high hardness and lightweight technology, which will provide more technologically superior lithium battery products.


In the higher level of consumption, such as Europe and the United States, the use of a soft lithium battery pack has an advantage.

In most developing countries, such as India and the Middle East, aluminum-clad batteries have apparent advantages.


In terms of technology maturity, aluminum shell technology has been very mature, and the material technology (such as gas expansion rate, expansion rate, and other indicators) requirements are not high. There are no technical barriers in the industry;

There are still many technical problems to be solved in soft-pack lithium batteries, especially in the index of battery cycle expansion, which has not been addressed in most cell factories.

The manufacturing automation degree of aluminum-case battery is higher than that of Li-ion battery, so the influence of human factors on product consistency is reduced to a certain extent. Labor cost is saved.


In terms of manufacturing cost, aluminum-encased lithium battery materials have been completely localized. In contrast, aluminum-plastic film materials for soft-encased lithium batteries still need to be imported, and aluminum-encased lithium batteries have lower technical requirements than soft-encased lithium batteries.

Therefore, the overall material cost is about 10% lower than the soft-pack lithium battery under the same capacity.

Also, the finished product processing simple, reliable, and distinct cost advantages.

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Also, the finished product of aluminum case lithium battery is simple to process. The Pack lithium battery Pack is reliable and has a distinct cost advantage.


The soft-pack lithium battery is mainly aimed at the middle and high-end market, with a high-profit margin per unit product. Under the condition of the same production capacity, the relative profit is higher than the aluminum-clad lithium battery, and the capital return cycle is also short.
Due to the natural formation of scale effect, product qualification rate, and cost control, both have considerable profits in their respective markets.


Aluminum-case lithium battery adopts a laser sealing process, while soft-cover lithium-ion battery adopts hot-melt method. In terms of sealing performance, aluminum-case battery is superior to the soft-cover lithium-ion battery, avoiding aging and air leakage at the sealing surface.
Soft package the burst pressure of the lithium-ion battery is much less than an aluminum battery, due to using lu: su composite film packaging, a soft bag of lithium-ion battery is not high mechanical strength, in the event of a security incident cases, such as short circuit inside the cell easy to summon up the exhaust, reduce the risk of explosion, the whole sealing technology on aluminum battery, the same condition, the pressure is not easy to discharge, increasing the safety hidden trouble.


The mass-energy density of soft-pack lithium battery is higher than that of aluminum-clad battery. For cells of the same volume (2Ah~5Ah), the soft-pack lithium-ion battery is about 10%-20% lighter than aluminum-clad lithium battery.

With the gradual improvement of technology maturity, lithium battery soft pack can replace aluminum-lithium battery, and its advantages will be further highlighted.