18650 battery bulk manufacturers explain the two process technologies of
18650 battery bulk winding and lamination
18650 battery bulk manufacturers explain the two process technologies of
18650 battery bulk winding and lamination. 18650 battery bulk winding and
lamination technology is like twin brothers fighting, and the market determines
life and death. The core manufacturing process of lithium-ion batteries is
divided into lamination process and winding process, which are mainly
distinguished by the assembly method of the pole pieces. In this article, 18650
battery bulk manufacturers will analyze the process and equipment
characteristics of the two processes of winding and lamination.
18650 battery bulk manufacturers explain the two process technologies of
18650 battery bulk winding and lamination
With the widespread use of lithium batteries as power sources in mobile
phones, digital products, laptops, drones, model aircraft, power tools, special
and new energy vehicles, portable energy storage, medical equipment and other
fields, the domestic 18650 battery bulk industry has developed rapidly. As an
important part of 18650 battery bulk manufacturing, the lamination and winding
process has attracted widespread attention from academia and business
circles.
Winding process: For example, cylindrical batteries, this process is to
stack the raw materials together in the order of negative electrode, separator,
positive electrode, and separator, directly roll them into a cylindrical shape
through the winding method, and then place them in a metal casing; because the
internal structure is not stable Uniformity, the internal reaction degree and
rate of the battery cell are uneven during charging and discharging; therefore,
for thicker coiled batteries, there is a possibility of deformation after
high-rate charging and discharging or after multiple cycles. Moreover, it can
only be made into a rectangular parallelepiped battery.
18650 battery bulk winding equipment includes automatic unwinding of
positive and negative electrode sheets and separators, automatic dust removal,
automatic winding of positive and negative electrode sheets, pasting of
termination tapes, automatic blanking of finished products, pre-pressure and
weighing, and QR code pasting. In the winding process, after the pole piece
separator is made into a battery core, the electrodes at the edges on both sides
have a large curvature. During the charging and discharging process, they are
easily deformed and twisted, which will lead to a decrease in the performance of
the 18650 battery bulk and even a safety hazard. In addition, during the
discharge process of the battery core, the current distribution on both sides is
uneven, the voltage polarization is large, and the discharge voltage is
unstable.
Lamination process: For example, soft-pack-shaped batteries rely on
"stacking", such as "z"-shaped lamination. First, the positive and negative
electrode raw materials are cut into rectangular pole pieces of the same size,
and then stacked on the separator respectively. The separator " Z" shape passes
through it, separating the two poles, and finally wrapped in aluminum plastic
packaging.
The lamination process is cumbersome, mainly cutting the pole pieces and
diaphragms into pieces. However, the pole piece slitting qualification rate is
low, the quality (section, burrs, etc.) is difficult to maintain a high degree
of consistency, and the alignment accuracy is insufficient.
Power lithium batteries can be divided into two types: coiled and laminated
in terms of structure. According to the shell material, they can be divided into
metal shells (steel, aluminum) and soft packs (aluminum plastic film). Domestic
small factories mainly choose the soft package lamination process. It is
estimated that the main starting point is to reduce equipment requirements and
reduce capital investment. Nowadays, major domestic manufacturers (BYD, Lishen,
ATL, etc.) have adopted the metal shell winding process, which requires a large
investment in equipment, but can increase the degree of automation and thereby
improve the consistency of lithium batteries.
Industry insiders generally believe that the lamination process can better
leverage the advantages of large-scale lithium batteries, and it has advantages
over winding in terms of safety, energy density, and process control. Therefore,
for the field of power lithium batteries, the lamination process is the soft
package There is no doubt about the long-term development trend of battery
applications.
The reason why soft pack power battery companies choose to switch from
lamination process to winding process
First, with the advantage of high energy density, the penetration rate of
soft-pack batteries in the power market has increased rapidly. Data show that in
the first quarter of 2018, soft-pack battery shipments were approximately
1.2GWh, accounting for 14% of shipments, a significant increase from the same
period last year. Lamination efficiency cannot well meet the needs of battery
companies.
Second, judging from the reasons for choosing to switch to the winding
process, whether it is semi-automatic or fully automatic winding, it can be
completed quickly and with high quality, and production control is relatively
simple. At the same time, subsequent slitting is convenient and the pole piece
qualification rate is high.
Third, the winding process is cheaper than the lamination process.
In general, the winding efficiency of 18650 battery bulk cells is high and
the process is simple, but the quality of the battery cells is not as good as
that of lamination. Although the lamination machine can improve efficiency
through multiple stations, the overall cost is still high, the consistency of
the cells is poor, and the competitiveness in the market is still weak, and it
can only be used by a small number of people.
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