Honeycomb Energy's short blade battery cell production and development route

Honeycomb Energy recently held a small-scale tour of its Jintan factory, mainly introducing the intelligent manufacturing process of the Short Blade battery. I will share what I saw.

Honeycomb Energy's Short Knife battery cell product first appeared at the Shanghai Auto Show in April 2019, and then occupied the C position in the product series after Honeycomb Energy released the "Lingfeng 600" full-range Short Knife at the end of 2021. This time, at Honeycomb Energy's Phase II Short Knife Battery Factory, the "Short Knife" battery mass production line was launched, with an annual production capacity of 2.5GWh.

▲Figure 1. Production of short-cut lithium iron phosphate

Part 1. Production process of short knife

Of the 8GWh capacity of the Phase II plant, iron-lithium and ternary (including cobalt-free) batteries account for about half. It is estimated that by 2022, iron-lithium batteries will account for more than 50% of the battery companies.

It can be seen on site that the first production process of lithium batteries, slurry homogenization, is also arranged according to this ratio. A single 2300L large-capacity dual planetary mixing equipment, each tank of slurry corresponds to 600KWh (about 10 pure electric vehicles) - this part actually has no direct relationship with the final form of the battery.

▲Figure 2. Proportion of chemical systems seen on site

The most obvious is the second coating process. The length of the short-blade battery (nearly 600mm) is longer than that of ordinary batteries (148mm or 220mm). The width, speed and precision of the coating determine the efficiency and quality of the battery pole production. On site, we can see a 1400mm ultra-wide coating machine, which produces two columns at a time, and the coating speed is also very high (80m/min). The width is wide. In order to ensure the coating accuracy, it is necessary to set up three sets of β-ray online surface density detection systems and two sets of CCD real-time coating width detection systems on the coating equipment to realize real-time data detection and control, and ensure automatic closed-loop control of the coating (surface density is controlled within ±1.5%, and the front and back misalignment is ≤0.5mm).

▲Figure 3. The short blade has changed a lot compared to the previous wide-width coating.

In the rolling process, there is not much difference in the overall process. Due to the wide range, the efficiency is greatly improved through the hot rolling of the positive electrode, continuous rolling of the negative electrode by two rollers, electromagnetic heating, infrared online baking, online laser thickness measurement, waste edge removal and other technical integration on the rolling machine.

In the die-cutting process, Honeycomb Energy applied laser die-cutting, which saved the cost of mold investment and equipment maintenance, and the die-cutting efficiency was also improved by 40% (from 30m/min to 40-50m/min).

The biggest challenge here is the burrs generated by the laser process, which requires very sophisticated algorithms at the detection level. The next step in the production line upgrade will mainly rely on roll-to-roll die-cutting + cutting and stacking equipment, which will be integrated at the process level.

For the blade series of batteries, in a sense, they have evolved from soft packs (battery production using the stacking process). The stacking speed has always been a pain point in the industry. What we see here is a double-station stacking efficiency of up to 0.4s/piece. The next-generation ultra-high-speed blade-type cell pole assembly molding equipment has been developed, with a stacking efficiency of 0.125s/piece. Combined with the cell design, it can pose a substantial challenge to the winding pole assembly molding efficiency at the cell packaging level.

▲Figure 4. High-speed lamination machine

The thickness bottleneck of soft-pack batteries has been broken through under the concept of blade design. Therefore, this lithium iron phosphate battery cell has reached 184Ah at a thickness of 21mm, and there is still room for further growth.

▲Figure 5. Double-wound core design with a thickness of 9mm and 21mm

From the production process, the second phase factory has many improvements in details compared to the first phase we saw before, mainly in terms of compatibility: the second phase is compatible with two different devices, VDA and short knife, and has made improvements in details such as transmission equipment, especially the introduction of the core magnetic suspension logistics system, plus the improved AGV transportation logistics, which greatly improves the beat and efficiency. During the visit, the factory has fewer people and has added more detection methods. Through powerful software systems and data analysis to improve the process pass rate, it has become more intelligent.

Taking the route of low cost and high volume utilization, evolving from VDA cells all the way to blades, the overall efficiency of the core to the Pack is still very advanced. From the current point of view, innovations around the cell level can reduce the cost of the cell at the manufacturing level, and will also improve the grouping efficiency at the Pack level, reduce the weight of the battery system (increase energy density), and reduce the number of parts inside the Pack, especially the reduction of related structural parts, effectively achieving the cost target of the battery system. In the end, the battery safety performance will be further improved-for square shells, thin batteries are relatively safer. If you don't make a fuss in the width direction and expand in thickness, the impact on battery safety will be great (small heat dissipation surface, heat cannot be conducted out, and the temperature difference between the inside and the outside is large).

▲Figure 6. The grouping rate of blade cells is really very efficient

Part 2: Technology Development Direction

● Iteration around the global short knife battery cell

During the technical exchange session, the more interesting topic was the evolution of the short-blade battery.

Due to the current progress of lithium iron phosphate material technology, further iterations can be made in the process and material links. For battery companies, the most popular evolutionary direction is this: in the battery production line, the cell size, the battery system and the vehicle interface, nothing needs to be changed, and the energy density can be directly upgraded by 5% or 10% through multiple iterations.

In the upgrade path of the short-blade battery, Honeycomb Energy is developing both lithium iron phosphate mixed with lithium iron manganese phosphate and lithium iron manganese phosphate mixed with ternary. The second and third generations will be launched from the end of this year to next year, and the energy density will be further improved.

From the perspective of R&D logic, the sources of raw materials are very extensive, which is a better solution and provides great contribution and value to the progress of the entire industry and the enhancement of the competitiveness of electric vehicles. The next step for lithium iron phosphate and lithium iron manganese is to develop fast charging capabilities. The current cost-effective products are equipped with 1.6C fast charging capabilities. The next step is to develop 2C-2.2C lithium iron, and then develop lithium iron phosphate in the direction of 4C.

● High nickel battery cell development

The emergence of low-cost lithium iron phosphate technology will force ternary and cobalt-free batteries to move forward. By increasing the gram capacity of high nickel and the voltage of medium nickel, mass production of 4.4V high-voltage products will be launched in the first half of 2022 and cobalt-free 4.4 products will be launched by the end of 2022 (or early 2023). In this technical direction, first of all, the design of fast charging can be used to achieve a high-performance battery route.

▲Figure 7. The design of the short sword is mainly based on performance.

The interesting thing about making batteries is that the products are constantly evolving: the production line is constantly upgraded to improve efficiency and yield. Platformization can adapt to the pack design of most customers, which is brought about by product flexibility.

With the rapid development of the new energy vehicle market in 2021, battery costs in 2022 will continue to rise due to the rise in upstream raw materials. This will require battery manufacturers and car companies to bear the burden together. In 2022, we can see that the product structure of new energy vehicles may be adjusted.

Currently, every battery company is facing enormous cost pressure, but this pressure is temporary. As the weather gets warmer, upstream supply, including salt lake production and lithium supply from mines, will increase, and will gradually be alleviated with the joint efforts of China and abroad.

From the material side, Honeycomb Energy has taken a lot of actions since mid-2021, including locking in some upstream raw materials (locking in quantity, underwriting, and prepayment). After laying the groundwork, the overall material supply can meet the demand for the whole year of 2022. In terms of cost control, multiple measures must be taken simultaneously: in addition to locking in some raw material purchases in advance, technological innovation must be made to reduce costs - replacing domestic raw materials, using new chemical systems, and absorbing some cost increases by adjusting the structure.

It is expected that in 2022, compared with last year, the proportion of lithium iron phosphate of Honeycomb Energy will increase (more than 50%), and the proportion of short-blade batteries will also increase. At present, the global scale (300GWh) is not very large, and the supply chain has already encountered relatively large supply risks and challenges. In the future, it will increase several times or ten times. In the TWh era, the supply challenges of battery materials will be even greater. In the long run, Honeycomb Energy will make some core raw materials by itself, and make some investments in upstream raw materials, and will make some investments in raw materials for next-generation battery technology.