Author: Zhu Yulong
After seeing the news about the “Short Sword” battery factory of Honeycomb Energy, it has attracted attention and discussion in the industry. I want to share with everyone some information that I have learned about the Honeycomb Energy “Short Sword” from another perspective.
Regarding the Honeycomb Energy “Short Sword,” we need to trace back to the 2019 Shanghai International Auto Show. Honeycomb Energy first appeared in the industry and showcased a short sword-shaped lithium iron phosphate cell with an internal code name of “L600”. Then, in July 2019, at the “Leading the Stacking Era and Guarding Core Safety” brand strategy planning and product launch conference, they showcased a stacked short sword battery. However, at that time, no detailed introduction was given.
Out of curiosity about the more detailed design of the “Short Sword” battery, I spent some time analyzing patents and summarized some of the Honeycomb Energy patents on the short sword design.
Analysis of Honeycomb Energy’s Short Sword Battery Patents
After searching for Honeycomb Energy’s patents, it was found that there are nearly 50 published patents. The first patent involving pole pieces appeared in 2019. In March 2020, they directly publicly revealed the “Short Sword” cell and group solution. In the claims of this patent, it is directly stated that “The length of said cell (22) is L, the height is H, 200 mm ≤ L ≤ 600 mm, and 50 mm ≤ H ≤ 150 mm,” directly limiting the length and height of the cell. Combining the information previously learned, limiting the length is on the one hand to consider the performance and scale indicators of stacked battery manufacturing, and on the other hand, the “Short Sword” has strong compatibility and supports flexible changes in series-parallel schemes with switching of the 590 standard module, which has high standardization and flexibility characteristics.
The patent application with authorization announcement CN 213988965 U, filed on December 31, 2020, introduces a monomer battery and battery module with a certain structure design, as shown in Figure 3. The short-blade battery includes a housing and a cover plate, with two open sides on the housing whose minimum surface area is set as an opening. The positive and negative cover plates are arranged respectively on the two openings of the housing. The positive cover plate has a positive pole and an explosion-proof valve, while the negative cover plate has a negative pole and a liquid injection hole. This design reduces the occupied space of the positive and negative cover plates in the monomer battery, enhances the space utilization rate, and thus increases the monomer battery’s energy storage capacity. Moreover, it reduces the risk of positive and negative short circuits, minimizes the risk of electrolyte contamination and explosion-proof valves, and improves the monomer battery’s qualification rate and safety performance.
In this patent, the size range of the battery core and the size ratio defined by FHE (FengKuangHai Energy) are both restricted, with a length ≤ 600 mm, 10% a ≤ height b ≤ 30% a, 2% a ≤ width c ≤ 10% a. The restricted size ratio covers all categories of short-blade battery whose length is up to or shorter than 600 mm.
From the design intention of the patent, we can see that the positive and negative cover plates are arranged separately at both ends of the housing. The positive pole and the explosion-proof valve are set on one end, and the negative pole and the liquid injection hole are set on the other end. This way of arrangement reduces the occupied space of the positive and negative cover plates in the battery core, which improves batteries’ energy storage capacity.
From the patent CN215911486U “Top cover of battery and battery” published on February 25, 2022, we can also find a lot of information about the short-blade battery of FHE.
Regarding the design of the battery pole, in order to meet the requirements of charge and discharge performance, the area of the pole needs to be as large as possible, thus improving the overcurrent capability of the battery. The actual way is to set multiple pole bodies to increase the total volume and sum of the cross-sectional areas of the pole bodies, thereby improving the overcurrent capability of the battery. Multiple pole bodies can be connected to the same pole rivet block, which increases the cross-sectional area of the pole rivet block.
The design of the battery top cover is shown in Figure 5.- In the cover design, there is also a part of the proportion design. Honeycomb Energy has specified the width of the cover and rivet blocks, as well as the distance between the rivet blocks and the explosion-proof valve from the edge of the cover. The length L2 of the rivet block and the length L1 of the cover satisfy 0.3≤L2/L1≤0.5, with the aim of maximizing the area of the pole piece.
Interesting, Table 1 below shows Honeycomb Energy’s patented design for the cover on traditional VDA and 590 battery cells. In the original square cell, simplification of the cover was one of the most important design elements as it reduced the volume of the battery cell and required a lot of effort and time.
What does the Honeycomb Battery Patent Highlight?
The short knife battery is an extension of the previous square cell stacking technology, which we have mentioned before. This technology revolves around maximizing the utilization of the core by rolling it around, which has allowed soft packaging manufacturing technology to be extended very well. Combining the advantages of soft packaging and square cell technology, the core of this product line is in the patented technology of using the packaging and cover design of original square cells and simplifying it to create a short knife product technology.
For Honeycomb, the short knife battery product line continues the development of the square cell stacking technology based on the VDA battery cell process. After the square cell stacking process was validated in the Jintan factory, it was well developed to this type of technology. As a result, we can see that Honeycomb Energy’s battery development for cobalt-free batteries, jelly batteries, and short knife slice batteries have all been transformed into patented technologies. According to the latest data from the patent database, Honeycomb Energy and its affiliates (mainly Honeycomb Energy Technology Co., Ltd.) have filed 2,900 patent applications in 126 countries/regions worldwide, including 1,957 valid patents and 50 overseas patent applications.
For Honeycomb Energy, the design of the Short Sword battery breaks away from the VDA design and has made systematic layout in patents. That is to say, all the patents that have been gradually displayed since December 2020 are based on this design. We will be able to see more technological innovations and optimizations in the future.
The power battery industry is a capital-intensive, knowledge-intensive, and rapidly innovative environment. To evaluate whether a power battery company has sustainable capabilities, a multidimensional view is needed, including product, process, cost control, and supply chain. In terms of research and product innovation, this is reflected through patents. Global power battery patents are rapidly increasing, mainly focusing on cell, cell grouping, and thermal management technologies.
Summary: Currently, power batteries cannot simply be replicated in terms of products, and considerable research and development investment is needed to break through the patent blockade and establish their own barriers to entry. When evaluating the innovation capabilities of a power battery company, we not only look at its existing products and technologies but also its ability to integrate resources. A power battery company depends not only on a few cell engineers and technicians but also on its organizational structure, which can continuously innovate based on existing technologies and product processes to improve efficiency and reduce costs. When facing current raw material prices, it is a true test of the comprehensive ability of a power battery company.
This article is a translation by ChatGPT of a Chinese report from 42HOW. If you have any questions about it, please email firstname.lastname@example.org.