(Press release, Moenchengladbach, 29.09.2020) – There is no doubt that we are currently in the energy century. Never in the history of mankind has the subject of environmentally friendly energy generation, energy distribution and storage of electrical energy been more important than today. In order to keep up with this phenomenon, this is one of the largest growth markets par excellence. Everyone is talking about electromobility and the industry is on the starting blocks to increasingly introduce new all-electric vehicles. This is imperative to achieve the fleet consumption levels prescribed by law and avoid penalty taxes. Here, the need for battery storage is obvious.
Less obvious and spurred on by the debate on the rapid charging capability of electric vehicles, is the fact that the existing electricity grids can be locally overloaded by the enormous short-term energy volumes. This is aggravated by the fact that Germany is increasingly withdrawing from nuclear energy and coal, which makes it necessary to set up a Smart Grid with decentrally-organised battery storage facilities. One thing is certain, it will not work without suitable low-cost, durable and reliable battery storage facilities. If we want to avoid a situation where the stability of the electricity grid can only be maintained by importing electricity from abroad, the way forward is clear.
This has also been proven by the company E-Stream Energy GmbH & Co. KG. This start-up company has developed a technology of modular construction kits for battery storage based on standardised round cells. This comes at a time when nearly all the world’s car manufacturers were relying on large-format prismatic cells in their development departments. Since almost all car manufacturers, as well as many manufacturers of industrial storage systems, rely on prismatic cells with high individual capacity, demand increasingly exceeds supply, which leads to a shortage of this type of battery in the world’s markets.
E-Stream Energy uses round cells instead of prismatic cells, as does the American car manufacturer Tesla. In addition to high energy density, good heat distribution, high safety and high performance, market availability is a strong argument for the use of round cells.
Why did so many OEMs rely on large-format prismatic cells in the past? This is mainly because lower costs were expected for the overall system. At the time when the decisions for current and future vehicle generations were being made, the investment and production costs for the integration of a large number of small-format round cells were still very high, as thousands of cells had to be intermetallically connected to each other and elaborately connected to a heat sink for cooling. This is precisely where E-Stream Energy comes in with its own assembly and connection technology. E-Stream Energy has succeeded in finding the optimum combination of manufacturing costs, contact resistance of the cells, thermal balancing and heat dissipation. The possibility of non-destructive cell or module exchange also opens new business models, such as Second Life at cell or module level.
A major challenge for start-ups in the battery sector is the very wide range of possible applications and thus the choice of the right product. These range from power-tool batteries to the e-bike, home energy storage, electric vehicle batteries and large industrial storage units, to name a few. The resulting requirements and cell configurations are very different. For this reason, E-Stream Energy has developed a flexible modular system referred to as the Lego principle. The aim of this is to be able to cover a wide range of applications using fixed common parts. This enables significantly shorter reaction times to changed requirements at remarkably reduced development costs. The time-to-market can thus be noticeably shortened. The use of common parts across different product groups also result in economies of scale, which can be passed on directly to the customer.
The battery storage systems developed by E-Stream Energy are designed for a future-proof maximum voltage of 1,000 V. The low-resistance connection technology, in conjunction with round cells, ensures very high electrical efficiency and thus low heat losses, which in turn allows the power density to be further increased. By using round cells, E-Stream Energy’s battery systems offer almost unlimited flexibility in terms of capacity, voltage, energy and performance, unlike large-format prismatic cells.
One of the main reasons for using a large number of smaller round cells connected in parallel, as opposed to one or two large prismatic cells is the issue of reliability and system availability. If, for instance, a cell fails in electric vehicles with one or two large format cells connected in parallel, this either halves the system performance or, in the worst case, leads to a safety-critical total failure of the battery and thus of the drive. However, the failure of a smaller round cell will hardly be noticed by the driver.
It behaves better in terms of internal resistance and offers a more homogeneous temperature distribution compared to prismatic cells, combined with the innovative connection technology of E-Stream Energy hotspots. Additionally, the heat generated during the operation can be dissipated much better. In contrast to large prismatic cells, the solution developed by E-Stream Energy enables the cells to be cooled directly at the same time. Large prismatic cells become hottest at the power connections, exactly where you cannot or do not want to connect the cooling system. The current state-of-the-art here is to cool on exactly the opposite side, which leads to a very high thermal asymmetry and the resulting faster aging. The above-mentioned rapid loading makes this even worse. With the battery storage units developed by E-Stream Energy, very short charging times can be achieved even at high charging rates and a charge from 20 to 80 per cent of the battery charge level.
The technology developed by E-Stream Energy offers an innovative and at the same time gentle cell connection technology without thermal processes and avoids pre-damage effects in the production of battery modules. In contrast to all other known battery storage solutions, the cells can be replaced non-destructively, which significantly reduces the recycling effort and the associated costs. Due to the possibility of non-destructive cell replacement, the product life can be extended almost indefinitely. This is an unbeatable advantage for investment-intensive battery storage solutions and their technologically limited cell life. The separation of product and cell also offers new approaches to cost reduction of investment-intensive products for industry, as the cell could be rented. At the end of the cell’s service life, the customer receives new cells, which now are more cost-effective and perform better than they were in the original equipment. The product thus follows the technological development of the cell. As a result, the product performance increases over time while costs decrease. Cells removed from automotive applications at the end of their service life can continue to perform their service for many years in stationary storage applications (Second Life).
What the market urgently needs today is a flexible battery platform that is as application independent as possible. However, if you look at the current battery storage market, countless solutions can be found that are tailored to the respective application. The solutions that these have in common are that the effort for cell integration and the resulting investment costs are very high, which makes market entry difficult or impossible for small dynamic companies.
At its research and development site in Mönchengladbach, E-Stream Energy is working on all the important levers simultaneously.
The battery technology developed by E-Stream shows what German engineering is capable of. With this high technical performance, the sophisticated manufacturing approach, the resulting possibility of low-investment worldwide production with high quality, it is only a matter of time before E-Stream slips onto the radar of other European battery customers.