What battery systems are we expecting in the future?

Let’s take a closer look at the battery cell. It plays a central role in both storing and releasing the energy. Basically, battery cells are built in one of these designs:

• Cylindrical (classic round cells)
• Prismatic
• Pouch (also known as coffee bag cell)

Each design has its advantages and disadvantages. For example, the cylindrical shape enables a very high volumetric energy density at cell and module level. However, the round shape cells fill the space very inefficiently. In terms of energy density, the battery cell in a pouch structure can keep up with the cylindrical shape. The space utilisation is efficient, but the pouch structure is very flexible and therefore inflates under pressure. Prismatic battery cells have a low energy density, but at the same time are very robust and make good use of space.

Lithium-ion (Li-ion) batteries are the most common type of batteries used in stationary systems today. Li-ion battery systems are well scalable, highly durable, require low maintenance, have high energy density, can withstand high/low temperatures and are less susceptible to humidity than other battery systems. In order to increase the safety of Li-ion battery cells and to avoid major damage/risks, the following elements are installed:

• PTC (Positive Temperature Coefficient) element: It breaks electrical contact with the cell when it heats up and can prevent the cell from overheating further.
• CID element (Current Interrupt Device): It breaks electrical contact with the cell in the event of overpressure.

The lithium-nickel-cobalt-aluminium-oxide (NCA) battery has been around since the late 1990s. It offers more specific energy and high performance. NCA battery cells require special monitoring mechanisms in electric cars to ensure greater safety. NCA battery cells are expensive to produce, despite the low use of cobalt in it. They are not widely used in the automotive industry.

Lithium-nickel-manganese-cobalt-oxide (NMC) battery cells can be produced with different cell properties by varying the proportions of nickel, manganese and cobalt. Less cobalt means lower cost. More nickel increases the energy density. A larger proportion of manganese increases the specific power. This flexibility is a great advantage of these batteries.

Lithium iron phosphate (LFP) battery cells offer higher intrinsic safety and power density. The element groups used for cell production have better availability, which makes the production process much easier. Disadvantages are faster self-discharge and lower energy density compared to NCA and NMC cells. Further comparisons:

The battery market is poised for growth – 214,000 residential storage systems and around 3900 commercial storage systems will be added in 2022 alone. Estimates suggest a demand of 2035 GW in 2030. Much of this will be used for electromobility.

In order to meet this demand, research is being carried out to find cost-effective and sustainable alternatives to the lithium-ion battery. A small overview of the projects:

The Fraunhofer Institute for Ceramic Technologies and Systems IKTS has set up a joint venture. The cell technology will be marketed under the brand name "Cerenergy ". This new technology is free from lithium, cobalt, graphite and copper. It can therefore reduce raw material shortages and supply chain problems.

According to the researchers, the production costs are about 40 % lower than the costs for lithium-ion batteries. The main components of the Cerenergy battery are sodium chloride or Na/NiCl2 and Na/S batteries. The newly developed Cerenergy ACB60 battery packs are said to have a longer life span and to be able to deliver the stored energy for a longer period.

In 2023, the Chinese manufacturer Contemporary Amperex Technology (CATL) will introduce a new Na-ion battery. Initially, Na batteries will replace lead-acid batteries in fuel-based cars, but in the medium or long term they will also be used in electric cars. This battery technology impresses with its super-fast charging and compatibility, which is important for e-cars. CATL has also developed a combination of lithium-ion and Na-ion cells. It is suitable for the manufacturer's cell-to-pack technology and can be used without battery modules in electric cars.

The aluminium-sulphur battery technology was developed by an international team of researchers at the Massachusetts Institute of Technology (MIT) in the USA. In addition to aluminium and sulphur, chloraluminate salt, which acts as an insulator, is used here to store energy. Numerous tests have shown that this battery technology has a high charging speed. In addition, the cost is 1/6 that of lithium-ion batteries. But the biggest advantage is that there is no fire hazard.

I think we have come a long way in terms of the sustainability of battery systems. If I compare resource extraction and recycling technologies now with those of a few years or decades ago, the industry has made great progress. In terms of cell construction and cell chemistry, we have reached a very high standard of safety and performance. In the future, we will need a mix of different battery technologies to provide the right solution for every application.

• Battery systems are becoming increasingly sustainable.
• There are 3 different cell types of batteries: cylindrical, prismatic and pouch.
• At present, Li-Ion batteries dominate the market and among them especially: NMC, NMA and LFP cell chemistries.
• Li-Ion alternatives are becoming increasingly important.