Authors: Engin, Alkan (R&D Engineer), Busra, Cetin (R&D Engineer), Neslihan, Yuca (R&D Director) – POMEGA

Lithium Iron Phosphate (LFP) battery cells have emerged as a prominent technology in energy storage systems and the integration of renewable energy production in recent years. Compared to other lithium-ion battery chemistries, LFP batteries offer advantages in durability, safety, and environmental friendliness. These attributes make them particularly ideal for large-capacity energy storage systems and electric vehicles. Renewable energy sources are crucial for reducing dependence on fossil fuels and enhancing environmental sustainability. However, renewable sources like solar and wind energy are inherently intermittent. Therefore, energy storage solutions play a critical role in enabling more effective utilisation of renewable energy. Energy storage systems help manage the imbalances between energy supply and demand, enhance energy security, and stabilise the electric grid (1,2).

Fig1: Schematic illustration of the battery value chain from the material level via the battery cell to the battery system level. In each step, inactive components are added which decrease the practical specific energy (3).

LFP battery cells for a more sustainable energy storage

The primary raw materials relevant in the production of LFP cathode active material are lithium carbonate, iron phosphate, and glucose. Additionally, cathode and anode active materials, electrolyte, separator, and housing materials are the most strategic components in LFP battery production. The materials in LFP batteries feature high electrochemical and thermal stability, along with significant safety advantages during charge and discharge cycles. The preparation of cathode and anode electrodes is the first step in the battery production process. The cathode material of LFP batteries consists of LFP powder, a conductive agent, and a binder. The anode material typically includes artificial graphite, conductive carbon, and primarily water-based binders. The cathode and anode materials are mixed with a binder and conductive additives, then coated onto aluminium foil and copper foil, respectively, to create the electrodes (1,2).

The coated electrodes are dried to evaporate and recapture the solvent (especially on the cathode side) using a long drying oven. The electrodes are then slit, calendared, and die-cut to obtain the desired sizes for the cell assembly process. After being dried in a vacuum oven, the electrodes are folded along with a separator and placed in a prismatic cell after undergoing ultrasonic and laser welding processes. Finally, an electrolyte solution fills the cell and seal for the formation and capacity grading process. At the end of the production process, the cells undergo a specific charging and discharging cycle to test their electrochemical performance and safety. Quality control and safety standards are among the most important stages in LFP cell and pack production. The cells are continuously tested for thermal durability, chemical stability, overcharge resistance, combustion resistance, vibration resistance, heavy impact resistance, and high-altitude characteristics. Additionally, the technical properties of the primary raw materials and produced intermediate materials are relevant indicators of the quality control procedures (2,3).

Fig2: Energy Storage System components

Renewable energy for storage: battery manufacturing supporting sustainability

In fact, energy storage systems are portable and modular solutions designed to store and manage electrical energy effectively. Specifically, these systems are particularly crucial for integrating renewable energy sources like solar and wind into the grid. They are able to provide a consistent and reliable power supply, even when energy generation isn’t continuous. The production of containerised or residential energy storage systems requires careful design and project planning. The first step is to determine the feasibility conditions, such as the specific application, the type of energy sources, and the critical requirements of the site where the system will be running. Once these parameters are clear, the process the entails the selection of appropriate components, including the battery packs, rack cabinets for battery packs, cooling systems, firefighting systems, inverters, and energy management systems (EMS).

Then, manufacturing process proceeds with the production of battery packs composed of series and parallel connected LFP battery cells. These different types of battery packs originate from individual battery cells and a battery management system (BMS), configured to meet the desired capacity and voltage output. The rack cabinets, containing these battery packs, are then installed into a standard ISO container of varying sizes (20ft or 40ft), which is modified to include additional features. After the rack cabinet installation, the next step is to integrate the EMS into the containerised energy storage system. The EMS is a key component that optimises the charging and discharging processes, ensuring the system operates efficiently and reliably. Inverters in the energy storage system are necessary to convert the direct current (DC) from the battery cells into alternating current (AC), which can go the grid or to end users (4, 6).

Fig3: Energy Storage System with solar energy supply integration.

Battery manufacturing supporting a wider usage of renewables

Renewable energy sources are an abundant and environmentally friendly energy generation methods in many parts of the world. Solar panels convert sunlight directly into electricity through photovoltaic cells. However, the intermittent nature of solar energy limits energy production to particular times of the daytime. Therefore, the efficiency of solar energy systems can be more reliable with energy storage solutions. LFP batteries store excess energy produced by sunlight, ensuring energy feed during night-time or intermittent energy supply like cloudy or rainy days. LFP batteries play a vital role in integrating renewable energy sources and providing reliable energy storage solution. Their safety, durability, and environmental friendliness make them a preferred choice in a variety of applications, from large-scale energy storage systems to electric vehicles. As technological advancements continue and market demand increases, LFP batteries will become even more important in the energy storage environment, contributing to a more sustainable and efficient energy future (6).

References:

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