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Skip to 0 minutes and 8 secondsProduction process is built upon three main different businesses. The first one is material synthesis. It's a chemistry business related to cathode, anode, electrolyte, salts, additives, polymer separator, metal foil collector, metal can or polymer pouch bag. The second one is cell manufacturing. It's a process chemistry in the mechanical manufacturing business. The third and last one is system assembly from cell, to module, to a EV battery pack, or ESS rack and container. It's an electrical, mechanical, and thermal engineering assembly business.

Skip to 0 minutes and 53 secondsMaterials can ever be purchased final, and directly incorporated into the cell manufacturing process, or it can be supplied as advanced precursors that are transformed on site into final materials. The largest plants are even vertically integrated, having directly on site some upstream plants to manufacture locally, for example, their own electrolyte or metal cans.

Skip to 1 minute and 23 secondsThe process most specific to the battery industry is for cathode active material synthesis and it will strongly depend on the targeted material. From continuous ball-milling, at high temperature with shearing capability, for example, for lithium iron phosphate, to batch wet synthesis in organic solvent or aqueous solvent, for example, for some kind of lithium nickel manganese cobalt oxide.

Skip to 1 minute and 52 secondsIn terms of order of magnitude, the worldwide material production capacity at the end of 2017 was about 400,000 tons per year of cathode material, 300,000 tons per year of anode material, 290,000 tons per year of electrolytes, 2,900 million square meters per year of separator. All those capacities allowed for production of about 164 GWh of lithium cells produced in 2017. Cell manufacturing process itself is organised around four main steps, often as a batch semi-continuous process. The first one is active material preparation. The second one is electrodes manufacturing. The third one is cell assembly. And the fourth and last one is cell formation.

Skip to 2 minutes and 46 secondsThe global process varies from one manufacturer to one other and we often have some specific features depending on the chemistry and on the cell form factor.

Skip to 2 minutes and 57 secondsFirst, the active material preparation. In two separated tanks, cathode material on one hand, and graphite anode material on the other hand are mixed with binder, graphite, and other additives, plus solvents, such as NMP to produce an ink. The formulation and the process associated to those inks are a key know-how, the order and the timing to introduce each component, the temperature, the mixing speed have a deep impact to ensure proper ink coating in the following step. It should be noted that a few companies are using lithium metallic anode. In that case, the production process is noticeably different, as the electrode is directly extruded.

Skip to 3 minutes and 49 secondsThe second step is electrodes manufacturing. Once the inks are ready, they are both coated through a slot-die process onto metallic substrates made of copper for the anode, and of aluminium for the cathode. The metallic foil can be coated on one or two phases, one at a time, or two at the same time, on a width up to one meter. Depending on the coating thickness, and the number of faces coated, each coating line can go from 10 up to 80 meters per minutes. Once coated, the foil goes through an oven that helps to evaporate the solvents used to create the ink, leaving at the end a solid substrate stick onto the metallic surface.

Skip to 4 minutes and 38 secondsOnce dry, the foil goes through a calendering step to compress electrode and to reduce its thickness. Each step is carefully controlled through various, physical means, for example, infrared or x-rays to ensure homogeneity along the electrode.

Skip to 4 minutes and 59 secondsThis stage yields two large rolls of electrode, one for the negative, one for the positive. That will go eventually to a splitting step to produce smaller rolls. Depending on the cell assembly process, especially if it involves electrode stacking and not electrode winding, then each roll goes through an additional step of notching to cut sheets of electrode and/or connectors.

Skip to 5 minutes and 28 secondsPrecision cutting is very important, as it can create defaults into the material leading to decreased performances, life, or safety concerns.

Skip to 5 minutes and 40 secondsSome other steps can be considered, depending on the chemistry and cell format, such as, for example, vacuum drying step.

Skip to 5 minutes and 50 secondsThe third step consists of assembling the electrodes and the separator together. The historical way is to wind together the anode a separator, the cathode, another separator into a cylindrical or prismatic cell called jelly-roll. Alternatively, for prismatic and pouch bags, electrode sheets can be stacked in various configuration, such as single-sheet stacking, Z-folding stacking, Z-folding with single electrode stackings. Once the roll or stack is assembled, it's attached with one or more stickers to keep it firm, and it's inserted into a can or a bag, which is then filled with the electrolyte. The cell is stored, degassed, and eventually refilled with electrolyte if required.

Skip to 6 minutes and 44 secondsThe last step is to give life to the newly assembled cell for the formation step or aging step. The cell is stored, charged, discharged along a very specific protocol function of the chemistry, of the cell format, and of the targeted application. Temperature, voltage, current, and many other parameters are used to initiate the cell, especially forming a specific interface within the active material called the SEI, meaning for Solid Electrolyte Interface It's also the time to detect any default and remove low performances cells. Last and final business is building systems upon the cells. The cells are wired together, enclosed into plastic or metal casing, and connected to a control card, including a battery management system, the BMS to produce finally a module.

Skip to 7 minutes and 43 secondsThis module is most often made up of 4 to 50 cells, in serial and/or in parallel, being in a range of a few hundreds of watt hour to a few kilowatt hour.

Skip to 7 minutes and 56 secondsBeing an assembly business, module and system are much less intensive regarding capital investment requirements than cell manufacturing business, about five to seven times less.

Skip to 8 minutes and 8 secondsMoreover, whereas cell manufacturing is a highly automatized process with only a few dozens of skilled technicians and engineers operating at the same time on the line. Module and system assembly can be very manual, but can also be very automatized.

Skip to 8 minutes and 28 secondsAs of 2017, the largest plants worldwide for EV and ESS module and pack assembly can be up to a few thousands pack per month. With increasing automation and growing volumes, we can expect some pack assembly plants to which a few tens of thousands units per months, or tens of MW- scale ESS 20-foot containers per month.

Lithium-ion batteries manufacturing process

In this video lecture, Yann Laot, Strategic Marketing Manager at SAFT, as representative of a large-scale battery production facility, explains every step of the manufacturing process of lithium-ion batteries.

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This video is from the free online course:

Understanding Energy Storage: The Battery Revolution

EIT InnoEnergy