“I used to work in the paintshop. That was clean, but nothing on the scale of this”
– Jim Wilkinson, Nissan
Nissan’s battery plant in Sunderland, north-east England, is unlike other automotive facilities. Parts of it have to be kept so clean that visitors must cover up like medics, and ballpoint pens are confiscated lest clicking them open discharges microscopic particles of plastic into the air. Nissan is incredibly secretive about the processes within. The facility opened last year at a cost of £420m ($637m) but only now was AMS able to take part in the very first tour. Even so, some areas were off limits, despite the fact that visitors' cameras were removed and that the exact chemistry of the process would have been a mystery to all but a battery scientist.
The facility sits next to where Nissan builds cars such as its C-segment Qashqai SUV and the smaller Juke B-segment SUV. It also makes the Leaf EV, which shifted to Sunderland last year for European markets. The Leaf was originally the plant's exclusive customer, but recently it started supplying battery modules for the e-NV200 van, which Nissan builds at Barcelona, Spain. It does not supply alliance partner Renault, nor are there are plans to do so, according to Colin Lawther, Nissan’s head of manufacturing, supply chain and purchasing for Europe.
The timing of the tour might have been significant. Renault-Nissan Alliance CEO Carlos Ghosn recently suggested that the company might rethink its policy of making its own batteries, while news agency Reuters quoted a source as saying it might farm out production of batteries at its three plants in Sunderland, Smyrna (Tennessee) and Zama (Japan) to an external supplier, possibly Korean battery specialist LG Chem.
Lawther admits that battery making is not a core competency at Nissan but believes it was initially paramount for the OEM to have control of supply. “Clearly, he who controls the batteries controls the world from an EV point of view,” he told AMS. There are no plans to sell, according to Lawther, but he did not exclude this possibility in future. At present, Nissan is still investing in the plant. For example, a new conveyor belt will be added in March to replace the rather awkward system of using boxes to move the modules to the final battery pack line 100 yards away.
The finished object is a battery pack in which 48 modules positioned as three stacks are sealed between two pressed steel trays. The whole assembly weighs 250kg and costs around £5,000 if a Leaf owner needs a new one. The cost to Nissan has not been disclosed. Each laptop-sized module contains four cells and in each cell are stacked 18 layers of anode, 17 layers of cathode and 34 layers of separator. The packs for the van are almost exactly the same as for the Leaf, but are assembled in Spain from modules made in Sunderland.
The whole production process starts with vast rolls of electrodes – aluminium for the cathode and copper for the anode – which are coated in lithium and sent from Japan in rolls 2km long, each making batteries for just seven cars. These are layered into a cell that will be filled with electrolyte, but before that can happen the rolls are moved into the clean room via air locks to prevent contamination.
Keeping it clean
The clean room (in fact a really clean room) is where the heart of the battery is created. Anyone entering the room has to put on a full bodysuit and cover hair, hands and mouth. No paper, cardboard, leather, wood, or cloth is allowed inside, and certainly no food or drink. After suiting up, visitors enter a four-person ‘air shower’ corridor where nozzles remove any last vestige of dirt. Only then can they enter the clean room.
Jim Wilkinson, the battery plant production manager, puts it best: “I used to work in the paintshop. That was clean, but nothing on the scale of this.” It is also incredibly dry – less than 1% humidity. A facilty able to accommodate all of these conditions costs money; the clean room took 65-75% of the £420m, says engineering manager Jett Pratt.
The rolls of electrode spend half a day in an oven to dry off before being split into three and sent to the cell production facility. The fact that the electrode comes in rolls before being sliced and layered by high-speed robots prompted Nissan to employ former printers among the clean-room staff. A total of 316 work in the battery plant.
The stacking machines are made specially for Nissan and sit behind glass enclosures. The working environment is all incredibly high-tech, more reminiscent of a semi-conductor factory than a car plant. Across one wall, what looks like a science lab is where the contamination team checks problematic cells. After the cells are sealed and welded on three sides, they are tested by passing a small electrical charge through them; any contaminants create a short circuit. “We have to jump on problems very quickly,” says Wilkinson.
Next comes the injection line, where the cells are filled with electrolyte via the single side of each cell which is not yet sealed. This is one room which is inaccessible to visitors. Only four people work there, monitoring the magazine-mounted cells as they go into the sealed chamber to be dipped in the solution of lithium-ion enriched electrolyte (sourced from nearby Teesport). Extra people would raise the humidity in the air too high by their very breath.
"He who controls the batteries controls the world, from an EV point of view"
– Colin Lawther, Nissan
Next comes the most secretive part of all: the ageing process. Nissan compares it to the ageing of a fine whisky, but it is obviously much more complex than that. During the tour, AMS was told that the whole process was “commercially sensitive” and few details were provided. Essentially, the cells are charged and discharged for up to 32 days “to allow the cell chemistry to develop”.
Afterwards, the batteries leave the clean area so that the cells can be stacked into two sets of two to create the modules. This section does not have to be quite so carefully monitored for cleanliness but is still surrounded by a pressurised air curtain and vistors have to change their shoes, or wear covers.
Like the clean room, this process is highly automated, with small robots working rapidly behind glass enclosures. Mitsubishi supplies the multi-axis robots and Hitachi the two-axis robots, but the overall machinery to connect the cells – using first ultrasonic welding then glue – is licensed to Nissan. After the modules have been made, they are put into protective aluminium cases and inserted into a vacuum where a machine checks for odours indicative of leaking electrolyte.
Data for each is logged at the module stage onwards so that Nissan can track the pack to a specific batch if there is a problem. This is facilitated by a system that feeds information back from the car automatically, and Wilkinson confirms that cars have been recalled, although only individually. With car buyers still skeptical about battery power, reliability is vital. “We’ve worked very hard to get a car into market that the customer can depend on,” says Wilkinson.
The finished modules are either sent off to Barcelona for the eNV200 van or moved across the room to the pack assembly area for the Leaf. There is only a small charge in the modules, but nonetheless assembly line staff have to stand on rubber mats while wearing insulated boots and two pairs of gloves. Here, the modules are assembled into three stacks and mounted onto the steel tray. This is produced at the plant’s press shop by a supplier. A robot lifts the packs into the tray and the assembly workers install the wiring harnesses, heaters and fuses, ready to be delivered to the Leaf line next door.
The facility is eerily quiet and the whole process seems so far removed from car manufacturing it is easy to imagine that Nissan might sell off its three battery-producing plants. The buyer will gain a highly polished, massively complicated and extraordinarily clean operation.