2023-09-11 06:30:13
The Bordeaux start-up Gouach has developed a lithium battery whose cells inside are neither glued nor welded together. This new design makes it easy to replace defective batteries inside and thus reduce the ecological impact of the battery. Meeting with the founder of this company.
Originally, in 2019, Alexandre Vallette wanted to make a bicycle from recycled materials. He is interested in used lithium batteries and recovers several thousand of them before they are crushed, to extract certain elements such as cobalt and nickel. He quickly discovers that only a few batteries inside are damaged, but most are in good condition. He also noticed that they were all soldered and stuck together, which meant that the entire battery had to be thrown away as soon as a few batteries became defective. He then invented a new battery design to easily replace the cells inside. Since 2021, it has been marketing 100% repairable batteries. Interview with the founder and CEO of Gouach.
Engineering Techniques: Describe to us how your batteries are designed?
Alexandre Vallette, founder and CEO of Gouach. Credit: Alexandre Vallette
Alexandre Vallette: Instead of soldering and gluing the cells together, we use a PCB (Printed circuit board), a somewhat specific printed circuit, which is placed along the two phases of the battery. On this PCB, tabs are placed which ensure contact with each cell. They are designed using a somewhat special alloy whose composition I cannot reveal, and which has elastic properties and behaves a bit like a spring. This ensures there are no disconnections, even in the event of battery vibrations and shocks. The energy from the cells therefore passes through the tabs and then the copper tracks of the PCB. The advantage of the PCB is that we can integrate other functionalities on this support, that is to say integrate components in CMS (surface mounted device), which enormously simplifies the assembly and disassembly of the battery. With this new wireless design, we have reduced the apparent complexity of the battery. Our batteries have been subject to several certifications from independent laboratories, such as LCIE (Central Laboratory of Electrical Industries) and Bureau Veritas.
What are the advantages of your batteries?
The company uses a specific circuit board to design its batteries. Credit: Gouach
They are 100% repairable, simply replace the faulty cells inside. We have developed our own BMS (Battery management system), it is an electronic card present in all batteries and which controls the operation of each cell in real time. Standard battery manufacturers tend to install low cost BMS, because their batteries have a limited lifespan, and sometimes almost a third of failures come from this element. Our BMS is more durable and can measure cell wear more precisely.
Over its entire life cycle, we almost manage to halve the ecological impact of our batteries compared to traditional batteries. They cost a little more to purchase, but thanks to the possibility of repairing them instead of throwing them away, the price is almost the same over the life cycle.
Generally, batteries intended for mobility are only used to 20% of their capacities, then are thrown away, because they are considered not to have enough autonomy. To avoid this waste, we remove all the cells that only have 80% autonomy left, and we replace them with new cells. We thus obtain a completely new battery, without having thrown away the case and all the electronic components inside, this is called reconditioning. As for the removed cells which still have at least 80% of their autonomy, we install them in batteries intended for other applications, such as electricity storage, where the energy density requirement is less important. This allows us to exploit all cells to their maximum capacity.
A final advantage concerns the ease of recycling. Unlike conventional batteries, it is no longer necessary to crush the entire battery, including plastic and aluminum, to extract certain elements (nickel, cobalt, etc.), but to recycle only the bare cells using ‘interior.
What use are your batteries intended for?
In 2021, we started by designing batteries for mobility, i.e. bicycles and scooters. We now also manufacture them for electricity storage as well as for industry, which needs them to make forklifts and small vehicles autonomous. We are currently working on the development of larger batteries for automobiles. The technological principle is exactly the same, except that we are addressing other markets. We are in contact with major car manufacturers who are currently testing our batteries.
What is your business model?
We design and design our batteries, manufacturing is then entrusted to manufacturers and marketing is carried out under our own brand. For maintenance, we are developing a network that will be authorized to carry out repairs. For now, we are carrying out repairs ourselves to finalize a specific maintenance protocol. We have several thousand batteries in operation, because we equip the Pony self-service bicycle fleet in particular. Every month, we collect defective batteries for repair.
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