Battery technology has evolved a lot in the last five years, but there are many more developments to come. Chemistries are arriving with improved energy density, there’s a switch from Nickel Manganese Cobalt (NMC) to Lithium Iron Phosphate (LFP), and new methods of integration are optimizing weight and space. There are other innovations on the horizon, too. Stellantis recently revealed it has been testing a technology called IBIS, which promises significant EV battery improvements. I talked to project leaders, Francis Roy (IBIS Product Manager) and Clement Dumand (Director of Breakthrough Programmes) about how the technology could take battery technology to a new level.
What Is IBIS?
IBIS stands for Intelligent Battery Integrated System, and Stellantis has been talking about it for a few years. The key thing this technology does is negate the need for the AC-DC inverter or a charger in an electric vehicle. EV batteries provide direct current, but motors require alternating current, and your home charger will be AC too. The inverter handles switching AC to DC, or vice versa, and it needs to operate at 400V or even 800V while handling currents potentially over 1,000A.
The IBIS innovation is to take a single battery cell or group of cells and provide circuitry that takes their DC power and converts it to AC more locally. Although this adds circuitry near the battery, the total weight across the entire pack isn’t as much as a single dedicated inverter. There are also efficiency benefits to be had as well.
“There is a dedicated electronic circuit that we call an H bridge,” says Roy. “The output voltage that we produce by the control at the terminals of the bridge, it’s the voltage of the cells, zero volts, or minus the voltage of the cells.” This turns the DC output of the cells into a three-phase AC output.
Stellantis claims that IBIS improves battery efficiency (and thereby range) by 10%, while increasing power delivery by 15%. There’s a 10kg weight reduction from losing the inverter and charger, plus 30kg from not needing so many batteries to go the same distance. This also frees up 17 liters of space inside the vehicle. Charging times are reduced by 15%, due to a more efficient delivery of energy.
Peugeot e-3008 IBIS Prototype
These figures are all based on testing with a prototype system built into a Peugeot e-3008, where the technology was integrated within a 65kWh pack. The car normally comes with a 73kWh pack, but IBIS was able to make this battery match the range with a smaller capacity. This pack has three columns of eight modules, with 12 cells in each one. Stellantis groups the cells into sixes, each of which have their own circuitry. The IBIS technology could work with individual cells, and Stellantis had experimented with four cell groups before, but six ended up being the sweet spot.
“There were too many components to have a control of each cell individually,” says Roy. This is a cost and space issue. “We found that six cells per cluster was the best trade off.” This was after considerable testing. “More than six could be good with other chemistry, for example, with LFP.” However, this is still a prototype, and Roy reckons further development could change the cluster number.
Not only can IBIS technology cope with whole packs using different chemistry types, it can potentially combine them in a single pack. This isn’t a new idea, with China’s CATL already offering hybrid batteries combining sodium and lithium ion cells via its Freevoy technology, and NIO combining NMC and LFP. But Roy reckons that IBIS “has mixing chemistry in its genes.” This could take advantage of the durability of LFP alongside the power output of NMC. “But we can also evolve the chemistry over time. If you want to improve your car after six or eight years of use, you can do it by changing a few modules. A company doesn’t have to keep in production the same electrochemistry for many years, because when you have to repair your car, if the electrochemistry that was integrated in your car has disappeared off the market, you can integrate a new generation of electrochemistry instead. You can have the benefits of a new generation of electrometry with a better vehicle range.”
The IBIS prototype currently uses a traditional module configuration, with cells built into modules built into packs. But automakers are now missing out some of these stages, such as the module-to-chassis approach British startup Longbow will be using, cell-to-pack where there are no modules, and structural batteries with no modules or packs, which Tesla has been promising for years. According to Roy, IBIS will have no problem accommodating any of these designs. Cells can still be grouped together. However, Roy does think this could reduce repairability, because with the current design modules can quite easily be replaced.
IBIS Promises AC Charging Up to 200kW
Another feature Stellantis suggested at the IBIS launch was the ability to support high power AC charging, suggesting up to 200kW would be possible. This isn’t something the current prototype can do, but the potential here is very efficient charging without the need to convert to DC from the grid’s AC that current rapid charging systems require.
“It doesn’t exist yet,” says Dumand. “But in theory, IBIS could do that. The plugs do not exist, but high-power AC would save a lot of energy and cost and copper, because you directly connect without any transformation of the AC to DC to AC again. Every transformation means efficiency and energy losses. But in theory we could offer cheaper high-power charging.” Dumand also argues that as modules operate with AC rather than DC, giving them a second life as home or grid storage would also be easier because they should slot in without the need for separate inverters.
The theory all sounds very promising, and the working Peugeot prototype shows that the benefits could be real. But unfortunately, we will have to wait a few years before IBIS enters production. “We are doing our best to make the technology available by the end of the decade,” says Roy. “But the decision is not taken yet, because we must improve its maturity. We need more demonstrations of functionality of vehicles in real and extreme life situations.” This will include applying IBIS to all-wheel-drive platforms.
“It’s early to say IBIS technology will be popping up everywhere,” says Dumand. “We see other company’s projects going in the same direction, but we have patents to protect our technology. We want to be the first with this technology in the automotive market, and it’s too early to announce timing, but it’s going to be a real game-changing solution.”
