When you’ll recall, in the course of the excessive warmth assessments, the pouch surrounding Donut’s battery misplaced its vacuum seal. This led to researchers at Finland’s state-owned VTT Technical Analysis Centre, which carried out all the lab’s earlier assessments, to discover whether or not the cell might nonetheless perform below these high-stress, high-temperature situations. As Donut notes, harm such because the one sustained by its pack in the course of the warmth check has been identified to trigger hearth or thermal runaway in standard lithium-ion batteries. The startup needed to see whether or not its solid-state battery might keep away from the same calamity.
Researchers carried out three assessments: a baseline check of 5 cycles at 1C (26 amps); a high-stress check of fifty cycles at 5C (130 amps) ; and one other closing baseline check of 5 cycles at 1C to measure degradation. After the assessments, the crew noticed a pointy drop in vitality capability, from 24.7 Amp-hours to 11.2 Ah, or a lack of roughly 55 %. In addition they recorded a drop in effectivity from 89.6 % to 83 %, and famous a 17 % improve within the pack’s thickness.
Given the harm sustained by the pack, the outcomes shouldn’t be that stunning. The lack of the vacuum seal actually accelerated the battery’s degradation and contributed to its thick, swollen state after the check. Nonetheless, Donut Lab stated this was additional proof that its battery can keep away from among the worst outcomes of a broken lithium-ion battery.
“No temperature spikes, no hearth threat,” the corporate stated on its IDonutBelieve.com website. “On this situation the Donut Battery fails gracefully when broken, persevering with to function safely at lowered capability reasonably than posing hazard to the person.”
However the assessments additionally signify the closest that Donut Lab’s battery has come to a cycle check — and it was below these broken situations. The startup has but to show how its pack holds up below an speed up getting older process that repeatedly prices and discharges the cells to guage their long-term efficiency and security. Donut has beforehand claimed its solid-state battery can final 100,000 cycles, which might signify roughly 270 years of charging and discharging. This is able to be orders of magnitude larger than the 1,000-2,000 full charging and discharging cycles that the common EV battery can stand up to earlier than its capability begins to degrade.
And extra importantly, Donut has but to ask for an impartial verification for its claimed 400 Watt-hours-per-kilogram of vitality density. That looks as if a easy sufficient check — all you need to do is weigh the cell and measure its output — and it’s unclear why Donut Lab hasn’t requested for it but.
We’ll have extra to say about Donut Lab’s assessments and what impartial specialists are saying in regards to the startup within the weeks to come back.
