Solid-state battery breakthrough: finnish firm claims 10-day charge retention

The quest for longer-range electric vehicles hinges on battery technology, and a Finnish startup, Donuts Lab, claims to have made a significant leap forward. Their solid-state battery reportedly retained 97.7% of its charge after ten days of inactivity, a result that challenges previous skepticism surrounding the technology.

Donuts lab's solid-state battery shows promise

Unlike conventional lithium-ion batteries that use liquid or gel electrolytes, solid-state batteries replace these with solid materials like ceramics, sulfides, or polymers. This eliminates flammable liquids, a key safety advantage. For years, industry experts predicted solid-state batteries wouldn't be ready before 2030. However, recent developments are shifting those timelines.

Donuts Lab, a small Finnish startup, has released data from a new test designed to address doubts about their battery's viability. The company asserts their cell maintained 97.7% of its charge after a 10-day period of being idle. This is the third test they've conducted, aiming to refute claims that they've developed a supercapacitor rather than a true battery.

“Since we presented the Donut battery, there has been a lot of speculation and theories about whether it’s a supercapacitor,” stated Ville Piippo, Chief Technology Officer of Donuts Lab. To address these claims, Donuts Lab partnered with the VTT Technical Research Centre of Finland to measure the battery’s self-discharge rate. A 50% charged cell was left inactive for 240 hours, with voltage readings taken every 10 seconds.

During the initial hour, the battery’s voltage dropped by 103 mV – a “relaxation” according to the company, not actual self-discharge. After 240 hours, the voltage decreased a further 12 mV, representing a total loss of 2.3% over the 10-day period. While not astonishing, this performance surpasses the 5% self-discharge often seen in lithium-ion batteries within the first 24 hours.

CATL, a major battery manufacturer, remains unconvinced about the long-term viability of solid-state batteries. However, Donuts Lab argues their results unequivocally demonstrate a battery, not a supercapacitor, pointing to the slower discharge rate over extended periods.