QuantumScape (QS -13.53%) is working to revolutionize the electric vehicle (EV) battery category. Its solid-state lithium-metal battery technology hasn't been commercialized, and its benefits haven't yet been proven beyond the laboratory.

But the company hit one major development milestone this week, and investors took notice. The news helped the stock soar about 63% above last Friday's closing price as of 11:15 a.m. ET, according to data provided by S&P Global Market Intelligence.

EV driver looking at monitor in car showing battery charging and at 60% capacity.

Image source: Getty Images.

EV sales continue to grow

QuantumScape announced that it has scaled up its production capabilities with the successful factory integration of its Cobra solid separator production process. QuantumScape co-founder and chief technology officer Tim Holme called it "a step-change innovation in ceramic processing, enabling a major improvement in productivity." This was an important goal for the company in 2025. It will allow field testing of QuantumScape's solid-state batteries to begin at EV manufacturers next year.

QuantumScape's battery technology could help spur EV sales growth, as many consumers wait for longer-range batteries before buying. Even so, EV sales remain in growth mode. European battery-electric vehicle (BEV) sales jumped 27.2% in May. China, the world's largest automotive market, saw BEV sales jump 23% in May.

In addition to providing better range on a single charge, QuantumScape's solid-state batteries are more efficient and should last longer. They are also safer due to the ceramic separator mitigating fire hazards.

The stock remains speculative, of course, as the company remains in development mode. But investors are sensing it is now closer to generating real revenue and potentially becoming profitable. The potential market is huge, and that's one big reason shares soared this week.