QuantumScape (QS -0.30%) was once a red-hot stock. The maker of solid-state batteries went public by merging with a special-purpose acquisition company (SPAC) on Nov. 27, 2020, and its stock opened at $24.80 before soaring to its all-time high of$131.67 less than a month later. But today, QuantumScape trades at about $7. The stock ran out of juice for three reasons: It wasn't generating any revenue yet, it was racking up steep losses, and the electric-vehicle market was cooling off. Rising interest rates a ...