QuantumScape (NYSE:QS) has been teasing investors with the promise of solid-state batteries for years. The San Jose company said it was close to production last year. Then CEO Jagdeep Singh said improvements would be needed first. That message brought investors to QuantumScape from its founding in 2010. At one point, it was worth more than Ford Motor (NYSE:F) despite having no revenue. Both Volkswagen (OTCMKTS:VWAGY) and Qatar have invested in it. But promises won’t work anymore. The Posse Is Coming Besides ...