Kim Bu-gi, Standard Energy CEO, speaks during an interview with the Korea JoongAng Daily at the company's office in Daejeon on April 10. [PARK SANG-MOON] Vanadium, a hard, silvery metal element, has been on an upward demand curve with its price soaring 84 percent over the past 10 years — lifted partly by its potential as a battery candidate that is safer than lithium.    And thi…