VIENNA – Lithium demand is surging, boosting shares of the companies linked to mining and manufacturing the light metal used in electric-car batteries.

Global X Lithium & Battery Tech, an exchange-traded fund of the 27 biggest companies linked to the light metal, has increased 65% in the past 18 months, outperforming stock indexes of all the world’s most-developed economies, according to data compiled by Bloomberg.

“The acceleration in technology, including electric vehicles, could push new metals a lot higher,” said Eily Ong, an analyst at Bloomberg Intelligence who published a model on Wednesday probing the risk-weighted demand for metals including lithium.

Among those most heavily weighted in the Global X fund are companies including Samsung SDI and Panasonic, which make the lithium-ion cells used in electric-car batteries, and automobile maker Tesla.

Sales of electric cars rocketed to two-million in 2016 after being virtually non-existent just five years ago. Mainstream carmakers from Renault-Nissan Motor to Volkswagen are pushing ahead with emissions-free vehicles.

Manufacturing demand for lithium is feeding orders at mining companies including Sociedad Quimica y Mindera de Chile SA and Albemarle, which also factor among the top ten holdings at the Global X ETF.

New deposits are being tapped from Australia to Argentina as investors angle to make money from the transition away from fossil fuels and toward a low-emissions lithium-powered economy.

The scramble to open new lithium mines has struggled to keep up with demand, according to Bloomberg Intelligence. Prices for lithium carbonate jumped 335% between 2004 and 2016.

“A further increase in global electric-vehicle sales amid declining mining grades and possible production-cost inflation could boost higher new-tech metals prices,” BI’s Ong wrote in a note published Thursday.