(Yicai Global) Dec. 24 -- Shares of Contemporary Amperex Technology plunged after the Chinese battery giant committed to paying one of its suppliers CNY850 million (USD133 million) in advance to ensure delivery of lithium battery separators next year, in a sign that suppliers may be gaining the upper hand.

After plunging by as much as 9.5 percent today, CATL [SHE: 300750] closed down 7.3 percent at CNY576.80 (USD90.56). The stock has soared 65 percent this year.

Shanghai Energy New Material, a unit of Yunnan Energy New Material, and CATL signed a prepayment contract yesterday for supplies worth CNY5.2 billion (USD813 million), its Wuxi-based parent firm said in a statement today. CATL will pay the rest in 12 monthly installments and Shanghai Energy will prioritize supplies to CATL.

Amid a boom in electric cars in China, lithium battery producers are expanding capacity. The resulting shortfall in raw materials and components has led suppliers to hike their prices.

Yunnan Energy [SHE: 002812] ended 1.6 percent down at CNY235.95 (USD37.04).

Editor: Futura Costaglione, Xiao Yi