Chinese lithium carbonate prices have made their strongest weekly gains yet, according to Fastmarkets.

It said the battery-grade price had risen 13.6% from a week earlier and the technical-grade rose 16.3%, both the biggest week-on-week gains since Fastmarkets launched its price assessment in October 2017.

It also noted the technical-grade lithium carbonate was trading at parity with battery-grade material in China for the first time since April 2018, both at 120,000-130,000 yuan.

"Strong demand from the LFP battery sector and gains in the lithium futures market have propelled lithium carbonate prices in China's domestic market higher over the past week," it said on Friday.

Benchmark Mineral Intelligence said its lithium price index rose 11.9% in August.

"In the last two weeks of August, battery grade [lithium carbonate] pricing rose 11.9% to an average of RMB 103,500/tonne (US$15,950), ranging between RMB97,000-110,000/t ($14,950-$16,950) (EXW China), underscoring a total increase throughout August of 16.9% month-on-month," Benchmark said.

Its global weighted lithium hydroxide price increased 13.5% from the previous month.

However spodumene fell 16.2%, according to Benchmark, due to Pilbara Minerals' record-breaking auction at the top end of pricing in July, settling at $1,250/t (FOB Australia).

Excluding the auction, spodumene would have improved 14.2% month-on-month to August's average $775/t, Benchmark said.

Cobalt steady

Both price reporting firms saw cobalt prices hold relatively steady.

Fastmarkets' cobalt hydroxide index, 30% cobalt minimum CIF China, was 0.04% lower week-on-week to $21.05 a pound.

Benchmark reported an average 0.6% decrease in cobalt sulphate prices in China throughout August, a 0.8% increase in cobalt hydroxide and a 2.5% lift in cobalt metal prices.

It pointed to continued growth in EV sales and cell production in China.

Benchmark also noted despite Tesla's plans to reduce then remove cobalt from its cells, the EV manufacturer had said in its Impact Report released in August that its absolute cobalt demand was set to increase over the coming years, as the scale of cell production outpaced efforts to reduce cobalt in the cathode chemistry.