Sumitomo Chemical has reportedly phased out its LED sapphire substrate business. SSLM, a South Korean sapphire wafer joint venture funded by Sumitomo Chemical and Samsung, stopped manufacturing sapphire substrates and Samsung also claimed to have halted investments in the company, reported The Nihon Keizai Shinbun.

Samsung and Sumitomo Chemical established SSLM in 2011, when LED was a core business of Samsung. The Japanese company is known for its high purity alumina. Back then, they wanted to expand their presence in emerging markets through the synergies. However, in face of threats from Chinese competitors, Samsung eventually decided to downsize its LED business, which consequently led to the phase out of sapphire substrate production in SSLM.
The SSLM plant in Daegu will be using its existing equipment to solely produce lithium battery separators.

Separators are used to separate the anode and cathode in the Li-ion battery at the same time enabling the movement of ions through the cell. Sumitomo provides its products to the Tesla Gigafactory.