Is Panasonic the only supplier for Tesla’s Lithium-ion batteries?

Yes, currently Panasonic is the only supplier for Tesla’s Lithium ion batteries. But, Tesla CEO Elon Musk wrote on Twitter that cell production for its so-called Gigafactory in Shanghai “will be sourced locally, most likely from several companies,” including Panasonic. So, in future Tesla can have more suppliers other than Panasonic.