A few notes about this which all seem to point to my initial knee jerk reaction: Apple was invited to participate in Tesla’s US battery Gigafactory, which it will announce next week

In a Bloomberg interview , Tesla CEO Elon Musk said of a possible acquisition by anyone:

LIU: Elon, yesterday your shareholders got a little bit richer on these reports that you had met with the acquisition team at Apple. Is there any truth to a possible partnership, merger with Apple?
MUSK: Well of course it’s – if – if – if one or more companies had approached us last year about such things, there’s no way we could really comment on that.
LIU: Well did you have a conversation with Apple?
MUSK: We had conversations with Apple. I can’t comment on whether those revolved around any kind of acquisition.
LIU: If anything, Elon, if Apple were to come to you and say, you know what? We want to get in the car business. We actually want to perhaps start making cars. What would you tell them, given your own experience?
MUSK: What would I tell Apple if they said they wanted to make cars?
LIU: Yeah.
MUSK: I’d probably tell them that I think it’s a great idea.

So Tesla wasn’t talking acquisition (which was pretty obvious if you follow the two companies) but he could have been shopping around the Lithium battery Gigafactory, and the likelihood of Apple being involved grew a little bit at Tesla’s earnings call earlier today.

While Tesla didn’t announce all of its Gigafactory partners, it did announce Panasonic and it hinted strongly at Solar City (where Tesla already has battery deals in place and Musk is Chairman of the Board) in its release today:

Very shortly, we will be ready to share more information about the Tesla Gigafactory. This will allow us to achieve a major reduction in the cost of our battery packs and accelerate the pace of battery innovation. Working in partnership with our suppliers, we plan to integrate precursor material, cell, module and pack production into one facility. With this facility, we feel highly confident of being able to create a compelling and affordable electric car in approximately three years. This will also allow us to address the solar power industry’s need for a massive volume of stationary battery packs.

Even if Apple isn’t interested in buying domestically-sourced lithium-ion batteries in huge scale on the cheap from a factory not owned by one of its Android competitors (Samsung, LG, Sony), it could use the batteries to augment its huge solar installations at its data centers or factories.