I can't find evidence that Tesla has graphene in their batteries. Why is this the case?
Huawei and Samsung holds the patent on graphene batteries. This means manufacturers of graphene composite (li-po) batteries will not disclose if there is graphene in their batteries as it violates patents. Huawei appears to be the first to launch products with graphene batteries, then Samsung, then Panasonic (and Tesla partnership with Panasonic) but this isn't publicly disclosed often or at all due to the graphene patents. Find Huawei and Samsung's graphene patents here.