I is battery owned. The non I was battery lease.
They got rid of battery lease with the ZE50, and so far all the registration data I have seen on these cars have absolutely no mention of the i despite being battery owned. I'd personally leave the i off as it's unlikely your car will be registered as such a model.
As mentioned there was going to be both battery lease and battery owned options so insurers listed both but have not amended the listing since Renault declared battery owned only.
So when I took out insurance I selected the i option as I think selecting the non i may cause issues in case of a claim.