It's not a current sensor. It's almost certainly a contactor.
https://na.industrial.panasonic.com...panasonic_aev_ev_new_product_introduction.pdf
It's probably a special part for Nissan. There is some speculation as to it's specs here
https://na.industrial.panasonic.com...panasonic_aev_ev_new_product_introduction.pdf
It's probably a special part for Nissan. There is some speculation as to it's specs here