Before deadlifts, I like to warmup my bis with some concentration curls and supinated grip pull ups.
It also helps if you pull the bar with "the fingers" instead of using the whole palm.
Grip work is essential. Barbell static holds or Kirk shrugs are good choices if your goal is to increase your dl grip. ( There are different types of grip training & grip strength. Trust a guy who did some armwrestling for fun. )