I've seen a page from a comic numerous times where Bruce Wayne is chosen as a Yellow Lantern, due to his ability to "instill great fear". Here's half below (I couldn't find the first half, where the ring approaches him, but you get the idea).
Obviously, in this moment he's surprised and reacting by instinct. The last panel makes it clear that he didn't even understand what was happening.
But it does raise the question, why doesn't Batman seek out a Yellow ring? God knows he's ok with using fear as a weapon, and he's got the imagination and willpower to use a power ring well. He's failed to measure up to being a Green Lantern because of his inability to get over the fear of losing his parents, but presumably the Yellow Corps wouldn't have such a requirement.
No doubt his friend Hal would have something to say about Batman working with Sinestro, but still, Batman and a Yellow ring seem like a match made in a terrifying, terrifying heaven.
Have we ever gotten any stated reason, in any canon, about why Batman doesn't want such a weapon, or why he doesn't consider it worth seeking out? It seems like, for a fear-monger obsessed with gadgets and ultra-preparedness, a fear-based weapon capable of producing any gadget with a thought would be the ultimate expression of his own ideal.