Hi-hats can be difficult instrument to recorded well. Part of the problem stems from the fact that there are two different kinds of sounds you're trying to capture: the attack on closed hi-hats, and the "swish" of open hi-hats.

You might think the best way to get a good "swish" sound would be from the edge of the hi-hat. But generally, miking the edge of a hi-hat tends to result in a gong-ish sound, and the opening and closing of the hi-hats forces air outward, right into the mic diaphragm. The effect is similar to the plosives experienced when recording vocals without a pop filter.

To avoid these problems, try aiming the mic at the bell of the hi-hat. Keep the mic back three or more inches away to help avoid issues as the cymbal opens and closes.

Another way to avoid these problems is to consider whether you need to close-mic the hi-hat at all. In many cases, you'll get plenty of hi-hat in the snare and the overhead mics, so you may not need a close mic (though it's often a good idea to put one up regardless, then you have the option to use it if necessary).