Can I use ni-mh batteries in my garden solar lights?

The solar light batteries in my garden are dead. Upon replacing them, I realized they were the old Ni-Cd rechargeable batteries.

I have heard that these batteries are not so good for the environment because they contain toxic chemicals (see Wikipedia). I would like to use Ni-MH batteries instead.

Would this be recommended or will slowly charging these batteries using solar panels shorten its life span?