My n4 charges happily through a 1.5mm hard plastic case. Just tried it with a magazine (about 5mm) between it and the pad - it began charging, though I can't comment on the rate. Thinking back to school physics, magnetic field strength relates to the square of distance, so the further from the source the slower the charge - since your phone consumes charge while it's on, the phone might actually discharge while indicating it's charging if you have it too far away.
FYI, the ones Tillaz mentioned above are 156 x 84 x 9 mm, so a bit thinner. Can probably lose a bit of the case above and below the coil if that would help it fit your device. Also I saw really slinky looking qi car chargers somewhere for 40 dollars or so (just noticed - SwiftKey has 3 pound keys and no dollar keys! Refreshing change!)