Yes. QI (the Chinese concept of life force or vital energy) is valid in both major Scrabble dictionaries — TWL (North America) and SOWPODS / Collins (international). Along with QAT, QADI, and QOPH, it's one of the few legal Q-without-U words.
Memorising the Q-without-U list is one of the highest-ROI moves in serious Scrabble play.