  We introduce a non-degenerate bilinear form and use it to provide a new
characterization of quantum Kac-Moody superalgebras with no isotropic odd
simple roots. We show that the spin quiver Hecke algebras introduced by
Kang-Kashiwara-Tsuchioka provide a categorification of half the quantum
Kac-Moody superalgebras, using the recent work of Ellis-Khovanov-Lauda. A new
idea here is that a super sign is categorified as spin (i.e., the parity-shift
functor).
