  Disordered superconducting nitrides with kinetic inductance have long been
considered a leading material candidate for high-inductance quantum-circuit
applications. Despite continuing efforts in reducing material dimensions to
increase the kinetic inductance and the corresponding circuit impedance, it
becomes a fundamental challenge to improve further without compromising
material qualities. To this end, we propose a method to drastically increase
the kinetic inductance of superconducting materials via spinodal decomposition
while keeping a low microwave loss. We use epitaxial
Ti\textsubscript{0.48}Al\textsubscript{0.52}N as a model system, and for the
first time demonstrate the utilization of spinodal decomposition to trigger the
insulator-to-superconductor transition with a drastically enhanced material
disorder. The measured kinetic inductance has increased by 2-3 orders of
magnitude compared with all the best reported disordered superconducting
nitrides. Our work paves the way for substantially enhancing and
deterministically controlling the inductance for advanced superconducting
quantum circuits.
