Dominant Kitaev interaction and field-induced quantum disordered phase in the cobaltate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>Na</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:msub> <mml:mi>Co</mml:mi>

The identification of quantum spin-liquid phases in Kitaev candidate materials remains a major experimental challenge. Since most Kitaev candidates develop antiferromagnetic (AFM) order at low temperatures, currently there is great interest on the field-induced magnetic disordered phase in these compounds that are distinct from (partially) polarized states. Recently, a cobaltate ${\mathrm{Na}}_{2}{\mathrm{Co}}_{2}{\mathrm{TeO}}_{6}$ has emerged as a promising Kitaev candidate with high-spin ${t}_{2g}^{5}{e}_{g}^{2}$ configuration and spin-orbit-entangled ${J}_{\mathrm{eff}}=1/2$ honeycomb lattice system. There are intensive studies on field-induced magnetic states and phase transitions under in-plane magnetic fields. In this study, we propose an intermediate disordered phase induced by an out-of-plane field along the $c$-axis, through high-field magnetization and magnetocaloric effect measurements. To explain the high-field behavior of ${\mathrm{Na}}_{2}{\mathrm{Co}}_{2}{\mathrm{TeO}}_{6}$, we develop an effective $K\text{\ensuremath{-}}J\text{\ensuremath{-}}\mathrm{\ensuremath{\Gamma}}\text{\ensuremath{-}}{\mathrm{\ensuremath{\Gamma}}}^{\ensuremath{'}}$ spin model featuring a dominant AFM Kitaev interaction. This framework uncovers an intermediate quantum spin-liquid phase, establishing the material as a unique platform for exploring Kitaev physics and field-induced quantum-disordered states.