Hydrogen storage in clathrate hydrates is a promising approach for industry-scale utilizations. However, extreme operation conditions such as high pressure (about GPa) limit the development. In this work hydrogen hydrate phase equilibrium in addition of methane, tert-butyl alcohol (tBA), trichloromethane (CHCl3) and 1,1-dichloro-1-fluoroethane (HCFC-141 b) are reported at 6 MPa-20 MPa and 274 K-286 K, which including 21 points in total. Mechanism studies using Raman spectroscopy show that tBA and H2O form metastable hydrate cages via hydrogen bonds, then form stable sII hydrates with the help of CH4. Hydrate-based hydrogen storage capacity in 5.6 mol%HCFC-141 b-water mixture could reach 46 V/V (0.36 wt%) at 273 K and 10 MPa. Combing with chemical energy of HCFC-141 b, this work achieved high capacity of hydrogen and chemical energy storage in gas hydrate at mild conditions. This study will provide guidance on hydrate-chemical hybrid hydrogen storage technology, and leads to the next generation of hybrid hydrate-based hydrogen technology in the future. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.