Multi-step sorption-reaction consists of sorption/desorption, dilution/crystallization & thermo-chemical reaction. The cold storage density can arrive at high value of 1.24 kWh/kg. The heat storage density can be improved to 1252 kWh/m3. The temp. can be upgraded from 55 °C to 105 °C in single stage cycle. The temp. can be upgraded from 70 °C to 130 °C in double stage cycle.