This work introduces a novel concept of sulfide heave to account for cathode deterioration in LiS pouch cell. Caused by the repeated sulfur segregation and sequent lithiation, sulfide heave leads to cavity formation in electrode-layer during cycling. Pressurizing cathode successfully suppresses sulfide heaving, achieving high and stable areal energy density. The pressurized cathode with sulfur loading of 90 wt% demonstrates an energy density of 11.7 mW h cm−2 and retains 8.4 mW h cm−2 after 900 cycles at 0.2C under 600 kg cm−2. When increasing the areal S-loading up to 15.125 mg cm−2, a stable areal energy density of 19.24 mW h cm−2 is reached, which is 1.7 times as high as that of cathodes in current Li-ion batteries.