Barocaloric Cooling: The Liquid Dissolution Breakthrough of January 2026
A January 2026 Nature paper demonstrated extreme barocaloric cooling in ammonium thiocyanate solutions — achieving a 26.8K temperature drop at room temperature, surpassing all known caloric materials by using pressure-triggered dissolution in liquid rather than solid-state phase transitions.
Barocaloric cooling applies hydrostatic pressure to materials to trigger heating, then releases pressure to trigger cooling — analogous to magnetocaloric cooling but using pressure instead of magnetic fields. Traditional barocaloric research focused on solid materials (plastic crystals, spin-crossover compounds), but heat transfer across solid boundaries limited practical efficiency. A January 2026 paper in Nature from the Chinese Academy of Sciences introduced a fundamentally different approach: **dissolution barocaloric cooling** in liquid. **The breakthrough:** Researchers discovered that applying ~600 MPa pressure to a saturated solution of ammonium thiocyanate (NH₄SCN) in water forces the salt to precipitate out. Releasing pressure causes rapid dissolution, which is strongly endothermic — absorbing massive amounts of heat. This achieved: - **26.8K temperature drop** in the solution at room temperature — surpassing ALL known solid-state caloric materials - **67 J/g cooling capacity** per cycle - **77% second-law efficiency** - Temperature drop achieved in approximately 20 seconds **Why liquid matters:** The key innovation is that the liquid acts as both the refrigerant AND the heat-transfer medium simultaneously. In solid barocaloric systems, heat must conduct across material boundaries (slow, lossy). In the dissolution approach, the solution self-circulates — no secondary heat-transfer fluid needed. This bypasses the fundamental thermal bottleneck that limited all prior solid-state caloric approaches. **Challenges:** - NH₄SCN is corrosive, which could damage system components over long cycling - 600 MPa is extremely high pressure (roughly 6,000 atmospheres), requiring robust containment - Very early stage — no prototype cooling device yet, only laboratory demonstration **Potential application:** AI datacenter cooling, where the high cooling density and liquid medium align well with existing liquid cooling infrastructure. See also: Cooling Technologies: Six Fundamental Approaches, Emerging Cooling Technologies: The Race to Replace Refrigerant Compressors (2025–2026)