Heat storage using phase change material coated with nanoparticles

There is provided a method for heat storage comprising charging by raising the temperature of a phase change material (PCM) above its melting temperature and discharging by lowering the temperature below its melting temperature, wherein the phase change material (PCM) is provided in particles (P) comprising a core (CPCM), said core (CPCM) comprising at least one phase change material (PCM) , said core (CPCM) being coated with an outer layer (Lpsmall) of smaller particles (PSMALL). The particles (P) can be made smaller giving an efficient heat exchange. Their manufacture is easy and cost efficient. The flexible outer layer allows the core to expand and shrink. Corrosion is prevented allowing less expensive materials to be used in devices. The particles can be made self-lubricating.