The first goal of the present work is to develop, fabricate, and characterise a novel composite part change materials for the medium temperature thermal power storage techniques. The proposed composite PCM is made up of a binary eutectic PCM (LiNO3 + NaCl), a supporting materials (activated bio char), and thermal conductivity-improving particles (i.e., multi walled carbon nano tubes). XRD, FTIR, and SEM-EDS evaluation was used to find out the chemical stability of the composite PCM samples. Utilizing differential scanning calorimetry (DSC), the thermophysical parameters of the composite PCM samples, similar to part transition temperature and latent warmth worth, are evaluated. With the addition of activated biochar (A-BC) and multiwalled carbon nano tube (MWCNT) particles, the latent warmth worth of PCM is diminished, and the thermal conductivity enhancement worth is elevated to 116.11%. The findings exhibit that using A-BC and MWCNT nanoparticles ensures the steadiness of the eutectic chloride and prevents leak. The corrosion charge of the copper, aluminium, stainless-steel, and Inconel 617 have been decided by immersing it in pure PCM and composite PCM for 12 weeks. The steel specimens that have been inserted within the composite PCM have been discovered to have good corrosion stability.