An electro-chemical energy conversion and storage device includes an enclosure, a first electrode operatively connected to the enclosure, a second electrode operatively connected to the enclosure, a nanofluid or particle suspension in the enclosure, a heat transfer unit, and a circulation system for circulating the nanofluid or particle suspension to the heat transfer unit. The nanofluid includes nanoparticles plus a dielectric or ionic fluid. The particle suspension includes particles plus a dielectric or ionic fluid. A wide range of nanoparticles or particles can be used. For example the following nanoparticles or particles can be used: metal and metal alloy particles for anodic dissolution and thermal transport; hydrides as source of hydrogen ions; lithium and lithium alloys; intercalated graphite and carbon aerogel as Li source (anodic material); intercalated transition metal oxide as Li sink (cathodic material); and semiconductors for photovoltaic conversion in photo-electrochemical or hybrid electrochemical cell.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
 The United States Government has rights in this invention pursuant to Contract No. DE-AC52-07NA27344 between the United States Department of Energy and Lawrence Livermore National Security, LLC for the operation of Lawrence Livermore National Laboratory.