This invention is related to Localized high concentration electrolytes (LHCE) that are stable with alkane metal anode, graphite anode, and various cathode materials in an electrochemical cell. LHCE electrolytes contain two parts of the solvents. First part of the solvent or solvent mixture (A) (such as carbonate solvents, ether solvents, or carbonate/ether solvent mixtures) has a high solvability for the active salt or salt mixture (S). When used separately, these high concentration electrolytes are stable with anode (such as lithium, sodium and graphite), cathode (including both ion intercalation and conversion compounds) and current collectors (such as Cu and Al) that are often unstable in the case of low concentration electrolytes. The second part of the solvent or solvent mixture (B) is miscible with the part A of the solvents used in the electrolytes, but has only a very low solvability of the active salt (S). Solvent B is also stable with anode (such as lithium, sodium and graphite), cathode (including both ion intercalation and conversion compounds) and current collectors (such as Cu and Al) even at low concentration conditions. When the active salt or salt mixture S is added to the solvent mixture consists of solvent A and B, salt S will preferentially coordinate with the solvent A and form a localized high concentration electrolyte which is stable with other part of the electrochemical cells, but the overall concentration of the electrolyte is still be low. The electrolyte containing localized high concentration salt consists of salt S, solvent A, and solvent B is not only stable with anode by forming high quality solid electrolyte interphase (SEI) layers, but also stable with high voltage cathodes, thereby improving long-term cycling stability of electrochemical cells. Furthermore, addition of solvent B effectively decreases the salt concentration (lowered cost), reduces the electrolyte viscosity and improves the ionic conductivity and wetting ability of the electrolyte. This invention could be widely applied to a variety of electrochemical systems, including lithium (Li) metal batteries, Li ion batteries, Li-S batteries, Li-O2 batteries, sodium metal and sodium ion batteries, magnesium ion batteries, aqueous Li batteries (such as dilution of concentrated LiTFSI/NaTFSI aqueous electrolyte), super capacitors, sensors.