Lithium (Li) and Sodium (Na) have comparable positions in the periodic table and hence similar chemical properties.
Lithium is relatively rare and expensive and its mining environmentally problematic, where sodium is cheap and abundant. Combined with the fact that they have similar chemical properties, sodium is considered to be a potential alternative for lithium-ion batteries. New Korean research suggests that copper-sulfide electrodes could play a role in boosting this form of storing electricity in chemical energy, offering a life-span of up to five years, based on a single charge-cycle per day.
Advantages: cheap, abundant, rapid charging, drainable to 0% without damage (Li-ion must keep 30%), safe storage and shipping, “excellent electrochemical features in terms of charge-discharge, reversibility, coulombic efficiency and high specific discharge capacity”.
Disadvantages: less energy density, heavier.
Less suitable for e-vehicles, but potentially very suitable for grid-or home-storage purposes.
[sciencedaily.com] – High-performance sodium ion batteries using copper sulfide
[cleantechnica.com] – Sodium-Ion Battery Research Shows Promising Results
[wikipedia.org] – Sodium-Ion Battery
[power-technology.com] – Are sodium-ion batteries worth their salt?
[phys.org] – Sodium is the new lithium