Compared to equivalent zinc-carbon cells they had greater capacity by volume, and longer shelf life.
[6] Magnesium anodes do not exhibit dendrite formation, albeit only in certain nonaqueous solvents and at current densities below ca.
[7] This allows magnesium metal to be used without an intercalation compound at the anode,[note 1] thus raising the theoretical maximum relative volumetric energy density to around 5 times that of a graphite electrode.
[10] Modeling and cell analysis indicate that magnesium-based batteries may have a cost advantage due to magnesium's relative abundance and ease of mining.
[11][12] In 2000, Israeli researchers reported dendrite-free Mg plating in AlCl3-ether electrolytes with a fairy high (>2 V vs. Mg/Mg2+) anodic voltage stability limit.
Despite research following that discovery, all attempts to develop a high-voltage Mg2+ intercalation anode for chloroaluminate (and related) electrolytes failed.
The problem is to find anode materials that show intercalation from the same solutions, which display reversible Mg metal plating.
A key drawback to magnesium anodes is the tendency to form a passivating (non-conducting) surface layer when recharging.
[24] Other electrolytes researched include borohydrides, phenolates, alkoxides, amido based complexes (e.g. based on hexamethyldisilazane), carborane salts, fluorinated alkoxyborates, a Mg(BH4)(NH2) solid state electrolyte, and gel polymers containing Mg(AlCl2EtBu)2 in tetraglyme/PVDF.
[29] One drawback compared to lithium is magnesium's higher charge (+2) in solution, which tends to increase viscosity and reduce mobility.
This system is easy to synthesize, showing ionic conductivity similar to that of Li-ion cells, its electrochemical stability window is up to 4.5 V, it is stable in air and usable across solvents.
The design used reusable materials, and coated parts of the battery with bismuth and bismuth-oxide to prevent dendrite formation, while still achieving energy density of 75 wH/kg.
Materials investigated include zirconium disulfide, cobalt(II,III) oxide, tungsten diselenide, vanadium pentoxide and vanadate.
Cobalt-based spinels showed inferior kinetics to magnesium insertion compared to their behaviour with lithium.
[8][1] In 2000 the chevrel phase form of Mo6S8 showed suitability as a cathode, enduring 2000 cycles at 100% discharge with a 15% loss; drawbacks were poor low temperature performance (reduced Mg mobility, compensated by substituting selenium), as well as low voltage (ca.
[40] A hybrid magnesium cell using a mixed magnesium/sodium electrolyte with sodium insertion into a nanocrystalline iron(II) disulfide cathode was reported in 2015.