Lithium Dendrite Formation on a Lithium Metal Anode from Liquid, Polymer and Solid Electrolytes

Lithium metal is the most attractive anode material for batteries because of its high specific capacity (3861 mAh g−1) and low negative potential (−3.04 V vs. NHE). However, lithium dendrite growth during lithium deposition leads to serious safety problems and poor cycling performance. The conventional liquid electrolyte used in lithium-ion batteries results in significant lithium dendrite formation at room temperature and a high current density. Thus, there has been much research effort to achieve the suppression of lithium dendrite formation. Recently, a new class of non-aqueous liquid electrolyte with a high concentration of lithium salts, such as solvated ionic liquid and solvent-in-salt electrolytes, has been reported to suppress lithium dendrite formation. Solid polymer electrolytes have been known to suppress lithium dendrite formation; however, the low lithium ion conductivity and high interface resistance between lithium and the polymer electrolyte at room temperature limits their use for conventional batteries. The interface resistance was significantly decreased by the addition of an ionic liquid into a polymer electrolyte and lithium dendrite formation was suppressed. A theoretical analysis predicted that if a homogenous solid electrolyte with a shear modulus of 6 GPa was obtained, then the lithium dendrite problem would be solved. However, some lithium conducting solid electrolytes such as Li7La3Zr2O12 still exhibit lithium dendrite formation. In this review, we introduce the recent status of lithium dendrite formation on lithium metal in contact with liquid, solid polymer, and solid electrolytes.