The highly concentrated lithium bis(fluorosulfonyl) imide/1,2edimethoxyethane electrolyte is in the good graces of researchers due to its excellent electrochemical performance in lithium-metal batteries. However, our study reveals that the more concentrated electrolyte incurred more drastic lithiumdendrite growth. Minimum onset time (t(sc)) of lithium- dendrite formation of only 7.4 and 18.6 h are observed in 4M lithium bis(fluorosulfonyl) imide/1,2-dimethoxyethane electrolyte galvanostatically polarized at current densities of 1.0 and 0.5 mA cm(-2), respectively. In contrast, tsc are as long as around 56 and > 190 h in 1M electrolyte at 1.0 and 0.5 mA cm(-2), respectively. We found that 1M electrolyte has comprehensive advantages in many respects, including Lithorn transference number (0.61), salt diffusion coefficient (1.47 x 10(-5) cm(2) s(-1)), ionic conductivity (1.52 x 10(-2) S cm(-1)), low polarization potential and solid electrolyte interphase protection, which collectively make contributions to outstanding lithiumdendrite suppression. (C) 2018 Elsevier Ltd. All rights reserved.