posted on 2018-03-23, 00:00authored byFulu Chu, Jiulin Hu, Jing Tian, Xuejun Zhou, Zheng Li, Chilin Li
Li dendrite suppression
enables a highly reversible Li-metal battery.
However the strategy to smooth Li surface, especially under long-term
cycling and high current density, is still a big challenge. Here,
we propose a facile additive strategy to reinforce Li dendrite inhibition
in a range of ether and carbonate electrolytes. Dissoluble Mg(TFSI)2 is employed as a degradable electrolyte additive, leading
to in situ plating of porous Mg network when contacting reductive
Li atoms. Mg adatoms with extremely low diffusion energy barrier as
lithiophilic sites enable a smooth or flaky morphology of Li surface
even under a high current density of 2 mA/cm2 and high
capacity of 6 mAh/cm2. Mg-salt additive significantly extends
the cycling life of Li||Cu asymmetric cells up to 240 and 200 cycles
for carbonate and ether electrolytes, respectively. Under a current
density as high as 5 mA/cm2, the Li||Cu cell based on ether
system can still survive up to 140 cycles with a small voltage hysteresis
close to 60 mV. The hysteresis can be reduced to below 25 mV for lasting
200 cycles at 1 mA/cm2. This additive strategy provides
a facile solution to in situ construction of conductive anode–electrolyte
interface with low interface resistance for alleviating uneven Li
nucleation.