(186aa) An Ion Redistributor for Dendrite-Free Lithium Metal Anodes

Lithium
(Li) metal anodes have attracted considerable interest due to their ultrahigh
theoretical gravimetric capacity and very low redox potential. However, the
issues of nonuniform lithium deposits (dendritic Li)
during cycling are hindering the practical applications of Li metal batteries.
Herein, we propose a concept of ion redistributors to eliminate dendrites by
redistributing Li ions with Al-doped Li_6.75La₃Zr_1.75Ta_0.25O₁₂
(LLZTO) coated polypropylene (PP) separators. The LLZTO with three-dimensional
ion channels can act as a redistributor to regulate the movement of Li ions,
delivering a uniform Li ion distribution for dendrite-free Li deposition. The
standard deviation of ion concentration beneath the LLZTO composite separator
is 13 times less than that beneath the routine PP separator. A Coulombic
efficiency larger than 98% over 450 cycles is achieved in a Li | Cu cell with
the LLZTO-coated separator. This approach enables a high specific capacity of
140 mAh g⁻¹ for LiFePO4 | Li pouch cells and
prolonged cycle life span of 800 hours for Li | Li pouch cells, respectively.
This strategy is facile and efficient in regulating
Li-ion deposition by separator modifications and is a universal method to
protect alkali metal anodes in rechargeable batteries.

Fig.
1. Schematic illustration of the electrochemical deposition behaviors of the Li
metal anodes using (A) a routine PP separator and (B) a composite separator
with the LLZTO layer as an ion redistributor to uniform Li-ion distribution.

Reference:
Sci. Adv. 2018; 4: eaat3446.