Liquid Polydimethylsiloxane Grafting to Enable Dendrite‐Free Li Plating for Highly Reversible Li‐Metal Batteries

Abstract

Li-metal is considered as the most promising anode material to advance the development of next-generation energy storage devices owing to its unparalleled theoretical specific capacity and extremely low redox electrochemical potential. However, safety concerns and poor cycling retention of Li-metal batteries (LMBs) caused by uncontrolled Li dendrite growth still limit their broad application. Herein, liquid polydimethylsiloxane (PDMS) terminated by -OCH 3 groups is proposed as a graftable additive to reinforce the anode dendrite suppression for LMBs. Such a grafting triggers the formation of a conformal hybrid solid electrolyte interphase (SEI) with increased fractions of LiF and Li-Si-O-based moieties, which serve as a rigid barrier and ionic conductor for uniform Li-ion flow and Li-mass deposition. The grafting protected anode endows Li/Li symmetric cells with a long lifetime over 1800 h with a much smaller voltage gap (≈25 mV) betweenLi plating and stripping, than the naked anode. The coulombic efficiency values for Li/Cu asymmetric cells in carbonate electrolyte can reach up to 97% even at a high current density of 3 mA cm −2 or high capacity up to 4 mAh cm −2 . The liquid PDMS additive shows advantage over solid siloxane additives with poor grafting ability in terms of Li surface compaction and SEI stabilization.

Electrode Engineering by Atomic Layer Deposition for Sodium‐Ion Batteries: From Traditional to Advanced Batteries

“…[16c,49] Compared with the SEI film, the CEI has attracted less attention because its effect is of less significance than that of the SEI for the electrochemical performance of SIBs. [50] Specifically, most SIB cathode materials except the high-voltage materials are operated within the stable voltage window of an organic electrolyte (< 4.3 V), in which the CEI exhibits only a slight contribution to the batteries' performance. [51] According to the similarities in function and composition, the role of the CEI can be well understood by investigating the SEI model.…”

Constructing Ionic Gradient and Lithiophilic Interphase for High‐Rate Li‐Metal Anode

“…[5,6] These sharp Li dendrites not only pierced through the separator and caused safety hazard, but also facilitated the side reactions with organic electrolytes, resulting in the formation of dead Li and thus caused severe capacity decay and poor Coulombic efficiency. [7][8][9][10][11] ion conduction channels formed a spatially homogenous ionic field distribution and regulated Li-ion flux distribution over the anode, while reduced the driving force of dendrite formation by decreasing the nucleation barrier ( Figure 1b). Benefiting from the synergetic effects, prolonged span lives of 1000 cycles in the symmetric Li//Li cells at both 3 and 5 mA cm −2 were obtained.…”

“…Although performance has been greatly improved, major degradation mechanisms such as Li‐dendrite growth and Li‐powdering in the Li anode remain . These sharp Li dendrites not only pierced through the separator and caused safety hazard, but also facilitated the side reactions with organic electrolytes, resulting in the formation of dead Li and thus caused severe capacity decay and poor Coulombic efficiency …”

“…[5,6] These sharp Li dendrites not only pierced through the separator and caused safety hazard, but also facilitated the side reactions with organic electrolytes, resulting in the formation of dead Li and thus caused severe capacity decay and poor Coulombic efficiency. [7][8][9][10][11] Small 2019, 15, 1905171…”

A Liquid/Liquid Electrolyte Interface that Inhibits Corrosion and Dendrite Growth of Lithium in Lithium‐Metal Batteries

“…In particular, SEM images and the corresponding EDS results (Supporting Information, Figure S6) show that there is a thin and uniform SEI film on the Li anode after 80 h of circulation. Furthermore, XPS results (Supporting Information, Figure S7 a) reveal that the peaks located at 281.6–283.2 eV in the C 1s spectrum is assigned to Li x C . The strong peak at 685.0 eV in the F 1s spectrum can be assigned to LiF (Supporting Information, Figure S7 b).…”