Dendrite‐Suppressed Lithium Plating from a Liquid Electrolyte via Wetting of Li₃N

Abstract

to the cathode to create an internal short circuit that ignites the cell. [1,2] Plating dendrite-free lithium anodes has been achieved with solid electrolytes that are wet by the lithium; wetting prevents dendrites from forming during plating. However, the liquid electrolyte has a Li + conductivity over two orders of magnitude higher than that of most solid electrolytes, and a critical question is whether a dendrite-free anode can be plated reversibly from the flammable liquid electrolyte and, if so, whether the cell can be used safely over a long cycle life.A second problem is that the Fermi level of lithium is about 1.2 eV above the lowest unoccupied molecular orbital of the liquid electrolyte, which means that a solid electrolyte interphase (SEI) must form on the surface of a lithium anode to passivate the reduction of the electrolyte by the anode; the SEI must be a Li + conductor and retain its interface with the solid anode over many charge/discharge cycles. Traditionally, it has been assumed that an artificial, uniform, mechanically robust, and thin solid SEI could block or prevent dendrite nucleation and growth during electrodeposition, [3] and electrolyte additives such as H 2 O, CO 2 , and halogenated salts have been added to the electrolyte for the formation of a uniform and dense LiF or Li 2 CO 3 SEI that lowers the resistance to Li + transfer across the lithium/electrolyte interfaces and increases the cycling efficiency, but they do not completely suppress or block dendrite formation and growth. [4][5][6][7][8] Artificial SEI coatings on a lithium anode have also been explored; thinfilm Al 2 O 3 and Li 3 N coatings have been reported to increase cycling stability of a lithium anode. [9][10][11][12] However, artificial SEI inorganic films are commonly too brittle to accommodate to the anode volume change with increasing plating, and they are not compatible with the conventional cell configuration based on flexible electrodes. [13] In contrast, a uniform polymer artificial SEI can suppress, to some degree at least, the formation of Li dendrites on plating and be mechanically robust and flexible. [14][15][16][17] Dynamic formation of an electrostatic shielding layer during Li depletion has also been reported to suppress dendrite formation on charging at low current densities. [18] Recently, more holistic surface modifications with 3D and electrically conductive nanostructures beyond the traditional surface modifications on a flat Li surface have been studied. For example, porous Cu, reduced graphene oxide (rGO) sheets, TiO 2 , and Si/Au-coated carbon frameworks as anode current collectors have been reported. [19][20][21][22][23][24] There are several advantages Lithium metal is an ultimate anode material to provide the highest energy density for a given cathode by providing a higher capacity and cell voltage. However, lithium is not used as the anode in commercial lithium-ion batteries because electrochemical dendrite formation and growth during charge can induce a cell short circuit that ignites the fla...

Review—Li Metal Anode in Working Lithium-Sulfur Batteries

“…172 These matrixes can regulate the nucleation and growth of Li ion by the lithiophilic sites and suppress Li dendrite growth by the increased surface areas. 173,174 The conventional Li−S batteries take elemental S as the cathode, while Li is stored in the anode. These above-mentioned hosts are merely matrixs without Li in them and most of conceptual advance- Even at 10.0 mA cm −2 , no Li dendrite is observed, enabling a 2000-cycle long lifespan in Li−S batteries with a Coulombic efficiency higher than 90%.…”

Interfacial Incompatibility and Internal Stresses in All‐Solid‐State Lithium Ion Batteries

“…[188] Copyright 2017, American Association for the Advancement of Science. [211] The Li 3 N was coated on a garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZT) pellet by plasma enhanced chemical vapor deposition (PECVD), enabling the total electrochemical impedance spectroscopy (EIS) resistance, including the garnet and interfacial impedance, to decrease from 2512 Ω cm 2 to 180 Ω cm 2 . f) Interfacial impedance for the pristine and Ge-coated LAGP.…”

“…Therefore, the Li 3 N seems to be a promising candidate because it can be wetted by Li. [211] The Li 3 N was coated on a garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZT) pellet by plasma enhanced chemical vapor deposition (PECVD), enabling the total electrochemical impedance spectroscopy (EIS) resistance, including the garnet and interfacial impedance, to decrease from 2512 Ω cm 2 to 180 Ω cm 2 . [212] Because of its high Li + ion conductivity close to 10 −3 S cm −1 and excellent wettability by Li, a stable Li stripping/plating behavior with a very small overpotential (≈23 mV) was exhibited (testing at 60 °C for 100 µA cm −2 ).…”

SnO2 as Advanced Anode of Alkali‐Ion Batteries: Inhibiting Sn Coarsening by Crafting Robust Physical Barriers, Void Boundaries, and Heterophase Interfaces for Superior Electrochemical Reaction Reversibility

“…[12,13] Great efforts have been made to develop new electrolytes that are nonflammable, capable of dendrite suppression, or exhibit good stability at high voltage in order to enhance the safety of LIBs or lithium metal batteries. [14][15][16][17][18] As for commercial LIB cathodes, the low lithium content of the active materials (e.g., LiCoO 2 and LiFe 2 O 4 ) render significantly improving their capacities impossible. Additionally, the lithium ions cannot be totally extracted from these materials without instigating the structural collapse of the cathode; this restriction leads to even lower obtainable capacities (e.g., LiCoO 2 (≈140 mAh g −1 ) and LiFe 2 O 4 (≈130 mAh g −1 )).…”