Toward Dendrite-Free Metallic Lithium Anodes: From Structural Design to Optimal Electrochemical Diffusion Kinetics

Abstract

Lithium metal anodes are ideal for realizing high-energy-density batteries owing to their advantages, namely high capacity and low reduction potentials. However, the utilization of lithium anodes is restricted by the detrimental lithium dendrite formation, repeated formation and fracturing of the solid electrolyte interphase (SEI), and large volume expansion, resulting in severe “dead lithium” and subsequent short circuiting. Currently, the researches are principally focused on inhibition of dendrite formation toward extending and maintaining battery lifespans. Herein, we summarize the strategies employed in interfacial engineering and current-collector host designs as well as the emerging electrochemical catalytic methods for evolving-accelerating-ameliorating lithium ion/atom diffusion processes. First, strategies based on the fabrication of robust SEIs are reviewed from the aspects of compositional constituents including inorganic, organic, and hybrid SEI layers derived from electrolyte additives or artificial pretreatments. Second, the summary and discussion are presented for metallic and carbon-based three-dimensional current collectors serving as lithium hosts, including their functionality in decreasing local deposition current density and the effect of introducing lithiophilic sites. Third, we assess the recent advances in exploring alloy compounds and atomic metal catalysts to accelerate the lateral lithium ion/atom diffusion kinetics to average the spatial lithium distribution for smooth plating. Finally, the opportunities and challenges of metallic lithium anodes are presented, providing insights into the modulation of diffusion kinetics toward achieving dendrite-free lithium metal batteries.

Revealing the importance of suppressing formation of lithium hydride and hydrogen in Li anode protection

“…Presently, the representative identified favorable species for Li anode protection includes LiF, [20,21] Li 3 N, [22][23][24] BN, [25,26] carbon nanomaterials, [27][28][29][30][31] carbon nitride, [32][33][34] Li 2 O, [35] and so on. There are mainly two classic theories to effectively guide the selection of Li protective species and explain their working mechanisms in suppressing Li dendrites growth and protecting Li anode: lithiophilicity chemistry theory [16,28,[30][31][32][33][34][35][36][37][38] and high interfacial-energy theory. [17,29,39] The lithiophilicity of protective species is usually evaluated by theoretically calculating their binding energy (Figure 2D) [16,28,[30][31][32][33][34][35]37,38] or adsorption energy [37] to Li atoms.…”

“…There are mainly two classic theories to effectively guide the selection of Li protective species and explain their working mechanisms in suppressing Li dendrites growth and protecting Li anode: lithiophilicity chemistry theory [16,28,[30][31][32][33][34][35][36][37][38] and high interfacial-energy theory. [17,29,39] The lithiophilicity of protective species is usually evaluated by theoretically calculating their binding energy (Figure 2D) [16,28,[30][31][32][33][34][35]37,38] or adsorption energy [37] to Li atoms. The SEI layer enriched by lithiophilic species with high binding energy and adsorption energy to Li atoms demonstrates a strong interaction with Li metal, promoting homogeneous Li + distribution and Li metal nucleation.…”

Locally Concentrated Ionic Liquid Electrolytes for Lithium‐Metal Batteries

“…Li metal, with a high theoretical capacity (3860 mAh g −1 , 2061 mAh cm −3 ) and the most negative redox potential (−3.04 V vs. SHE), is a promising anode material for the next‐generation high‐energy‐density batteries, i.e., lithium metal batteries (LMBs) [1] . However, the lack of sufficiently protective solid electrolyte interphases (SEIs) on lithium metal anodes (LMAs) leads to low lithium stripping/plating Coulombic efficiency (CE) and lithium dendrite growth, which limits the lifespan of LMBs [2, 3] . Moreover, the heat generation from the side reactions and internal short circuit, together with the conventionally used flammable electrolytes, result in safety concerns [4, 5] .…”

Enhanced Electrochemical Performance of Rare-Earth Metal-Ion-Doped Nanocrystalline Li4Ti5O12Electrodes in High-Power Li-Ion Batteries

“…Lithium-ion batteries (LIBs) have received significant attention from the scientific and engineering community in recent years due to their efficiency as power systems for electrical vehicles (EVs), hybrid electrical vehicles (HEVs), and grid storage plants. − Continuously increasing the demand for energy and environmental problems brought on by the burning of fossil fuels made LIBs, which are known for high energy density, power density, and long shelf-life, an attractive choice. − The efficiency of a Li-ion battery mainly depends on the performance of both negative (anode) and positive (cathode) electrode materials. Most marketed LIBs are fabricated with a graphite-based anode operating at a low lithiation potential (<0.2 V vs Li + /Li), which causes the growth of a solid electrolyte interphase (SEI) layer deposited on the electrode surface.…”