Advanced Electrolyte Design for High‐Energy‐Density Li‐Metal Batteries under Practical Conditions

Abstract

Given the limitations inherent in current intercalation‐based Li‐ion batteries, much research attention has focused on potential successors to Li‐ion batteries such as lithium–sulfur (Li‐S) batteries and lithium–oxygen (Li‐O2) batteries. In order to realize the potential of these batteries, the use of metallic lithium as the anode is essential. However, there are severe safety hazards associated with the growth of Li dendrites, and the formation of “dead Li” during cycles leads to the inevitable loss of active Li, which in the end is undoubtedly detrimental to the actual energy density of Li‐metal batteries. For Li‐metal batteries under practical conditions, a low negative/positive ratio (N/P ratio), a electrolyte/cathode ratio (E/C ratio) along with a high‐voltage cathode is prerequisite. In this Review, we summarize the development of new electrolyte systems for Li‐metal batteries under practical conditions, revisit the design criteria of advanced electrolytes for practical Li‐metal batteries and provide perspectives on future development of electrolytes for practical Li‐metal batteries.

Lithium‐Metal Batteries via Suppressing Li Dendrite Growth and Improving Coulombic Efficiency

“…As the blood of a human, the electrolyte is served as the bridge of Li þ transport and is recognized as the most crucial component that affects the CE of LMBs during cycling. [107,108] Figure 5 summarizes the development of liquid electrolytes to stabilize LMAs. [105,[109][110][111][112][113][114][115][116][117][118][119] Despite tremendous efforts that have been made in the past decades, to date, there are no suitable electrolytes that can support the long-term operation of LMBs.…”

Confined Lithium Deposition Triggered by an Integrated Gradient Scaffold for a Lithium-Metal Anode

“…Lithium (Li) metal is a competitive anode material as an alternative to graphite for high-energy-density lithium metal batteries (LMBs) because of its high theoretical capacity (3860 mAh g –1 ) and low electrode potential (−3.04 V vs standard hydrogen electrode), especially for the batteries system of lithium–sulfur and lithium–oxygen batteries . However, limited to the hostless stripping/plating behavior of Li, the dilemma of the historic failure of LMBs results from the nonideal growth of Li dendrites, large volume expansion of Li, and unstable solid electrolyte interface (SEI) during repeated cycling, which causes many severe problems, including low-Coulombic efficiency, short cycle life, and potential safety hazards. − Recently, considerable researches have been proposed to suppress the dendritic growth of metallic Li and indeed effective in improving the overall performance of the Li anode in LMBs, including an interlayer, , porous current collectors, − artificial SEI, − and an electrolyte formula. − …”

A Competitive Solvation of Ternary Eutectic Electrolytes Tailoring the Electrode/Electrolyte Interphase for Lithium Metal Batteries

“…Electrolytes, which insulate electrons but conduct ions between electrodes, play a vital role in promoting the battery performance. As electrochemical energy storage technology has undergone significant development, traditional electrolytes cannot satisfy the demands of high-energy density batteries . Moreover, lithium metal, as the ultimate anode material, places high demands on the electrolyte .…”

“…As electrochemical energy storage technology has undergone significant development, traditional electrolytes cannot satisfy the demands of high-energy density batteries . Moreover, lithium metal, as the ultimate anode material, places high demands on the electrolyte . The safety hazards resulting from lithium dendrite growth and flammable electrolytes are the main issues that limit the practical applications of lithium metal anodes .…”

“…13 Moreover, lithium metal, as the ultimate anode material, places high demands on the electrolyte. 13 The safety hazards resulting from lithium dendrite growth and flammable electrolytes are the main issues that limit the practical applications of lithium metal anodes. 14 In addition to optimizing traditional electrolytes, various concepts for electrolyte design, including superconcentration, 15 polymer, 16 solid-state, 17 ionic liquid, 18 and eutectic electrolytes, 19 nontoxicity, low cost, and environmental friendliness compared to organic carbonate and ionic liquid electrolytes (Figure 1a).…”