Lithium–sulfur (Li–S) batteries with high energy density and long cycle life are considered to be one of the most promising next‐generation energy‐storage systems beyond routine lithium‐ion ...batteries. Various approaches have been proposed to break down technical barriers in Li–S battery systems. The use of nanostructured metal oxides and sulfides for high sulfur utilization and long life span of Li–S batteries is reviewed here. The relationships between the intrinsic properties of metal oxide/sulfide hosts and electrochemical performances of Li–S batteries are discussed. Nanostructured metal oxides/sulfides hosts used in solid sulfur cathodes, separators/interlayers, lithium‐metal‐anode protection, and lithium polysulfides batteries are discussed respectively. Prospects for the future developments of Li–S batteries with nanostructured metal oxides/sulfides are also discussed.
Nanostructured metal oxides and sulfides are considered as polysulfide anchoring sites in working Li–S batteries for the battery's high sulfur utilization and long life span. The relationships between the intrinsic properties of the metal oxide/sulfide hosts and the electrochemical performances of Li–S batteries are reviewed.
The performance of Li‐ion batteries (LIBs) is highly dependent on their interfacial chemistry, which is regulated by electrolytes. Conventional electrolyte typically contains polar solvents to ...dissociate Li salts. Herein we report a weakly solvating electrolyte (WSE) that consists of a pure non‐polar solvent, which leads to a peculiar solvation structure where ion pairs and aggregates prevail under a low salt concentration of 1.0 M. Importantly, WSE forms unique anion‐derived interphases on graphite electrodes that exhibit fast‐charging and long‐term cycling characteristics. First‐principles calculations unravel a general principle that the competitive coordination between anions and solvents to Li ions is the origin of different interfacial chemistries. By bridging the gap between solution thermodynamics and interfacial chemistry in batteries, this work opens a brand‐new way towards precise electrolyte engineering for energy storage devices with desired properties.
A weakly solvating electrolyte affords a new path towards anion‐derived interfacial chemistry in lithium‐ion batteries. By formulating electrolyte with a non‐polar solvent, ion pairs and aggregates prevail under normal concentrations and give rise to anion‐derived interphases on graphite electrodes with superior electrochemical performances.
Lithium–sulfur (Li–S) batteries deliver a high theoretical energy density of 2600 Wh kg−1, and hold great promise to serve as a next‐generation high‐energy‐density battery system. Great progress has ...been achieved in cathode design to deal with the intrinsic problems of sulfur cathodes, including low conductivity, the dissolution of polysulfide intermediate, and volume fluctuation. However, aiming at the practical applications of Li–S batteries, the weight percentage of sulfur in cathode materials and the overall areal sulfur loading need to be significantly increased, which inevitably complicate the process and cause heavy shuttle effect, slow redox kinetics, and more undesirable reaction pathways. Recently, rationally designing efficient mediators, as well as incorporating them into a working battery, emerges to be a promising method to construct high‐energy‐density Li–S batteries. The influence of mediators on Li–S batteries appears to be the enhancement in redox kinetics and the increase in reaction efficiency. In this feature article, the mechanistic understanding of redox kinetics in Li–S reactions is discussed, and then a comprehensive analysis of the recent advances in both heterogeneous and homogeneous mediator design is provided. A mediator perspective in building high‐energy‐density Li–S batteries is also included.
Mediators in lithium–sulfur batteries can enhance the redox kinetics and increase the reaction efficiency, which benefit the practical applications requiring a high sulfur content and a high areal loading amount. This feature article discusses the mechanism of redox kinetics, and reviews the recent advances in heterogeneous/homogeneous mediator design in lithium–sulfur batteries.
Safe and rechargeable lithium metal batteries have been difficult to achieve because of the formation of lithium dendrites. Herein an emerging electrolyte based on a simple solvation strategy is ...proposed for highly stable lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions, and forming a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiNxOy on a working lithium metal anode with dendrite‐free lithium deposition. Ultrahigh Coulombic efficiency (99.96 %) and long lifespans (1000 cycles) were achieved when the FEC/LiNO3 electrolyte was applied in working batteries. The solvation chemistry of electrolyte was further explored by molecular dynamics simulations and first‐principles calculations. This work provides insight into understanding the critical role of the solvation of lithium ions in forming the SEI and delivering an effective route to optimize electrolytes for safe lithium metal batteries.
Not dead ′Li′: Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions and forming a uniform solid electrolyte interphase (SEI). An abundance of LiF and LiNxOy is formed on the working lithium metal anode and contributes to dendrite‐free lithium deposition.
A cooperative interface constructed by “lithiophilic” nitrogen‐doped graphene frameworks and “sulfiphilic” nickel–iron layered double hydroxides (LDH@NG) is proposed to synergistically afford ...bifunctional Li and S binding to polysulfides, suppression of polysulfide shuttles, and electrocatalytic activity toward formation of lithium sulfides for high‐performance lithium–sulfur batteries. LDH@NG enables high rate capability, long lifespan, and efficient stabilization of both sulfur and lithium electrodes.
High‐energy‐density Li metal batteries suffer from a short lifespan under practical conditions, such as limited lithium, high loading cathode, and lean electrolytes, owing to the absence of ...appropriate solid electrolyte interphase (SEI). Herein, a sustainable SEI was designed rationally by combining fluorinated co‐solvents with sustained‐release additives for practical challenges. The intrinsic uniformity of SEI and the constant supplements of building blocks of SEI jointly afford to sustainable SEI. Specific spatial distributions and abundant heterogeneous grain boundaries of LiF, LiNxOy, and Li2O effectively regulate uniformity of Li deposition. In a Li metal battery with an ultrathin Li anode (33 μm), a high‐loading LiNi0.5Co0.2Mn0.3O2 cathode (4.4 mAh cm−2), and lean electrolytes (6.1 g Ah−1), 83 % of initial capacity retains after 150 cycles. A pouch cell (3.5 Ah) demonstrated a specific energy of 340 Wh kg−1 for 60 cycles with lean electrolytes (2.3 g Ah−1).
A solid electrolyte interphase (SEI) was proposed for practical high‐energy‐density Li batteries. The intrinsic uniformity and the constant supplements of building blocks of SEI jointly afford a sustainable SEI. A pouch cell with a specific energy of 340 Wh kg−1 underwent 60 cycles with a retention of 90 %.
The lithium metal anode is regarded as a promising candidate in next‐generation energy storage devices. Lithium nitrate (LiNO3) is widely applied as an effective additive in ether electrolyte to ...increase the interfacial stability in batteries containing lithium metal anodes. However, because of its poor solubility LiNO3 is rarely utilized in the high‐voltage window provided by carbonate electrolyte. Dissolution of LiNO3 in carbonate electrolyte is realized through an effective solvation regulation strategy. LiNO3 can be directly dissolved in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding trace amounts of copper fluoride as a dissolution promoter. LiNO3 protects the Li metal anode in a working high‐voltage Li metal battery. When a LiNi0.80Co0.15Al0.05O2 cathode is paired with a Li metal anode, an extraordinary capacity retention of 53 % is achieved after 300 cycles (13 % after 200 cycles for LiNO3‐free electrolyte) and a very high average Coulombic efficiency above 99.5 % is achieved at 0.5 C. The solvation chemistry of LiNO3‐containing carbonate electrolyte may sustain high‐voltage Li metal anodes operating in corrosive carbonate electrolytes.
Liquid assets: LiNO3 can be dissolved directly in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding a trace amount of copper fluoride to promote dissolution. The solvation structure of the electrolyte system protects the lithium metal anode in a working high‐voltage lithium metal battery. NCA=LiNi0.80Co0.15Al0.05O2.
Lithium–sulfur (Li–S) batteries have been recognized as promising substitutes for current energy‐storage technologies owing to their exceptional advantage in energy density. The main challenge in ...developing highly efficient and long‐life Li–S batteries is simultaneously suppressing the shuttle effect and improving the redox kinetics. Polar host materials have desirable chemisorptive properties to localize the mobile polysulfide intermediates; however, the role of their electrical conductivity in the redox kinetics of subsequent electrochemical reactions is not fully understood. Conductive polar titanium carbides (TiC) are shown to increase the intrinsic activity towards liquid–liquid polysulfide interconversion and liquid–solid precipitation of lithium sulfides more than non‐polar carbon and semiconducting titanium dioxides. The enhanced electrochemical kinetics on a polar conductor guided the design of novel hybrid host materials of TiC nanoparticles grown within a porous graphene framework (TiC@G). With a high sulfur loading of 3.5 mg cm−2, the TiC@G/sulfur composite cathode exhibited a substantially enhanced electrochemical performance.
Li–S batteries: The electrochemical reaction kinetics of reversible polysulfide interconversion and Li2S nucleation/precipitation are substantially enhanced on the conductive and polar surface of titanium carbide, guiding the design of advanced host materials towards high‐energy and stable Li–S batteries.
A nanostructured lithium‐metal anode employing an unstacked graphene “drum” and dual‐salt electrolyte brings about a dendrite‐free lithium depositing morphology. On the one hand, the unstacked ...graphene framework with ultrahigh specific surface area guarantees an ultralow local current density that prevents the growth of lithium dendrites. On the other hand, the stable, flexible, and compact solid electrolyte interphase layer induced by the dual‐salt electrolyte protects the deposited lithium layers.
Lithium metal batteries (such as lithium–sulfur, lithium–air, solid state batteries with lithium metal anode) are highly considered as promising candidates for next‐generation energy storage systems. ...However, the unstable interfaces between lithium anode and electrolyte definitely induce the undesired and uncontrollable growth of lithium dendrites, which results in the short‐circuit and thermal runaway of the rechargeable batteries. Herein, a dual‐layered film is built on a Li metal anode by the immersion of lithium plates into the fluoroethylene carbonate solvent. The ionic conductive film exhibits a compact dual‐layered feature with organic components (ROCO2Li and ROLi) on the top and abundant inorganic components (Li2CO3 and LiF) in the bottom. The dual‐layered interface can protect the Li metal anode from the corrosion of electrolytes and regulate the uniform deposition of Li to achieve a dendrite‐free Li metal anode. This work demonstrates the concept of rational construction of dual‐layered structured interfaces for safe rechargeable batteries through facile surface modification of Li metal anodes. This not only is critically helpful to comprehensively understand the functional mechanism of fluoroethylene carbonate but also affords a facile and efficient method to protect Li metal anodes.
A dual‐layered film is obtained on a Li metal anode by spontaneous chemical reaction between lithium plates and fluoroethylene carbonate solvents. Such film can protect the Li metal anodes from the corrosion of electrolytes and regulate the uniform deposition of Li to achieve a dendrite‐free Li metal anode.
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