Lithium–sulfur (Li–S) batteries hold great promise to serve as next‐generation energy storage devices. However, the practical performances of Li–S batteries are severely limited by the sulfur cathode ...regarding its low conductivity, huge volume change, and the polysulfide shuttle effect. The first two issues have been well addressed by introducing mesoporous carbon hosts to the sulfur cathode. Unfortunately, the nonpolar nature of carbon materials renders poor affinity to polar polysulfides, leaving the shuttling issue unaddressed. In this contribution, atomic cobalt is implanted within the skeleton of mesoporous carbon via a supramolecular self‐templating strategy, which simultaneously improves the interaction with polysulfides and maintains the mesoporous structure. Moreover, the atomic cobalt dopants serve as active sites to improve the kinetics of the sulfur redox reactions. With the atomic‐cobalt‐decorated mesoporous carbon host, a high capacity of 1130 mAh gS−1 at 0.5 C and a high stability with a retention of 74.1% after 300 cycles are realized. Implanting atomic metal in mesoporous carbon demonstrates a feasible strategy to endow nanomaterials with targeted functions for Li–S batteries and broad applications.
Atomic cobalt implantation to mesoporous carbon enhances the sulfur kinetics in Li–S batteries. Atomic cobalt dopants with high polarity endow the mesoporous carbon (represented by the apes) with high affinity with polysulfides (represented by the bananas). Therefore, the shuttle effect is eliminated and the sulfur kinetics is improved, facilitating highly stable Li–S batteries.
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.
Lithium (Li)‐metal batteries promise energy density beyond 400 Wh kg−1, while their practical operation at an extreme temperature below −30 °C suffers severe capacity deterioration. Such battery ...failure highly relates to the remarkably increased kinetic barrier of interfacial processes, including interfacial desolvation, ion transportation, and charge transfer. In this work, the interfacial kinetics in three prototypical electrolytes are quantitatively probed by three‐electrode electrochemical techniques and molecular dynamics simulations. Desolvation as the limiting step of interfacial processes is validated to dominate the cell impedance and capacity at low temperature. 1,3‐Dioxolane‐based electrolyte with tamed solvent–solute interaction facilitates fast desolvation, enabling the practical Li|LiNi0.5Co0.2Mn0.3O2 cells at −40 °C to retain 66% of room‐temperature capacity and withstand remarkably fast charging rate (0.3 C). The barrier of desolvation dictated by solvent–solute interaction environments is quantitatively uncovered. Regulating the solvent–solute interaction by low‐affinity solvents emerges as a promising solution to low‐temperature batteries.
Desolvation is validated as the predominant contributor to energy loss at low temperatures, largely overwhelming the contributions from other interfacial ion transportation processes. A rational and original design by taming solvent–solute interaction with low‐affinity solvents like 1,3‐dioxolane is proposed to enable high capacity and durable operation of practical lithium‐metal batteries at −40 °C.
The lithium–sulfur (Li–S) battery is regarded as a promising secondary battery. However, constant parasitic reactions between the Li anode and soluble polysulfide (PS) intermediates significantly ...deteriorate the working Li anode. The rational design to inhibit the parasitic reactions is plagued by the inability to understand and regulate the electrolyte structure of PSs. Herein, the electrolyte structure of PSs with anti‐reductive solvent shells was unveiled by molecular dynamics simulations and nuclear magnetic resonance. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether (DIPE) as a cosolvent, DIPE molecules tend to distribute in the outer solvent shell due to poor solvating power. Furthermore, DIPE is more stable than conventional ether solvents against Li metal. The reactivity of PSs is suppressed by encapsulating PSs into anti‐reductive solvent shells. Consequently, the cycling performance of working Li–S batteries was significantly improved and a pouch cell of 300 Wh kg−1 was demonstrated. The fundamental understanding in this work provides an unprecedented ground to understand the electrolyte structure of PSs and the rational electrolyte design in Li–S batteries.
The electrolyte structure of lithium polysulfides (PSs) with anti‐reductive solvent shells was unveiled. The reduction resistance of the solvent shell is proven to be a key reason for the decreased reactivity of PSs towards Li. With isopropyl ether as a cosolvent, the reactivity of PSs is suppressed by encapsulating PSs into anti‐reductive solvent shells. The stability of practical Li–S batteries was improved and a pouch cell of 300 Wh kg−1 was demonstrated.
Lithium (Li) metal anodes hold great promise for next‐generation high‐energy‐density batteries, while the insufficient fundamental understanding of the complex solid electrolyte interphase (SEI) is ...the major obstacle for the full demonstration of their potential in working batteries. The characteristics of SEI highly depend on the inner solvation structure of lithium ions (Li+). Herein, we clarify the critical significance of cosolvent properties on both Li+ solvation structure and the SEI formation on working Li metal anodes. Non‐solvating and low‐dielectricity (NL) cosolvents intrinsically enhance the interaction between anion and Li+ by affording a low dielectric environment. The abundant positively charged anion–cation aggregates generated as the introduction of NL cosolvents are preferentially brought to the negatively charged Li anode surface, inducing an anion‐derived inorganic‐rich SEI. A solvent diagram is further built to illustrate that a solvent with both proper relative binding energy toward Li+ and dielectric constant is suitable as NL cosolvent.
The introduction of cosolvents with non‐solvating and low‐dielectricity (NL) properties can intrinsically enhance the interaction between anion and Li+ and regulate the solvation structures in electrolytes, which favors an upgraded anion‐derived solid electrolyte interphase (SEI) on lithium metal anodes.
Surface reactions constitute the foundation of various energy conversion/storage technologies, such as the lithium–sulfur (Li‐S) batteries. To expedite surface reactions for high‐rate battery ...applications demands in‐depth understanding of reaction kinetics and rational catalyst design. Now an in situ extrinsic‐metal etching strategy is used to activate an inert monometal nitride of hexagonal Ni3N through iron‐incorporated cubic Ni3FeN. In situ etched Ni3FeN regulates polysulfide‐involving surface reactions at high rates. Electron microscopy was used to unveil the mechanism of in situ catalyst transformation. The Li‐S batteries modified with Ni3FeN exhibited superb rate capability, remarkable cycling stability at a high sulfur loading of 4.8 mg cm−2, and lean‐electrolyte operability. This work opens up the exploration of multimetallic alloys and compounds as kinetic regulators for high‐rate Li‐S batteries and also elucidates catalytic surface reactions and the role of defect chemistry.
Inert hexagonal Ni3N can be activated by an extrinsic metal‐incorporating strategy with in situ etching that uses cubic Ni3FeN. Vacancy‐rich Ni3FeN catalysts kinetically regulate polysulfide‐involving reactions at high rates for use in advanced lithium–sulfur batteries.
Lithium–sulfur (Li–S) batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications. Expediting redox kinetics of sulfur species is a ...decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution. Herein, we proposed a porphyrin‐derived atomic electrocatalyst to exert atomic‐efficient electrocatalytic effects on polysulfide intermediates. Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst. Benefiting from atomically dispersed “lithiophilic” and “sulfiphilic” sites on conductive substrates, the finely designed atomic electrocatalyst endows Li–S cells with remarkable cycling stablity (cyclic decay rate of 0.10% in 300 cycles), excellent rate capability (1035 mAh g−1 at 2 C), and impressive areal capacity (10.9 mAh cm−2 at a sulfur loading of 11.3 mg cm−2). The present work expands atomic electrocatalysts to the Li–S chemistry, deepens kinetic understanding of sulfur species evolution, and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.
An atomic‐scale electrocatalyst is proposed to exert atom‐efficiency electrocatalytic effects on polysulfide intermediates in working Li–S batteries. Quantifying electrocatalytic effects on multiphase evolution by kinetic characterizations reveal their unique electrocatalytic benefits on the sulfur conversion reactions, thus enabling impressive battery performances.
In situ evolution of electrocatalysts is of paramount importance in defining catalytic reactions. Catalysts for aprotic electrochemistry such as lithium–sulfur (Li‐S) batteries are the cornerstone to ...enhance intrinsically sluggish reaction kinetics but the true active phases are often controversial. Herein, we reveal the electrochemical phase evolution of metal‐based pre‐catalysts (Co4N) in working Li‐S batteries that renders highly active electrocatalysts (CoSx). Electrochemical cycling induces the transformation from single‐crystalline Co4N to polycrystalline CoSx that are rich in active sites. This transformation propels all‐phase polysulfide‐involving reactions. Consequently, Co4N enables stable operation of high‐rate (10 C, 16.7 mA cm−2) and electrolyte‐starved (4.7 μL mgS−1) Li‐S batteries. The general concept of electrochemically induced sulfurization is verified by thermodynamic energetics for most of low‐valence metal compounds.
The electrochemical phase evolution of metal‐based pre‐catalysts (Co4N) to polycrystalline CoSx that are rich in active sites in working Li‐S batteries is revealed. This transformation propels all‐phase polysulfide‐involving reactions and enables stable operation of high‐rate and electrolyte‐starved Li‐S batteries.
Activation of the phagocytosis of macrophages to tumor cells is an attractive strategy for cancer immunotherapy, but the effectiveness is limited by the fact that many tumor cells express an ...increased level of anti‐phagocytic signals (e.g., CD47 molecules) on their surface. To promote phagocytosis of macrophages, a pro‐phagocytic nanoparticle (SNPACALR&aCD47) that concurrently carries CD47 antibody (aCD47) and a pro‐phagocytic molecule calreticulin (CALR) is constructed to simultaneously modulate the phagocytic signals of macrophages. SNPACALR&aCD47 can achieve targeted delivery to tumor cells by specifically binding to the cell‐surface CD47 and block the CD47‐SIRPα pathway to inhibit the “don't eat me” signal. Tumor cell‐targeted delivery increases the exposure of recombinant CALR on the cell surface and stimulates an “eat me” signal. Simultaneous modulation of the two signals enhances the phagocytosis of 4T1 tumor cells by macrophages, which leads to significantly improved anti‐tumor efficacy in vivo. The findings demonstrate that the concurrent blockade of anti‐phagocytic signals and activation of pro‐phagocytic signals can be effective in macrophage‐mediated cancer immunotherapy.
The phagocytosis of tumor cells by macrophages requires both the coordinated disruption of “don't eat me” signals and simultaneous activation of “eat me” signals. Herein, a nanoparticle‐enabled strategy is proposed to concurrently modulate the cell surface levels of calreticulin (CALR) and CD47 to improve macrophage phagocytosis for improved cancer immunotherapy.
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