The battery community has recently witnessed a considerable progress in the cycle lives of lithium‐sulfur (Li‐S) batteries, mostly by developing the electrode structures that mitigate fatal ...dissolution of lithium polysulfides. Nonetheless, most of the previous successful demonstrations have been based on limited areal capacities. For realistic battery applications, however, the chronic issues from both the anode (lithium dendrite growth) and the cathode (lithium polysulfide dissolution) need to be readdressed under much higher loading of sulfur active material. To this end, the current study integrates the following three approaches in a systematic manner: 1) the sulfur electrode material with diminished lithium polysulfide dissolution by the covalently bonded sulfur‐carbon microstructure, 2) mussel‐inspired polydopamine coating onto the separator that suppresses lithium dendrite growth by wet‐adhesion between the separator and Li metal, and 3) addition of cesium ions (Cs+) to the electrolyte to repel incoming Li ions and thus prevent Li dendrite growth. This combined strategy resolves the long‐standing problems from both electrodes even under the very large sulfur‐carbon composite loading of 17 mg cm−2 in the sulfur electrode, enabling the highest areal capacity (9 mAh cm−2) to date while preserving stable cycling performance.
The highest areal energy density to date of a lithium‐sulfur battery is demonstrated by the combined smart engineering of the key cell components (electrode, electrolyte, and separator). The integrated strategy suppresses both lithium polysulfide dissolution from the sulfur cathode and lithium dendrite growth from the lithium anode, leading to the highest areal capacity of 9 mAh cm−2 while preserving stable cyclability.
A carbon nanostructured hybrid fiber is developed by integrating mesoporous carbon and graphene oxide into aligned carbon nanotubes. This hybrid fiber is used as a 1D cathode to fabricate a new ...cable‐shaped lithium–sulfur battery. The fiber cathode exhibits a decent specific capacity and lifespan, which makes the cable‐shaped lithium–sulfur battery rank far ahead of other fiber‐shaped batteries.
Nafion-coated polypropylene separator (Celgard 2500) is used as cation-selective membrane for lithium sulfur batteries to suppress polysulfide diffusion enhancing the charge efficiency of the cells ...especially at low charge/discharge rates. The charge efficiency of the 10th cycle rises from about 70% to nearly 90% at a rate of C/20. The reduction of polysulfide penetration through the Nafion-coated Celgard 2500 is also proven by visual characterization. FTIR and SEM investigations verify a smooth and dense Nafion-coating on the porous polypropylene backbone of the separator. The influence of Nafion-loading on rate capability and discharge voltage is investigated by galvanostatic charge–discharge measurements. With the lowest Nafion-loading of 0.25 mg cm−2 we are able to achieve a rate capability comparable to uncoated Celgard 2500 up to current densities of 3 mA cm−2, whereas the functionality as polysulfide shuttle inhibitor is largely preserved.
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•Nafion-coated propylene separator (Celgard 2500) for improved charge efficiency.•Single-sided dense Nafion-coating after lithiation.•Enhanced rate capability and voltage compared to free standing Nafion membranes.•Substantial reduced polysulfide diffusion through separator.
Dilute alloying is an effective strategy to tune properties of solid catalysts but is rarely leveraged in complex reactions beyond small molecule conversion. In this work, dilute dopants are ...demonstrated to serve as activating centers to construct multiatom catalytic domains in metal nitride electrocatalysts for lithium–sulfur (Li–S) batteries, of which the sulfur cathode suffers from sluggish and complex conversion reactions. With titanium nitride (TiN) as a model system, the dilute cobalt alloying is shown to greatly improve the reaction kinetics while inducing negligible catalyst reconstruction. Compared to the pristine TiN, the dilute nitride alloy catalyst enables onefold increase in the high rate (2.0 C) capacities of Li–S batteries, as well as an impressively low cyclic decay rate of 0.17% at a sulfur loading of 4.0 mgS cm−2. This work opens up new opportunities toward the rational design of Li–S electrocatalysts by dilute alloying and also enlightens the understandings of complex domain‐catalyzed reactions in energy applications.
Dilute alloying implants “activating” centers in nitride alloy electrocatalysts to boost lithium–sulfur (Li–S) batteries. Dilute Co dopants activate the surrounding N and Ti atoms to construct multiatom active domains for efficient bidirectional catalysis of S redox reactions. The corresponding dilute nitride alloy improves the reaction kinetics and electrochemical performance of Li–S batteries.
A space‐confined “sauna” reaction system is introduced for the simultaneous reduction and functionalization of graphene oxide to unique graphene–sulfur hybrid nanosheets, in which thin layers of ...amorphous sulfur are tightly anchored on the graphene sheet via strong chemical bonding. Upon being used as the cathode material in lithium–sulfur batteries, the as‐synthesized composite shows an excellent electrochemical performance.
With the significant progress made in the development of cathodes in lithium‐sulfur (Li‐S) batteries, the stability of Li metal anodes becomes a more urgent challenge in these batteries. Here the ...systematic investigation of the stability of the anode/electrolyte interface in Li‐S batteries with concentrated electrolytes containing various lithium salts is reported. It is found that Li‐S batteries using LiTFSI‐based electrolytes are more stable than those using LiFSI‐based electrolytes. The decreased stability is because the N–S bond in the FSI− anion is fairly weak and the scission of this bond leads to the formation of lithium sulfate (LiSOx) in the presence of polysulfide species. In contrast, in the LiTFSI‐based electrolyte, the lithium metal anode tends to react with polysulfide to form lithium sulfide (LiSx), which is more reversible than LiSOx formed in the LiFSI‐based electrolyte. This fundamental difference in the bond strength of the salt anions in the presence of polysulfide species leads to a large difference in the stability of the anode‐electrolyte interface and performance of the Li‐S batteries with electrolytes composed of these salts. Therefore, anion selection is one of the key parameters in the search for new electrolytes for stable operation of Li‐S batteries.
The electrolyte selection for lithium‐sulfur batteries is critical to achieve high energy and stable cycling. The stability of concentrated electrolytes containing various lithium salts for lithium‐sulfur batteries is investigated. The anion stability of lithium salt greatly affects the anode/electrolyte interface stability and the electrochemical performance.
Electrochemical impedance spectroscopy (EIS) study was done in order to go deeper into the electrochemical processes of Li/S battery in a common CR2032 coin-type cell. In order to separate the ...contributions of each electrode (i. e. lithium negative electrode and sulfur composite positive electrode), impedance measurements on symmetrical cells consisting of two previously cycled electrodes was used. This methodology enables to propose an overall interpretation of the different electrochemical phenomena present during cycling. Low temperature tests were also applied, which brought fruitful information concerning the kinetics of the reactions and allowed to confirm the chemical-physical interpretations performed on the cell cycled at 25°C.
Lithium-Sulfur (Li-S) batteries are a promising next-generation technology providing high gravimetric energy density compared to existing lithium-ion (Li-ion) technologies in the market. The ...literature shows that in Li-S, estimation of state of charge (SoC) is a demanding task, in particular due to a large flat section in the voltage-SoC curve. This study proposes a new SoC estimator using an online parameter identification method in conjunction with a classification technique. This study investigates a new prototype Li-S cell. Experimental characterization tests are conducted under various conditions; the duty cycle - intended to represent a real-world application - is based on an electric city bus. The characterization results are then used to parameterize an equivalent-circuit-network (ECN) model, which is then used to relate real-time parameter estimates derived using a Recursive Least Squares (RLS) algorithm to state of charge using a Support Vector Machine (SVM) classifier to estimate an approximate SoC range. The estimate is used together with a conventional coulomb-counting technique to achieve continuous SoC estimation in real-time. It is shown that this method can provide an acceptable level of accuracy with less than 3% error under realistic driving conditions.
Lithium metal is a promising anode candidate for the next-generation rechargeable battery due to its highest specific capacity (3860 mA h g
) and lowest potential, but low Coulombic efficiency and ...formation of lithium dendrites hinder its practical application. Here, we report a self-formed flexible hybrid solid-electrolyte interphase layer through co-deposition of organosulfides/organopolysulfides and inorganic lithium salts using sulfur-containing polymers as an additive in the electrolyte. The organosulfides/organopolysulfides serve as "plasticizer" in the solid-electrolyte interphase layer to improve its mechanical flexibility and toughness. The as-formed robust solid-electrolyte interphase layers enable dendrite-free lithium deposition and significantly improve Coulombic efficiency (99% over 400 cycles at a current density of 2 mA cm
). A lithium-sulfur battery based on this strategy exhibits long cycling life (1000 cycles) and good capacity retention. This study reveals an avenue to effectively fabricate stable solid-electrolyte interphase layer for solving the issues associated with lithium metal anodes.The practical application of lithium metal anodes suffers from the poor Coulombic efficiency and growth of lithium dendrites. Here, the authors report an approach to enable the self-formation of stable and flexible solid-electrolyte interphase layers which serve to address both issues.
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