Because of their high theoretical energy density and low cost, lithium–sulfur (Li–S) batteries are promising next-generation energy storage devices. The electrochemical performance of Li–S batteries largely depends on the efficient reversible conversion of Li polysulfides to Li2S in discharge and to elemental S during charging. Here, we report on our discovery that monodisperse cobalt atoms embedded in nitrogen-doped graphene (Co–N/G) can trigger the surface-mediated reaction of Li polysulfides. Using a combination of operando X-ray absorption spectroscopy and first-principles calculation, we reveal that the Co–N–C coordination center serves as a bifunctional electrocatalyst to facilitate both the formation and the decomposition of Li2S in discharge and charge processes, respectively. The S@Co–N/G composite, with a high S mass ratio of 90 wt %, can deliver a gravimetric capacity of 1210 mAh g–1, and it exhibits an areal capacity of 5.1 mAh cm–2 with capacity fading rate of 0.029% per cycle over 100 cycles at 0.2 C at S loading of 6.0 mg cm–2 on the electrode disk.

Highly concentrated electrolytes (HCEs) significantly improve the stability of lithium metal anodes, but applications are often impeded by their limitation of density, viscosity, and cost. Here, fluorobenzene (FB), an economical hydrocarbon with low density and low viscosity, is demonstrated as a bifunctional cosolvent to obtain a novel FB diluted highly concentrated electrolyte (FB‐DHCE). First, the addition of FB suppresses the decomposition of dimethoxyethane (DME) on the Li metal by strengthening the interactions of DME and FSI− around Li+. Second, FB efficiently elevates the content of LiF in the solid electrolyte interphase (SEI) based on its electrochemical reduction reaction. The unique solvation and interfacial chemistry of FB‐DHCE enable dendrite‐free deposition of lithium with high Coulombic efficiency (up to 99.3%) and prolong cycling life (over 500 cycles at 1 mA cm−2). The performance of FB‐DHCE is further demonstrated in full cells under practical conditions, including ambient to low temperature (–20 °C), high areal capacity (7.6 mAh cm−2), high current density (3 mA cm−2), limited excess Li (20 µm Li), and lean electrolyte (3 g Ah−1). Employing FB as a cosolvent not only opens a novel pathway to stabilize Li metal anodes, but also could greatly advance the development of Li metal batteries.

Lithium-metal anodes are recognized as the most promising next-generation anodes for high-energy-storage batteries.H owever,l ithium dendrites lead to irreversible capacity decayi nl ithium-metal batteries (LMBs). Besides, the strict assembly-environment conditions of LMBs are regarded as ac hallenge for practical applications.I nt his study,aworkable lithium-metal anode with an artificial hybrid layer composed of ap olymer and an alloy was designed and prepared by as imple chemical-modification strategy.T reated lithium anodes remained dendrite-free for over 1000 hinaLi-Li symmetric cell and exhibited outstanding cycle performance in high-areal-loading Li-S and Li-LiFePO 4 full cells.M oreover,t he treated lithium showed improved moisture stability that benefits from the hydrophobicity of the polymer,t hus retaining good electrochemical performance after exposure to humid air.

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Room temperature (RT) sodium–sulfur batteries suffer from slow reaction kinetics and polysulfide dissolution, resulting in poor performance. Sulfurized polyacrylonitrile is a unique sulfur cathode which is suggested to involve only S3–4 and shows high specific capacity. Herein, the designed Te0.04S0.96@pPAN with 4 mol % Te used as eutectic accelerator exhibits significantly enhanced reaction kinetics and excellent sulfur utilization, leading to a high performance RT Na–S battery. Te0.04S0.96@pPAN delivers capacities of 1236 and 629 mA h g–1 and 1111 and 601 mA h g–1 at 0.1 and 6 A g–1 in carbonate and ether electrolytes, respectively. Furthermore, UV–vis spectra and the shuttle current test reveal diminished sodium polysulfides in ether electrolyte, attributed to the fast kinetics enabled by Te doping. More significantly, the spectral technique and electrochemical analysis demonstrate a two-step reaction pathway in which Na2S3 and Na2S are the main intermediate and final discharge product, respectively. This method provides a promising approach toward applicable RT Na–S batteries.

Surface-enhanced Raman spectroscopy (SERS) is a powerful technique that can capture the electronic− vibrational "fingerprint" of molecules on surfaces. Ab initio prediction of Raman response is a long-standing challenge because of the diversified interfacial structures. Here we show that a cost-effective machine learning (ML) random forest method can predict SERS signals of a trans-1,2-bis (4-pyridyl) ethylene (BPE) molecule adsorbed on a gold substrate. Using geometric descriptors extracted from quantum chemistry simulations of thousands of ab initio molecular dynamics conformations, the ML protocol predicts vibrational frequencies and Raman intensities. The resulting spectra agree with density functional theory calculations and experiment. Predicted SERS responses of the molecule on different surfaces, or under external fields of electric fields and solvent environment, demonstrate the good transferability of the protocol.

Infrared (IR) absorption provides important chemical fingerprints of biomolecules. Protein secondary structure determination from IR spectra is tedious since its theoretical interpretation requires repeated expensive quantum-mechanical calculations in a fluctuating environment. Herein we present a novel machine learning (ML) protocol that uses a few key structural descriptors to rapidly predict amide I IR spectra of various proteins and agrees well with experiment. Its transferability enabled us to distinguish protein secondary structures, probe atomic structure variations with temperature, and monitor protein folding. This approach offers a cost-effective tool to model the relationship between protein spectra and their biological/chemical properties.

Practical applications of lithium metal anodes are gravely impeded by inhomogeneous lithium deposition, which results in dendrite growth. Electrolyte additives are proven to be effective in improving performance but usually serve only a single function. Herein, nitrofullerene is introduced as a bifunctional additive with a smoothing effect and forms a protective solid electrolyte interphase (SEI) layer on stable lithium metal anodes. By design, nitro-C 60 can gather on electrode protuberances via electrostatic interactions and then be reduced to NO 2 − and insoluble C 60 . Next, the C 60 anchors on the uneven groove of the lithium surface, resulting in a homogeneous distribution of Li ions. Finally, NO 2 − anions can react with metallic Li to build a compact and stable SEI with high ion transport. With a 5 mM nitro-C 60 additive, Li−Li symmetric cells show superior cycle stability in both carbonate and ether electrolytes, Li−sulfur batteries with a high cathode loading (10.6 mg cm −2 , 6 mAh cm −2 ) can achieve improved cycle retention of 63.2% over 100 cycles in a carbonate electrolyte, and full cells paired with a high-areal-capacity LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode (3.5 mAh cm −2 ) exhibit a significantly enhanced cycle lifespan even under lean electrolyte conditions.