No abstract

Substrates able to rectify transport of ions based on charge and/or size are ubiquitous in biological systems. Electrolytes and interphases that selectively transport electrochemically active ions are likewise of broad interest in all electrical energy storage technologies. In lithium-ion batteries, electrolytes with singleor near-single-ion conductivity reduce losses caused by ion polarization. In emergent lithium or sodium metal batteries, they maintain high conductivity at the anode and stabilize metal deposition by fundamental mechanisms. We report that 20-to 300-nm-thick, single-ion-conducting membranes deposited at the anode enable electrolytes with the highest combination of cation transference number, ionic conductivity, and electrochemical stability reported. By means of direct visualization we find that single-ion membranes also reduce dendritic deposition of Li in liquids. Galvanostatic measurements further show that the electrolytes facilitate long (3 mAh) recharge of full Li/LiNi 0.8-Co 0.15 Al 0.05 O 2 (NCA) cells with high cathode loadings (3 mAh cm À2 /19.9 mg cm À2) and at high current densities (3 mA cm À2).

We report a facile in situ synthesis that utilizes readily accessible SiCl cross-linking chemistry to create durable hybrid solid-electrolyte interphases (SEIs) on metal anodes. Such hybrid SEIs composed of Si-interlinked OOCOR molecules that host LiCl salt exhibit fast charge-transfer kinetics and as much as five-times higher exchange current densities, in comparison to their spontaneously formed analogues. Electrochemical analysis and direct optical visualization of Li and Na deposition in symmetric Li/Li and Na/Na cells show that the hybrid SEI provides excellent morphological control at high current densities (3-5 mA cm ) for Li and even for notoriously unstable Na metal anodes. The fast interfacial transport attributes of the SEI are also found to be beneficial for Li-S cells and stable electrochemical cycling was achieved in galvanostatic studies at rates as high as 2 C. Our work therefore provides a promising approach towards rational design of multifunctional, elastic SEIs that overcome the most serious limitations of spontaneously formed interphases on high-capacity metal anodes.

Stable electrochemical interphases play a critical role in regulating transport of mass and charge in all electrochemical energy storage (EES) systems. In state-of-the-art rechargeable lithium ion batteries, they are rarely formed by design but instead spontaneously emerge from electrochemical degradation of electrolyte and electrode components. High-energy secondary batteries that utilize reactive metal anodes (e.g., Li, Na, Si, Sn, Al) to store large amounts of charge by alloying and/or electrodeposition reactions introduce fundamental challenges that require rational design in order to stabilize the interphases. Chemical instability of the electrodes in contact with electrolytes, morphological instability of the metal-electrolyte interface upon plating and stripping, and hydrodynamic-instability-induced electroconvection of the electrolyte at high currents are all known to cause metal electrode-electrolyte interfaces to continuously evolve in morphology, uniformity, and composition. Additionally, metal anodes undergo large changes in volume during lithiation and delithiation, which means that even in the rare cases where spontaneously formed solid electrode-electrolyte interphases (SEIs) are in thermodynamic equilibrium with the electrode, the SEI is under dynamic strain, which inevitably leads to cracking and/or rupture during extended battery cycling. There is an urgent need for interphases that are able to overcome each of these sources of instability with minimal losses of electrolyte and electrode components. Complementary chemical synthesis strategies are likewise urgently needed to create self-limited and mechanically durable SEIs that are able to flex and shrink to accommodate volume change. These needs are acute for practically relevant cells that cannot utilize large excesses of anode and electrolyte as employed in proof-of-concept-type experiments reported in the scientific literature. This disconnect between practical needs and research practices makes it difficult to translate promising literature results, underscoring the importance of research designed to reveal principles for good interphase design. This Account considers the fundamental processes involved in interphase formation, stability, and failure and on that basis identifies design principles, synthesis procedures, and characterization methods for enabling stable metal anode-electrolyte interfaces for EES. We first review results from experimental, continuum theoretical, and computational analyses of interfacial transport to identify fundamental connections between the composition of the SEI at metal-electrolyte interfaces and stability. Design principles and tools for creating stable artificial solid-electrolyte interphases (ASEIs) based on polymers, ionic liquids, ceramics, nanoparticles, salts, and their combinations are subsequently discussed. Interphases composed of a second electrochemically active material that stores charge by different processes from the underlying metal electrode emerge as particularly attractive routes toward ...

Plasma technology is an eco‐friendly way to modify or fabricate carbon‐based materials (CBMs) due to plasmas’ distinctive abilities in tuning the surface physicochemical properties by implanting functional groups or incorporating heteroatoms into the surface without changing the bulk structure. However, the mechanisms of functional groups formation on the carbon surface are still not clearly explained because of the variety of different discharge conditions and the complexity of plasma chemistry. Consequently, this paper contains a comprehensive review of plasma‐treated carbon‐based materials and their applications in environmental, materials, and energy fields. Plasma‐treated CBMs used in these fields have been significantly enhanced in recent years because these related materials possess unique features after plasma treatment, such as higher adsorption capacity, enhanced wettability, improved electrocatalytic activity, etc. Meanwhile, this paper also summarizes possible reaction routes for the generation of functional groups on CBMs. The outlook for future research is summarized, with suggestions that plasma technology research and development shall attempt to achieve precise control of plasmas to synthesize or to modify CBMs at the atomic level.

Increasing numbers of cement furnaces have applied selective catalytic reduction (SCR) units for advanced treatment of NO in the flue gas. However, the SCR catalysts may face various poisons, such as acidic, alkaline, and heavy metal species, in the fly ash. In this work, we studied the deactivation mechanisms of multipoisons (Ca, Pb, and S) on the CeO2–WO3/TiO2 catalyst, using the in situ diffuse reflectance infrared Fourier transform spectroscopy method. Calcium promoted the conversion of Ce­(III) to Ce­(IV) and, thus, (i) suppressed the redox cycle, (ii) decreased the NO adsorption (monodentate NO3 – and bridged NO2 –), and (iii) enriched the Lewis acid sites. Pb­(IV) blocked Ce2(WO4)3, aggravating the electronegativity of W6+, which inhibited (i) the binding stability of tungsten and ammonia species, (ii) bridged NO3 – (bonded to tungsten), and (iii) the Brønsted acid sites. The multipoisoning processes enriched O2– by repairing partial surface oxygen defects, which suppressed O2 2– and O–. Sulfur occupied the surface base sites and formed PbSO4 after Ce2(WO4)3 was saturated.

Lithium–sulfur (Li–S) battery is one of the most promising alternatives for the current state‐of‐the‐art lithium‐ion batteries due to its high theoretical energy density and low production cost from the use of sulfur. However, the commercialization of Li–S batteries has been so far limited to the cyclability and the retention of active sulfur materials. Using co‐electrospinning and physical vapor deposition procedures, we created a class of chloride–carbon nanofiber composites, and studied their effectiveness on polysulfides sequestration. By trapping sulfur reduction products in the modified cathode through both chemical and physical confinements, these chloride‐coated cathodes are shown to remarkably suppress the polysulfide dissolution and shuttling between lithium and sulfur electrodes. From adsorption experiments and theoretical calculations, it is shown that not only the sulfide‐adsorption effect but also the diffusivity in the vicinity of these chlorides materials plays an important role on the reversibility of sulfur‐based cathode upon repeated cycles. Balancing the adsorption and diffusion effects of these nonconductive materials could lead to the enhanced cycling performance of an Li–S cell. Electrochemical analyses over hundreds of cycles indicate that cells containing indium chloride‐modified carbon nanofiber outperform cells with other halogenated salts, delivering an average specific capacity of above 1200 mAh g−1 at 0.2 C.

We report af acile in situ synthesis that utilizes readily accessible SiCl 4 cross-linking chemistry to create durable hybrid solid-electrolyte interphases (SEIs) on metal anodes.Such hybrid SEIs composed of Si-interlinked OOCOR molecules that host LiCl salt exhibit fast charge-transfer kinetics and as mucha sf ive-times higher exchange current densities,i nc omparison to their spontaneously formed analogues.E lectrochemical analysis and direct optical visualization of Li and Na deposition in symmetric Li/Li and Na/Na cells showt hat the hybrid SEI provides excellent morphological control at high current densities (3-5 mA cm À2 )for Li and even for notoriously unstable Na metal anodes.T he fast interfacial transport attributes of the SEI are also found to be beneficial for Li-S cells and stable electrochemical cycling was achieved in galvanostatic studies at rates as high as 2C.O ur work therefore provides ap romising approach towards rational design of multifunctional, elastic SEIs that overcome the most serious limitations of spontaneously formed interphases on high-capacity metal anodes.Advances in rechargeable battery systems rely on the synergistic functioning of multiple components that interact through interfaces. [1] Thesolid-electrolyte interphase (SEI) in al ithium-ion battery has received significant attention because of its important role in maintaining long-term stability in ac ell in which the electrolyte is thermodynamically unstable at the operating potential of the graphitic carbon anode. [2] How the SEI achieves this feat is still amatter of ongoing research, but it is generally thought to hinge on the composition of the SEI and on the unique mass and ion transport properties provided by the combination of ionically conducting organic polymers and thermodynamically stable, electronically insulating binary salts (e.g., Li 2 CO 3 ,L iF,L i 3 P, Li 2 O) formed by reduction of electrolyte components in contact with the anode. [3] This combination of ingredients is for example thought to enable fast ion transport between electrolyte and electrode,w hile at the same time presenting al arge-enough diffusion barrier for direct contact between electrolyte and electrode.V ery little is known fundamentally, however, about how the components interact and how one might go about achieving ab etter balance between their respective physical properties to achieve aS EI for faster ion transport and/or better electrochemical stability. [4] Recently,r echargeable batteries that utilize metallic anodes have received significant attention owing to their potential to provide high gravimetric and volumetric energy densities, [5] and in some cases to increase the number of viable cathode chemistries (e.g., O 2 ,S 8 )that might be used. [6] These opportunities unfortunately come with new challenges,which stem largely from non-uniformity,f ragility,a sw ell as poor electrochemical and mechanical stability of the spontaneously formed SEI on the most energy-dense of these metal anodes. [7] These problems are compounded by ...