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Electrochemical approaches for generating hydrogen from water splitting can be more promising if the challenges in the anodic oxygen evolution reaction (OER) can be harnessed. The interface heterostructure materials offer strong electronic coupling and appropriate charge transport at the interface regions, promoting accessible active sites to prompt kinetics and optimize the adsorption–desorption of active species. Herein, we have designed an efficient multi-interface-engineered Ni3Fe1LDH/Ni3S2/TW heterostructure on in situ generated titanate web layers from the titanium foam. The synergistic effects of the multi-interface heterostructure caused the exposure of rich interfacial electronic coupling, fast reaction kinetics, and enhanced accessible site activity and site populations. The as-prepared electrocatalyst demonstrates outstanding OER activity, demanding a low overpotential of 220 mV at a high current density of 100 mA cm–2. Similarly, the designed Ni3Fe1LDH/Ni3S2/TW electrocatalyst exhibits a low Tafel slope of 43.2 mV dec–1and excellent stability for 100 h of operation, suggesting rapid kinetics and good structural stability. Also, the electrocatalyst shows a low overpotential of 260 mV at 100 mA cm–2for HER activity. Moreover, the integrated electrocatalyst exhibits an incredible OER activity in simulated seawater with an overpotential of 370 mV at 100 mA cm–2and stability for 100 h of operation, indicating good OER selectivity. This work might benefit further fabricating effective and stable self-sustained electrocatalysts for water splitting in large-scale applications.

Ga-doped Li7La3Zr2O12garnet solid electrolytes exhibit the highest Li-ion conductivities among the oxide-type garnet-structured solid electrolytes, but instabilities toward Li metal hamper their practical application. The instabilities have been assigned to direct chemical reactions between LiGaO2coexisting phases and Li metal by several groups previously. Yet, the understanding of the role of LiGaO2in the electrochemical cell and its electrochemical properties is still lacking. Here, we are investigating the electrochemical properties of LiGaO2through electrochemical tests in galvanostatic cells versus Li metal and complementary ex situstudies via confocal Raman microscopy, quantitative phase analysis based on powder X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron energy loss spectroscopy. The results demonstrate considerable and surprising electrochemical activity, with high reversibility. A three-stage reaction mechanism is derived, including reversible electrochemical reactions that lead to the formation of highly electronically conducting products. The results have considerable implications for the use of Ga-doped Li7La3Zr2O12electrolytes in all-solid-state Li-metal battery applications and raise the need for advanced materials engineering to realize Ga-doped Li7La3Zr2O12for practical use.

The use of the “Holy Grail” lithium metal anode is pivotal to achieve superior energy density. However, the practice of a lithium metal anode faces practical challenges due to the thermodynamic instability of lithium metal and dendrite growth. Herein, an artificial stabilization of lithium metal was carried out via the thermal pyrolysis of the NH4F salt, which generates HF(g) and NH3(g). An exposure of lithium metal to the generated gas induces a spontaneous reaction that forms multiple solid electrolyte interface (SEI) components, such as LiF, Li3N, Li2NH, LiNH2, and LiH, from a single salt. The artificially multilayered protection on lithium metal (AF-Li) sustains stable lithium stripping/plating. It suppresses the Li dendrite under the Li||Li symmetric cell. The half-cell Li||Cu and Li||MCMB systems depicted the attributions of the protective layer. We demonstrate that the desirable protective layer in AF-Li exhibited remarkable capacity retention (CR) results. LiFePO4(LFP) showed a CR of 90.6% at 0.5 mA cm–2after 280 cycles, and LiNi0.5Mn0.3Co0.2O2(NCM523) showed 58.7% at 3 mA cm–2after 410 cycles. Formulating the multilayered protection, with the simultaneous formation of multiple SEI components in a facile and cost-effective approach from NH4F as a single salt, made the system competent.

Currently, hydrogen peroxide (H2O2) manufacturing involves an energy-intensive anthraquinone technique that demands expensive solvent extraction and a multistep process with substantial energy consumption. In this work, we synthesized Pd–N4-CO, Pd–S4–NCO, and Pd–N2O2–C single-atom catalysts via an in situ synthesis approach involving heteroatom-rich ligands and activated carbon under mild reaction conditions. It reveals that palladium atoms interact strongly with heteroatom-rich ligands, which provide well-defined and uniform active sites for oxygen (O2) electrochemically reduced to hydrogen peroxide. Interestingly, the Pd–N4–CO electrocatalyst shows excellent performance for the electrocatalytic reduction of O2to H2O2via a two-electron transfer process in a base electrolyte, exhibiting a negligible amount of onset overpotential and >95% selectivity within a wide range of applied potentials. The electrocatalysts based on the activity and selectivity toward 2e–ORR follow the order Pd–N4–CO > Pd–N2O2–C > Pd–S4–NCO in agreement with the pull–push mechanism, which is the Pd center strongly coordinated with high electronegativity donor atoms (N and O atoms) and weakly coordinated with the intermediate *OOH to excellent selectivity and sustainable production of H2O2. According to density functional theory, Pd–N4is the active site for selectivity toward H2O2generation. This work provides an emerging technique for designing high-performance H2O2electrosynthesis catalysts and the rational integration of several active sites for green and sustainable chemical synthesis via electrochemical processes.

The sulfide-based solid-state electrolyte has garnered attention as a potential material for next-generation all-solid-state batteries. However, during cycling, interfacial reactions between the sulfide solid-state electrolytes and the cathode can occur, which is a serious issue that needs to be addressed. Therefore, resolving interfacial reactions has become a crucial issue in the development of solid-state batteries. A sulfide-based all-solid-state battery paired with LiFePO4has shown poor first-cycle discharge capacity and efficiency, which have been attributed to LiFePO4/Li6PS5Cl interfacial reactions. Thus, in this study, the microscopic LiFePO4/Li6PS5Cl interface reactions were visualized using nano-beam X-ray fluorescence (nano-XRF) mapping and nano-beam X-ray absorption spectroscopy (nano-XAS). The mapping evolution of the Fe valence state of LFP in a different state of charge was observed. The nano-XRF and nano-XAS tools at the nanoscale allowed for the decoupling of the interfacial reactions on the cathode/sulfide, which can shed light on new directions for an in-depth understanding of the interfacial phenomena of solid-state batteries. This study paves the way for the development of all-solid-state batteries with improved performance and stability.

Dendrite growth and low Coulombic efficiency impede the practical application of Li-metal batteries. As such, monitoring Li deposition and stripping in real-time is crucial to understanding the fundamental lithium growth kinetics. This work presents an operandooptical microscopic technique that enables precise current density control and quantification of Li layer properties (i.e., thickness and porosity) to study Li growth in various electrolytes. We discover the robustness and porosity of the remaining capping layer after the Li stripping process as the critical features governing the subsequent dendrite propagation behavior, resulting in distinct capping and stacking phenomena that affect Li growth upon cycling. While dendrite propagation quickly occurs through the fracture of the fragile Li capping layer, uniform Li plating/stripping can be facilitated by the compact and robust capping layer even at high current densities. This technique can be extended to evaluate dendrite suppression treatments in various metal batteries, providing in-depth information on metal growth mechanisms.

Developing new types of high-capacity and high-energy density rechargeable batteries is important to future generations of consumer electronics, electric vehicles, and mass energy storage applications. Recently, we reported ∼3.5 V sodium/chlorine (Na/Cl2) and lithium/chlorine (Li/Cl2) batteries with up to 1200 mAh g–1reversible capacity, using either a Na or a Li metal as the negative electrode, an amorphous carbon nanosphere (aCNS) as the positive electrode, and aluminum chloride (AlCl3) dissolved in thionyl chloride (SOCl2) with fluoride-based additives as the electrolyte [Zhu et al., Nature, 2021, 596(7873), 525–530]. The high surface area and large pore volume of aCNS in the positive electrode facilitated NaCl or LiCl deposition and trapping of Cl2for reversible NaCl/Cl2or LiCl/Cl2redox reactions and battery discharge/charge cycling. Here, we report an initially low surface area/porosity graphite (DGr) material as the positive electrode in a Li/Cl2battery, attaining high battery performance after activation in carbon dioxide (CO2) at 1000 °C (DGr_ac) with the first discharge capacity ∼1910 mAh g–1and a cycling capacity up to 1200 mAh g–1. Ex situ Raman spectroscopy and X-ray diffraction (XRD) revealed the evolution of graphite over battery cycling, including intercalation/deintercalation and exfoliation that generated sufficient pores for hosting LiCl/Cl2redox. This work opens up widely available, low-cost graphitic materials for high-capacity alkali metal/Cl2batteries. Lastly, we employed mass spectrometry to probe the Cl2trapped in the graphitic positive electrode, shedding light into the Li/Cl2battery operation.

In recent years, layered ternary transition metal oxides with a high nickel content have gained substantial attention as a potential positive electrode material for lithium-ion batteries. However, its poor rate capability, cyclability, and capacity retention at high working voltages limit its use in commercial lithium-ion batteries. To overcome these challenges, we synthesize a cost-effective wet-chemical deposition of novel TiSiO4nano-coatings over the surface of LiNi0.83Mn0.06Co0.11O2(NMC-83). X-ray diffraction and electron microscopy confirm the presence of a coating and verify that the deposition process did not alter the crystallinity and morphology of the NMC-83 particles. In addition, during cycling, it completely protects NMC-83 with enhancements in hexagonal phase transitions between H2 and H3, resulting in excellent cycling stability at upper cut-off voltages. Likewise, when the amount of coated material is equal to 1 wt%, it provides faster ion kinetics and a stable electrode-electrolyte interface. The 1 wt% TiSiO4coating provides 35 % retention after 250 cycles at a 0.5C rate, while the pristine NMC-83 shows only 13.7 %. From postmortem analysis, the 1 wt% TiSiO4-coated NMC-83 cathode maintains its stable polycrystalline nature compared with pristine NMC-83. Thus, this novel TiSiO4nanocoating has significant implications for developing high-performance rechargeable batteries for energy applications.

We successfully prepared nitrogen-doped defective carbon spheres (Mo-N4/d-C) with a high loading of 0.996 wt % via a designed vapor-deposition process for IOR-based hydrogen generation. The synthesized Mo-N4/d-C catalyst provides a record current density of 10 mA cm–2at 0.77 V. Further, the Mo-N4/d-C catalyst shows a Tafel slope of 25.58 mV dec–1, exceptional stability over time in acidic media, a higher hydrogen generation rate of 0.1063 mL gcat–1min–1, a high Faradaic efficiency of 99.8%, and a reduction of the energy consumption up to ∼50% for hydrogen evolution by anodic oxidation reaction of iodide (IOR) compared with the conventional OER-based electrolysis. Computational calculations demonstrate that the Mo-N4/d-C structure plays a vital effect on the activity of iodide oxidation, which is competitive with the Pt catalyst.

A zinc metal anode for zinc-ion batteries is a promising alternative to solve safety and cost issues in lithium-ion batteries. The Zn metal is characterized by its high theoretical capacity (820 mAh g–1), low redox potential (0.762 V vsSHE), low toxicity, high abundance on Earth, and high stability in water. Taking advantage of the stability of Zn in water, an aqueous Zn ion battery with low cost, high safety, and easy-to-handle features can be developed. To minimize water-related parasitic reactions, this work utilizes a highly concentrated salt electrolyte (HCE) with dual salts─1 m Zn(OTf)2+ 20 m LiTFSI. MD simulations prove that Zn2+is preferentially coordinated with O in the TFSI–anion from HCE instead of O in H2O. HCE has a broadened electrochemical stability window due to suppressed H2and O2evolution. Some advanced ex situand in situ/in operandoanalysis techniques have been applied to evaluate the morphological structure and the composition of the in situformed passivation layer. A dual-ion full Zn||LiMn2O4cell employing HCE has an excellent capacity retention of 92% after 300 cycles with an average Coulombic efficiency of 99.62%. Meanwhile, the low concentration electrolyte (LCE) cell degrades rapidly and is short-circuited after 66 cycles with an average Coulombic efficiency of 96.91%. The battery’s excellent cycling performance with HCE is attributed to the formation of a stable anion-derived solid-electrolyte interphase (SEI) layer. On the contrary, the high free water activity in LCE leads to a water-derived interfacial layer with unavoidable dendrite growth during cycling.

Anode-free lithium metal batteries (AFLMBs) have been extensively studied due to their intrinsic high energy and safety without a metallic Li anode in cell design. Yet, the dendrite and dead-Li buildup continuously consumes the active Li upon cycling, leading to the poor lifespan of AFLMBs. Here, we introduce lithium oxalate into the cathode as an electrode additive providing a Li reservoir to extend the lifespan of AFLMBs. The AFLMB using 20% lithium oxalate and a LiNi0.3Co0.3Mn0.3O2composite cathode exhibits >80 and 40% capacity retention after 50 and 100 cycles, respectively, outperforming the poor cycle life of fewer than 20 cycles obtained from the cell using a pure LiNi0.3Co0.3Mn0.3O2cathode. Surprisingly, the average Coulombic efficiency of AFLMBs is found to improve as the amount of lithium oxalate increases in the composite cathode. This abnormal phenomenon could be attributed to the as-formed carbon dioxide after the first activation cycle forming a Li2CO3-rich solid–electrolyte interphase and improving the Li deposition and stripping efficiency. The findings in this work provide a new strategy to delay the capacity roll-over of AFLMBs from an electrode engineering perspective, which can be coupled with other approaches such as functional electrolytes synergistically to further improve the cycle life of AFLMBs for practical application.

Lithium (Li) metal is the ultimate negative electrode due to its high theoretical specific capacity and low negative electrochemical potential. However, the handling of lithium metal imposes safety concerns in transportation and production due to its reactive nature. Recently, anode-free lithium metal batteries (AFLMBs) have drawn much attention because of several of their advantages, including higher energy density, lower cost, and fewer safety concerns during cell production compared to LMBs. Pushing the reversible Coulombic efficiency (CE) of AFLMBs up to 99.98% is key to achieving their 80% capacity retention over more than 1000 cycles. However, interfacial irreversible phenomena such as electrolyte decomposition reactions on both electrodes, dead Li formation, and Li dendrite formation result in poor capacity retention and short circuits in LMBs and AFLMBs. Therefore, it is of great importance and scientific interest to explore those interfacial irreversible phenomena to improve the cell’s cycle life. Although significant contributions toward mitigating electrolyte decomposition, dead lithium, and dendritic lithium formation have been reported at the lithium anode, real irreversible phenomena are usually hidden or difficult to discover due to excess lithium employed in LMBs and simultaneous events taking place in both electrodes or at the interfaces.

The active phase and catalytic mechanisms of Ni-based layered double hydroxide (LDH) materials for oxygen evolution reaction (OER) have no common consensus and remain controversial. Moreover, engineering the site activity and the number of active sites of LDHs is an efficient approach to advance the OER activity, as the thickness and stacking structure of the LDHs layer limit the catalytic activity. This work presents an interesting in situapproach of tuning the site activity and number of active sites of NiMn-LDHs, which exhibit the superior OER performance (onset overpotential of 0.17 V and overpotential of 0.24 V at 10 mA cm–2). The fundamental mechanistic insights and active phases during the OER process are characterized by in operandotechniques along with the computational density functional theory calculations, revealing that the Ni site constitutes the OER activity and the dynamically generated NiOOH moiety is the active phase. We also prove that Ni sites undergo a reversible oxidation state under the working conditions to create active NiOOH species which catalyze the water to generate oxygen. These findings suggest that the Ni(III) phase in NiMn-LDHs is the OER active site and Mn promotes the electronic properties of Ni sites. Utilizing in situ/in operandotechniques and theoretical calculation, we find that the in situintercalation of guest anions allows the expansion of the LDH layers and keeps the active NiOOH species under the oxidation state of +3 viaelectron coupling, which ultimately tunes the site populations and site activity toward the superior OER activity, respectively. This work thus targets to provide insight into strategies to design the next generation of highly active catalysts for water electrolysis and fuel cell technologies.

Lithium-ion batteries (LIBs) are widely used in applications ranging from electric vehicles to wearable devices. Before the invention of secondary LIBs, the primary lithium-thionyl chloride (Li-SOCl2) battery was developed in the 1970s using SOCl2as the catholyte, lithium metal as the anode and amorphous carbon as the cathode1–7. This battery discharges by lithium oxidation and catholyte reduction to sulfur, sulfur dioxide and lithium chloride, is well known for its high energy density and is widely used in real-world applications; however, it has not been made rechargeable since its invention8–13. Here we show that with a highly microporous carbon positive electrode, a starting electrolyte composed of aluminium chloride in SOCl2with fluoride-based additives, and either sodium or lithium as the negative electrode, we can produce a rechargeable Na/Cl2or Li/Cl2battery operating via redox between mainly Cl2/Cl−in the micropores of carbon and Na/Na+or Li/Li+redox on the sodium or lithium metal. The reversible Cl2/NaCl or Cl2/LiCl redox in the microporous carbon affords rechargeability at the positive electrode side and the thin alkali-fluoride-doped alkali-chloride solid electrolyte interface stabilizes the negative electrode, both are critical to secondary alkali-metal/Cl2batteries.

In this study, we investigated the synergetic effect of a novel lithium-ion conducting hybrid oligomer [N, N′-bismaleimide-4, 4′-diphenylmethane (BMI), lithiated trithiocyanuric acid (Li-TCA) and Jeffamine®-M1000 (JA®); Li-BTJ] coating layer on a nickel-rich LiNi0.8Co0.1Mn0.1O2(NCM811) cathode material wrapped with highly electron-conductive single-walled carbon nanotubes (SWCNTs) to enhance electrochemical performance and thermal stability for high-power and high-safety lithium-ion batteries (LIBs). Morphological analyses using scanning electron microscopy/energy dispersive spectroscopy and transmission electron microscopy showed that the NCM811 active material surface was uniformly coated with a hybrid oligomer to form NCM811@Li-BTJ, which was subsequently wrapped with SWCNTs (NCM@Li-BTJ/SWCNT composite cathode). CR2032 coin-type cells with optimized NCM811@1 wt% Li-BTJ/0.2 wt% SWCNT composite electrodes delivered a significantly enhanced capacity retention (CR) of 90.1 % relative to that of bare NCM811 electrodes (CR: 82.1 %) at 1C for 200 cycles from 2.8 to 4.3 V (vs. Li/Li+). Electrochemical impedance spectroscopy and cyclic voltammetry revealed that this superior cycling performance resulted from a lower charge transfer resistance (Rct: 96.2 vs. 324.3 Ω) and a lower polarization voltage (∆V: 0.243 vs. 0.411 V vs. Li/Li+). The in-situ micro-calorimetric results presented the total heat generation (Qt) values of the coin cells with the delithiated NCM811@Li-BTJ and NCM@Li-BTJ/SWCNT electrodes at 5C and 35 °C were substantially lower by ~9.3 % and ~ 14.6 %, respectively, compared to the bare NCM811 counterpart, indicating that the surface modifications on the NCM811 active materials could prevent the LIBs' thermal instability. Furthermore, X-ray photoelectron spectroscopy studies revealed that the Li-BTJ hybrid oligomer coating layer effectively suppressed the formation of residual Li side products such as Li2CO3evidently on the surface of the NCM811 active material particles, thereby inhibiting undesirable side reactions. Post-mortem analyses of the dual-modified NCM811 electrode after cycling revealed that the microstructure and particle morphology of the NCM composite cathode material were extensively maintained through the synergistic effects of the Li-BTJ ion-conductive and SWCNTs electron-conductive agents.

In this study, we developed the benefit of TEMPO additive for the suppression of the solvent/additive decomposition by trapping the radicals formed. With unusual stability as a neutral radical the 2 % TEMPO as an additive into STD + 5% FEC electrolyte resulted in the modification of the interphase. Through in-situ DRIFTS results we can find out and investigate the mechanism for the decomposition of TEMPO. The studies described herein also demonstrate that MCMB-electrodes in STD + 5% FEC solution containing TEMPO additive can be utilized together with high voltage cathode.

Li7La3Zr2O12(LLZO) garnet is one kind of solid electrolyte drawing extensive attention due to its good ionic conductivity, safety, and stability toward lithium metal anodes. However, the stability problem during synthesis and storage results in high interfacial resistance and prevents it from practical applications. We synthesized air-stable dual-doped Li6.05La3Ga0.3Zr1.95Nb0.05O12((Ga, Nb)-LLZO) cubic-phase garnets with ionic conductivity of 9.28 × 10–3S cm–1. The impurity-phase species formation on the garnet pellets after air exposure was investigated. LiOH and Li2CO3can be observed on the garnet pellets by Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) once the garnets are exposed to humid air or come in contact with water. The (Ga, Nb)-LLZO garnet is found to form less LiOH and Li2CO3, which can be further reduced or removed after drying treatment. To confirm the stability of the garnet, an electrochemical test of the Li//Li symmetric cell was also performed in comparison with previously reported garnets (Li7La2.75Ca0.25Zr1.75Nb0.25O12, (Ca, Nb)-LLZO). The dual-doped (Ga, Nb)-LLZO showed less polarized and stable plating/stripping behavior than (Ca, Nb)-LLZO. Through Rietveld refinement of XRD patterns of prepared materials, dopant Ga was found to preferably occupy the Li site and Nb takes the Zr site, while dopant Ca mainly substituted La in the reference sample. The inherited properties of the dopants in (Ga, Nb)-LLZO and their structural synergy explain the greatly improved air stability and reduced interfacial resistance. This may open a new direction to realize garnet-based solid electrolytes with lower interfacial resistance and superior air stability.

Herein, we report hierarchical 3D NiMn-layered double hydroxide (NiMn-LDHs) shells grown on conductive silver nanowire (Ag NWs) cores as efficient, low-cost, and durable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional electrocatalysts for metal–air batteries. The hierarchical 3D architectured Ag NW@NiMn-LDH catalysts exhibit superb OER/ORR activities in alkaline conditions. The outstanding bifunctional activities of Ag NW@NiMn-LDHs are essentially attributed to increasing both site activity and site populations. The synergistic contributions from the hierarchical 3D open-pore structure of the LDH shells, improved electrical conductivity, and small thickness of the LDHs shells are associated with more accessible site populations. Moreover, the charge transfer between Ag cores and metals of LDH shells and the formation of defective and distorted sites (less coordinated Ni and Mn sites) strongly enhance the site activity. Thus, Ag NW@NiMn-LDH hybrids exhibit a 0.75 V overvoltage difference between ORR and OER with excellent durability for 30 h, demonstrating the distinguished bifunctional electrocatalyst reported to date. Interestingly, the homemade rechargeable Zn–air battery using the hybrid Ag NW@NiMn-LDHs (1:2) catalyst as the air electrode exhibits a charge–discharge voltage gap of ∼0.77 V at 10 mA cm–2and shows excellent cycling stability. Thus, the concept of the hierarchical 3D architecture of Ag NW@NiMn-LDHs considerably advances the practice of LDHs toward metal–air batteries and oxygen electrocatalysts.

Tuning the type and degree of heterometallic bonding in bimetallic catalysts is crucial to achieving optimal catalytic performance. In this study density functional theory (DFT) and X-ray absorption spectroscopy (XAS) were used to investigate the use of Ru-based bimetallic electrocatalysts for hydrogen oxidation/evolution reactions (HOR/HER) under alkaline conditions. The catalyst's hydrogen absorption and OH adsorption energies can both be tuned by altering the heterometallic bonding in bimetallic systems. DFT calculations were used in conjunction with a RuNi bimetallic system to optimize the hydrogen adsorption energy and weaken the OH adsorption energy. The degree of heterometallic bonding (i.e.the alloying extent) in the Ru2.3Ni1/C catalyst was experimentally confirmed by XAS analysis. Our findings indicate that tuning the hydrogen and OH adsorption energies on the RuNi bimetallic catalyst's surface leads to superior activity and stability in the alkaline HOR/HER compared to as-prepared Ru/C, commercial Pt/C and the reported catalysts. We showed that the oxophilic effect can be manipulated by altering heterometallic bonding and that both the hydrogen and OH adsorption energies are important determinants of the efficiency of low-cost HER/HOR catalysts in alkaline media.

To address the issue that a single coating agent cannot simultaneously enhance Li+-ion transport and electronic conductivity of Ni-rich cathode materials with surface modification, in the present study, we first successfully synthesized a LiNi0.8Co0.1Mn0.1O2(NCM811) cathode material by a Taylor-flow reactor followed by surface coating with Li-BTJ and dispersion of vapor-grown carbon fibers treated with polydopamine (PDA-VGCF) filler in the composite slurry. The Li-BTJ hybrid oligomer coating can suppress side reactions and enhance ionic conductivity, and the PDA-VGCFs filler can increase electronic conductivity. As a result of the synergistic effect of the dual conducting agents, the cells based on the modified NCM811 electrodes deliver superior cycling stability and rate capability, as compared to the bare NCM811 electrode. The CR2032 coin-type cells with the NCM811@Li-BTJ + PDA-VGCF electrode retain a discharge specific capacity of ∼92.2% at 1C after 200 cycles between 2.8 and 4.3 V (vs Li/Li+), while bare NCM811 retains only 84.0%. Moreover, the NCM811@Li-BTJ + PDA-VGCF electrode-based cells reduced the total heat (Qt) by ca. 7.0% at 35 °C over the bare electrode. Remarkably, the Li-BTJ hybrid oligomer coating on the surface of the NCM811 active particles acts as an artificial cathode electrolyte interphase (ACEI) layer, mitigating irreversible surface phase transformation of the layered NCM811 cathode and facilitating Li+ion transport. Meanwhile, the fiber-shaped PDA-VGCF filler significantly reduced microcrack propagation during cycling and promoted the electronic conductance of the NCM811-based electrode. Generally, enlightened with the current experimental findings, the concerted ion and electron conductive agents significantly enhanced the Ni-rich cathode-based cell performance, which is a promising strategy to apply to other Ni-rich cathode materials for lithium-ion batteries.

Due to its good mechanical properties and high ionic conductivity, the sulfide-type solid electrolyte (SE) can potentially realize all-solid-state batteries (ASSBs). Nevertheless, challenges, including limited electrochemical stability, insufficient solid–solid contact with the electrode, and reactivity with lithium, must be addressed. These challenges contribute to dendrite growth and electrolyte reduction. Herein, a straightforward and solvent-free method was devised to generate a robust artificial interphase between lithium metal and a SE. It is achieved through the incorporation of a composite electrolyte composed of Li6PS5Cl (LPSC), polyethylene glycol (PEG), and lithium bis(fluorosulfonyl)imide (LiFSI), resulting in the in situ creation of a LiF-rich interfacial layer. This interphase effectively mitigates electrolyte reduction and promotes lithium-ion diffusion. Interestingly, including PEG as an additive increases mechanical strength by enhancing adhesion between sulfide particles and improves the physical contact between the LPSC SE and the lithium anode by enhancing the ductility of the LPSC SE. Moreover, it acts as a protective barrier, preventing direct contact between the SE and the Li anode, thereby inhibiting electrolyte decomposition and reducing the electronic conductivity of the composite SE, thus mitigating the dendrite growth. The Li|Li symmetric cells demonstrated remarkable cycling stability, maintaining consistent performance for over 3000 h at a current density of 0.1 mA cm–2, and the critical current density of the composite solid electrolyte (CSE) reaches 4.75 mA cm–2. Moreover, the all-solid-state lithium metal battery (ASSLMB) cell with the CSEs exhibits remarkable cycling stability and rate performance. This study highlights the synergistic combination of the in-situ-generated artificial SE interphase layer and CSEs, enabling high-performance ASSLMBs.

In this study, one-dimensional Cu2–xSe nanorods synthesized by a simple water evaporation-induced self-assembly approach are served as the anode material for Na-ion batteries for the first time. Cu2–xSe electrodes express outstanding electrochemical properties. The initial discharge capacity is 149.3 mA h g–1at a current density of 100 mA g–1, and the discharge capacity can remain at 106.2 mA h g–1after 400 cycles. Even at a high current density of 2000 mA g–1, the discharge capacity of the Cu2–xSe electrode still remains at 62.8 mA h g–1, showing excellent rate performance. Owing to the excellent electronic conductivity and one-dimensional structure of Cu2–xSe, the Cu2–xSe electrodes manifest fast Na+ion diffusion rate. Moreover, detailed Na+insertion/extraction mechanism is further investigated by ex situ measurements and theoretical calculations.

Ether electrolytes are chemically stable against Li-metal. However, the enormous capacity discrepancies between coin cell and pouch cell systems with imide salt-based ether electrolytes are unclear yet. Herein, the fundamental phenomena that cause capacity disparity between anode-free NMC532||Cu coin cell and pouch cell systems configured with imide salt-based ether electrolytes are systematically investigated by probing the cross-talk effects of transition metals at the anode side. Meanwhile, the corrosion mechanism of stainless steel (SS) coin cells is clarified in detail. The higher accumulation of Ni (6.2), Cr (8.5), and Fe (34.9 ppm) metals on the anode surface after 15 cycles of the NMC532||Cu coin cell indicates that cross-take of metals is the main source of irreversible coulombic efficiency (>10.4%). NMC532||Cu pouch cells, on the other hand, provided greater average CE (99.1%) after the 120thcycle and only ∼0.3 ppm Ni was detected, originated from the cathode. The results proved that at high cell voltages, imide salt-based ether electrolytes seriously corrode SS coin cells, resulting in crossover of metals to the anode surface. This work clarifies the corrosion mechanism of SS coin cells and explores anode-free pouch cells for the actual designing of ether electrolytes.

We reveal a concept of adding K and Na to dual-cation systems and investigate their effects on dendrite growth morphology and electrolyte decomposition reactivity in lithium metal batteries (LMBs). We analyze the effects of Li/K- and Li/Na-alloyed surfaces on Li ion diffusion along the deposition direction, as well as the reactivity of the electrolytes and the composition of the solid electrolyte interface (SEI) resulting from electrolyte decomposition. Compared with the Li/K system, the Li/Na-alloyed surface can significantly reduce Li diffusion along the z-direction and effectively prevent the formation of dendrite-like morphologies. Furthermore, the Li/Na-alloyed surface substantially mitigates the reactivity of the bis(fluorosulfonyl)imide (FSI−) anion and fluorinated ether (TTE) solvent, thus inhibiting the generation of excessive SEI species. Additionally, the regulated and simplified components of a hybrid LiF/NaF SEI layer in the Li/Na system are observed. This hybrid layer is expected to promote the uniform deposition of Li and exhibit excellent electrical insulating properties, thereby effectively preventing electron transfer to the electrolytes and enhancing the Coulombic efficiency of LMBs. This study presents new insights into the dendrite-suppressing potential of alkali-metal alloys for improving the stability and safety of LMBs.

The combined effect of concentrated electrolyte and cycling protocol on the cyclic performance of the anode-free battery (AFB) is evaluated systematically. In situ deposition of Li in the AFB configuration in the presence of a concentrated electrolyte containing fluorine-donating salt and resting the deposit enables the formation of stable and uniform SEI. The SEI intercepts the undesirable side reaction between the deposit and solvent in the electrolyte and reduces electrolyte and Li consumption during cycling. The synergy between the laboratory-prepared concentrated 3 M LiFSI in the ester-based electrolyte and our resting protocol significantly enhanced cyclic performances of AFBs in comparison to the commercial carbonate-based dilute electrolyte, 1 M LiPF6. Benefitting from the combined effect, Cu∥LiFePO4cells delivered excellent cyclic performance at 0.5 mA/cm2with an average CE of up to 98.78%, retaining a reasonable discharge capacity after 100 cycles. Furthermore, the AFB can also be cycled at a high rate up to 1.0 mA/cm2with a high average CE and retaining the encouraging discharge capacity after 100 cycles. The fast cycling and stable performance of these cells are attributed to the formation of robust, flexible, and tough F-rich conductive SEI on the surface of the in situ-deposited Li by benefiting from the combined effect of the resting protocol and the concentrated electrolyte. A condescending understanding of the mechanism of SEI formation and material choice could facilitate the development of AFBs as future advanced energy storage devices.

Pt-based electrocatalysts are usually used in several catalytic reactions. However, its high cost, scarcity, and susceptibility towards poisonous intermediate species highly limit these catalysts' large-scale applications. Downsizing catalysts to single-atom scale (SAC) have fascinated extensive research interests due to their higher activity, selectivity, and stability. Herein, we prepared highly active, selective, and poisoning-tolerant PtSACs on Ni-doped TiO2support (PtSAC-Ni0.1Ti0.9O2). Ni in the catalyst creates a suitable environment to adsorb more OH−and make Pt accessible and ready for further oxidations. Thus, it exhibits higher electrocatalytic performance towards EGO than PtSAC-TiO2does. It is also by far better than PtNP– Ni0.1Ti0.9O2. The higher catalytic performance by PtSAC-Ni0.1Ti0.9O2is due to the synergistic effects of Ni and Pt. The catalyst selectively produces glycolate, formate, and hydrogen. Glycolate and formate are high-value chemicals for domestic uses or as inputs for industries to produce other chemicals. The catalyst also shows excellent Faradaic efficiency (>98 %) and stability towards EGO in alkaline media. The strong metal-support interactions between the catalyst and the support retard the agglomeration of the single atoms, thereby increasing their stability.

Understanding the mechanism of Li nucleation and growth is essential for providing long cycle life and safe lithium ion batteries or lithium metal batteries. However, no quantitative report on Li metal deposition is available, to the best of our knowledge. We propose a model for quantitatively understanding the Li nucleation and growth mechanism associated with the solid–electrolyte interphase (SEI) formation, which we name the Li-SEI model. The current transients at various overpotentials initiate the nucleation and growth of Li metal on bare Cu foil. The Li-SEI model considering a three-dimensional diffusion-controlled instantaneous process (J3D-DC) with the simultaneous reduction of electrolyte decomposition (JSEI) due to the SEI fracture is employed for investigating the Li nucleation and growth mechanism. The individual contributions of experimental and theoretical transient states, i.e., the fundamental kinetic values of diffusion coefficient (D), rate of nucleation (N0), and rate constant of electrolyte decomposition (kSEI), can be determined from the Li-SEI model. Interestingly, JSEIincreases with time, indicating that the current contributing from the electrolyte decomposition increases with time due to the SEI fracture upon Li deposition. Meanwhile, the kSEIincreases with overpotential, indicating the SEI fracture is more serious at higher overpotential or higher growth rate. The kSEIis smaller in the electrolyte with fluoroethylene carbonate (FEC) additive, indicating that FEC additive can significantly suppress the SEI fracture during Li metal deposition. This proposed model opens a new way to quantitatively understand the Li nucleation and growth mechanism and electrolyte decomposition on various substrates or in different electrolytes.

In the present study, stable sodium plating/stripping has been achieved on a bare aluminum current collector, without any surface modifications or artificial SEI deposition. The crucial role of predeposited sodium using cyclic voltammetry on bare aluminum as a matrix for plating/stripping has been highlighted using different protocols for cycling. The predeposition strategy ensures stable and efficient cycling of sodium in anode-free sodium batteries without dendritic formations. The study highlights the difference of sodium plating/stripping in carbonate and glyme solvent electrolytes on the bare aluminum current collector. Contrary to the carbonate solvent electrolyte, the cell with the tetraglyme solvent electrolyte and sodium loading of 1 mA h/cm2has an overpotential under 20 mV during the sodium plating/stripping cycles at 0.5 mA/cm2for a testing period of 650 h. Overpotentials under 40 and 100 mV have been achieved at current densities up to 1 and 2 mA/cm2for loadings up to 5 and 10 mA h/cm2, respectively, for a testing time up to 1500 h. Density functional theory simulations have been performed to obtain the solvation energies, and the highest occupied molecular orbital–lowest unoccupied molecular orbital band gap of the solvent–sodium ion complexes for the glyme solvent electrolytes and their trends have been correlated with the experimental observations.

Electrochemical energy storage and conversion devices play a key role in the development of clean, sustainable, and efficient energy systems to meet the sustainable growth of our society. However, challenging issues including the sluggish kinetics of oxygen electrode reactions involving the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are present, limiting the implementation of devices such as metal‐air batteries, water electrolyzers, and regenerative fuel cells. In this review, various monometallic and bimetallic transition metal oxides (TMOs) and hydroxides are summarized in terms of their application for ORR/OER, in which the merits and demerits of various precious metal and carbon‐based metal oxide materials are discussed, with requirements for better electrocatalysts and catalyst support being introduced as well. Following this, different approaches to improve catalytic activity such as the introduction of doping and defects, the manipulation of crystal facets, and the engineering of supports, compositions, and morphologies are summarized in which TMOs with improved ORR/OER catalytic activities can be synthesized, further improving the speed, stability, and polarization of electrochemical energy storage and conversion devices. Finally, perspectives into the improvement of performance and the better understanding of ORR/OER mechanisms for bifunctional electrocatalysts using in situ spectroscopic techniques and density functional theory calculations are also discussed. It is important to design and enhance activity and stability of bifunctional electrocatalyst. In order to improve both activity and stability, doping engineering, morphology and compositional engineering, defect engineering, support engineering, and crystal facet engineering are most important factors.

Defect sites are often proposed as key active sites in the design of catalysts. A promising strategy for improving activity is to achieve a high density of homogeneously dispersed atomic defects; however, this is seldom accomplished in metals. We hypothesize that vacancy-rich catalysts could be obtained through the synthesis of quantum dots (QDs) and their electrochemical reduction during the CO2reduction reaction (CO2RR). Here, we report that QD-derived catalysts (QDDCs) with up to 20 vol % vacancies achieve record current densities of 16, 19, and 25 mAcm−2with high faradic efficiencies in the electrosynthesis of formate, carbon monoxide, and ethylene at low potentials of –0.2, –0.3, and –0.9 V versus reversible hydrogen electrode (RHE), respectively. The materials are stable after 80 hr of CO2RR. These CO2RR performances in aqueous solution surpass those of previously reported catalysts by 2×. Together, X-ray absorption spectroscopy and computational studies reveal that the vacancies produce a local atomic and electronic structure that enhances CO2RR.

Designing a MoS2catalyst having a large number of active sites and high site activity enables the catalytic activity toward the hydrogen evolution reaction to be improved. Herein, we report the synthesis of a low-cost and catalytically active immobilized single molecular molybdenum disulfide on carbonized polyacrylonitrile (MoS2-cPAN) electrocatalyst. From the extended X-ray absorption fine structure spectra analysis, we found that the as-prepared material has no metal–metal scattering and it resembles MoS2with a molecular state. Meanwhile, the size of the molecular MoS2has been estimated to be about 1.31 nm by high-angle annular dark-field scanning transmission electron microscopy. A low coordination number and maximum utilization of the single molecular MoS2surface enable MoS2-cPAN to demonstrate electrochemical performance significantly better than that of bulk MoS2by two orders of exchange current density (jo) and turnover frequency to the hydrogen evolution.

A twin reactor was constructed for the separate evolution of hydrogen and oxygen during photocatalytic water splitting using a redox mediator free Z-scheme approach. In this work, the overall water splitting process was carried out in a single reactor with a Nafion membrane dividing into twin chambers where CuFeO2and Bi20TiO32are as hydrogen and oxygen photocatalyst powders respectively. Reduced graphene oxides were used as a collector extender for electron conduction during in a Z-scheme photocatalytic water splitting system. Branched copper wires were employed to enhance electron collection from the reduced graphene oxides in the twin reactor system used for water splitting under light illumination. The evolution rate of hydrogen and oxygen was 2.23 and 1.14 μmol/h, respectively in the twin reactor, which is close to the stoichiometric ratio of 2:1. As compared to a single reactor, photocatalytic water splitting with separate evolution of H2and O2using a twin reactor device is vital since it avoids the explosion potential and hydrogen-purification cost. This redox mediator-free device has the potential for a wider range of applications and reduced the resistance losses resulting from the wiring and the cost related to a mediator. Consequently, this twin reactor with a redox mediator-free approach provides a new opportunity for further improving the efficiency of solar energy conversion reactions.

Currently, concentrated electrolyte solutions are attracting special attention because of their unique characteristics such as unusually improved oxidative stability on both the cathode and anode sides, the absence of free solvent, the presence of more anion content, and the improved availability of Li+ions. Most of the concentrated electrolytes reported are lithium bis(fluorosulfonyl)imide (LiFSI) salt with ether-based solvents because of the high solubility of salts in ether-based solvents. However, their poor anti-oxidation capability hindered their application especially with high potential cathode materials (>4.0 V). In addition, the salt is very costly, so it is not feasible from the cost analysis point of view. Therefore, here we report a locally concentrated electrolyte, 2 M LiPF6, in ethylene carbonate/diethyl carbonate (1:1 v/v ratio) diluted with fluoroethylene carbonate (FEC), which is stable within a wide potential range (2.5–4.5 V). It shows significant improvement in cycling stability of lithium with an average Coulombic efficiency (ACE) of ∼98% and small voltage hysteresis (∼30 mV) with a current density of 0.2 mA/cm2for over 1066 h in Li||Cu cells. Furthermore, we ascertained the compatibility of the electrolyte for anode-free Li–metal batteries (AFLMBs) using Cu||LiNi1/3Mn1/3Co1/3O2(NMC, ∼2 mA h/cm2) with a current density of 0.2 mA/cm2. It shows stable cyclic performance with ACE of 97.8 and 40% retention capacity at the 50th cycle, which is the best result reported for carbonate-based solvents with AFLMBs. However, the commercial carbonate-based electrolyte has <90% ACE and even cannot proceed more than 15 cycles with retention capacity >40%. The enhanced cycle life and well retained in capacity of the locally concentrated electrolyte is mainly because of the synergetic effect of FEC as the diluent to increase the ionic conductivity and form stable anion-derived solid electrolyte interphase. The locally concentrated electrolyte also shows high robustness to the effect of upper limit cutoff voltage.

The performance of lithium ion batteries rapidly falls at lower temperatures due to decreasing conductivity of electrolytes and solid electrolyte interphase (SEI) on graphite anode. Hence, it limits the practical use of lithium ion batteries at subzero temperatures and also affects the development of lithium ion batteries for widespread applications. The SEI formed on the graphite surface is very influential in determining the performance of the battery. Herein, a new electrolyte additive, 4-chloromethyl-1,3,2-dioxathiolane-2-oxide (CMDO), is prepared to improve the properties of commonly used electrolyte constituents—ethylene carbonate (EC), and fluoroethylene carbonate. The formation of an efficient passivation layer in propylene carbonate-based electrolyte for MCMB electrode was investigated. The addition of CMDO resulted in a much less irreversible capacity loss and induces thin SEI formation. However, the combination of the three additives played a key role to enhance reversible capacity of MCMB electrode at lower or ambient temperature. The electrochemical measurement analysis showed that the SEI formed from a mixture of the three additives gave better intercalation–deintercalation of lithium ions.

In this work, nonstoichiometric Cu2–xSe fabricated by a facile water evaporation process is used as high-performance Al-ion battery cathode materials. Cu2–xSe electrodes show high reversible capacity and excellent cycling stability, even at a high current density of 200 mA g–1, the specific charge capacity in the initial cycle is 241 mA h g–1and maintains 100 mA h g–1after 100 cycles with a Coulombic efficiency of 96.1%, showing good capacity retention. The prominent kinetics of Cu2–xSe electrodes is also revealed by the GITT, which is attributed to the ultrahigh electronic conductivity of the Cu2–xSe material. Most importantly, an extensive research is dedicated to investigating the detailed intercalation and de-intercalation of relatively large chloroaluminate anions into the cubic Cu2–xSe, which is conducive to better understand the reaction mechanism of the Al/Cu2–xSe battery.

Escalating both electrochemically active and stable materials at a time is an important challenge in the field of catalysis till to date. Carbon as a pillar material has been used for long time due to its intrinsic properties like high conductivity and large surface area that can increase activity of electrocatalyst. However, severe drop in activity due to carbon corrosion is the main challenge. Here, we introduce robust, conductive and stable Magnéli phase Ti4O7nano-pillar in to flower like nickel ruthenium-layered double hydroxide (3D-FL-NiRu-LDH/ Ti4O7) through an easy in situ growth approach for the first time. The decoration of Magnéli phase Ti4O7not only significantly improves the activity but also stability of LDH nanosheet catalyst. The as-synthesized materials retain 98% of the activity after 45 h which surpasses all the reported LDH catalysts for oxygen reduction reaction under alkaline media. The key roles of Ti4O7are to provide the effective charge transfer networks of LDH catalyst and prevent agglomeration of LDH catalysts though strongly coupled interactions evidenced by X-ray photoelectron spectroscopy (XPS). Therefore, the developed catalyst demonstrates promising conductivity, together with durability. The reported approach of introducing a robust and conductive pillar coupled with LDH catalysts provides a novel pathway for developing a highly efficient and durable electrocatalyst.

Applications of lithium ion battery have been hampered by a lack of ideal anode materials in terms of capacity and stability. The emergence of metal chalcogenide as a candidate material has reinvigorated the search of a low cost and high capacity material system. However, debate about the underlying mechanisms and overall appraisal of its usage in lithium ion battery system remains. Here, a comprehensive study on the energy storage mechanism of copper zinc tin sulfide (CZTS) nanowalls possessing ultrahigh rate capability (500mAhg−1charged within 60s) is reported. Structural evolutions along with the accompanying changes in the oxidation state upon charge/discharge were monitored by ex-situ X-ray diffraction and X-ray photoelectron spectroscopy. During lithiation, lithium ion reacted with CZTS to form lithium sulfides. At the same time, a sequential conversion reactions of copper, zinc and tin sulfides enabled the CZTS nanowalls to achieve excellent electrochemical performance (1400mAhg−1at a current density of 1000mAg−1over 400 cycles). Multi-element metal chalcogenides in conjunction with an adhesion-enhancing seed layer and a rational nanostructure design hold the key to such ultrahigh capacity and stable anode materials for next generation energy storage devices.

Among inorganic solid-state electrolytes, argyrodite sulfides are capable candidates for their superb-ionic conductivity, versatility over synthesis, and cost. However, the growth of resistive interphase, limited oxidative stability, and highly-oxophilic nature are limiting factors. Herein, we report iodized-oxychloride argyrodite with robust SEI containing in-situ formed LiI and Li2O upon treating the sulfide via fumy iodine. Sacrificial iodine-induced dendrite suppression capability up to 21 mA cm−2was achieved. Ultrahigh-lithium compatibility with a high cutoff-capacity of 10 mAh cm−2was cycled at 10 mA cm−2for 260 hr. Moreover, durable cycling was performed at 0.1 mA cm−2for 11,000 h, 2 mA cm−2for 1000 h, and 6 mA cm−2for 460 h. Stepwise CV measurement demonstrates enhanced “True practical potential window” stability up to 3.42 V vs. Li/Li+. Cell performance of Li6PS4.8O0.2Cl-5 wt. % I2with Li-In at 1 C and 3 C has achieved capacity retention of 89.6 % and 89.9 % after 200 and 300 cycles. Outstanding cyclability with Li-metal at 0.4 C with an initial-discharge capacity of 137.27 mAh g−1was achieved. Enhanced tolerance to moisture with suppressed H2S gas generation was proven by coupling in-situ Raman measurements.

Energy conversion from chemical to electrical energy through electrochemical processes using fuel cells is a promising advanced technology to address global environmental issues. However, the development of cathode materials for proton exchange membrane fuel cells (PEMFCs) still faces challenges due to their practical requirements for activity and stability. Introducing oxides into the electrocatalysts is an important way to improve performance. Here, we propose a one-pot hydrothermal synthesis to load Pt and TiO2nanoparticles (NPs) onto the treated carbon (TC). Through the TiO2reconciliation between the Pt NPs and the carbon support, the tightly bound Pt–TiO2–TC electrocatalyst shows excellent activity and stability in the oxygen reduction reaction (ORR) due to the strong electronic interaction. At 0.9 V vs. reversible hydrogen electrode, the Pt–TiO2–TC electrocatalyst has about twice the specific activity (SA) and mass activity (MA) of commercial Pt/C. Moreover, the decline of Pt- SA and MA in Pt–TiO2-TC after the accelerated durability test (ADT) was 4.2% and 12.3%, respectively. Therefore, we strongly recommend hybrid metal-oxide-carbon materials with high conductivity, electronic interaction, and carbon corrosion resistance as support materials for Pt NPs to develop Pt-based electrocatalysts for fuel cell applications.

The lithium–sulfur battery is considered as a prospective candidate for a high-energy-storage system because of its high theoretical specific capacity and energy. However, the dissolution and shutter of polysulfides lead to low active material utilization and fast capacity fading. Electrospinning technology is employed to directly coat an interlayer composed of polyacrylonitrile (PAN) and nitrogen-doped carbon black (NC) fibers on the cathode. Benefiting from electrospinning technology, the PAN-NC fibers possess good electrolyte infiltration for fast lithium-ion transport and great flexibility for adhering on the cathode. The NC particles provide good affinity for polysufides and great conductivity. Thus, the polysulfides can be trapped on the cathode and reutilized well. As a result, the PAN-NC-coated sulfur cathode (PAN-NC@cathode) exhibits the initial discharge capacity of 1279 mAh g–1and maintains the reversible capacity of 1030 mAh g–1with capacity fading of 0.05% per cycle at 200 mA g–1after 100 cycles. Adopting electrospinning to directly form fibers on the cathode shows a promising application.

Lithium dendrite growth dynamics on Cu surface is first visualized through a versatile and facile experimental cell by in operandotransmission X-ray microscopy (TXM). Galvanostatic plating and stripping cycle(s) are applied on each cell. Upon plating/stripping at ∼1 mA cm–2, mossy lithium is clearly found growing and shrinking on the Cu surface as the application time increases. It is interesting to note that the aspect ratio (height/width) of deposited lithium has increased with charge passed during plating, indicating a faster growing from the base. In addition, the dendritic or mossy lithium has also been observed when various high current densities (25, 12.5, and 6.3 mA cm–2) are applied in different cycles, showing a severe dendritic lithium formation that could be induced by inhomogeneous current distribution. The clear structure of dead lithium is found after the cycling, which also shows a lower efficiency and higher hazard when a higher current density is applied. This work explores TXM as a useful tool for in operandodynamic visualization and quantitative measurement of lithium dendrite, which is difficult to achieve with ex situmeasurements and other microscopy techniques. The understanding of the growth mechanism from TXM can be beneficial for the development of safe lithium ion and lithium metal batteries.

Trace water content in the electrolyte causes the degradation of LiPF6, and the decomposed products further react with water to produce HF, which alters the surface of anode and cathode. As a result, the reaction of HF and the deposition of decomposed products on electrode surface cause significant capacity fading of cells. Avoiding these phenomena is crucial for lithium ion batteries. Considering the Lewis-base feature of the N–Si bond, 1-(trimethylsilyl)imidazole (1-TMSI) is proposed as a novel water scavenging electrolyte additive to suppress LiPF6decomposition. The scavenging ability of 1-TMSI and beneficiary interfacial chemistry between the MCMB electrode and electrolyte are studied through a combination of experiments and density functional theory (DFT) calculations. NMR analysis indicated that LiPF6decomposition by water was effectively suppressed in the presence of 0.2 vol % 1-TMSI. XPS surface analysis of MCMB electrode showed that the presence of 1-TMSI reduced deposition of ionic insulating products caused by LiPF6decomposition. The results showed that the cells with 1-TMSI additive have better performance than the cell without 1-TMSI by facilitating the formation of solid–electrolyte interphase (SEI) layer with better ionic conductivity. It is hoped that the work can contribute to the understanding of SEI and the development of electrolyte additives for prolonged cycle life with improved performance.