Showing papers by "Jun Lu published in 2020"
TL;DR: A generic Lewis acidic etching route for preparing high-rate negative-electrode MXenes with enhanced electrochemical performance in non-aqueous electrolyte is proposed and validated by the synthesis of various MXenes from unconventional MAX-phase precursors with A elements Si, Zn and Ga.
Abstract: Two-dimensional carbides and nitrides of transition metals, known as MXenes, are a fast-growing family of materials that have attracted attention as energy storage materials. MXenes are mainly prepared from Al-containing MAX phases (where A = Al) by Al dissolution in F-containing solution; most other MAX phases have not been explored. Here a redox-controlled A-site etching of MAX phases in Lewis acidic melts is proposed and validated by the synthesis of various MXenes from unconventional MAX-phase precursors with A elements Si, Zn and Ga. A negative electrode of Ti3C2 MXene material obtained through this molten salt synthesis method delivers a Li+ storage capacity of up to 738 C g−1 (205 mAh g−1) with high charge–discharge rate and a pseudocapacitive-like electrochemical signature in 1 M LiPF6 carbonate-based electrolyte. MXenes prepared via this molten salt synthesis route may prove suitable for use as high-rate negative-electrode materials for electrochemical energy storage applications. Two-dimensional transition metal carbides and nitrides, known as MXenes, are currently considered as energy storage materials. A generic Lewis acidic etching route for preparing high-rate negative-electrode MXenes with enhanced electrochemical performance in non-aqueous electrolyte is now proposed.
623 citations
TL;DR: In this paper, a copper-incorporated crystalline 3,4,9,10-perylenetetetracarboxylic dianhydride was used to synthesize ammonia from nitrate ions.
Abstract: Ammonia (NH3) is essential for modern agriculture and industry and is a potential energy carrier. NH3 is traditionally synthesized by the Haber–Bosch process at high temperature and pressure. The high-energy input of this process has motivated research into electrochemical NH3 synthesis via nitrogen (N2)–water reactions under ambient conditions. However, the future of this low-cost process is compromised by the low yield rate and poor selectivity, ascribed to the inert N≡N bond and ultralow solubility of N2. Obtaining NH3 directly from non-N2 sources could circumvent these challenges. Here we report the eight-electron direct electroreduction of nitrate to NH3 catalysed by copper-incorporated crystalline 3,4,9,10-perylenetetracarboxylic dianhydride. The catalyst exhibits an NH3 production rate of 436 ± 85 μg h−1 cm−2 and a maximum Faradaic efficiency of 85.9% at −0.4 V versus a reversible hydrogen electrode. This notable performance is achieved by the catalyst regulating the transfer of protons and/or electrons to the copper centres and suppressing hydrogen production. Electrochemically reducing nitrogen-containing molecules could provide less energy-intense routes to produce ammonia than the traditional Haber–Bosh process. Here the authors use a catalyst comprising Cu embedded in an organic molecular solid to synthesize ammonia from nitrate ions.
514 citations
TL;DR: From superconcentrated solvent-in-salt electrolytes to solid-state electrolytes, the current research realm of novel electrolyte systems has grown to unprecedented levels and this review will avoid discussions on current state-of-the-art electrolytes but instead focus exclusively on unconventional electrolytes systems that represent new concepts.
Abstract: Over the past decades, Li-ion battery (LIB) has turned into one of the most important advances in the history of technology due to its extensive and in-depth impact on our life. Its omnipresence in all electric vehicles, consumer electronics and electric grids relies on the precisely tuned electrochemical dynamics and interactions among the electrolytes and the diversified anode and cathode chemistries therein. With consumers' demand for battery performance ever increasing, more and more stringent requirements are being imposed upon the established equilibria among these LIB components, and it became clear that the state-of-the-art electrolyte systems could no longer sustain the desired technological trajectory. Driven by such gap, researchers started to explore more unconventional electrolyte systems. From superconcentrated solvent-in-salt electrolytes to solid-state electrolytes, the current research realm of novel electrolyte systems has grown to unprecedented levels. In this review, we will avoid discussions on current state-of-the-art electrolytes but instead focus exclusively on unconventional electrolyte systems that represent new concepts.
455 citations
TL;DR: It is reported that disordered rock salt can be used as a fast-charging anode that can reversibly cycle two lithium ions at an average voltage of about 0.6 volts versus a Li/Li+ reference electrode, alleviating a major safety concern (short-circuiting related to Li dendrite growth).
Abstract: Rechargeable lithium-ion batteries with high energy density that can be safely charged and discharged at high rates are desirable for electrified transportation and other applications1-3. However, the sub-optimal intercalation potentials of current anodes result in a trade-off between energy density, power and safety. Here we report that disordered rock salt4,5 Li3+xV2O5 can be used as a fast-charging anode that can reversibly cycle two lithium ions at an average voltage of about 0.6 volts versus a Li/Li+ reference electrode. The increased potential compared to graphite6,7 reduces the likelihood of lithium metal plating if proper charging controls are used, alleviating a major safety concern (short-circuiting related to Li dendrite growth). In addition, a lithium-ion battery with a disordered rock salt Li3V2O5 anode yields a cell voltage much higher than does a battery using a commercial fast-charging lithium titanate anode or other intercalation anode candidates (Li3VO4 and LiV0.5Ti0.5S2)8,9. Further, disordered rock salt Li3V2O5 can perform over 1,000 charge-discharge cycles with negligible capacity decay and exhibits exceptional rate capability, delivering over 40 per cent of its capacity in 20 seconds. We attribute the low voltage and high rate capability of disordered rock salt Li3V2O5 to a redistributive lithium intercalation mechanism with low energy barriers revealed via ab initio calculations. This low-potential, high-rate intercalation reaction can be used to identify other metal oxide anodes for fast-charging, long-life lithium-ion batteries.
257 citations
TL;DR: Research efforts that could further decrease or even eliminate cobalt content in LIBs to lower their cost while maintaining high performance are outlined.
Abstract: Replacements are sought for cobalt, a costly element used in lithium-ion battery cathodes The use of cobalt in lithium-ion batteries (LIBs) traces back to the well-known LiCoO2 (LCO) cathode, which offers high conductivity and stable structural stability throughout charge cycling. Compared to the other transition metals, cobalt is less abundant and more expensive and also presents political and ethical issues because of the way it is mined in Africa (1). Cheaper cathodes have been developed that substitute some of the cobalt with nickel and manganese, and LiNi0.80Co0.15Al0.05O2 (NCA) and LiNi1-x-y CoxMnyO2 (NMC, where x and y <1) are used in the majority of the LIBs in electric vehicles. Nonetheless, in NCA and NMC, cobalt enables high-rate performance and to some extent, enhances cycle stability. We outline research efforts that could further decrease or even eliminate cobalt content in LIBs to lower their cost while maintaining high performance.
232 citations
TL;DR: In this review, the recent emerging strategies and perspectives on LMAs are summarized, following which the current huge evolution in interfacial chemistry regulation, optimizing electrolyte components, designing a rational 'host' for lithium metal, optimizing "solid-state electrolytes" and other emerging strategies for developing high-safety LMAs is highlighted.
Abstract: Developing high-safety Li-metal anodes (LMAs) is extremely important for the application of high-energy Li-metal batteries (LMBs), especially Li–S and Li–O2 battery systems. However, the notorious Li-dendrite growth problem results in serious safety concerns for any energy storage application. Through a recent combination of interface-based science, nanotechnology-based solutions and characterization methods, the LMA is now primed for a technological boom. In this review, the recent emerging strategies and perspectives on LMAs are summarized, following which the current huge evolution in interfacial chemistry regulation, optimizing electrolyte components, designing a rational ‘host’ for lithium metal, optimizing “solid-state electrolytes” and other emerging strategies for developing high-safety LMAs is highlighted. Furthermore, several state-of-the-art in situ/operando synchrotron-based X-ray techniques for high safety LMB research are introduced. With the further development of LMAs in the future, subsequent application in high energy LMBs is to be expected.
208 citations
TL;DR: A directional freeze-casting and annealing approach is reported for the construction of a 3D honeycomb nanostructured, N,P-doped carbon aerogel incorporating in situ grown FeP/Fe2 O3 nanoparticles as the cathode in a flexible Zn-air battery (ZAB).
Abstract: Mechanically stable and foldable air cathodes with exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are key components of wearable metal-air batteries Herein, a directional freeze-casting and annealing approach is reported for the construction of a 3D honeycomb nanostructured, N,P-doped carbon aerogel incorporating in situ grown FeP/Fe2 O3 nanoparticles as the cathode in a flexible Zn-air battery (ZAB) The aqueous rechargeable Zn-air batteries assembled with this carbon aerogel exhibit a remarkable specific capacity of 648 mAh g-1 at a current density of 20 mA cm-2 with a good long-term durability, outperforming those assembled with commercial Pt/C+RuO2 catalyst Furthermore, such a foldable carbon aerogel with directional channels can serve as a freestanding air cathode for flexible solid-state Zn-air batteries without the use of carbon paper/cloth and additives, giving a specific capacity of 676 mAh g-1 and an energy density of 517 Wh kg-1 at 5 mA cm-2 together with good cycling stability This work offers a new strategy to design and synthesize highly effective bifunctional air cathodes to be applied in electrochemical energy devices
196 citations
TL;DR: This work investigates the correlation of the surface structure, internal strain, and capacity deterioration by using operando X-ray spectroscopy imaging and nano-tomography and discovers that surface chemistry can significantly enhance the cyclic performance.
Abstract: Single-crystal cathode materials for lithium-ion batteries have attracted increasing interest in providing greater capacity retention than their polycrystalline counterparts. However, after being cycled at high voltages, these single-crystal materials exhibit severe structural instability and capacity fade. Understanding how the surface structural changes determine the performance degradation over cycling is crucial, but remains elusive. Here, we investigate the correlation of the surface structure, internal strain, and capacity deterioration by using operando X-ray spectroscopy imaging and nano-tomography. We directly observe a close correlation between surface chemistry and phase distribution from homogeneity to heterogeneity, which induces heterogeneous internal strain within the particle and the resulting structural/performance degradation during cycling. We also discover that surface chemistry can significantly enhance the cyclic performance. Our modified process effectively regulates the performance fade issue of single-crystal cathode and provides new insights for improved design of high-capacity battery materials.
192 citations
TL;DR: The high efficiency of rationally-designed Ni3N0.85 demonstrates the effectiveness of the d-band tuning strategy to de-velop low-activation-energy catalysts and to promote the atomic understanding of polysulfides conversion in Li-S batteries.
Abstract: Slow kinetics of polysulfide conversion reactions lead to severe issues for lithium-sulfur (Li-S) batteries, for example, low rate capability, polysulfide migration, and low Coulombic efficiencies. These challenges hinder the practical applications of Li-S batteries. In this study, we proposed a rational strategy of tuning the d-band of catalysts to accelerate the conversion of polysulfides. Nitrogen vacancies were engineered in hexagonal Ni3N (space group P6322) to tune its d-band center, leading to the strong interaction between polysulfides and Ni3N. Because of the greater electron population in the lowest occupied molecular orbital of Li2S4, the terminal S-S bonds were weakened for breaking. Temperature-dependent experiments confirm that Ni3N0.85 demonstrates a much low activation energy, thereby accelerating the conversion of polysulfides. A Li-S cell using Ni3N0.85 can deliver a high initial discharge capacity of 1445.9 mAh g-1 (at 0.02 C) and low decay per cycle (0.039%). The Ni3N0.85 cell can also demonstrate an initial capacity of 1200.4 mAh g-1 for up to 100 cycles at a high loading of 5.2 mg cm-2. The high efficiency of rationally designed Ni3N0.85 demonstrates the effectiveness of the d-band tuning strategy to develop low-activation-energy catalysts and to promote the atomic understanding of polysulfide conversion in Li-S batteries.
178 citations
TL;DR: In this paper, a defect-targeted regenerative regeneration of spent LiFePO4 (LFP) cathodes is proposed to reduce energy usage and greenhouse gas emissions. But, the defect-based regenerative regenerative method is limited to a single battery.
171 citations
TL;DR: New findings on the DM-specific MSAs and their clinical associations in both adults and children are highlighted.
Abstract: Dermatomyositis (DM) is an idiopathic inflammatory myopathy that is clinically heterogeneous and that can be difficult to diagnose. Cutaneous manifestations sometimes vary and may or may not parallel myositis and systemic involvement in time course or severity. Recent developments in our understanding of myositis-specific antibodies have the potential to change the diagnostic landscape of DM for dermatologists. Although phenotypic overlap exists, anti-Mi2, -MDA5, -NXP2, -TIF1, and -SAE antibodies may be correlated with distinct DM subtypes in terms of cutaneous manifestations, systemic involvement, and malignancy risk. This review highlights new findings on the DM-specific myositis-specific antibodies and their clinical associations in both adults and children.
TL;DR: A general method of fast-moving bed pyrolysis, uniformly dispersing high-entropy alloy nanoparticles on various granular supports is developed, providing an improved methodology for synthesizing HEA-NPs on various supports.
Abstract: High-entropy alloy nanoparticles (HEA-NPs) are important class of materials with significant technological potential. However, the strategies for synthesizing uniformly dispersed HEA-NPs on granular supports such as carbon materials, γ-Al2O3, and zeolite, which is vital to their practical applications, are largely unexplored. Herein, we present a fast moving bed pyrolysis strategy to immobilize HEA-NPs on granular supports with a narrow size distribution of 2 nm up to denary (MnCoNiCuRhPdSnIrPtAu) HEA-NPs at 923 K. Fast moving bed pyrolysis strategy ensures the mixed metal precursors rapidly and simultaneously pyrolyzed at high temperatures, resulting in nuclei with a small size. The representative quinary (FeCoPdIrPt) HEA-NPs exhibit high stability (150 h) toward hydrogen evolution reaction with high mass activity, which is 26 times higher than the commercial Pt/C at an overpotential of 100 mV. Our strategy provides an improved methodology for synthesizing HEA-NPs on various supports. The large-scale application of extremely small, high-entropy alloy nanoparticles is limited by the phase separation and immobilization. Here, the authors develop a general method of fast-moving bed pyrolysis, uniformly dispersing high-entropy alloy nanoparticles on various granular supports.
TL;DR: In this article, the theoretical mechanisms which enable enhanced and sustained ORR activity and the practical methods to achieve them in catalysts are illuminated, and the critical aspects of Pt-based electrocatalysts to tune oxygen reduction properties from the viewpoints of active sites exposure and altering the surface electronic structure, and further summarize representative research progress towards practically achieving these activity enhancements with a focus on platinum size reduction, shape control and core Pt elimination methods.
Abstract: Pt-based electrocatalysts are considered as one of the most promising choices to facilitate the oxygen reduction reaction (ORR), and the key factor enabling their success is to reduce the required amount of platinum. Herein, we focus on illuminating both the theoretical mechanisms which enable enhanced and sustained ORR activity and the practical methods to achieve them in catalysts. The various multi-step pathways of ORR are firstly reviewed and the rate-determining steps based on the reaction intermediates and their binding energies are analyzed. We then explain the critical aspects of Pt-based electrocatalysts to tune oxygen reduction properties from the viewpoints of active sites exposure and altering the surface electronic structure, and further summarize representative research progress towards practically achieving these activity enhancements with a focus on platinum size reduction, shape control and core Pt elimination methods. We finally outline the remaining challenges and provide our perspectives with regard to further enhancing their activities.
TL;DR: It is demonstrated that alloying is an effective strategy to alleviate palladium operation stability due to CO poisoning on surface by co-reduction of palladium and silver precursors in aqueous solution using dioctadecyldimethylammonium chloride as the structure-directing agent.
Abstract: Palladium is a promising material for electrochemical CO2 reduction to formate with high Faradaic efficiency near the equilibrium potential. It unfortunately suffers from problematic operation stability due to CO poisoning on surface. Here, it is demonstrated that alloying is an effective strategy to alleviate this problem. Mesoporous PdAg nanospheres with uniform size and composition are prepared from the co-reduction of palladium and silver precursors in aqueous solution using dioctadecyldimethylammonium chloride as the structure-directing agent. The best candidate can initiate CO2 reduction at zero overpotential and achieve high formate selectivity close to 100% and great stability even at <-0.2 V versus reversible hydrogen electrode. The high selectivity and stability are believed to result from the electronic coupling between Pd and Ag, which lowers the d-band center of Pd and thereby significantly enhances its CO tolerance, as evidenced by both electrochemical analysis and theoretical simulations.
TL;DR: In this paper, a 3D porous CuZn current collector that mitigates dendrites formed from non-uniform Li deposition is presented, which limits potential uses of Li metal as an anode material.
Abstract: Lithium (Li) dendrites formed from nonuniform Li deposition limit potential uses of Li metal as an anode material. Here, we report a lithiophilic 3D porous CuZn current collector that mitigates den...
TL;DR: Lithium-sulfur batteries are considered a possible next-generation energy storage solution, but their commercial viability is still in question because of several technical challenges, including th... as mentioned in this paper.
Abstract: Lithium–sulfur batteries are considered a possible next-generation energy-storage solution, but their commercial viability is still in question because of several technical challenges, including th...
08 Jan 2020
TL;DR: In this article, the authors bridge some of the ideas from fuel cell to metal-air batteries with the aim of inspiring new ideas and directions for future research, which can potentially utilize the electrical grid network for charging, bypassing the need for establishing a hydrogen infrastructure.
Abstract: Summary With the ever-increasing demand for higher-performing energy-storage systems, electrocatalysis has become a major topic of interest in an attempt to enhance the electrochemical performance of many electrochemical technologies. Discoveries pertaining to the oxygen reduction reaction catalyst helped enable the commercialization of fuel-cell-based electric vehicles. However, a closely related technology, the metal-air battery, has yet to find commercial application. Much like the Li-ion battery, metal-air batteries can potentially utilize the electrical grid network for charging, bypassing the need for establishing a hydrogen infrastructure. Among the metal-air batteries, Li-air and Zn-air batteries have drawn much interest in the past decade. Unfortunately, state-of-the art metal-air batteries still produce performances that are well below practical levels. In this brief perspective, we hope to bridge some of the ideas from fuel cell to that of metal-air batteries with the aim of inspiring new ideas and directions for future research.
TL;DR: The recent technical advances together with the major dilemmas facing currently available flexible metal–gas batteries are reviewed, highlighting how flexible cathodes and gel polymer electrolytes with various structures and components can affect the electrochemical performance and functionality of flexible metal-gas batteries.
Abstract: Flexible metal–gas batteries have become increasingly attractive for use in wearable electronics in the recent years due to their large theoretical energy density and superior adaptability to irregular geometric surfaces, such as the human body. With continuous improvements in design strategies and assembly technologies, the fabrication of various advanced flexible metal–gas batteries has been attempted. In spite of these efforts, the synchronous integration of high flexibility, safety, comfort, and high performance into flexible metal–gas batteries with specifically functionalized configurations still remains a formidable challenge. To resolve these dilemmas, the redesign of cathode catalysts, gel polymer electrolyte, and battery configurations/components has been investigated. In this paper, we review the recent technical advances together with the major dilemmas facing currently available flexible metal–gas batteries, highlighting how flexible cathodes and gel polymer electrolytes with various structures and components can affect the electrochemical performance and functionality of flexible metal–gas batteries. Flexible Zn–air, Li–O2/air, and Li–CO2 batteries are mainly exemplified to elucidate their promising potential. Finally, based on our considerations, unresolved technical hurdles and future research perspectives involving flexible metal–gas batteries for wearable electronics are proposed.
TL;DR: A practical pathway to optimize the K-Se battery performance through structure engineering and manipulation of selenium chemistry for the formation of selective species and reveal its internal reaction mechanism in the carbonate electrolyte is offered.
Abstract: The potassium-selenium (K-Se) battery is considered as an alternative solution for stationary energy storage because of abundant resource of K. However, the detailed mechanism of the energy storage process is yet to be unraveled. Herein, the findings in probing the working mechanism of the K-ion storage in Se cathode are reported using both experimental and computational approaches. A flexible K-Se battery is prepared by employing the small-molecule Se embedded in freestanding N -doped porous carbon nanofibers thin film (Se@NPCFs) as cathode. The reaction mechanisms are elucidated by identifying the existence of short-chain molecular Se encapsulated inside the microporous host, which transforms to K2 Se by a two-step conversion reaction via an "all-solid-state" electrochemical process in the carbonate electrolyte system. Through the whole reaction, the generation of polyselenides (K2 Sen , 3 ≤ n ≤ 8) is effectively suppressed by electrochemical reaction dominated by Se2 molecules, thus significantly enhancing the utilization of Se and effecting the voltage platform of the K-Se battery. This work offers a practical pathway to optimize the K-Se battery performance through structure engineering and manipulation of selenium chemistry for the formation of selective species and reveal its internal reaction mechanism in the carbonate electrolyte.
TL;DR: The functional roles of CatK in bone and beyond bone are summarized, and the potential relevance of the CatK action beyond bone to the adverse effects of inhibitingCatK in non-bone sites is discussed.
Abstract: Cathepsin K (CatK) is one of the most potent proteases in lysosomal cysteine proteases family, of which main function is to mediate bone resorption. Currently, CatK is among the most attractive targets for anti-osteoporosis drug development. Although many pharmaceutical companies are working on the development of selective inhibitors for CatK, there is no FDA approved drug till now. Odanacatib (ODN) developed by Merck & Co. is the only CatK inhibitor candidate which demonstrated high therapeutic efficacy in patients with postmenopausal osteoporosis in Phase III clinical trials. Unfortunately, the development of ODN was finally terminated due to the cardio-cerebrovascular adverse effects. Therefore, it arouses concerns on the undesirable CatK inhibition in non-bone sites. It is known that CatK has far-reaching actions throughout various organs besides bone. Many studies have also demonstrated the involvement of CatK in various diseases beyond the musculoskeletal system. This review not only summarized the functional roles of CatK in bone and beyond bone, but also discussed the potential relevance of the CatK action beyond bone to the adverse effects of inhibiting CatK in non-bone sites.
TL;DR: Inspired by the processes of thrombus formation and thrombolysis in blood vessels, the authors construct an electrochemically recoverable protective layer of polysulfides using an electrolyte additive, realizing high performance Li–S batteries.
Abstract: Encapsulation strategies are widely used for alleviating dissolution and diffusion of polysulfides, but they experience nonrecoverable structural failure arising from the repetitive severe volume change during lithium−sulfur battery cycling. Here we report a methodology to construct an electrochemically recoverable protective layer of polysulfides using an electrolyte additive. The additive nitrogen-doped carbon dots maintain their “dissolved” status in the electrolyte at the full charge state, and some of them function as active sites for lithium sulfide growth at the full discharge state. When polysulfides are present amid the transition between sulfur and lithium sulfide, nitrogen-doped carbon dots become highly reactive with polysulfides to form a solid and recoverable polysulfide-encapsulating layer. This design skilfully avoids structural failure and efficiently suppresses polysulfide shuttling. The sulfur cathode delivers a high reversible capacity of 891 mAh g−1 at 0.5 C with 99.5% coulombic efficiency and cycling stability up to 1000 cycles at 2 C. Inspired by the processes of thrombus formation and thrombolysis in blood vessels, the authors here construct an electrochemically recoverable protective layer of polysulfides using an electrolyte additive, realizing high performance Li–S batteries.
03 Jun 2020
TL;DR: In this paper, the authors discuss scientific advancements in reaction kinetics control, electrochemical stability improvements, and reaction mechanism understanding in three-dimensional beyond-lithium battery systems and call for intensive research efforts to address the challenges and develop strategies that can pave the way toward their commercialization.
Abstract: Summary Ubiquitous implementation of microelectronics in microelectromechanical systems requires stable power supplies and necessitates development of on-chip miniature power sources, such as microbatteries. However, conventional thin-film batteries exhibit limited surface area and sluggish diffusion kinetics with insufficient energy and power density. In contrast, three-dimensional beyond-lithium (e.g., sodium, zinc, aluminum) battery architectures can significantly enhance the areal energy and power and meanwhile maintain the low-cost mass production. Despite this, the future of beyond-lithium systems is being questioned as they each present shortcomings. In this Perspective, we discuss scientific advancements in reaction kinetics control, electrochemical stability improvements, and reaction mechanism understanding in three-dimensional beyond-lithium battery systems and call for intensive research efforts to address the challenges and develop strategies that can pave the way toward their commercialization.
TL;DR: Mn ion activation and a previously unobserved structural distortion are discovered at high voltages, and can be related to structural strain present in the Li2MnO3-like phase upon substantial lithium ion extraction, and a correlation between this structural distortion and irreversible phase transitions is elucidated by thermally perturbing delithiated samples.
Abstract: The search for batteries with high energy density has highlighted lithium-rich manganese-based layered oxides due to their exceptionally high capacity. Although it is clear that both cationic and anionic redox are present in the charge compensation mechanism, the microstructural evolution of the Li2MnO3-like phase during anionic redox and its role in battery performance and structural stability are still not fully understood. Here, we systematically probe microstructural evolution using spatially resolved synchrotron X-ray measurements and reveal an underlying interaction between the Li2MnO3-like domains and bulk rhombohedral structure. Mn ion activation and a previously unobserved structural distortion are discovered at high voltages, and can be related to structural strain present in the Li2MnO3-like phase upon substantial lithium ion extraction. Moreover, we elucidate a correlation between this structural distortion and irreversible phase transitions by thermally perturbing delithiated samples. These insights highlight a pathway toward achieving high capacity cathode materials required for future commercial applications.
TL;DR: In this paper, it is shown that achieving both high power densities and extreme fast charging (XFC) is a crucial technology for lithium-ion batteries (LIBs), but it is generally believed that attaining both high energy densit...
Abstract: Energy storage materials with extreme fast charging (XFC) is currently a crucial technology for lithium-ion batteries (LIBs). However, it is generally believed that attaining both high power densit...
TL;DR: In this paper, the authors report 15 inherently nanolaminated V2(AxSn1-x)C (A = Fe, Co, Ni, Mn, and combinations thereof, with x ∼ 1/3) MAX phases synthesized by an alloy-guided reaction.
Abstract: Tailoring of individual single–atom-thick layers in nanolaminated materials offers atomic-level control over material properties. Nonetheless, multielement alloying in individual atomic layers in nanolaminates is largely unexplored. Here, we report 15 inherently nanolaminated V2(AxSn1-x)C (A = Fe, Co, Ni, Mn, and combinations thereof, with x ∼ 1/3) MAX phases synthesized by an alloy-guided reaction. The simultaneous occupancy of the 4 magnetic elements and Sn in the individual single–atom-thick A layers constitutes high-entropy MAX phase in which multielemental alloying exclusively occurs in the 2-dimensional (2D) A layers. V2(AxSn1-x)C exhibit distinct ferromagnetic behavior that can be compositionally tailored from the multielement A-layer alloying. Density functional theory and phase diagram calculations are performed to understand the structure stability of these MAX phases. This 2D multielemental alloying approach provides a structural design route to discover nanolaminated materials and expand their chemical and physical properties. In fact, the magnetic behavior of these multielemental MAX phases shows strong dependency on the combination of various elements.
TL;DR: The design strategy for future separators is provided, which not only meets the requirements of different type of batteries, but also aims for multifunctionality.