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Pengfei Yan

Bio: Pengfei Yan is an academic researcher from Beijing University of Technology. The author has contributed to research in topics: Cathode & Lithium. The author has an hindex of 45, co-authored 127 publications receiving 8182 citations. Previous affiliations of Pengfei Yan include Environmental Molecular Sciences Laboratory & Battelle Memorial Institute.


Papers
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TL;DR: In this paper, the authors demonstrate a highly reversible zinc/manganese oxide system in which optimal mild aqueous ZnSO4-based solution is used as the electrolyte, and nanofibres of a manganese oxide phase, α-MnO2, are used as a cathode.
Abstract: Rechargeable aqueous batteries such as alkaline zinc/manganese oxide batteries are highly desirable for large-scale energy storage owing to their low cost and high safety; however, cycling stability is a major issue for their applications. Here we demonstrate a highly reversible zinc/manganese oxide system in which optimal mild aqueous ZnSO4-based solution is used as the electrolyte, and nanofibres of a manganese oxide phase, α-MnO2, are used as the cathode. We show that a chemical conversion reaction mechanism between α-MnO2 and H+ is mainly responsible for the good performance of the system. This includes an operating voltage of 1.44 V, a capacity of 285 mAh g−1 (MnO2), and capacity retention of 92% over 5,000 cycles. The Zn metal anode also shows high stability. This finding opens new opportunities for the development of low-cost, high-performance rechargeable aqueous batteries. Rechargeable aqueous batteries are attractive owing to their relatively low cost and safety. Here the authors report an aqueous zinc/manganese oxide battery that operates via a conversion reaction mechanism and exhibits a long-term cycling stability.

1,965 citations

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TL;DR: In-situ transmission electron microscopy and continuum media mechanical calculations are combined to demonstrate that large (>20 μm) mesoporous silicon sponge prepared by the anodization method can limit the particle volume expansion at full lithiation to ~30% and prevent pulverization in bulk silicon particles.
Abstract: Silicon is a promising anode material for lithium ion batteries, but suffers from poor cyclability especially at high mass loading. Here, Li et al. synthesize mesoporous silicon sponge-like structures, which show promising performance at the deep lithiation and high loading conditions required for practical applications.

1,145 citations

Journal ArticleDOI
TL;DR: It is found the formation of the intragranular cracks is directly associated with high-voltage cycling, an electrochemically driven and diffusion-controlled process.
Abstract: LiNi1/3Mn1/3Co1/3O2-layered cathode is often fabricated in the form of secondary particles, consisting of densely packed primary particles. This offers advantages for high energy density and alleviation of cathode side reactions/corrosions, but introduces drawbacks such as intergranular cracking. Here, we report unexpected observations on the nucleation and growth of intragranular cracks in a commercial LiNi1/3Mn1/3Co1/3O2 cathode by using advanced scanning transmission electron microscopy. We find the formation of the intragranular cracks is directly associated with high-voltage cycling, an electrochemically driven and diffusion-controlled process. The intragranular cracks are noticed to be characteristically initiated from the grain interior, a consequence of a dislocation-based crack incubation mechanism. This observation is in sharp contrast with general theoretical models, predicting the initiation of intragranular cracks from grain boundaries or particle surfaces. Our study emphasizes that maintaining structural stability is the key step towards high-voltage operation of layered-cathode materials.

597 citations

Journal ArticleDOI
TL;DR: In situ tensile tests in a transmission electron microscope demonstrate radically different deformation behaviour for monolithic metallic-glass samples with dimensions of the order of 100 nm, suggesting that metallic glasses can plastically deform in a manner similar to their crystalline counterparts, via homogeneous and inhomogeneous flow without catastrophic failure.
Abstract: Metallic glasses have a very high strength, hardness and elastic limit. However, they rarely show tensile ductility at room temperature and are considered quasi-brittle materials(1,2). Although these amorphous metals are capable of shear flow, severe plastic instability sets in at the onset of plastic deformation, which seems to be exclusively localized in extremely narrow shear bands similar to 10nm in thickness(3-13). Using in situ tensile tests in a transmission electron microscope, we demonstrate radically different deformation behaviour for monolithic metallic-glass samples with dimensions of the order of 100 nm. Large tensile ductility in the range of 23-45% was observed, including significant uniform elongation and extensive necking or stable growth of the shear offset. This large plasticity in small-volume metallic-glass samples did not result from the branching/deflection of shear bands or nanocrystallization. These observations suggest that metallic glasses can plastically deform in a manner similar to their crystalline counterparts, via homogeneous and inhomogeneous flow without catastrophic failure. The sample-size effect discovered has implications for the application of metallic glasses in thin films and micro-devices, as well as for understanding the fundamental mechanical response of amorphous metals.

516 citations

Journal ArticleDOI
TL;DR: In this article, a solid electrolyte is injected into the grain boundaries of the secondary particles of the Ni-rich layered lithium transition metal oxides to prevent penetration of liquid electrolyte into the boundaries, and eliminate the detrimental factors, which include cathode-liquid electrolyte interfacial reactions, intergranular cracking and layered-to-spinel phase transformation.
Abstract: A critical challenge for the commercialization of layer-structured nickel-rich lithium transition metal oxide cathodes for battery applications is their capacity and voltage fading, which originate from the disintegration and lattice phase transition of the cathode particles. The general approach of cathode particle surface modification could partially alleviate the degradation associated with surface processes, but it still fails to resolve this critical barrier. Here, we report that infusing the grain boundaries of cathode secondary particles with a solid electrolyte dramatically enhances the capacity retention and voltage stability of the cathode. We find that the solid electrolyte infused in the boundaries not only acts as a fast channel for lithium-ion transport, it also, more importantly, prevents penetration of the liquid electrolyte into the boundaries, and consequently eliminates the detrimental factors, which include cathode–liquid electrolyte interfacial reactions, intergranular cracking and layered-to-spinel phase transformation. This grain-boundary engineering approach provides design ideas for advanced cathodes for batteries. The development of Ni-rich layered lithium transition metal oxides is plagued by their voltage and capacity fading on battery cycling. Here, the authors demonstrate an effective approach to treat these problems by infusing a solid electrolyte into the grain boundaries of the secondary particles of these layered materials.

483 citations


Cited by
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TL;DR: This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth, summarizing the theoretical and experimental achievements and endeavors to realize the practical applications of lithium metal batteries.
Abstract: The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

3,812 citations

01 Jun 2005

3,154 citations

Journal ArticleDOI
TL;DR: Current research on materials is summarized and discussed and future directions for SIBs are proposed to provide important insights into scientific and practical issues in the development of S IBs.
Abstract: Energy production and storage technologies have attracted a great deal of attention for day-to-day applications. In recent decades, advances in lithium-ion battery (LIB) technology have improved living conditions around the globe. LIBs are used in most mobile electronic devices as well as in zero-emission electronic vehicles. However, there are increasing concerns regarding load leveling of renewable energy sources and the smart grid as well as the sustainability of lithium sources due to their limited availability and consequent expected price increase. Therefore, whether LIBs alone can satisfy the rising demand for small- and/or mid-to-large-format energy storage applications remains unclear. To mitigate these issues, recent research has focused on alternative energy storage systems. Sodium-ion batteries (SIBs) are considered as the best candidate power sources because sodium is widely available and exhibits similar chemistry to that of LIBs; therefore, SIBs are promising next-generation alternatives. Recently, sodiated layer transition metal oxides, phosphates and organic compounds have been introduced as cathode materials for SIBs. Simultaneously, recent developments have been facilitated by the use of select carbonaceous materials, transition metal oxides (or sulfides), and intermetallic and organic compounds as anodes for SIBs. Apart from electrode materials, suitable electrolytes, additives, and binders are equally important for the development of practical SIBs. Despite developments in electrode materials and other components, there remain several challenges, including cell design and electrode balancing, in the application of sodium ion cells. In this article, we summarize and discuss current research on materials and propose future directions for SIBs. This will provide important insights into scientific and practical issues in the development of SIBs.

3,009 citations

Journal ArticleDOI
TL;DR: The main roles of material science in the development of LIBs are discussed, with a statement of caution for the current modern battery research along with a brief discussion on beyond lithium-ion battery chemistries.
Abstract: Over the past 30 years, significant commercial and academic progress has been made on Li-based battery technologies. From the early Li-metal anode iterations to the current commercial Li-ion batteries (LIBs), the story of the Li-based battery is full of breakthroughs and back tracing steps. This review will discuss the main roles of material science in the development of LIBs. As LIB research progresses and the materials of interest change, different emphases on the different subdisciplines of material science are placed. Early works on LIBs focus more on solid state physics whereas near the end of the 20th century, researchers began to focus more on the morphological aspects (surface coating, porosity, size, and shape) of electrode materials. While it is easy to point out which specific cathode and anode materials are currently good candidates for the next-generation of batteries, it is difficult to explain exactly why those are chosen. In this review, for the reader a complete developmental story of LIB should be clearly drawn, along with an explanation of the reasons responsible for the various technological shifts. The review will end with a statement of caution for the current modern battery research along with a brief discussion on beyond lithium-ion battery chemistries.

2,867 citations

Journal ArticleDOI
TL;DR: In this article, a vanadium oxide bronze was used as the positive electrode for a Zn cell with reversible intercalation of Zn ions in a layered Zn0.25V2O5⋅nH2O-based positive electrode.
Abstract: Although non-aqueous Li-ion batteries possess significantly higher energy density than their aqueous counterparts, the latter can be more feasible for grid-scale applications when cost, safety and cycle life are taken into consideration. Moreover, aqueous Zn-ion batteries have an energy storage advantage over alkali-based batteries as they can employ Zn metal as the negative electrode, dramatically increasing energy density. However, their development is plagued by a limited choice of positive electrodes, which often show poor rate capability and inadequate cycle life. Here we report a vanadium oxide bronze pillared by interlayer Zn2+ ions and water (Zn0.25V2O5⋅nH2O), as the positive electrode for a Zn cell. A reversible Zn2+ ion (de)intercalation storage process at fast rates, with more than one Zn2+ per formula unit (a capacity up to 300 mAh g−1), is characterized. The Zn cell offers an energy density of ∼450 Wh l−1 and exhibits a capacity retention of more than 80% over 1,000 cycles, with no dendrite formation at the Zn electrode. High-performing positive electrode materials are crucial for the development of aqueous Zn-ion batteries. Here the authors report a battery based on reversible intercalation of Zn ions in a layered Zn0.25V2O5⋅nH2O-based positive electrode, which exhibits high-capacity and long-term cycling stability.

1,948 citations