Haotian Wang

Bio: Haotian Wang is an academic researcher from Tongji University. The author has contributed to research in topics: Electrolyte & Solvation. The author has an hindex of 1, co-authored 2 publications receiving 6 citations.

Tailoring Electrolyte Solvation Chemistry toward an Inorganic-Rich Solid-Electrolyte Interphase at a Li Metal Anode

Abstract: The solid-electrolyte interphase (SEI) is known to dictate the performance of a Li metal anode, where its inorganic compositions are primarily responsible for Li+ conduction, electron insulation, a...

Knocking down the kinetic barriers towards fast-charging and low-temperature sodium metal batteries

Abstract: Current knowledge on Na metal anode has been limited on its room-temperature or high-temperature (molten Na-S system) performances. However, the properties related to its low-temperature and fast-charging performances are rarely covered. Herein, we show that, using a conventional carbonate-based electrolyte, needle-like Na deposits sprout at −20 °C with a spiking impedance of ∼2.8 × 104 Ω observed in symmetric cell configuration, making an early failure of the battery within tens of hours. By knocking down the kinetic barriers of Na+ ion de-solvation and its subsequent diffusion through the solid electrolyte interphase (SEI), we enable flat and spherical Na deposits at −20 °C with a massively reduced interfacial impedance. This has been realized by using (i) a weakly solvated electrolyte that shows a low solvation energy towards Na+ ions, and (ii) a Na15Sn4/NaF biphasic artificial SEI for promoting unhindered Na+ ion transfer at the Na metal/electrolyte interface. Ultimately, a high-voltage Na/Na3V2(PO4)2O2F battery is developed to stand low temperatures down to −30 °C and fast charging up to 30C. The design strategy provided herein underlines the simultaneous de-solvation and SEI control for achieving low-temperature and fast-charging sodium metal batteries and presents as a prototype of how the kinetic barriers can be overcome under extreme conditions.

A Nonflammable Electrolyte for Ultrahigh−Voltage (4.8 V−Class) Li||NCM811 Cells with A Wide Temperature Range of 100 °C

Abstract: The development of ultrahigh-voltage lithium metal batteries is one of the most promising ways to increase the energy density. However, commercial ethylene carbonate (EC)-based electrolytes have poor compatibility with both...

High‐Performance Microsized Si Anodes for Lithium‐Ion Batteries: Insights into the Polymer Configuration Conversion Mechanism

Abstract: Microsized silicon particles are desirable Si anodes because of their low price and abundant sources. However, it is challenging to achieve stable electrochemical performances using a traditional microsized silicon anode due to the poor electrical conductivity, serious volume expansion, and unstable solid electrolyte interface. Herein, a composite microsized Si anode is designed and synthesized by constructing a unique polymer, poly(hexaazatrinaphthalene) (PHATN), at a Si/C surface (PCSi). The Li+ transport mechanism of the PCSi is elucidated by using in situ characterization and theoretical simulation. During the lithiation of the PCSi anode, CN groups with high electron density in the PHATN first coordinate Li+ to form CNLi bonds on both sides of the PHATN molecule plane. Consequently, the original benzene rings in the PHATN become active centers to accept lithium and form stable Li‐rich PHATN coatings. PHATN molecules expand due to the change of molecular configuration during the consecutive lithiation process, which provides controllable space for the volume expansion of the Si particles. The PCSi composite anode exhibits a specific capacity of 1129.6 mAh g−1 after 500 cycles at 1 A g−1, and exhibits compelling rate performance, maintaining 417.9 mAh g−1 at 16.5 A g−1.

Ion Transport Kinetics in Low‐Temperature Lithium Metal Batteries

Abstract: The deployment of rechargeable batteries is crucial for the operation of advanced portable electronics and electric vehicles under harsh environment. However, commercial lithium‐ion batteries using ethylene carbonate electrolytes suffer from severe loss in cell energy density at extremely low temperature. Lithium metal batteries (LMBs), which use Li metal as anode rather than graphite, are expected to push the baseline energy density of low‐temperature devices at the cell level. Albeit promising, the kinetic limitations of standard cell chemistries under subzero operation condition inevitably hamper the cyclability of LMBs, resulting in a severe decline in plating/stripping reversibility and short‐circuit hazards due to the dendritic growth. Such performance degradation becomes more pronounced with decreasing temperature, ascribing to sluggish ion transport kinetics during charging/discharging processes which includes Li+ solvation/desolvation, ion transport through bulk electrolyte, as well as ion diffusion within solid electrolyte interphase and bulk electrode materials at low temperature. In this review, the critical limiting factors and challenges for low‐temperature ion transport behaviors are systematically reviewed and discussed. The strategies to enhance Li+ transport kinetics in electrolytes, electrodes, and electrolyte/electrode interface are comprehensively summarized. Finally, perspective on future research direction of low‐temperature LMBs toward practical applications is proposed.

A High‐Efficiency Mo2C Electrocatalyst Promoting the Polysulfide Redox Kinetics for Na–S Batteries

Abstract: Room‐temperature sodium–sulfur (RT Na–S) batteries, as promising next‐generation energy storage candidates, are drawing more and more attention due to the high energy density and abundant elements reserved in the earth. However, the native downsides of RT Na‐S batteries (i.e., enormous volume changes, the polysulfide shuttle, and the insulation and low reactivity of S) impede their further application. To conquer these challenges, hierarchical porous hollow carbon polyhedrons embedded with uniform Mo2C nanoparticles are designed deliberately as the host for S. The micro‐ and mesoporous hollow carbon indeed dramatically enhances the reactivity of the S cathodes and accommodates the volume changes. Meanwhile, the highly conductive dispersed Mo2C has a strong chemical adsorption to polysulfides and catalyzes the transformation of polysulfides, which can effectively inhibit the dissolution of polysulfides and accelerate the reaction kinetics. Thus, the as‐prepared S cathode can display a high reversible capacity (1098 mAh g−1 at 0.2 A g−1 after 120 cycles) and superior rate performance (483 mAh g−1 at 10.0 A g−1). This work provides a new method to boost the performance of RT Na–S batteries.

Anion Reinforced Solvation for Gradient Inorganic-Rich Interphase Enables High-Rate and Stable Sodium Batteries.

Abstract: Metallic Na is a promising anode for rechargeable batteries, however, it is plagued by unstable solid electrolyte interphase (SEI) and Na dendrites. Herein, a robust anion-derived SEI is constructed on Na anode in high-concentration 1,2-dimethoxyethane (DME) based electrolyte with a cosolvent hydrofluoroether, which effectively restrain Na dendrite growth. The hydrofluoroether can tune the solvation configuration of the electrolyte from three-dimensional network aggregates to solvent-cation-anion clusters, enabling more anions to enter and reinforce the inner solvation sheath and their step-wise decomposition. The gradient inorganic-rich SEI leads to reduced energy barrier of Na+ migration and enhanced interfacial kinetics. These render the Na||Na3V2(PO4)3 battery with excellent rate capability of 79.9 mAh g-1 at 24C and high capacity retention of 94.2% after 6000 cycles at 1C. This highlights modulation of the electrode-electrolyte interphase chemistry for advanced batteries.