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Sun, Yipeng

Publications and source records attributed to Sun, Yipeng.

8 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

A Dual Anion Chemistry-Based Superionic Glass Enabling Long-Cycling All-Solid-State Sodium-Ion Batteries

Glassy Na-ion solid-state electrolytes (GNSSEs) are an important group of amorphous SSEs. However, the insufficient ionic conductivity of state-of-the-art GNSSEs at room temperature lessens their promise in the development of all-solid-state Na-ion batteries (ASSNIBs) with high energy density and improved safety. Here we report the discovery of a new sodium superionic glass, 0.5Na 2 O 2 -TaCl 5 (NTOC), based on dual-anion sublattice of oxychlorides. The unique local structures with abundant bridging and non-bridging oxygen atoms contributes to a highly disordered Na-ion distribution as well as low Na + migration barrier within NTOC, enabling an ultrahigh ionic conductivity of 4.62 mS cm −1 at 25 °C (more than 20 times higher than those of previously reported GNSSEs). Moreover, the excellent formability of glassy NTOC electrolyte and its high electrochemical oxidative stability ensure a favourable electrolyte-electrode interface, contributing to superior cycling stability of ASSNIBs for over 500 cycles at room temperature. The discovery of glassy NTOC electrolyte would reignite research enthusiasm in superionic glassy SSEs based on multi-anion chemistry.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Porosity Development at Li-Rich Layered Cathodes in All-Solid-State Battery during In Situ Delithiation

Structural evolutions are crucial for determining the performance of high-voltage lithium, manganese-rich layered cathodes. Moreover, interface between electrode and electrolyte plays a critical role in governing ionic transfer in all-solid-state batteries. In this work, we unveil two different types of porous structure in Li 1.2 Ni 0.2 Mn 0.6 O 2 cathode with LiPON solid-state electrolyte. Na-nopores are found near the cathode/electrolyte interface at pristine state, where cation mixing, phase transformation, oxygen loss and Mn reduction are also found. In situ Li + extraction induces the evolution of nanovoids, initially formed near the inter-face then propagated into the bulk. Despite the development of nanovoids, layered structure is conserved, suggesting the nature of nanopores and nanovoids are different and their impact would be divergent. This work demonstrates the intrinsic interfacial layer, as well as the dynamic scenario of nanovoid formation inside high-capacity layered cathode, which help understanding the performance fading in cathodes and offer insights into the all-solid-state battery design.

25 ENERGY STORAGE↗
DOE OSTI2022

Designing Ceria/Alumina for Efficient Trapping of Platinum Single Atoms

Cerium oxide (ceria) has been shown to be very effective at trapping platinum atoms, due to formation of stable surface complexes at step edges, where coordinatively unsaturated cerium cations are present. But ceria loses its effectiveness when heated to high temperatures, due to loss of surface area and growth in particle size associated with sintering of the oxide. Being a rare-earth, and with limited supplies worldwide, it is important to develop methods to improve the effectiveness of ceria as a catalyst support. Here we explore the performance for trapping Pt atoms when the ceria is supported on a high surface area alumina carrier. This helps create a more sustainable catalyst formulation, especially if we can retain the high dispersion of Pt seen on ceria supports. For this work, we studied the atom trapping efficacy of ceria/alumina samples with increasing ceria content (8 wt% - 50%) and contrasted the behavior with pure ceria. Electron microscopy reveals that when dispersed on alumina, ceria is present in the form of crystalline nanoparticles as well as isolated cerium ions. These two forms of ceria differ markedly in their ability to trap Pt atoms. Atomically dispersed cerium is present in the form of Ce 3+ cations on alumina, however this form of ceria is not effective for trapping Pt atoms. Our results show that the atom trapped Pt resides primarily on crystalline ceria nanoparticles. CO oxidation was used as a probe reaction to evaluate the performance of these Pt AT /ceria-alumina catalysts. As a result, we conclude that over the range of ceria loadings we investigated, 50% ceria/alumina represents the optimal catalyst support for achieving high surface area and atom trapping efficiency while helping reduce the total ceria content in this catalyst system.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Deciphering Interfacial Chemical and Electrochemical Reactions of Sulfide-Based All-Solid-State Batteries

Large interfacial resistance resulting from interfacial reactions is widely acknowledged as one of the main challenges in sulfide electrolytes (SEs)-based all-solid-state lithium batteries (ASSLBs). However, the root cause of the large interfacial resistance between the SEs and typical layered oxide cathodes is not fully understood yet. Here we deciphered that interfacial oxygen loss from single-crystal LiNi 0.5 Mn 0.3 Co 0.2 O 2 (SC-NMC532) chemically oxidizes Li 10 GeP 2 S 12 , generating oxygen-containing interfacial species. Meanwhile, the interfacial oxygen loss also induces a structural change of oxide cathodes (layered-to-rocksalt). Besides, the high operation voltage can electrochemically oxidize SEs to form non-oxygen species (e.g. polysulfides). These chemically and electrochemically oxidized species, together with the interfacial structural change, are responsible for the large interfacial resistance at the cathode interface. More importantly, the widely adopted interfacial coating strategy is effective in suppressing chemically oxidized oxygen-containing species and mitigating the coincident interfacial structural change but is unable to prevent electrochemically induced non-oxygen species. These findings provide a deeper insight into the large interfacial resistance between the typical SE and layered oxide cathodes, which may be of assistance for the rational interface design of SE-based ASSLBs in future.

25 ENERGY STORAGE↗
DOE OSTI2021

Atomic/molecular layer deposition for energy storage and conversion

Energy storage and conversion systems, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting, have played vital roles in the reduction of fossil fuel usage, addressing environmental issues and the development of electric vehicles. The fabrication and surface/interface engineering of electrode materials with refined structures are indispensable for achieving optimal performances for the different energy-related devices. Atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques, the gas-phase thin film deposition processes with self-limiting and saturated surface reactions, have emerged as powerful techniques for surface and interface engineering in energy-related devices due to their exceptional capability of precise thickness control, excellent uniformity and conformity, tunable composition and relatively low deposition temperature. In the past few decades, ALD and MLD have been intensively studied for energy storage and conversion applications with remarkable progress. In this work, we give a comprehensive summary of the development and achievements of ALD and MLD and their applications for energy storage and conversion, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting. Moreover, the fundamental understanding of the mechanisms involved in different devices will be deeply reviewed. Furthermore, the large-scale potential of ALD and MLD techniques is discussed and predicted. Finally, we will provide insightful perspectives on future directions for new material design by ALD and MLD and untapped opportunities in energy storage and conversion.

25 ENERGY STORAGE↗
DOE OSTI2020

Stabilizing and understanding the interface between nickel-rich cathode and PEO-based electrolyte by lithium niobium oxide coating for high-performance all-solid-state batteries

The pursuit of high energy density and safe lithium ion batteries (LIBs) is the urgent goal for the development of next-generation electric vehicles (EVs). All-solid-state batteries (ASSBs) with the combination of poly(ethylene oxide) (PEO)-based solid polymer electrolyte (SPE) and Ni-rich lithium nickel manganese cobalt oxide LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode are promising candidates for EVs due to their improved energy density and safety. However, the low electrochemical oxidation window of PEO-based SPE and the instability of NMC811 at the charge/discharge process seriously restrict the battery performance. Herein, a high voltage stable solid-state electrolyte layer lithium niobium oxide (LNO) is coated on the NMC811 electrode surface by atomic layer deposition for stabilizing NMC811-PEO solid polymer batteries. Electrochemical tests show that LNO coating can stabilize the NMC811 active materials and mitigate the decomposition of SPE upon the cycling process, rendering a good performance of NMC811-PEO solid polymer battery. Mechanism studies by SEM, STEM, XAS, and XPS disclose that the uncoated NMC811 suffers from chemomechanical degradations along with oxygen release triggering the decomposition of SPE, which results in unstable cathodic electrolyte interphase. With LNO coating, chemomechanical degradations and oxygen release are inhibited and the decomposition of SPE is mitigated. This paper renders a stable and high-performance high-energy-density SSB for high voltage application, which paves the way toward next-generation solid-state LIBs.

25 ENERGY STORAGE↗
DOE OSTI2020

Single crystal cathodes enabling high-performance all-solid-state lithium-ion batteries

All-solid-state lithium-ion batteries (ASSLIBs) are receiving significant attention owing to their improved safety and energy density over liquid counterparts. However, single-crystal cathodes have never been investigated in ASSLIBs. In this work, single-crystal Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 (SC-NMC532) is used as the cathode material for ASSLIBs, which exhibits 6~14 times higher Li + diffusion coefficient than polycrystalline Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 (PC-NMC532). As a result, SC-NMC532 exhibits an initial specific capacity of 156.4 mAh.g -1 while PC-NMC532 shows an initial capacity of only 127.5 mAh.g -1 . After 150 cycles, SC-NMC532 retains the capacity of 94.5 mAh.g -1 . More impressively, under a high current density of 1.3 mA.cm -2 , SC-NMC532 exhibits a capacity of 82 mAh.g -1 , much higher than that of PC-NMC532 (2.1 mAh.g -1 ). This work demonstrates that single-crystal NMC cathodes could enable both high power density and high energy density of ASSLIBs.

25 ENERGY STORAGE↗