Search NASA⌕ Search

Engineering topics

Xu, Yaobin

Publications and source records attributed to Xu, Yaobin.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Nanoengineering of non-aqueous liquid electrolyte solutions for future lithium metal batteries

Research and development of non-aqueous electrolyte solutions are essential for practical advancement towards the production of high-energy lithium metal batteries (LMBs). An ideal LMB electrolyte solution should enable highly efficient, uniform and prolonged lithium metal plating and stripping, preserve the electrodes’ electro(chemo)mechanical properties and ensure compatibility with all cell components. However, despite extensive research efforts, scientists have yet to achieve an electrolyte design that meets these requirements simultaneously. Here, by examining the nanoengineering aspects of various non-aqueous electrolyte solution designs, we elucidate the understanding of the nanoscale physicochemical and electrochemical processes taking place in LMBs, which are mainly governed by the thermodynamic and kinetic properties of the electrolyte system. We also explore emerging research directions and propose an accelerated, iterative framework that integrates nanoengineering principles with machine learning, high-throughput computation and experimentation to facilitate the development of next-generation non-aqueous electrolyte solutions for practical LMBs.

Weintz, Dominik↗
DOE OSTI2024

Hybrid polymer network cathode-enabled soluble-polysulfide-free lithium–sulfur batteries

Among the emerging 'beyond lithium-ion' technologies for maximized sustainability, lithium-sulfur (Li-S) is a favoured chemistry because of its exceptional energy density from the conversion of sulfur, an element in abundant supply. However, the dissolution of several intermediate polysulfides formed during conversion leads to rapid performance degradation over cycling. Here, in this study, we address this issue by sulfurizing a hybrid polymer network with polyphosphazene and carbon as a cathode for Li-S batteries. With rich sites to re-bond and adsorb dissociative sulfur species, this hybrid polymer network circumvents the formation of soluble polysulfides and enables a unique, reversible inserting conversion reaction. Thus, our cathode delivers both high capacity (~900 mAh g -1 cathode ) and excellent cycling stability in Li-S coin cells, with a pouch cell demonstration of projected energy density of ~300 Wh kg -1 and 84.9% capacity retention after 150 cycles. The strategy can be extended to other cost-effective, recyclable polymers, advancing sulfur-based batteries towards practical energy storage application.

25 ENERGY STORAGE↗
DOE OSTI2024

Assessing cathode–electrolyte interphases in batteries

The cathode-electrolyte interphase plays a pivotal role in determining the usable capacity and cycling stability of electrochemical cells, yet it is overshadowed by its counterpart, the solid-electrolyte interphase. This is primarily due to the prevalence of side reactions, particularly at low potentials on the negative electrode, especially in state-of-the-art Li-ion batteries where the charge cutoff voltage is limited. However, as the quest for high-energy battery technologies intensifies, there is a pressing need to advance the study of cathode-electrolyte interphase properties. Here, we present a comprehensive approach to analyse the cathode-electrolyte interphase in battery systems. We underscore the importance of employing model cathode materials and coin cell protocols to establish baseline performance. Additionally, we delve into the factors behind the inconsistent and occasionally controversial findings related to the cathode-electrolyte interphase. In conclusion, we also address the challenges and opportunities in characterizing and simulating the cathode-electrolyte interphase, offering potential solutions to enhance its relevance to real-world applications.

25 ENERGY STORAGE↗
DOE OSTI2024

Enhancing Cycling Stability of Lithium Metal Batteries by a Bifunctional Fluorinated Ether

Abstract The lifespan of lithium (Li) metal batteries (LMBs) can be greatly improved by the formation of inorganic‐rich electrode‐electrolyte interphases (EEIs) (including solid‐electrolyte interphase on anode and cathode‐electrolyte interphase on cathode). In this work, a localized high‐concentration electrolyte containing lithium bis(fluorosulfonyl)imide (LiFSI) salt, 1,2‐dimethoxyethane (DME) solvent and 1,2‐bis(1,1,2,2‐tetrafluoroethoxy)ethane (BTFEE) diluent is optimized. BTFEE is a fluorinated ether with weakly‐solvating ability for LiFSI so it also acts as a co‐solvent in this electrolyte. It can facilitate anion decomposition at electrode surfaces and promote the formation of more inorganic‐rich EEI layers. With an optimized molar ratio of LiFSI:DME:BTFEE = 1:1.15:3, LMBs with a high loading (4 mAh cm −2 ) lithium nickel manganese cobalt oxide (LiNi 0.8 Mn 0.1 Co 0.1 ) cathode can retain 80% capacity in 470 cycles when cycled in a voltage range of 2.8–4.4 V. The fundamental understanding on the functionality of BTFEE revealed in this work provides new perspectives on the design of practical high‐energy density battery systems.

25 ENERGY STORAGE↗
DOE OSTI2024

Synergetic Dual‐Additive Electrolyte Enables Highly Stable Performance in Sodium Metal Batteries

Sodium (Na)-metal batteries (SMBs) are considered one of the most promising candidates for the large-scale energy storage market owing to their high theoretical capacity (1,166 mAh g -1 ) and the abundance of Na raw material. However, the limited stability of electrolytes still hindered the application of SMBs. Herein, sulfolane (Sul) and vinylene carbonate (VC) are identified as effective dual additives that can largely stabilize propylene carbonate (PC)-based electrolytes, prevent dendrite growth, and extend the cycle life of SMBs. The cycling stability of the Na/NaNi 0.68 Mn 0.22 Co 0.1 O 2 (NaNMC) cell with this dual-additive electrolyte is remarkably enhanced, with a capacity retention of 94% and a Coulombic efficiency (CE) of 99.9% over 600 cycles at a 5 C (750 mA g -1 ) rate. The superior cycling performance of the cells can be attributed to the homogenous, dense, and thin hybrid solid electrolyte interphase consisting of F- and S-containing species on the surface of both the Na metal anode and the NaNMC cathode by adding dual additives. Such unique interphases can effectively facilitate Na-ion transport kinetics and avoid electrolyte depletion during repeated cycling at a very high rate of 5 C. This electrolyte design is believed to result in further improvements in the performance of SMBs.

25 ENERGY STORAGE↗
DOE OSTI2024

Regenerative Solid Interfaces Enhance High-Performance All- Solid-State Lithium Batteries

All-solid-state Lithium batteries (ASSLBs) have gained widespread attention in recent years. However, their performance is still largely limited by the poor transport properties and stability of the solid-solid interfaces (SSIs). In this study, we report a new strategy for creating a reversible interface with good conductivity and self-adaptive mechanical properties for high-performance all-solid-state lithium batteries (ASSLBs). The interface is formed in situ from nanosized lithium iodide (LiI), a component of the solid-state electrolyte (SSE), which flows plastically along the SSE interfaces under high pressure due to its high ductility. Moreover, LiI segregates and enriches along the Li/SSE interfaces, reversibly enhancing Li plating/stripping due to its lithophilicity and high ionic conductivity. This dynamic LiI interface enables stable operation of metallic Li anode (>1000 h) at high current densities and elevated temperatures, and long-term cycling of all-solid-state Li-sulfur batteries (>250 cycles) with high sulfur utilization rate (>1400 mAh g-1) and areal capacity (>2 mAh cm-2). This study reveals a unique role of LiI in building robust SSIs and provides new insights into the design of novel SSEs and interfaces for high-performance ASSLBs.

Yu, Zhaoxin↗
DOE OSTI2024

Extending Calendar Life of Si-Based Lithium-Ion Batteries by a Localized High Concentration Electrolyte

Silicon (Si) is one of the most promising anode materials for the next generation lithium-ion batteries (LIBs). Although significant progresses have been made on the cycle life of Si-based LIBs, their calendar-life is still far less than those required for electrical vehicle applications. Here, in this work, the fundamental mechanisms behind the limited calendar life of Si-LIBs have been investigated. It is found that the unstable interphase layers formed on electrodes during the formation/cycling of batteries using conventional electrolyte with fluoroethylene carbonate (FEC) additive are responsible for the rapid impedance-increase of Si-LIBs during storage at elevated temperature (55°C). By using an FEC-free localized high concentration electrolyte (lithium bis(fluorosulfonyl)imide:ethyl propionate:ethylene carbonate:1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (1:2.8:0.2:1 by mol.) with 1 wt.% lithium difluorophosphate), stable interphase layers formed on electrodes can effectively block the crosstalk between cathode and anode, minimize the impedance increase of Si||LiNi 0.6 Mn 0.2 Co 0.2 (NMC622) batteries during storage at elevated temperature (55°C), therefore largely improve their calendar life. Si||NMC622 batteries using this electrolyte also demonstrated a high-capacity retention of ~92.4% after 500 cycles at 45°C with well-preserved electrode structure. Hence, this novel electrolyte is a good candidate to extend the cycling life and calendar life of Si-LIBs.

25 ENERGY STORAGE↗
DOE OSTI2024

Controlled large-area lithium deposition to reduce swelling of high-energy lithium metal pouch cells in liquid electrolytes

Lithium (Li) metal battery technology, renowned for its high energy density, faces practical challenges, particularly concerning large volume change and cell swelling. Despite the profound impact of external pressure on cell performance, there is a notable gap in research regarding the interplay between external pressure and the electroplating behaviours of Li+ in large-format pouch cells. Here we delve into the impact of externally applied pressure on electroplating and stripping of Li in 350 Wh kg –1 pouch cells. Employing a hybrid design, we monitor and quantify self-generated pressures, correlating them with observed charge–discharge processes. A two-stage cycling process is proposed, revealing controlled pouch cell swelling of less than 10%, comparable to state-of-the-art Li-ion batteries. Finally, the pressure distribution across the cell surface unveils a complex Li+ detour behaviour during electroplating, highlighting the need for innovative strategies to address uneven Li plating and enhance Li metal battery technology.

25 ENERGY STORAGE↗
DOE OSTI2023

Direct in situ measurements of electrical properties of solid–electrolyte interphase on lithium metal anodes

The solid–electrolyte interphase (SEI) critically governs the performance of rechargeable batteries. An ideal SEI is expected to be electrically insulative to prevent persistently parasitic reactions between the electrode and the electrolyte and ionically conductive to facilitate Faradaic reactions of the electrode. However, the true nature of the electrical properties of the SEI remains hitherto unclear due to the lack of a direct characterization method. Here we use in situ bias transmission electron microscopy to directly measure the electrical properties of SEIs formed on copper and lithium substrates. We reveal that SEIs show a voltage-dependent differential conductance. A higher rate of differential conductance induces a thicker SEI with an intricate topographic feature, leading to an inferior Coulombic efficiency and cycling stability in Li||Cu and Li||LiNi 0.8 Mn 0.1 Co 0.1 O 2 cells. Further, our work provides insight into the targeted design of the SEI with desired characteristics towards better battery performance.

25 ENERGY STORAGE↗
DOE OSTI2023

Dynamic Molecular Investigation of the Solid-Electrolyte Interphase of an Anode-Free Lithium Metal Battery Using In Situ Liquid SIMS and Cryo-TEM

Solid electrolyte interphase (SEI) has been widely perceived to play a critical role in the stable cycling of rechargeable batteries. However, associated with the fragile and air-sensitive nature of the SEI layer, delineation of the formation process and the nature of SEI remains a big challenge. Here, we use in situ liquid time-of-flight secondary ion mass spectroscopy (TOF-SIMS), cryo- transmission electron microscope (TEM) and density functional theory (DFT) calculation to delineate molecular process on the formation of SEI layer under the dynamic operating condition. We discover that the onset potential for SEI layer formation and the thickness of the SEI show dependence on the solvation shell structure. Using LiCoO 2 as a cathode and Cu film as an anode, the SEI is noticed to start to form at around 2.0 V and reach its final thickness (irreversible part, ~ 40-50 nm) at about 3.0 V in the 1 M LiPF 6 –EC/DMC electrolyte, while for the case of 1 M LiFSI–DME, the SEI starts to form at around 1.5 V and reaches its final thickness (~ 20 nm) at about 2.0 V. The in situ TOF-SIMS clearly indicates the outer SEI layer formation and dissipation upon charging and discharging, implying a continued evolution of electrolyte structure with extended cycling. In conclusion, the present work establishes a direct correlation between the molecular signature of SEI layer with solvation feature of electrolytes in lithium batteries, providing insights for tailoring SEI layer toward improved electrochemical properties of lithium batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Simultaneous Single Crystal Growth and Segregation of Ni-Rich Cathode Enabled by Nanoscale Phase Separation for Advanced Lithium-Ion Batteries

Here, a novel nanoscale phase separation process has been discovered to promote the growth and segregation of single-crystal LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811). This process occurs directly during high-temperature calcination without significant agglomeration. The key lies in converting transition metal hydroxide (TM(OH) 2 ) precursors with well-controlled morphology into transition metal oxide (TMO) intermediates before reacting them with lithium salt. The nanoscale redistribution of Ni in TMO, resulting from the concurrent formation of spinel and rock salt phases, helps to deagglomerate the clusters of later-formed NMC811 crystals. The as-prepared single-crystal NMC811 is further validated in a 2Ah pouch cell, demonstrating 1,000 stable cycles. The fundamentally new reaction mechanism of single-crystal growth and segregation provides a new direction for large-scale synthesis of a broad range of single crystals for advanced energy storage.

25 ENERGY STORAGE↗
DOE OSTI2023

Designing Electrolytes With Controlled Solvation Structure for Fast‐Charging Lithium‐Ion Batteries

Recharging battery-powered electric vehicles (EVs) in a similar timeframe as those used for refueling gas-powered internal combustion vehicles is highly desirable for rapid penetration of the EV market. It is well known that the electrolyte in a battery plays a critical role in fast-charging capability of the battery because it determines the rate of ion transport together with its derived electrode/electrolyte interphases on both cathode and anode of the battery. In this study, the effects of contents of salt, coordinating solvent, and noncoordinating diluent on salt dissociation degree and electrolyte ionic conductivity are investigated, and a controlled solvation structure electrolyte is developed to improve the lithium ion mobility and conductivity in the electrolyte and to enhance the kinetics and stability of the electrode/electrolyte interphases in the battery. This electrolyte enables fast-charging capability of high energy density lithium-ion batteries (LIBs) at up to 5 C rate (12-min charging), which significantly outperforms the state-of-the-art electrolyte. The controlled solvation structure sheds light on the future electrolyte design for fast-charging LIBs.

25 ENERGY STORAGE↗
DOE OSTI2023

In Situ Visualization of the Pinning Effect of Planar Defects on Li Ion Insertion

Longevity of Li ion batteries strongly depends on the interaction of transporting Li ions in electrode crystals with defects. However, detailed interactions between the Li ion flux and structural defects in the host crystal remain obscure due to the transient nature of such interactions. Here, by in situ transmission electron microscopy and density function theory calculations, we reveal how the diffusion pathways and transport kinetics of a Li ion can be affected by planar defects in a tungsten trioxide lattice. We uncover that changes in charge distribution and lattice spacing along the planar defects disrupt the continuity of ion conduction channels and dramatically increase the energy barrier of Li diffusion, thus, arresting Li ions at the defect sites and twisting the lithiation front. In conclusion, the atomic-scale understanding holds critical implications for rational interface design in solid-state batteries and solid oxide fuel cells.

25 ENERGY STORAGE↗
DOE OSTI2023

A Systematic Study on the Effects of Solvating Solvents and Additives in Localized High‐Concentration Electrolytes over Electrochemical Performance of Lithium‐Ion Batteries

Abstract Localized high‐concentration electrolytes (LHCEs) based on five different types of solvents were systematically studied and compared in lithium (Li)‐ion batteries (LIBs). The unique solvation structure of LHCEs promotes the participation of Li salt in forming solid electrolyte interphase (SEI) on graphite (Gr) anode, which enables solvents previously considered incompatible with Gr to achieve reversible lithiation/delithiation. However, the long cyclability of LIBs is still subject to the intrinsic properties of the solvent species in LHCEs. Such issue can be readily resolved by introducing a small amount of additive into LHCEs. The synergetic decompositions of Li salt, solvating solvent and additive yield effective SEIs and cathode electrolyte interphases (CEIs) in most of the studied LHCEs. This study reveals that both the structure and the composition of solvation sheaths in LHCEs have significant effect on SEI and CEI, and consequently, the cycle life of energetically dense LIBs.

Jia, Hao↗
DOE OSTI2023

A Systematic Study on the Effects of Solvating Solvents and Additives in Localized High‐Concentration Electrolytes over Electrochemical Performance of Lithium‐Ion Batteries

Abstract Localized high‐concentration electrolytes (LHCEs) based on five different types of solvents were systematically studied and compared in lithium (Li)‐ion batteries (LIBs). The unique solvation structure of LHCEs promotes the participation of Li salt in forming solid electrolyte interphase (SEI) on graphite (Gr) anode, which enables solvents previously considered incompatible with Gr to achieve reversible lithiation/delithiation. However, the long cyclability of LIBs is still subject to the intrinsic properties of the solvent species in LHCEs. Such issue can be readily resolved by introducing a small amount of additive into LHCEs. The synergetic decompositions of Li salt, solvating solvent and additive yield effective SEIs and cathode electrolyte interphases (CEIs) in most of the studied LHCEs. This study reveals that both the structure and the composition of solvation sheaths in LHCEs have significant effect on SEI and CEI, and consequently, the cycle life of energetically dense LIBs.

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

Tracking the Oxidation of Silicon Anodes Using Cryo-EELS upon Battery Cycling

Silicon is a high-capacity material for the anode of a rechargeable lithium-ion battery. One of the fundamental challenges for using Si in anodes is capacity fading, which has been revealed to be partially associated with the interfacial instability between the Si and liquid electrolyte due to the large volume swing of Si upon charging and discharging. Smart nanoscale design concepts, either pre-synthesized or formed in-situ, have led to the mitigation of the detrimental factors associated with the volume swing of Si. However, it has never been clear as how the chemical state of Si evolves and contributes to the capacity fading upon battery cycling. Here, we use cryo-electron energy loss spectroscopy (EELS) to directly monitor, at sub-nanometer scale, the chemical evolution of Si upon battery cycling. We discover that during the cycling process, Si particles are progressively oxidized to form SiO 2 , which is initiated from the particle surface and gradually penetrates toward the interior of the particle, directly contributing to the capacity fading. Possible mechanisms of Si oxidation are postulated. We further show how the cycling stability can be improved by an electrolyte additive to form an effective passivation layer, representatively, even a small concentration of fluoroethylene carbonate (FEC) causes the formation of an LiF layer on the Si nanoparticle surface that prevents Si oxidation and improves cycling stability. Furthermore, the present work unveils Si oxidation as a previously unrecognized factor that contributes to capacity fading, therefore providing insight into the design of anodes with Si based materials.

25 ENERGY STORAGE↗