Engineering topics

He, Xiangming

Publications and source records attributed to He, Xiangming.

At least 19 records

DOE OSTI2024

Insight of Synthesis of Single Crystal Ni-Rich LiNi 1-x-y Co x Mn y O 2 Cathodes

Single-crystal Ni-rich LiNi 1-x-y Co x Mn y O 2 (NCM) cathodes have garnered widespread attention in the lithium-ion battery community due to their unique advantages in mechanical performance and their ability to minimize interfacial electrochemical side reactions. The synthesis of single-crystal materials with monodisperse and appropriate size, minimal lattice defects, and highly ordered structures is the key for high-performance batteries. However, achieving this goal poses challenges due to the lack of in-depth understanding regarding specific experimental parameters and the solid reaction mechanism during the synthesis process. Further, in this review, the aim is to provide an in-depth analysis of the critical process parameters involved in the synthesis and their impact on crystal morphology, structure, and electrochemical performance. Consequently, the first section focuses on the effect of the precursor morphology, lithium salt, atmosphere, and sintering procedure. In the second section, the study delves into an in-depth discussion of the solid reaction and crystal growth mechanism. Lastly, it is concluded by highlighting the prospects and challenges associated with the synthesis and application of single-crystal Ni-rich NCM cathodes.

25 ENERGY STORAGE↗

DOE OSTI2023

Challenges and Prospects of All-Solid-State Electrodes for Solid-State Lithium Batteries

In the development of all-solid-state lithium batteries (ASSLB), progress is made with solid-state electrolytes; however, challenges regarding compatibility and stability still exist with solid electrodes. These issues result in a low battery capacity and short cycle life, which limit the commercial application of ASSLBs. Here, this review summarizes the recent research progress on solid-state electrodes in ASSLBs including the solid–solid interface phenomena such as the interface between electrode materials and electrolytes. The mechanical stability problems in solid electrodes, including fracture, brittleness, and deformation of electrode materials, are also discussed, and corresponding methods to measure the solid electrode stress are provided. In addition, strategies for mitigating stress-related issues are examined. Finally, the fabrication process of solid electrodes is introduced and their future developments, including the exploration of new electrode materials and the design of more intelligent electrode structures, are proposed.

25 ENERGY STORAGE↗

DOE OSTI2023

Unveiling the parasitic-reaction-driven surface reconstruction in Ni-rich cathode and the electrochemical role of Li 2 CO 3

Nickel-rich transition-metal oxides are widely regarded as promising cathode materials for high-energy-density lithium-ion batteries for emerging electric vehicles. However, achieving high energy density in Ni-rich cathodes is accompanied by substantial safety and cycle-life obstacles. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions towards surface reconstructions of cathode materials is not well understood. In this work, we controlled the Li 2 CO 3 impurity content on LiNi 0.83 Mn 0.1 Co 0.07 O 2 cathodes using air, tank-air, and O 2 synthesis environments. Home-built high-precision leakage current and on-line electrochemical mass spectroscopy experiments verify that Li 2 CO 3 impurity is a significant promoter of parasitic reactions on Ni-rich cathodes. The rate of parasitic reactions is strongly correlated to Li 2 CO 3 content and severe performance deterioration of Ni83 cathodes. The post-mortem characterizations via high-resolution transition electron microscope and X-ray photoelectron spectroscopy depth profiles reveal that parasitic reactions promote more Ni reduction and O deficiency and even rock-salt phase transformation at the surface of cathode materials. Here, our observation suggests that surface reconstructions have a strong affiliation to parasitic reactions that create chemically acidic environment to etch away the lattice oxygen and offer the electrical charge to reduce the valence state of transition metal. Thus, this study advances our understanding on surface reconstructions of Ni-rich cathodes and prepares us for searching for rational strategies.

36 MATERIALS SCIENCE↗

DOE OSTI2023

Cathode regeneration and upcycling of spent LIBs: toward sustainability

‘Green ambition towards sustainability’ is one of the hot research topics of the 21st century. With the sharp steering of the energy infrastructure toward fulfilling this radical expectation, the last decade has seen a global trend toward diversified sustainable renewable energy sources (such as solar, wind, and hydroelectric power) and electrification. Lithium-ion batteries (LIBs) are playing a significant role in this energy revolution. However, with the massive scale of the production of LIBs and their eventual retirement, attention has been turned to the erratic supply of raw materials used to manufacture these batteries and their disposal. Cathode regeneration technology is likely to be an optimal solution for the disposal of waste cathodes, aimed at non-destructively repairing and straightforwardly reusing degraded cathode materials for re-manufacturing LIBs with a shortened circular process, reasonable profits, and excellent efficiency. Additionally, cathode upcycling technology, aimed at upgrading the electrochemical performance of degraded materials, can be well adapted to the upgrading of battery chemistry and show excellent flexibility and potential for transforming the LIB industry from a resource-based to a circular economy. Thus, a holistic perspective based on the complete life cycle of LIBs is encouraged, and sustainability must be at the forefront regarding battery and pack design, raw material acquisition, materials synthesis, manufacturing, operating, retiring, and recycling processes of LIBs.

25 ENERGY STORAGE↗

DOE OSTI2023

Rational synthesis of high-performance Ni-rich layered oxide cathode enabled via probing solid-state lithiation evolution

Lithium (Li)-ion batteries using nickel (Ni)-rich layered oxide cathode have been pursued with interest due to high practical energy density. A fundamental understanding of the reaction pathways and structural evolution of the solid-phase synthesis of these materials is crucial for their rational design and process development for mass production. In this work, structural evolution during solid-state synthesis was traced via in situ technique, with a particular emphasis on the lithiation reaction and migration of transition metal (TM) ions. The sintering process is governed by the competitive relationship of decomposition and lithiation reactions, which can be regulated through temperature windows. Controlling the melting point of the Li sources, as well as their affinity to cathode precursors, is highly desired to maintain the layered ordering of TM ions throughout the whole synthesis process, which simplifies the manufacturing process and improves the quality of the manufactured cathode material.

25 ENERGY STORAGE↗

DOE OSTI2023

Incombustible Polymer Electrolyte Boosting Safety of Solid–State Lithium Batteries: A Review

Lithium-ion batteries with their portability, high energy density, and reusability are frequently used in today's world. Under extreme conditions, lithium-ion batteries leak, burn, and even explode. Therefore, improving the safety of lithium-ion batteries has become a focus of attention. Researchers believe using a solid electrolyte instead of a liquid one can solve the lithium battery safety issue. Due to the low price, good processability and high safety of the solid polymer electrolytes, increasing attention have been paid to them. However, polymer electrolytes can also decompose and burn under extreme conditions. Moreover, lithium dendrites are formed continuously due to the uneven charge distribution on the surface of the lithium metal anode. A short circuit caused by a lithium dendrite can cause the battery to thermal runaway. As a result, the safety of polymer solid-state batteries remains a challenge. In this review, the thermal runaway mechanism of the batteries is summarized, and the batteries abuse test standard is introduced. In addition, the recent works on the high-safety polymer electrolytes and the solution strategies of lithium anode problems in polymer batteries are reviewed. Finally, the development direction of safe polymer solid lithium batteries is prospected.

25 ENERGY STORAGE↗

DOE OSTI2023

Safety perceptions of solid-state lithium metal batteries

Safety concerns hamper the wide application of lithium-ion batteries (LIBs) in the fields of electric vehicles and stationary energy storage. As the blame of the battery thermal runway was widely cast on the flowable, volatile, and flammable nature of liquid organic electrolytes, solid-state lithium batteries with solid and nonflammable electrolytes are highly praised for potentially better safety characteristics. Furthermore, solid-state lithium metal batteries (SS-LMBs) may become an ultimate solution for safe, high-energy density batteries. Whether SS-LMBs are safe enough to meet emerging demands remains unclear, as recent publications have presented serious safety concerns at both the material and device levels. In conclusion, this review summarizes recent investigations into SS-LMB safety, and systematic analysis and discussion are provided in this discussion of the safety concerns of SS-LMBs.

25 ENERGY STORAGE↗

DOE OSTI2022

Ultrahigh rate capability of manganese based olivine cathodes enabled by interfacial electron transport enhancement

In this study, manganese-based Olivine is a promising cathode candidate with high energy and low cost for Li-ion batteries (LIBs). Its rate capability and cyclability challenges still remain even with nano-size and carbon coating. Herein, an ultrahigh rate performance is achieved by introducing an affinitive conductor to enhance the interfacial electron transport of LiMn 0.7 Fe 0.3 PO 4 via Li 3 V 2 (PO 4 ) 3 . It is found that the Li 3 V 2 (PO 4 ) 3 facilitates sp 2 hybridization to form a highly conductive carbon coating during the carbonized process. The composite 0.9LiMn 0.7 -Fe 0.3 PO 4 .0.1Li 3 V 2 (PO 4 ) 3 can deliver a capacity of 90.9 mAh g -1 and power density of 11444 W kg -1 at 50 C-rate. Both in situ X-ray diffraction and conductive-atomic force microscopy are conducted to understand the synergetic effect between LiMn 0.7 Fe 0.3 PO 4 and Li 3 V 2 (PO 4 ) 3 . The results suggest that the interfacial electron transfer between LiMn 0.2 Fe 0.3 PO 4 particles and the electron conducting medium, such as binder/carbon black composite, is greatly improved so that the highly Li + conductive nature of olivine materials can be fully unleashed. This work demonstrates the importance of efficient interfacial electron transfer to the active cathode particles, and opens up a new venue for the rational design of high-energy and high-power batteries.

25 ENERGY STORAGE↗

DOE OSTI2022

Single-Crystalline Ni-Rich LiNi x Mn y Co 1– x – y O 2 Cathode Materials: A Perspective

To drive electrical vehicles for long-range, the energy density of Li-ion batteries must be further enhanced, which requires high-energy cathode materials. Among them, Ni-rich LiNi x Mn y Co 1–x–y O 2 (x > 0.5, NMC) is one of the most promising candidates. However, traditional poly-crystal (PC) NMC materials, whose particles are secondary clusters consisting of many primary crystalline particles, are susceptible to pulverization along the inter grain/particle boundaries, resulting in poor cycle stability. Recently, single crystal (SC)-NMC cathodes are proposed as they are believed to have several merits such as high structural integrity, lower interface with electrolyte, and potentially better energy storage performance. Nevertheless, several queries, such as the merits of SC structure and the mechanism for their structure degradation, are still controversial and required to be addressed. Here, in this study, the synthesis parameters, properties, energy storage as well as safety of SC- and PC-NMC cathodes with various Ni contents are critically reviewed, for clarifying the merits and drawbacks of SC. Furthermore, the study focuses on the recent advances of insight mechanisms and strategies for stabilizing the structure/interface by doping, morphology engineering, surface coating, and composition tailoring. The remaining challenges, safety concerns, and perspectives to enhance the electrochemical performance of SC-NMC cathodes for electric vehicle application are followed.

25 ENERGY STORAGE↗

DOE OSTI2022

Thermal Runaway of Nonflammable Localized High‐Concentration Electrolytes for Practical LiNi 0.8 Mn 0.1 Co 0.1 O 2 |Graphite‐SiO Pouch Cells

Abstract With continuous improvement of batteries in energy density, enhancing their safety is becoming increasingly urgent. Herein, practical high energy density LiNi 0.8 Mn 0.1 Co 0.1 O 2 |graphite‐SiO pouch cell with nonflammable localized high concentration electrolyte (LHCE) is proposed that presents unique self‐discharge characteristic before thermal runaway (TR), thus effectively reducing safety hazards. Compared with the reference electrolyte, pouch cell with nonflammable LHCE can increase self‐generated heat temperature by 4.4 °C, increase TR triggering temperature by 47.3 °C, decrease the TR highest temperature by 71.8 °C, and extend the time from self‐generated heat to triggering TR by ≈8 h. In addition, the cell with nonflammable LHCE presents superior high voltage cycle stability, attributed to the formation of robust inorganic‐rich electrode–electrolyte interphase. The strategy represents a pivotal step forward for practical high energy and high safety batteries.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Revisiting the initial irreversible capacity loss of LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode material batteries

Layered LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) attracts widespread attention primarily due to its potential for high energy density and moderate thermal stability. However, the low initial coulombic efficiency (ICE) of the material limits the maximum utilization of their capacity. The capacity loss in the first cycle occurs under 4.0V and keep almost constant are considered as common characteristics for NCM-based materials. A clear cognition on the initial capacity loss may light the way to improve the practical reversible capacity of NCM622 at 4.0V. Conducting operando X-ray diffraction during galvanostatic charge/discharge cycling at different temperature (25 degrees C, 45 degrees C and 60 degrees C) and different current (0.1C, 0.01C, 1C=120 mA g -1 ) in the voltage range of 2.7-4.0V, we find that only 8% of the measured initial irreversible capacity loss is associated with parasitic reactions that form cathode/electrolyte interface, and that the dominant contributors include the slow Li + diffusion kinetics (similar to 46% contribution) and irreversible O3/H1-3 phase transition (similar to 46% contribution). Finally, this semi-quantitative study provides new insight on initial capacity loss, guiding further targeted modification and fully utilization of NCM622.

25 ENERGY STORAGE↗

DOE OSTI2022

Targeted masking enables stable cycling of LiNi 0.6 Co 0.2 Mn 0.2 O 2 at 4.6V

Layered LiNi x Co y Mn 1–x-y O 2 (NCM, or NCMxy(1-x-y)) is a dominant family of cathode materials for lithium-ion batteries (LIBs) due to its high energy density. Among all NCM cathode materials, NCM622 possess the optimal energy density at high potential (≥ 4.6 V vs. Li/Li + ). However, the practical application of NCM622 at high voltage (≥ 4.6 V) is limited by its parasitic reactions and associated safety concerns. Completely physical isolation has been considered as the main approach to mitigate the parasitic reaction. It has also been previously demonstrated that the interface reaction has active site selectivity, and that the reactivity of the active sites can effectively suppressed by blocking the chemically active sites. Herein, a targeted masking by LiFePO 4 @C nanoplates is reported to unlock the stable performance of NCM622 up to 4.6 V vs. Li/Li + . The (targeted masked-NCM622)|graphite pouch cell shows 86.5% capacity retention after 1000 cycles and its maximum temperature during thermal runaway is dramatically reduced from 570 °C to 415 °C. Systematic in/ex situ characterizations, first-principles calculations and half/pouch targeted LiFePO 4 @C covers the surface of NCM partcell evaluation prove that PO 4 3- is preferentially adsorbed on transition metal sites, stabilizing both the transition metal ions and oxygen ions on the surface against the ethylene carbonate-containing traditional electrolyte even under high voltage (≥ 4.6 V vs. Li/Li + ). Furthermore, this work opens up new venue for rational design of high-performance cathode materials through a low-cost and scalable decoration process, and reveal a new understanding of interfacial activity of materials.

25 ENERGY STORAGE↗

DOE OSTI2022

Suppressing electrolyte-lithium metal reactivity via Li + -desolvation in uniform nano-porous separator

Lithium reactivity with electrolytes leads to their continuous consumption and dendrite growth, which constitute major obstacles to harnessing the tremendous energy of lithium-metal anode in a reversible manner. Considerable attention has been focused on inhibiting dendrite via interface and electrolyte engineering, while admitting electrolyte-lithium metal reactivity as a thermodynamic inevitability. Here, we report the effective suppression of such reactivity through a nano-porous separator. Calculation assisted by diversified characterizations reveals that the separator partially desolvates Li + in confinement created by its uniform nanopores, and deactivates solvents for electrochemical reduction before Li 0 -deposition occurs. The consequence of such deactivation is realizing dendrite-free lithium-metal electrode, which even retaining its metallic lustre after long-term cycling in both Li-symmetric cell and high-voltage Li-metal battery with LiNi 0.6 Mn 0.2 Co 0.2 O 2 as cathode. The discovery that a nano-structured separator alters both bulk and interfacial behaviors of electrolytes points us toward a new direction to harness lithium-metal as the most promising anode.

25 ENERGY STORAGE↗

DOE OSTI2021

High-Voltage and High-Safety Practical Lithium Batteries with Ethylene Carbonate-Free Electrolyte

Serious safety issues are impeding the widespread adoption of high-energy lithium-ion batteries for transportation electrification and large-scale grid storage. Herein, a triple-salt ethylene carbonate (EC) free electrolyte for high-safety and high-energy pouch-type LiNi 0.8 Mn 0.1 Co 0.1 O 2 |graphite (NMC811|Gr) cells is reported. This EC-free electrolyte can effectively stabilize the NMC811 surface under high potential (up to 4.5 V), as well as generate a stable interphase to achieve a superior compatibility with the Gr anode. The electrolyte strategy enables significantly enhanced intrinsic safety (trigger temperature of thermal runaway (TR) increased by 67.0 °C), excellent electrochemical properties (4.2V, ≈100% after 200 cycles), and superior high voltage stability (4.5 V, 82.1% after 200 cycles). Furthermore, the work opens up a new avenue for developing novel electrolyte systems to build safer high-energy batteries for practical applications.

25 ENERGY STORAGE↗

DOE OSTI2021

Simultaneously Blocking Chemical Crosstalk and Internal Short Circuit via Gel-Stretching Derived Nanoporous Non-Shrinkage Separator for Safe Lithium-Ion Batteries

The separator, an ionic permeable and electronic insulating membrane between cathode and anode, plays a crucial role in the electrochemical and safety performance of batteries. However, the commercial polyolefin separators not only suffer from inevitable thermal shrinkage at elevated temperature, but also fail to inhibit the hidden chemical crosstalk of reactive gases such as O 2 , leading to often reported thermal runaway (TR) and hence preventing large-scale implementation of high-energy-density lithium-ion batteries. Herein, a nanoporous non-shrinkage separator (GS-PI) was fabricated via a novel gel-stretching orientation approach to eliminate TR. In situ synchrotron small angle X-ray scattering during heating clearly showed that the as-prepared thin GS-PI separator exhibits superior mechanical tolerance at high temperature, thus effectively preventing internal short circuit. Meanwhile, the unique nanoporous structure design further blocks chemical crosstalk and the associated exothermic reactions. Accelerating Rate Calorimetry test revealed that the practical 1 Ah LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622)/graphite pouch cell using GS-PI nanoporous separator show a maximum temperature rise (dT/dt max ) of only 3.7 °C s -1 compared to 131.6 °C s -1 in the case of Al 2 O 3 @PE macroporous separator. Furthermore, despite the reduced pore size, the GS-PI separator demonstrates better cycling stability than conventional Al 2 O 3 @PE separator at high temperature without sacrificing specific capacity and rate capability.

25 ENERGY STORAGE↗

DOE OSTI2021

In-built ultraconformal interphases enable high-safety practical lithium batteries

There is an urgent need for high-safety and high-energy lithium-ion batteries to satisfy the rapidly increasing need for energy storage. Nickel-rich layered cathodes have been at the forefront of the revolution for batteries due to their relatively high capacity and low cost. However, with the increase of nickel content, the batteries suffer from severe safety concerns, which caused by thermal runaway. Herein, we show that the ultraconformal cathode-electrolyte interphase (CEI) protective skin with high inorganic content dramatically enhances the safety of high-energy practical Li-ion pouch cells. We find that the robust CEI skin significantly improves the intrinsic thermal stability, mitigates the evolution of oxygen resulting from phase transition, and effectively suppresses the associated parasitic reactions between the delithiated cathodes and electrolyte. The in-situ CEI engineering strategy is simple and suitable for practical industrial manufacture, and it provides design ideas for aggressive nickel-rich cathodes towards safe and high-energy batteries.

25 ENERGY STORAGE↗

DOE OSTI2021

Unlocking the self-supported thermal runaway of high-energy lithium-ion batteries

Layered Ni-rich LiNi x Mn y Co 1-x-y O 2 (NMC) materials are the most promising cathode materials for Li-ion batteries due to their favorable energy densities. However, the low thermal stability typically caused by detrimental oxygen release leads to significant safety concerns. Determining the pathways of oxygen evolution reaction is essential, as the ideal safety countermeasure is to break the reaction chain of thermal runaway. In this study, we demonstrate that two endogenous pathways of oxygen involved in strong exothermic reactions lead the NMC811|graphite pouch cell to an uncontrollable state, and we quantify the individual contribution of the pathways to thermal runaway. Approximately 41% of thermal-induced oxygen reacts aggressively with ethylene carbonate (EC) at the cathode/electrolyte interface with 16% heat generation, accelerating the self-heating rate and thereby further triggering thermal runaway. The residual oxygen that survives the reaction with carbonate spreads to the lithiated anode with major heat generation (65%), bringing the battery to the maximum destructive temperature during thermal runaway. By confirming the significant roles of EC and anode, a deeper understanding on battery fire was achieved. Finally, the revealed mechanism can help guide studies on stopping the two reaction pathways, allowing for the safer use of high-energy lithium-ion batteries in the future.

25 ENERGY STORAGE↗

DOE OSTI2021

Thermal runaway mechanism of lithium-ion battery with LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode materials

Battery safety is critical to the application of lithium-ion batteries, especially for high energy density battery applied in electric vehicles. In this paper, the thermal runaway mechanism of LiNi 0.8 Co 0.1 Mn 0.1 O 2 based lithium-ion battery is illustrated. And the reaction between cathode and flammable electrolyte is proved as the trigger of the thermal runaway accident. In detail, with differential scanning calorimeter tests for battery components, the material combination contributing to thermal runaway was decoupled. Characterization with synchrotron X-ray diffraction and transmission electron microscopy with in-situ heating proved that the vigorous exothermic reaction is initiated by the liberated oxygen species. The pulse of highly active oxygen species reacted quickly with the electrolyte, accompanied with tremendous heat release, which accelerated the phase transformation of charged cathode. Also, the mechanism is verified by a confirmatory experiment when the highly active oxygen species were trapped by anion receptor, the phase transformation of the charged cathode was inhibited. Clarifying the thermal runaway mechanism of LiNi 0.8 Co 0.1 Mn 0.1 based lithium-ion battery may light the way to battery chemistries of both high energy density and high safety.

25 ENERGY STORAGE↗