bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrasonic Monitoring of Li-Ion Batteries
Authors: Milano Lorenzo , Magagnin Luca
Published: December 2024

To improve the accuracy of lithium-ion battery (LIB) monitoring, a recent trend involves using data that reflect changes in material properties caused by the intercalation and deintercalation of lithium ions. By focusing on specific layers within the battery, a broader array of information can be obtained to determine its state of charge (SoC) and health (SoH) locally. Since the speed of sound changes depending on the material properties and traveling waves are partly reflected at each interface, ultrasonic analysis (UA) offers the potential to enhance LIB monitoring by providing real-time, through-thickness data.

In this study, NMC-graphite LIBs were cycled and monitored using UA in pulse-echo and through-thickness modes with a center frequency of 5 MHz. The primary focus was to examine the effect of cycling on each peak's intensity and shift on the time axis. An NMC631-graphite battery was monitored in pulse-echo mode while cycling according to a fixed-capacity protocol. Results showed the appearance of two sets of peaks appearing in different position on the time axis when the end of discharge and end of charge, respectively, are approaching. The time shift and amplitude of each peak had the same periodicity of the cycling protocol, moreover, such variations are compatible with the evolution of materials properties induced by lithiation.

Following this, the battery was cycled fixing the charge/discharge capacity and varying its value at each cycle (50, 20, 300, 400 mAh) while monitored in through transmission. Here, rather than focussing on peaks position and intensity, the frequency domain analysis revealed three main waves composing the signal. The one with lowest frequency became progressively more influent while discharging, the one close to the center frequency did not show dependency on the stored charge while the highest in frequency had opposite trend to the first one. Interestingly, the waves with lowest and highest frequency had a Fourier coefficient which was quasi-linearly dependent on the stored charge.

Overall the main outcomes of this work are:

I. The possibility to observe different battery layers directly from the waveform.

II. The Fourier coefficient of two main frequencies is a linearly dependent on the stored charge.
Positive-to-Negative Electrode Cross-Talk in Lithium-Ion Batteries
Authors: Rinkel Bernardine L. D. , McCloskey Bryan D.
Published: December 2024

Electrolyte decomposition reactions are the dominant source for capacity fade in (commercial) lithium-ion batteries. Even though the parasitic reactions at the graphite electrode have been identified as a major source for this, the observed capacity fade also appears to be strongly tied to the choice of material for the positive electrode, indicating that the positive electrode may indirectly or partially contribute to the overall capacity fade. In particular, electrolyte decomposition products formed at the positive electrode may diffuse or migrate to the negative electrode, where they can react further or damage the SEI, in a process called “electrode cross-talk”. One product could initiate a disproportionate number of secondary reactions, leading to increased degradation (more than what would be expected from a single molecule). Unfortunately, up until recently, the electrolyte oxidation reactions at the positive electrode and specifically the products that are formed, were unknown, making it impossible to investigate any cross-talk processes and their contribution to battery degradation. Fortunately, with the recent identification of soluble decomposition products formed at positive electrodes, 1,2 it has now become possible to explore positive-to-negative electrode cross-talk.

In this work, the impact and reactivity of electrolyte decomposition products formed at layered transition metal oxide electrodes on the SEI were studied. First, a representative SEI was formed on graphite electrodes, after which it was carefully exposed to various decomposition products (e.g., acids: HF, formic acid; alcohols: methanol, acetals, etc.). After exposure, solution NMR spectroscopy was used to detect newly formed products, as well as dissolution of the existing SEI. Operando gas measurements were employed to assess the integrity and composition of the SEI after exposure. The experimentally detected soluble and gaseous products were then used to gain mechanistic insights into inter-electrode reactions. The findings on positive to negative electrode cross-talk processes will further the understanding of why lithium-ion batteries degrade, and will enable the design of highly effective strategies to mitigate degradation.

(1) Rinkel, B. L. D.; Hall, D. S.; Temprano, I.; Grey, C. P. Electrolyte Oxidation Pathways in Lithium-Ion Batteries. J Am Chem Soc
2020, 142 (35), 15058–15074. https://doi.org/10.1021/jacs.0c06363.

(2) Rinkel, B. L. D.; Vivek, J. P.; Garcia-Araez, N.; Grey, C. P. Two Electrolyte Decomposition Pathways at Nickel-Rich Cathode Surfaces in Lithium-Ion Batteries. Energy Environ Sci
2022, 15 (8), 3416–3438. https://doi.org/10.1039/d1ee04053g.
High-Energy-Density Battery Design with COF Modified MXene Coating on Li Metal as Anode
Authors: Niu Junjie
Published: December 2024

Lithium metal battery with Li meal instead of graphite as anode electrode material shows promising potential in providing high energy density, which is required in large electronic devices and electric vehicles. However, the dendrite formation on lithium metal surface poses extensive safety concerns. Also the un-stable solid electrolyte interphase on the surface lead to a low coulombic efficiency of the battery. In our previous work, lithium metal surface was modified by using MXene coating (Advanced Materials, 35, 2023, 2210111), constructing pre-solid electrolyte interphase (ACS Applied Materials & Interfaces, 13, 2021, 34064), forming inter-layer-calated thin Li metal (Nano Letters, 20 (2020), 2639), and ironing controllable lithium into lithiotropic carbon fiber fabric (ACS Applied Materials & Interfaces, 11, 2019, 21584). Here I will introduce our recent work in modifying the Li metal anode electrode by using covalent organic framework (COF). The COF covered Li metal displays uniform Li deposition and extraction during the plating and stripping. It was found that the dendrite was greatly suppressed under large current density. The assembled battery displayed a high capacity retention upon long cycling. The pouch cell full battery with over 1.0 Ah capacity by using the designed Li metal as anode electrode exhibited a large energy density and long cycling performance. The electrochemical property and battery performance results indicate that a reliable Li metal anode with COF modification can be achieved.
Towards Understanding the Structure and Dynamics of Localized High-Concentration Battery Electrolytes
Authors: Hockmann Anne , Diddens Diddo , Cekic-Laskovic Isidora , Schönhoff Monika
Published: December 2024

In recent years high-concentration liquid electrolytes (HCEs) received much attention in the battery research due to the evident performance advancement achieved in lithium-based batteries. HCEs offer lots of advantages comprising, among others, broad electrochemical stability window, current collector protection, high safety, an effective solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) formation, and therefore a high rate capability and stable galvanostatic cycling.[1] However, due to the high conducting salt content, HCEs are very viscous thus resulting in low ionic conductivity. This is why the concept of localized high-concentration electrolytes (LHCEs) was developed and first published by Chen et al. in 2018.[2] Here, a third component next to salt and solvent, the diluent, is added to the system to reduce the viscosity without participating in the ion solvation. With this addition, a heterogeneous structure consisting of conducting salt-rich and diluent-rich phases is created. Thereby, the local environment of the ions, which is responsible for the described benefits of a HCE, remains unchanged and the main disadvantage, the low ionic conductivity, is improved.

However, the structural heterogeneity of the LHCEs, the complexity of the composition of conducting salt- and diluent-rich phases, and their interfacial interactions require further research to gain a profound understanding of the structure and ion dynamics in order to reach the full potential of this type of electrolyte formulation. Therefore, in this work a comparative study of LHCEs based on lithium bis(trifluoro-methanesulfonyl)imide (LiTFSI) or lithium bis(fluorosulfonyl)imide (LiFSI) as the conducting salt, dissolved in 1,2-dimethoxyethane (DME), and diluted with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) was carried out. A combination of selected complementary spectroscopic methods, namely NMR, Raman, and impedance spectroscopy supported by molecular dynamics (MD) simulations, was used to study the effects of an increasing dilution on the two types of electrolyte formulations. We show that varying the anion structure already has a significant impact on the conducting salt/diluent-interface influencing the lithium coordination and dynamics: While the TFSI- anion appears to interact with the diluent at the interface resulting in a higher degree of ion dissociation and increased dynamics in the conducting salt-rich phase, the FSI- anion leads to stronger ionic interactions and a more compact conducting salt-phase with slower dynamics.

References

Yamada, J. Wang, S. Ko, E. Watanabe, A. Yamada, Nat Energy
4 (2019), 269–280.

Chen, J. Zheng, D. Mei, K. S. Han, M. H. Engelhard, W. Zhao, W. Xu, J. Liu, J.-G. Zhang, Adv.
Mater.
30 (2018), 1706102.

Figure 1
Aqueous Processing of Ni-Rich Layered Oxide-Based Cathodes: Evaluating Strategies Via Additives, Binders and Coatings
Authors: Albers Simon , Winter Martin , Kasnatscheew Johannes
Published: December 2024

The growing demand of batteries for electric mobility enhances the overall environmental impact of battery production. Among the different cathode cell chemistries, the Ni-rich layered oxide LiNi
x
Co
y
Mn
z
O2 (NCM)-based cathode active material (CAM) is regarded to have the lowest global warming potential of around 75.5 kg CO2-Eq/kWh1, whereas ≈25 % is attributed to cell manufacturing. The global warming potential could be reduced by 16 % via aqueous cathode electrode production2, as water instead of N-methyl-2-pyrrolidone (NMP) as processing solvent is generally advantageous in several aspects e.g., not necessitating solvent recovery. However, Ni-rich NCMs are water sensitive and prone to structural degradation, leading to e.g., particle cracking and surface layer reconstructions. Consequently, lithium and transition metals dissolve in the aqueous media forming soluble (such as LiOH and Li2CO3) and insoluble (such as NiOOH) species.3 The formation of LiOH leads to an increase in pH and can cause corrosion of the aluminium current collector.

Promising strategies for aqueous processing are either based on CAM coating, processing aspects (e.g., functionalized binders, electrode paste additives) or electrolyte additives. A common processing additive is phosphoric acid, which is aimed to lower the pH, protect the aluminium current collector, and form a protective Li3PO4 layer on the NCM particle surface. However, further investigations are required to gain a full understanding of the NCM interphase changes and to evaluate other interphase engineering strategies to overcome the remaining obstacles.

In this study, the well-known strategies are evaluated with respect to electrochemical performance of LiNi83Co12Mn05O2||Graphite cells. Each strategy is applied within a characteristic time scale of NCM path, i.e., from synthesis to end-of-life (see scheme 1), and reveal characteristic advantages and disadvantages on cathode particle degradation and interphase formation.

References

M. Mohr, J. F. Peters, M. Baumann and M. Weil, Journal of Industrial Ecology,
24(6), 1310–1322 (2020).

K. Shen, Q. Zhai, Y. Gu, W. Wang, H. Cao, M. Hauschild and C. Yuan, Resources, Conservation and Recycling,
198, 107152 (2023).

M. Hofmann, M. Kapuschinski, U. Guntow and G. A. Giffin, J. Electrochem. Soc.,
167(14), 140535 (2020).

Figure 1
Electrolyte Li⁺ Chemical Potential as a Descriptor of Li+ Intercalation Behavior of Graphite Negative Electrodes
Authors: Nakajima Haruna , Kondo Yasuyuki , Katayama Yu , Yamada Yuki
Published: December 2024

Introduction

Better electrolytes are being extensively explored to improve the performance and safety of lithium-ion batteries. One of the challenges in developing new electrolytes is to avoid the co-intercalation of lithium ions (Li⁺) and solvents into graphite negative electrodes during charging. In this reaction, solvated Li⁺ intercalates between the graphite layers without de-solvation, leading to lower capacities and poor reversibility. Previous works showed that the solvent co-intercalation could be suppressed by employing highly concentrated electrolytes1,2, weakly coordinating solvents3, or adopting proper co-solvents.1 However, a quantitative and experimental factor that dominates the Li⁺ intercalation behavior has yet to be identified. In this study, we focused on Li+ chemical potential (μ
Li⁺) in electrolytes as a novel descriptor. We show how the μ
Li⁺ is related to the Li⁺ intercalation behavior at graphite electrodes.

Experimental

Electrolytes with various concentrations of lithium bis(fluorosulfonyl)imide (LiFSI) were prepared using 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE), or dimethyl sulfoxide (DMSO), all of which easily co-intercalate into graphite electrodes. Li⁺ intercalation behavior was categorized as follows: only Li+ intercalates into graphite (noted as Li-GIC), both Li+ and solvated Li⁺ intercalates into graphite (noted as incomplete Li-GIC), and solvated Li⁺ intercalates into graphite (noted as Li-solv-GIC). The Li⁺ intercalation behavior was judged from charge-discharge curves observed in graphite|Li coin cells. To quantify the μ
Li⁺, we used lithium electrode potential (E
Li) with reference to the redox potential of ferrocene (Fc/Fc+) using a previously reported method by our group.4

Results and discussion

E
Li (and μ
Li⁺) and Li⁺ intercalation behavior in various electrolytes. In all electrolytes, the E
Li (and μ
Li⁺) increased with increasing salt concentration, which is consistent with the previous study.4 We found that the Li⁺ intercalation behavior depended on the E
Li (and μ
Li⁺); solvent co-intercalation was mainly observed in the electrolytes with E
Li < -3.25 V vs. Fc/Fc+, whereas only Li⁺ tended to intercalate into graphite by suppressing solvent co-intercalation in electrolytes with E
Li > -3.25 V vs. Fc/Fc+. Therefore, the obtained trend suggests that μ
Li⁺ could be a quantitative descriptor of the Li⁺ intercalation behavior at graphite electrodes.

Acknowledgment

A part of this study was supported by JSPS KAKENHI Grant-in-Aid for Transformative Research Areas (B) (23H03824, 23H03827).

Reference

(1) Yamada, Y. et al., J. Phys. Chem. C, 114, 11680–11685 (2010). (2) Yamada, Y. et al. ACS Appl. Mater. Interfaces, 6, 10892–10899 (2014). (3) Li, Z. et al., J. Mater. Chem. A, 11, 19996–20010 (2023). (4) Ko, S. et al., Nat. Energy, 7, 1217-1224 (2022)

Figure 1
Simulation-Guided Dual Functional Ta-Modified Ni-Rich LiNi0.92Co0.04Mn0.04O2 Cathode Material Development
Authors: Kuo Liang-Yin , Hendri Yola Bertilsya , Ihrig Martin , Yang Chun-Chen
Published: December 2024

Ni-rich cathode materials are one of the most promising materials for high-energy Li-ion batteries. Numerous synthesis techniques have been explored to tailor their structure, morphology, and particle size to obtain longevity, stability, and power. In this work, a simulation-guided process based on density functional theory was developed to obtain a Ta-modified Ni-rich LiNi0.92Co0.04Mn0.04O2 (T-NCM92) material fulfilling the aforementioned requirements. The T-NMC92 was synthesized through a one-step synthesis process via a controlling suitable amount of Ta and Li-salt in a Taylor-Couette reaction (TCR). Ta doping allows the tailoring of the microstructure, orientation, and morphology of the primary T-NCM92 particles, resulting in a needle-like shape with fine structures that considerably enhance Li+ ion diffusion and electrochemical charge/discharge stability. The Ta-based surface-coating layer effectively prevented microcrack formation and inhibited electrolyte decomposition and surface-side reactions during cycling, thereby significantly improving the electrochemical performance and long-term cycling stability of T-NCM92 cathodes. Thus, T-NMC92 had assembled in a full Li-ion battery a high initial capacity of 178.8 mAh/g at 1C, with 67.6 % capacity retention after 200 cycles at 45 ℃. The benefits of the Ta incorporation and coating were especially observable at harsh conditions e.g., at high-rate conditions (10C), T-NCM92 demonstrates a capacity retention of 66.9 % (157.6 mAh g−1) after 100 cycles. A detailed structural characterization prior to and after the cycling of T-NMC92 allowed us to understand the Ta contribution and the effects it has on the structure. Therefore, the presented DFT technique as well as the T-NMC92 can act as a base material for further development and optimization of Ni-rich materials.

Figure 1
Improvement of Cycling Performance of Lithium-Ion Batteries by Use of a Polymerizable Additive for Forming Ion-Conductive Solid Electrolyte Interphase
Authors: Seok Jinhong , Lim Da-ae , Hong Dayoung , Oh Jin-Young , Lee Chul Haeng , Ahn Kyoung Ho , Kim Dong-Won
Published: December 2024

Lithium-ion batteries (LIBs) are being widely used in various portable electronic devices, becoming an essential part of our daily life due to their high energy density and affordable price. In recent decades, their application has broadened rapidly to electric vehicles and energy storage system, in response to demand for carbon neutrality. However, the continuous decomposition of liquid electrolyte at the electrolyte-electrode interface results in large increase of interfacial resistances in LIB. Such a large interfacial resistance impedes the transport of lithium-ion at the interface, which reduces the cyclability and rate capability of LIBs. Therefore, the construction of ion-conductive solid electrolyte interphase (SEI) is essential for achieving good cycling performance of LIBs. The Li+ ion-conducting film-forming additives can be decomposed on the surface of the electrode to form chemically and electrochemically inert layer that maintains low interfacial resistance as cycle progresses. Consequently, it can enhance the cycle life and rate capability of LIBs. In this regard, we designed and synthesized a film-forming additive for maintaining low interfacial resistances during the repeated cycling. The formation of single lithium-ion conducting SEI on graphite anode surface was confirmed through various analyses including nuclear magnetic resonance and X-ray photoelectron spectroscopy. The additive was applied to the lithium-ion cell composed of graphite anode and LiNixCoyMn1-x-yO2 cathode as a film-forming additive to enhance the cycling performance of LIBs. Our results reveal that the addition of proper amount of additive to the liquid electrolyte enhanced the cycling performance of the lithium-ion cell in terms of capacity retention and rate performance.
Pre-Passivation of Lithium-Metal Anodes through Electrodeposition for Durable Cycling in Practical Lithium-Metal Batteries
Authors: Seo Jiyeon , Lee Hongkyung
Published: December 2024

This research introduces an electrochemical pre-passivation technique that creates an electrolyte-derived native layer (ENL) on lithium-metal anodes (LMAs) through the electrodeposition of lithium (ED-Li). Typically, commercially produced LMAs (M-Li) develop an inherent native passivation layer (NPL) during production, which can be non-uniform and trigger sporadic lithium dendrite growth as well as chemical and structural degradation of LMAs. The proposed method utilizes localized high-concentration electrolytes and post-calendering processes to form a fluorinated, smoother ENL without Li2CO3. This ENL not only promotes uniform lithium nucleation at the onset of lithium plating but also reduces pitting during lithium stripping, thus limiting LMA swelling. The improved ENL helps enhance the cycling stability of Li||NMC622 cells, making ED-Li superior to M-Li. Further assessments with various electrolytes under practical scenarios confirm the effectiveness of ED-Li as a foundational LMA for subsequent treatments like protective layer applications and electrolyte-induced passivation.
Stabilizing Lithium Metal Anode and Conversion Cathode Interphases for High Energy Density Batteries
Authors: Lopez Jeffrey
Published: December 2024

Lithium metal batteries offer great promise for higher energy density, but are presently limited by significant side reactions, poor quality deposition, and the potential to form hazardous dendrites. This is especially true when paired with conversion cathodes, which could potentially result in cells with specific energy > 700 Wh/kg. In this presentation, recent advances made toward high energy full cells will be discussed. A particular emphasis will be placed on the electrode-electrolyte interphases that form in these devices in high performance localized high concentration electrolytes (LHCE).

Specifically, we employ electron paramagnetic resonance (EPR) spectroscopy to identify radical intermediates and operando surface enhanced IR absorption (SEIRA) spectroscopy to clarify electrolyte reduction/oxidation mechanisms. Operando SEIRA provides detailed information about the organic components of the solid electrolyte interphase (SEI) and cathode electrolyte interphase (CEI) on lithium metal anodes and FeF2 cathodes respectively. Common SEI components from high Coulombic efficiency fluorinated electrolytes are identified and mechanisms will be discussed in the context of moving toward more environmentally friendly fluorine-free electrolytes. Furthermore, strategies to stabilize FeF2 conversion cathodes through interphase modification to produce more mechanically robust composite electrodes and improve cycling stability will be discussed. With the understanding developed through this holistic approach, we provide new insight into electrolytes and the formation of interphase components that promote stable cycling of lithium metal- FeF2 full cells.
Approach to Regulating Crystal Nucleation for High-Performance Lithium-Chalcogen Batteries
Authors: Kim Mihyun , Yu Seung-Ho
Published: December 2024

Chalcogen cathodes, with their high theoretical energy density, have shown promise for advancing lithium-ion battery (LIB) technology. However, the structure of chalcogen crystals significantly impacts cycle performance and could constrain rate capability due to their intrinsic insulating nature. Therefore, this study explores approaches to regulate the nucleation of chalcogen elements to enhance cycle performance beyond that of lithium-sulfur batteries.

We investigate the dissolution and deposition mechanisms of the chalcogen cathode materials, as well as nucleation phenomena by using advanced techniques such as operando X-ray diffraction (XRD) and transmission X-ray microscopy (TXM). Particularly, operando TXM imaging captures the growth of chalcogen crystals, shedding light on their nucleation behavior. Expending on these discoveries, we control the crystal nucleation of the chalcogen cathodes, resulting in impressive specific capacity and improved rate capability.

This work offers valuable insights into the chalcogen crystal nucleation, paving the way for high-performance lithium-sulfur batteries with improved energy densities and rate performance.

Figure 1. The scheme of the chalcogen crystal growth mechanism and the corresponding cycle performance at a current density of 1.0 A g-1.

Figure 1
Explaining the Voltage Hysteresis and Slow Relaxation of Silicon Nanoparticles with a Chemo-Mechanical Particle-SEI Model
Authors: Köbbing Lukas , Latz Arnulf , Horstmann Birger
Published: December 2024

Silicon is widely considered to be a promising next-generation anode material, primarily due to its remarkably high theoretical capacity. Furthermore, silicon is an abundant, cheap, and widely spread material. However, a major challenge for the commercialization of silicon anodes is the significant voltage hysteresis reducing efficiency and leading to detrimental heat generation during fast-charging. Additionally, the hysteresis causes an unclear state-of-charge (SOC) to voltage relation impeding precise SOC estimation.

The voltage hysteresis behavior of silicon anodes is addressed in literature with three different arguments: phase transformations, plastic flow of silicon, and slow diffusion. These approaches can interpret the voltage hysteresis of crystalline silicon, thin films, and large anode particles, respectively. Nevertheless, we show that they cannot explain the hysteresis observed for silicon anodes consisting of amorphous nanoparticles, the relevant material for next-generation lithium-ion batteries.

Our investigation highlights the chemo-mechanical interplay between the silicon nanoparticle and the covering Solid-Electrolyte Interphase (SEI) as the underlying cause for the significant voltage hysteresis. The SEI, a thin passivating layer, forms on negative electrode particles due to electrolyte decomposition [1]. In the case of silicon particles, the volume changes during lithiation and delithiation result in massive strains and plastic deformation occurring within the SEI [2]. Our chemo-mechanical particle-SEI description successfully replicates the observed open-circuit voltage hysteresis in experiments and aligns with the Plett model [3]. Moreover, our visco-elastoplastic SEI model reproduces the voltage difference between slow cycling and the relaxed open-circuit voltage. In our recent work, we show that a sophisticated mechanical model explains the slow voltage relaxation observed for silicon nanoparticles as well as the observed C rate dependence [4].

To conclude, we explain the voltage hysteresis and the slow voltage relaxation of silicon nanoparticles with a visco-elastoplastic particle-SEI model and discuss options to mitigate the size of the voltage hysteresis. This detailed physical understanding can improve the performance of all-silicon anodes and contribute to their commercialization.

[1] Köbbing, L.; Latz, A.; Horstmann, B. J. Power Sources
2023, DOI: 10.1016/j.jpowsour.2023.232651.

[2] Kolzenberg, L.; Latz, A.; Horstmann, B. Batter.
Supercaps
2022, DOI: 10.1002/batt.202100216.

[3] Köbbing, L.; Latz, A.; Horstmann, B. Adv. Funct. Mater. 2024, DOI: 10.1002/adfm.202308818.

[4] Köbbing, L.; Latz, A.; Horstmann, B. (in preparation).

Figure 1
Decoupling Lithium Salt and Lithium Polysulfide Solvation By Partially-Fluorinated Ether Boosts Cycle Life of Lithium-Sulfur Batteries
Authors: Yang Jingtian , Zhu Qijia , Wang Xiaowei , Liu Qian , Zhang Zhengcheng
Published: December 2024

Lithium-sulfur (Li-S) batteries are regarded as one of the most promising next-generation energy storage systems due to their advantages of high energy density and low material cost. However, the conventional Li-S cell construction with ether-based electrolyte, composed of 1,2-dimethoxyethane (DME) and 1,3-dioxalane (DOL), suffers from severe shuttle effect and lithium metal anode corrosion because of soluble lithium polysulfide (LiPS) intermediates. These deficiencies further lead to limited cell calendar life and impedes Li-S batteries from practical applications. Weakening the electrolyte solvation power towards lithium polysulfide by adding hydrofluoroethers (HFEs) has been intensively explored and considered as an effective strategy to suppress LiPS dissolution and improve the electrochemical stability of electrolyte against lithium anode. Nevertheless, excessive fluorination of the current HFE cosolvents simultaneously confines the dissolution and solvation towards lithium salt, which detrimentally limits the ionic conductivity and therefore the electrochemical performance of the electrolyte. Herein, with the aim of decoupling lithium salt and LiPS solubility, we developed a partially fluorinated glyme, 1,2-bis(2,2-difluoroethoxy) ethane (F4DEE) as a novel solvent in Li-S battery electrolyte. The targeted design of F4DEE molecular structure enables F4DEE itself a considerable lithium salt solubility (> 6 M for LiTFSI) yet a confined LiPS solubility (< 100 mM for Li2S6). By combining F4DEE with conventional solvent DOL, the resulted DOL/F4DEE electrolyte realizes an extraordinary balance between reasonable ionic conductivity and suppressed LiPS dissolution. Furthermore, DOL/F4DEE electrolyte can induce a fluorine-rich solid-electrolyte interface (SEI) on Li anode surface, which is proven to be sturdy and thus benefit Li stripping/plating stability under real Li-S cycling conditions. When tested in coin cell configuration at room temperature, the Li-S cell with DOL/F4DEE electrolyte delivers a high initial specific capacity of 1081 mAh g-1 at 0.05 C and an extended lifetime of over 180 cycles before cell failure at 0.1 C. This cycle life is a threefold increase compared to the conventional DME/DOL electrolytes, highlighting the promising potential of our electrolyte design strategy.
(Battery Division Postdoctoral Associate Research Award Sponsored by MTI Corporation and the Jiang Family Foundation) Silicon SEI Instability and its Effect on Calendar Aging
Authors: McBrayer Josey D, , Schorr Noah B. , Harrison Katharine L. , Allcorn Eric , Lam Mila Nhu , Meyerson Melissa L , Minteer Shelley
Published: December 2024

Poor calendar aging has been identified as a major hurdle for commercialization of high-loading silicon anodes. Here, we will discuss a series of efforts identifying and defining the problem of silicon calendar aging and hypotheses for why aging is worse in silicon than in graphite. Some of these hypotheses were tested through a specially designed variable open circuit (OCV) protocol modified from the USABC’s calendar aging protocol to determine contributions from mechanical and chemical degradation. Microcalorimetry and scanning electrochemical microscopy (SECM) were performed to study changes in the solid electrolyte interphase (SEI) on silicon with time. From SECM, the passivation of silicon thin films was found to decrease with increasing time and potential relative to Li/Li+. The overall failure mode of the SEI with time appeared to be global suggesting possible SEI dissolution. X-ray photoelectron spectroscopy supported that there was a loss of SEI species with time. In further support for chemical degradation during calendar aging, when the frequency of reference performance tests (RPTs) was varied, capacity fade was minimally affected. This suggests that time since assembly, rather than cycling, dominated the capacity fade in the calendar aging tests. Microcalorimetry demonstrated changes in heat during the rest as well as after an RPT, highlighting the complexity of silicon aging and setting the stage for our next efforts of in situ quantification of electrolyte degradation products.

This research was supported by the U.S. Department of Energy’s Vehicle Technologies Office under the Silicon Consortium Project, directed by Brian Cunningham, and managed by Anthony Burrell. This work was conducted in part by the Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Sandia National Laboratories is a multimission Laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Maximizing Battery Performance: Unveiling the Potential of Ion Pair-Based Electrolytes
Authors: Ko Seongjae , Yamada Atsuo
Published: December 2024

Developing next-generation rechargeable batteries with high energy density, low cost, high scalability, and long-term cycleability is of utmost importance for realizing a carbon-neutral society amidst the increasing adoption of renewable energies. In this context, high-voltage Li-ion batteries, high-capacity Li-metal batteries, and cobalt-free Li-ion batteries have been proposed. These batteries offer substantially high energy density while maintaining compatibility with current battery production processes and reducing heavy reliance on rare metals. However, significant challenges such as extreme reaction potentials of the cathode and anode that lie outside the electrochemical potential window of the electrolyte, damage/crack of the solid electrolyte interface (SEI) due to the huge volume change of the anode, corrosion of the Al cathode current collector, transition metals disslution from the cathode, and degradation of cathode carbon additives lead to severe electrolyte decomposition, a large consumption of Li+ sources, and an increase in battery resistance, thus hindering their practical utilization.

In this presentation, strategies to overcome these side reactions based on electrolyte design with aggressive ion-pair formation will be discussed. Specifically, the importance of i) kinetic hindrance of anion intercalation into the cathode carbon additives (S. Ko et al., and A. Yamada, Joule 5, 998–1009, 2021), ii) the thermodynamic upshift of electrode potential (S. Ko et al., A. Yamada, and Y. Yamada, Nature Energy, 7, 1217–1224, 2022), and iii) optimization of the overall potential diagram of full cells and electrolytes (S.Ko et al., and A. Yamada, Nature Sustainability, 6, 1705–1714, 2023) will be presented in detail.
Alkali-Catalyzed Coating of Covalent Triazine Frameworks for Enhanced Interfacial Stability of High-Nickel Ternary Cathode Materials
Authors: Fan Juntian , Dai Sheng
Published: December 2024

Covalent triazine frameworks (CTFs) exhibit exceptional electron/ion conductivity and superior chemical and thermal stability, making them promising coating materials for enhancing the interfacial stability of cathode materials such as LiNixMnyCozO2 (NMC). However, the synthesis of CTFs via nitrile trimerization typically requires superacids (e.g., CF3SO3H) or Lewis acids (e.g., ZnCl2) as catalysts, which can react with metal oxides, posing challenges for the in-situ coating of CTFs on NMC. Herein, this issue has been addressed by achieving in situ CTF coating on LiNi0.1Mn0.1Co0.1O2 (NMC811) using alkali as a catalyst for the trimerization of 1,4-dicyanobenzene. The successful synthesis of CTFs was confirmed through Fourier-transform infrared spectroscopy (FTIR), revealing distinctive peaks at 1507, 1353, and 810 cm-1 that correspond to the triazine rings of CTFs. After coating with CTFs, NMC811 exhibits reduced interfacial impedance, a more stable H2-H3 phase transition, improved rate capability and cycling stability. For example, the CTF@NMC811 demonstrated larger capacity under high current density conditions, achieving 138.2 mAh g-1 at the current density of 2 C and 83.8 mAh g-1 at 5 C, whereas pristine NMC811 showed 109.7 mAh g-1 at 2 C and negligible capacity at 5 C (1 C = 200 mA g-1). Moreover, the CTF@NMC811 exhibited a capacity rentention of 88.8%, surpassing 64.8% of prinstine NMC811 after 100 cycles at the current density of 1 C. Furthermore, this method can be extended to catalyze the trimerization of fluorine-containing monomers (e.g., tetrafluoroterephthalonitrile) on the surface of NMC, facilitating the development of NMC cathodes with dual CTFs and LiF coatings. This innovative strategy introduces a novel approach for coating CTFs, especially on metal oxides incompatible with superacids or Lewis acids, offering insights into enhancing performance and stability on NMC cathodes and other materials.

Figure 1
Advancements in Property Predictions and Optimization of Highly Complex Electrolytes
Authors: Gering Kevin L.
Published: December 2024

The world-wide endeavor to improve battery energy storage carries the need for expanded exploratory research of electrolyte systems. Such research requires considerable resource and time commitments, resulting in delayed market entries of advanced cell chemistries. One answer to this need is the computational tool Advanced Electrolyte Model (AEM) developed at the Idaho National Laboratory, which has been used most prominently for Li-ion, Li metal and Na-ion battery systems. AEM has a molecular chemical physics (statistical mechanical) basis that enables fast property predictions, yielding over 100 property metrics per run over broad conditions of salt concentrations and temperatures with runs that span only seconds. More than 60 solvents and about 40 salts reside in the AEM library, although recent expanded AEM capability accommodates the input of arbitrarily-chosen chemical compounds (ACCC) that do not exist in the library. As such, AEM is equipped to consider a massive list of candidate solvents and salts. AEM has demonstrated excellent efficacy in predicting properties for complex electrolyte systems, defined by mixtures containing a high number of possibly chemically-diverse compounds. Examples of AEM outputs will be given in terms of supporting design of fast-charge electrolytes, quantifying solution microstructure, and implementation of ACCC options.
(Invited) Interface Design Strategy for Solid State Batteries
Authors: Li Xin
Published: December 2024

Solid state battery technology shows the potential to be competitive to commercial Li ion batteries. This talk will focus on understanding the fundamental interface reaction and evolution of electrochemical processes in related battery materials and devices, and discuss the design opportunities for advanced solid state batteries. Specifically, unique electrochemical reaction related to constriction susceptibility at solid-solid interface will be discussed, understanding of which forms the opportunity to design solid state batteries with stable cycling at high current density and areal capacity.
The Effect of Cation-Disorder on Lithium Transport in Halide Superionic Conductors
Authors: Zhong Peichen , Gupta Sunny , Deng Bowen , Jun KyuJung , Ceder Gerbrand
Published: December 2024

Among the chloride-based Li-ion solid electrolytes, Li2ZrCl6 (LZC) have emerged as potential candidates due to their affordability, moisture stability, and high ionic conductivity. LZC synthesized by solid-state heating exhibits limited Li-ion conductivity while the mechanochemical ball-milled material is more conductive. In this computational study, we integrate thermodynamic modeling, using cluster-expansion Monte Carlo, and kinetic modeling, using molecular dynamics, to investigate whether cation disorder can be achieved in LZC, and how it affects Li-ion transport. Our results indicate that fast Li-ion conductivity is induced by the activation of Li/vacancy disorder, which itself depends on the degree of Zr disorder. We find that the very high-temperature scale at which equilibrium Zr-disorder can form precludes any equilibrium synthesis processes for achieving fast Li-ion conductivity, rationalizing why only non-equilibrium synthesis methods, such as ball milling leads to good conductivity. We identify as the critical mechanism the lack of Li/vacancy disorder near room temperature when Zr is well-ordered. Our simulations further show that the Li/vacancy order-disorder transition temperature is lowered by Zr disorder, which is necessary for creating high Li diffusivity at room temperature. The insights obtained from this study raise a challenge for the large-scale production of these materials and the potential for the long-term stability of their properties.
Enabling 5V Solid-State Lithium Metal Batteries Using Catholyte for LiNi0.5Mn1.5O4 Spinel
Authors: Yim Chae-Ho , Karkar Zouina , Houache Mohamed S.E. , Kim Daeil , Jang Boyun , Abu-Lebdeh Yaser
Published: December 2024

Solid-state lithium metal batteries, SSLMBs, are widely sought after as the next generation battery technology due to their potential intrinsic safety and higher energy density. However, several challenges need to be addressed to achieve this goal. Previous studies have identified various challenges with the cathode electrode, including interphases, low active material contents, and limited overall ionic and electronic conductivity for high power density. [1] Additionally, there are different types of cathode materials that are currently under R&D for SSBs such as layered oxides, olivine phosphates, and spinel oxides. Among these, the spinel oxide LiNi0.5Mn1.5O4 (LNMO) has the highest voltage compared to other cathode materials, making it an attractive candidate for maximizing the energy density of active materials in solid-state batteries.

However, most solid-state batteries require a catholyte,[2] solid electrolyte in the cathode electrode, to provide bulk ionic conductivity, but this, in turn, reduces energy density due to the addition of inactive materials.[3] Therefore, utilizing LNMO, a high energy density cathode, is a promising solution for solid-state batteries to compensate for this energy density loss.

To ensure high voltage stability, it is crucial to have a well-designed catholyte composition that minimizes the use of solid electrolyte while ensuring excellent electronic and ionic conductivity to the cathode. In this work, we introduce a catholyte formulation that can effectively utilize LNMO and demonstrate promising cycling results with a Garnet-based solid electrolyte, having cycled over 100 times. This research opens up new possibilities for enhancing the performance of 5V solid-state lithium batteries using catholyte for the LMNO spinel cathode while maintaining high energy densities.

Liang, Y., et al., Challenges, interface engineering, and processing strategies toward practical sulfide‐based all‐solid‐state lithium batteries. InfoMat, 2022. 4(5): p. e12292.

Al-Salih, H., Houache, M.S.E., Baranova, E.A. and Abu-Lebdeh, Y. (2022), Composite Cathodes for Solid-State Lithium Batteries: “Catholytes” the Underrated Giants. Adv. Energy Sustainability Res., 3: 2200032.

Yim, C.-H., et al., Understanding key limiting factors for the development of all-solid-state-batteries. Chemical Engineering Journal Advances, 2023. 13: p. 100436.
Azacyclic Anchor-Enabled Cohesive Graphite Electrodes for Sustainable Anion Storage
Authors: Kang Jieun , Ryu Jaegeon , Park Soojin
Published: December 2024

Advanced energy-storage devices are indispensable for expanding electric mobility applications. While anion intercalation-type redox chemistry in graphite cathodes has opened the path to high-energy-density batteries, surpassing the limited energy density of conventional lithium-ion batteries, a significant challenge remains: the large volume expansion of graphite upon anion intercalation. In this study, a novel polymeric binder and cohesive graphite cathode design for dual-ion batteries (DIBs) is presented, which exhibits remarkable stability even under high voltage conditions (>5 V). The innovative binder incorporates an acrylate moiety ensuring superior oxidative stability and self-healing features, along with an azide moiety, which allows for azacyclic covalent bonding with graphite and interchain crosslinking. A simple 1-h ultraviolet treatment is sufficient for binder fixation within the electrode, leading to the covalent bond formation with graphite and the creation of a robust three-dimensional network. This modification facilitates deeper and more reversible anion intercalation, leading to improved capacity, extended lifespan, and sustainable anion storage. The binder design, exhibiting exceptional adhesive properties and effective stress mitigation, enables the construction of ultrathick graphite cathodes. These findings provide valuable insights for the development of advanced binders, paving the way for high-performance DIBs.
Enhancing Performance of Li-Metal Batteries through Optimization of Their Overall Potential Diagram
Authors: Fang Zhong , Ko Seongjae , Yamada Atsuo
Published: December 2024

Various electrolyte strategies have been explored to improve the cycling stability of Li-metal batteries. Specifically, high-concentration electrolytes and localized high-concentration electrolytes, which facilitate the formation of an anion-derived solid electrolyte interphase on the Li metal surface, thereby kinetically preventing electrolyte reduction, have been extensively studied. However, the issue of drastic capacity decay still persists, indicating the presence of overlooked issues in the development of Li-metal batteries.

Recently, our group has discovered that the electrode potentials of both the cathode and anode shift substantially, by over 0.6 V, governed by the electrostatic potential (Liquid Madelung potential) of Li+ ions in the electrolyte.1-4 This large shift occurs identically at both the cathode and anode, maintaining the overall battery voltage but often resulting in a significant imbalance between the potential diagram of full cells and the potential window of electrolytes.

In this study, we systematically investigated the essential relationship between electrode potential shifts and battery performance using LiNi0.8Mn0.1Co0.1O2 | Li and LiFePO4 | Li batteries with diverse localized high-concentration electrolytes. Our findings underscore important insights for designing batteries and electrolytes:

Optimizing the overall potential diagram of full cells alongside electrolytes substantially improves battery performance.

An excessive upward shift in the Li/Li+ redox potential leads to cycling decay in LiNi0.8Mn0.1Co0.1O2 | Li batteries by accelerating electrolyte oxidation at the cathode surface.

The mild-potential LiFePO4 cathode enables the use of electrolytes that largely upshift the Li/Li+ redox potential, thus maximizing the battery performance.

References

S.Ko, T. Obukata, et al., and A. Yamada, Y. Yamada, Nature Energy, 7, 1217-1224 (2022)

S.Ko, N.Takenaka, A.Kitada, and A.Yamada, Next Energy, 1 (2), 100014 (2023)

S.Ko et al., and A. Yamada, Nature Sustainability, 6, 1705-1714 (2023)

N.Takenaka, S.Ko, A.Kitada, and A. Yamada, Nature Communications, 15, 1319 (2024)