Reversible Oxygen Redox Reaction Research Articles

Achieving complete solid-solution reaction in layered cathodes with reversible oxygen redox for high-stable sodium-ion batteries

P2-type layered Mn-based oxides are promising cathode materials for sodium-ion batteries (SIBs), but it is still challenging to achieve both high capacity and stability because of complex phase transitions and irreversible oxygen release at high voltage. To address these challenges, an optimal P2-type Na0.67Mn0.8Cu0.15Ti0.05O2 (NMCT) cathode with a complete solid-solution reaction and reversible oxygen redox reaction over a wide voltage range was developed. The introduction of the Na–O–Ti configuration leads to fewer delocalized electrons on oxygen and thus enhances oxygen redox activity, while the high energetic overlap between O 2p and Cu 3d states and the increased Mn–O hybridization strengthen the rigidity of oxygen framework to achieve reversible and stable oxygen redox reaction. In addition, the reinforced TM–O interaction, combined with the ameliorated Mn3+ Jahn-Teller distortion and disrupted Na+/vacancy ordering, synergistically eliminate the undesired P2–OP4 phase transition and lead to a complete solid-solution reaction, which greatly facilitates Na+ transport kinetics and stabilizes structural integrity. As a consequence, improved rate performance and cycling stability are achieved for NMCT. Our present study provides a promising avenue for simultaneously utilizing the reversible oxygen redox activity and maintaining the structural integrity to accomplish the capacity-stability trade-off of Mn-based oxide cathodes for constructing practical SIBs.

Recent Advances in Oxygen Redox Activity of Lithium‐Rich Manganese‐Based Layered Oxides Cathode Materials: Mechanism, Challenges and Strategies

AbstractLithium‐rich manganese‐based layered oxides (LRMOs) have been regarded as a promising category of cathode materials due to their high specific capacity on basis of joint anionic(oxygen) /cationic redox chemistry at a high voltage, thus high energy density. The anionic redox play the key and restive roles in LRMOs, contributing the extra capacity, meanwhile being associated with several unfavorable structural and electrochemical issues. This work systematically enumerates the oxygen redox mechanisms, and challenges associated with oxygen‐anion redox in LRMOs, including irreversible transition metal migration, phase transition, and the capacity/voltage decay, etc. The recent progress made in modification of LRMOs with particular emphasis to promoting the reversible oxygen redox reaction and inhibiting the irreversible oxygen release are summarized, followed by an outlook on the future rational design and development of LRMOs. This comprehensive review and perspective are expected to provide insights for the greater utilization of oxygen redox in LRMOs and other related materials.

Fluorine-doped K0.39Mn0.77Ni0.23O1.9F0.1 microspheres with highly reversible oxygen redox reaction for potassium-ion battery cathode

Fluorine-doped K0.39Mn0.77Ni0.23O1.9F0.1 microspheres with highly reversible oxygen redox reaction for potassium-ion battery cathode

Stabilizing the Reversible Oxygen Redox Reactions in Lithium-Rich Layered Cathodes Via the Surface-to-Bulk Enhanced D-P Hybridization

The oxygen redox (OR) reaction in layered Li-rich oxide (LLO) cathode materials has been an attractive topic as it provides additional capacity. However, the suppression of the irreversible transition metal (TM) migration and oxygen release induced by the OR reaction is still a challenging issue, as it would lead to a severe capacity and voltage decay. Here, we introduce a surface-to-bulk structure modification strategy, namely surface Ni segregation and bulk Mo doping structure. Based on this strategy, the oxygen atoms near the surface are fully coordinated, and meanwhile the distortion of the metal–oxygen octahedron is alleviated in the bulk phase, thereby enhancing the degree of TM 3d and O 2p hybridization to stabilize the metal–oxygen framework for the OR reaction. It suppresses cation migration and oxygen release and maintains phase stability, allowing a reversible OR reaction. As a result, the capacity and voltage retention of the modified materials were significantly improved. This work gives an efficient method to stabilize the OR reaction through the surface-to-bulk enhanced d-p hybridization and provides new paths for the design of Li-rich cathodes.

Metastable Cubic Structure Exceeds Capacity Limit of Antifluorite Li5FeO4 Cathode Using Small Polarized Oxygen Redox

AbstractCost‐effective Fe‐based cathode materials have attracted significant attention. Recently, antifluorite‐type Li5FeO4 has been investigated as a high‐capacity cathode material owing to its high lithium content and solid‐state oxygen redox reactions. However, its reversible capacity is restricted to transition‐metal redox reactions because of its irreversible structural transformation and oxygen evolution. This study demonstrates the reversible oxygen redox reaction in metastable cubic antifluorite Li5FeO4 obtained by mechanochemical treatment. It exhibits a reversible capacity of more than 300 mAh g‐1, corresponding to an approximately 1.7‐electron reaction, without oxygen gas evolution. Combined analyses of X‐ray absorption spectroscopy (XAS) and theoretical calculations reveal that both Fe3+/Fe4+ and O2‐/O22‐ redox reactions proceed under semi‐coherent structural transformations between antifluorite and rocksalt, which differs from the known orthorhombic Li5FeO4 phase. Although the cyclability of oxygen redox is poor, its solid solution with Co2+ enhances cyclability by suppressing oxygen evolution. Tuning the structural symmetry and transition‐metal content can overcome the reversible capacity limit of antifluorite cathode materials, which is useful for the development of high‐energy cathode materials by the effective utilization of solid‐state oxygen redox reactions.

A Y-doped P2-Na0.6Li0.11Fe0.27Mn0.62O2 cathode with improved high-rate capability and cycling stability for Na-ion batteries

A promising P2-Na0.6Li0.11Fe0.26Mn0.62Y0.01O2 cathode with a more reversible oxygen redox reaction and higher Na+ transport kinetics was successfully synthesized and studied, showing better high-rate capability and cycling stability.

Spin-State Regulation of Nickel Cobalt Spinel toward Enhancing the Electron Transfer Process of Oxygen Redox Reactions in Lithium–Oxygen Batteries

The development of a high-energy-density lithium–oxygen (Li–O2) battery is mainly determined by highly efficient electrocatalysts with excellent activity and stability, facilitating reversible oxygen redox reactions. Engineering the electron spin state provides a novel strategy to enhance the electrocatalytic activity of electrode materials. In this work, sulfur vacancy-enriched spinel NiCo2S4 (Vs-NiCo2S4) with high spin polarization is designed as an effective electrocatalyst for high-performance Li–O2 batteries. Subtle lattice distortion is induced by sulfur vacancy in spinel Vs-NiCo2S4, which strongly contributes to the formation of high spin states of Co3+ (HS, t2g4eg2) from the low spin states of Co3+ (LS, t2g6eg0) at active octahedral sites. The electron transitions of Co3+ from low to high spin enable the increase of the spin polarization and produce abundant unpaired electrons in the 3d orbital of Co3+, enhancing the adsorption of oxygen intermediates and boosting the electron transfer process of oxygen redox reactions. Density functional theory calculations indicate that the spin magnetic moment of Co3+ in Vs-NiCo2S4 is raised in comparison to that in NiCo2S4, which improves the catalytic activity of the material via lowering the energy barrier for electron transfer. Experimentally, Vs-NiCo2S4-based Li–O2 batteries exhibit a large specific capacity of 8707.0 mAh g–1 and long cycling life of 487 h. Furthermore, in situ differential electrochemical mass spectrometry results show that the ratio of electron to oxygen during oxygen redox reactions is close to 2, demonstrating the favorable formation and decomposition of Li2O2 on Vs-NiCo2S4 in a Li–O2 battery. This work presents a powerful strategy to rationally design efficient electrocatalysts via spin engineering to boost oxygen redox reaction kinetics in Li–O2 batteries.

Creating low coordination atoms on MoS2/NiS2 heterostructure toward modulating the adsorption of oxygenated intermediates in lithium-oxygen batteries

To boost the energy efficiency of lithium-oxygen (Li-O2) batteries, it is incredibly vital to explore highly effective electrocatalysts for reversible oxygen redox reactions. Incorporating low coordination atoms (LCAs) on the catalyst surface has shown great potential in improving electrocatalytic performance. Herein, MoS2/NiS2 heterostructure with abundant LCAs is designed toward efficiently promote oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Adopting the MoS2/NiS2 heterostructure as the oxygen electrode, Li-O2 batteries exhibit a high discharge capacity of 12377.4 mAh g−1 at 200 mA g−1 and long cycling life over 1101 h. Density functional theory calculations uncover that the modulated d-band center of interfacial MoS2 and NiS2 originated from the electron interaction between LCAs and adjacent atoms can result in the strong adsorption of oxygen intermediates on the catalyst surface, which contributes to the outstanding catalytic performance. This work emphasizes the key role of LCAs in promoting the development of highly efficient electrocatalysts for Li-O2 batteries.

Importance of Chemical Distortion on the Hysteretic Oxygen Capacity in Li-Excess Layered Oxides.

Nonhysteretic redox capacity is a critical factor in achieving high energy density without energy loss during cycling for rechargeable battery electrodes, which has been considered a major challenge in oxygen redox (OR) for Li-excess layered oxide cathodes for lithium-ion batteries (LIBs). Until recently, transition metal migration into the Li metal layer and the formation of O-O dimers have been considered major factors affecting hysteretic oxygen capacity. However, Li-excess layered oxides, particularly Ru oxides, exhibit peculiar voltage hysteresis that cannot be sufficiently described by only these factors. Therefore, this study aims to unlock the critical impeding factors in restraining the non-polarizing oxygen capacity of Li-excess layered oxides (herein, Li2RuO3) that exhibit reversible OR reactions. First, Li2RuO3 undergoes an increase in the chemical potential fluctuation as both the thermodynamic material instability and vacancy content increase. Second, the chemical compression of O-O bonds occurs at the early stage of the OR reaction (0.5 ≤ x ≤ 0.75) for Li1-xRu0.5O1.5, leading to flexible voltage hysteresis. Finally, in the range of 0.75 ≤ x ≤ 1.0, for Li1-xRu0.5O1.5, the formation of an O(2p)-O(2p)* antibonding state derived from the structural distortion of the RuO6 octahedron leads to the irreversibility of the OR reaction and enhanced voltage hysteresis. Consequently, our study unlocks the new decisive factor, namely, the structural distortion inducing the O(2p)-O(2p)* antibonding state, of the hysteretic oxygen capacity and provides insights into enabling the full potential of the OR reaction for Li-excess layered oxides for advanced LIBs.

Long-enduring oxygen redox enabling robust layered cathodes for sodium-ion batteries

Anionic redox chemistry has emerged as a promising pathway attracted extensively attention to meet the demands of high energy sodium-ion batteries. Nonetheless, suchlike cathode materials suffer from poor reversible oxygen redox reactions leading to severe capacity degradation along with sluggish kinetics and voltage decay. In this work, layered sodium transition metal oxides Na0.67Mg0.28Mn0.72-xRuxO2 (x = 0–0.6) are presented, where the optimized sample (x = 0.12) offers an attractively sustainable capacity of 222 mAh g−1 and a distinguished rate capability of 101.7 mAh g−1 at 50C, based on the anionic and cationic activity. The results reveal that the oxygen redox retention is endured at 94.1% in the optimized sample (x = 0.12) after 55 cycles, in contrast to 48.9% of the pristine sample (x = 0), which is the maximum value reported up to now. Meanwhile the lattice parameters show almost no variation, according to the in situ/ex situ X-ray diffraction experiments. Ru-substitution significantly improves the anionic redox reversibility, the structural stability and sodium diffusion, resulting in the noteworthy electrochemical performance advancement. The research performs an effective method to moderate the problems existing in anionic redox reactions and makes a reference for subsequent materials design.

Anionic Redox Activities Boosted by Aluminum Doping in Layered Sodium-Ion Battery Electrode.

Sodium-ion batteries (SIBs) have attracted widespread attention for large-scale energy storage, but one major drawback, i.e., the limited capacity of cathode materials, impedes their practical applications. Oxygen redox reactions in layered oxide cathodes are proven to contribute additionally high specific capacity, while such cathodes often suffer from irreversible structural transitions, causing serious capacity fading and voltage decay upon cycling, and the formation process of the oxidized oxygen species remains elusive. Herein, a series of Al-doped P2-type Na0.6 Ni0.3 Mn0.7 O2 cathode materials for SIBs are reported and the corresponding charge compensation mechanisms are investigated qualitatively and quantitatively. The combined analyses reveal that Al doping boosts the reversible oxygen redox reactions through the reductive coupling reactions between orphaned O 2p states in NaOAl local configurations and Ni4+ ions, as directly evidenced by X-ray absorption fine structure results. Additionally, Al doping also induces an increased interlayer spacing and inhibits the unfavorable P2 to O2 phase transition upon desodiation/sodiation, which is common in P2-type Mn-based cathode materials, leading to the great improvement in capacity retention and rate capability. This work provides deeper insights into the development of structurally stable and high-capacity layered cathode materials for SIBs with anion-cation synergetic contributions.

Coexistence of (O2)n- and Trapped Molecular O2 as the Oxidized Species in P2-Type Sodium 3d Layered Oxide and Stable Interface Enabled by Highly Fluorinated Electrolyte.

The interface stability of cathode/electrolyte for Na-ion layered oxides is tightly related to the oxidized species formed during the electrochemical process. Herein, we for the first time decipher the coexistence of (O2)n- and trapped molecular O2 in the (de)sodiation process of P2-Na0.66[Li0.22Mn0.78]O2 by using advanced electron paramagnetic resonance (EPR) spectroscopy. An unstable interface of cathode/electrolyte can thus be envisaged with conventional carbonate electrolyte due to the high reactivity of the oxidized O species. We therefore introduce a highly fluorinated electrolyte to tentatively construct a stable and protective interface between P2-Na0.66[Li0.22Mn0.78]O2 and the electrolyte. As expected, an even and robust NaF-rich cathode-electrolyte interphase (CEI) film is formed in the highly fluorinated electrolyte, in sharp contrast to the nonuniform and friable organic-rich CEI formed in the conventional lowly fluorinated electrolyte. The in situ formed fluorinated CEI film can significantly mitigate the local structural degeneration of P2-Na0.66[Li0.22Mn0.78]O2 by refraining the irreversible Li/Mn dissolutions and O2 release, endowing a highly reversible oxygen redox reaction. Resultantly, P2-Na0.66[Li0.22Mn0.78]O2 in highly fluorinated electrolyte achieves a high Coulombic efficiency (CE) of >99% and an impressive cycling stability in the voltage range of 2.0-4.5 V (vs Na+/Na) under room temperature (147.6 mAh g-1, 100 cycles) and at 45 °C (142.5 mAh g-1, 100 cycles). This study highlights the profound impact of oxidized oxygen species on the interfacial stability of cathode/electrolyte and carves a new path for building stable interface and enabling highly stable oxygen redox reaction.

Boron-doped sodium layered oxide for reversible oxygen redox reaction in Na-ion battery cathodes

Na-ion cathode materials operating at high voltage with a stable cycling behavior are needed to develop future high-energy Na-ion cells. However, the irreversible oxygen redox reaction at the high-voltage region in sodium layered cathode materials generates structural instability and poor capacity retention upon cycling. Here, we report a doping strategy by incorporating light-weight boron into the cathode active material lattice to decrease the irreversible oxygen oxidation at high voltages (i.e., >4.0 V vs. Na+/Na). The presence of covalent B–O bonds and the negative charges of the oxygen atoms ensures a robust ligand framework for the NaLi1/9Ni2/9Fe2/9Mn4/9O2 cathode material while mitigating the excessive oxidation of oxygen for charge compensation and avoiding irreversible structural changes during cell operation. The B-doped cathode material promotes reversible transition metal redox reaction enabling a room-temperature capacity of 160.5 mAh g−1 at 25 mA g−1 and capacity retention of 82.8% after 200 cycles at 250 mA g−1. A 71.28 mAh single-coated lab-scale Na-ion pouch cell comprising a pre-sodiated hard carbon-based anode and B-doped cathode material is also reported as proof of concept.

Origin of reversible oxygen redox reactions in high energy density layered oxides

Oxygen redox reactions (ORRs) are considered a new strategy in reaching a high-energy density for rechargeable batteries. Here, we propose the concept “band coherency” for identifying the origin of reversible ORRs in alkali-excess compounds, i.e., Na 2 RuO 3 and Li 2 RuO 3 . Band coherency redox chemistry exhibits non-discrete transition metal (TM) nd –O 2 p electron activity. This can be explained by the charge variations of O and Ru, including thermodynamic-phase stability. After the cation-based redox reaction (Ru 4+ /Ru 5+ ), a dominant ORR, accompanied by the partial Ru-redox reaction, takes place in the band-coherency region. Subsequently, pure anion redox through oxygen occurs. This three-step redox mechanism is consistent with the electrochemical behavior of the oxygen-redox-tuned cathodes, until the band-coherency region shows great ORR reversibility. Triggering band coherency is a rational-design principle in using ORRs, excluding pure anionic activity and maintaining their high-energy-density properties upon cycling for the next generation of alkali-ion batteries. Band coherency redox chemistry exhibits non-discrete TM nd −O 2 p electron activity The band coherency redox mechanism is experimentally consistent with cathode materials A cumulative cationic redox before an activating oxygen redox is an essential element Choi et al. present a “band coherency” concept for identifying the origin of reversible oxygen-redox reactions in alkali-excess compounds that exhibit non-discrete TM nd –O 2 p electron activity. Triggering band coherency is a rational-design principle in using oxygen-redox reactions, excluding the pure anionic activity, for the next generation of alkali-ion batteries.

Unlocking the Intrinsic Origin of the Reversible Oxygen Redox Reaction in Sodium‐Based Layered Oxides

AbstractUnlike cathodes for lithium‐ion batteries, oxygen redox (OR) processes at a high voltage ( 4.2 V) during the first charge in sodium‐ion batteries (SIBs) employ some Li‐incorporated Mn oxides that is recovered during subsequent discharge. To determine the intrinsic origin, P2‐type Na0.6[Li0.2Mn0.8]O2 exhibiting a reversible OR‐induced two‐phase reaction was investigated using experiments and first‐principle calculations. First, operando X‐ray diffraction results in reversible P2‐Z phase transformations and thermodynamic analysis show the two‐phase reaction features Li migration into the tetrahedral sites from the transition‐metal layer in the latter phase. Second, Li‐induced decoupling of the oxygen 2p‐electron led to selective anion redox activity depending on the oxygen sites that are Li‐rich (redox‐active) and Mn‐rich (redox‐inactive) environments. Third, redox‐active oxygen coordinated to the Li vacancy predominantly participates in the formation of peroxo‐like dimers with distortion of the MnO6 octahedron, as observed in the reversible extended X‐ray absorption fine structure spectra during the OR reaction. Considering three physicochemical perspectives, we reveal that Li ions play a role in activating OR reactions and control OR participation in the charge‐compensation process. Our findings suggest that the Li/Mn ratio is a critical factor for achieving a reversible OR reaction, and broaden the possibilities of exploiting OR to reach high‐energy densities in next‐generation SIBs.

Cycling mechanism of Li2MnO3: Li–CO2 batteries and commonality on oxygen redox in cathode materials

Summary Li2MnO3 has been considered to be a representative Li-rich compound with active debates on oxygen activities. Here, by evaluating the Mn and O states in the bulk and on the surface of Li2MnO3, we clarify that Mn(III/IV) redox dominates the reversible bulk redox in Li2MnO3, while the initial charge plateau is from surface reactions with oxygen release and carbonate decomposition. No lattice oxygen redox is involved at any electrochemical stage. The carbonate formation and decomposition indicate the catalytic property of the Li2MnO3 surface, which inspires Li-CO2/air batteries with Li2MnO3 acting as a superior electrocatalyst. The absence of lattice oxygen redox in Li2MnO3 questions the origin of the oxygen redox in Li-rich compounds, which is found to be of the same nature as that in conventional materials based on spectroscopic comparisons. These findings provide guidelines on understanding and controlling oxygen activities toward high-energy cathodes and suggest opportunities on using alkali-rich materials for catalytic reactions.

Promoting the Reversible Oxygen Redox Reaction of Li-Excess Layered Cathode Materials with Surface Vanadium Cation Doping.

Li‐excess layered cathode (LLC) materials have a high theoretical specific capacity of 250 mAh g−1 induced by transition metal (cationic) and oxygen (anionic) redox activity. Especially, the oxygen redox reaction related to the activation of the Li2MnO3 domain plays the crucial role of providing a high specific capacity. However, it also induces an irreversible oxygen release and accelerates the layered‐to‐spinel phase transformation and capacity fading. Here, it is shown that surface doping of vanadium (V5+) cations into LLC material suppresses both the irreversible oxygen release and undesirable phase transformation, resulting in the improvement of capacity retention. The V‐doped LLC shows a high discharge capacity of 244.3 ± 0.8 mAh g−1 with 92% retention after 100 cycles, whereas LLC delivers 233.6 ± 1.1 mAh g−1 with 74% retention. Furthermore, the average discharge voltage of V‐doped LLC drops by only 0.33 V after 100 cycles, while LLC exhibits 0.43 V of average discharge voltage drop. Experimental and theoretical investigations indicate that doped V‐doping increase the transition metal–oxygen (TM—O) covalency and affect the oxidation state of peroxo‐like (O2)n − species during the delithiation process. The role of V‐doping to make the oxygen redox reversible in LLC materials for high‐energy density Li‐ion batteries is illustrated here.

(Invited) Coulombic Self-Ordering upon Charging a Large-Capacity Layered Cathode Material

Lithium- and sodium-rich layered transition-metal oxides have recently been attracting sig- nificant interest because of their large capacity achieved by additional oxygen-redox reac- tions. However, layered transition-metal oxides exhibit structural degradation such as cation migration, layer exfoliation or cracks upon deep charge, which is a major obstacle to achieve higher energy-density batteries. Here we demonstrate a self-repairing phenomenon of stacking faults upon desodiation from an oxygen-redox layered oxide Na2RuO3, realizing much better reversibility of the electrode reaction. The phase transformations upon charging A2MO3 (A: alkali metal) can be dominated by three-dimensional Coulombic attractive interactions driven by the existence of ordered alkali-metal vacancies, leading to counter- intuitive self-repairing of stacking faults and progressive ordering upon charging. The coop- eratively ordered vacancy in lithium-/sodium-rich layered transition-metal oxides is shown to play an essential role, not only in generating the electro-active nonbonding 2p orbital of neighbouring oxygen but also in stabilizing the phase transformation for highly reversible oxygen-redox reactions.

Insights of the anionic redox in P2–Na0.67Ni0.33Mn0.67O2

The search for high-energy batteries has promoted intense attention to anionic redox in layered transition metal oxides because of their ability of delivering much higher capacity than traditional cathodes. P2–Na 0.67 Ni 0.33 Mn 0.67 O 2 electrode exhibits outstanding air-stability and high average potential. Very recently, the anionic redox in this promising sodium cathode has been evidenced by mapping of resonant inelastic X-ray scattering. However, the origin of this oxygen redox has not been recognized yet. Here, based on the combination of X-ray absorption spectroscopy and density functional theory (DFT) calculations, we demonstrate that with the remove of Na + , the Ni 2+ oxidized to Ni 3+ and followed by the oxidation of lattice oxygen. Our DFT calculation further confirms that the oxygen redox in Na 0.67 Ni 0.33 Mn 0.67 O 2 is rooted from Ni–O anti-bonding ( e g *) state rather than the non-bonding O 2p band and result in the highly reversible oxygen redox reactions without O 2 loss. Moreover, at very low sodium contents, it is highly possible that a charge redistribution process between the Ni and O ions occurs, which results in the inconsistent experimental observations in previous references. • Confirm the anionic redox reactions in P2–Na 0.67 Ni 0 . 33 Mn 0 . 67 O 2 at low sodium contents via h-XAS and DFT calculations. • No oxygen loss is observed during the first charge process of P2–Na 0.67 Ni 0.33 Mn 0.67 O 2 . • Clarify the insights of anionic redox in P2–Na 0.67 Ni 0.33 Mn 0.67 O 2 .

A reversible oxygen redox reaction in bulk-type all-solid-state batteries.

An all-solid-state lithium battery using inorganic solid electrolytes requires safety assurance and improved energy density, both of which are issues in large-scale applications of lithium-ion batteries. Utilization of high-capacity lithium-excess electrode materials is effective for the further increase in energy density. However, they have never been applied to all-solid-state batteries. Operational difficulty of all-solid-state batteries using them generally lies in the construction of the electrode-electrolyte interface. By the amorphization of Li2RuO3 as a lithium-excess model material with Li2SO4, here, we have first demonstrated a reversible oxygen redox reaction in all-solid-state batteries. Amorphous nature of the Li2RuO3-Li2SO4 matrix enables inclusion of active material with high conductivity and ductility for achieving favorable interfaces with charge transfer capabilities, leading to the stable operation of all-solid-state batteries.