Solid-state Lithium Batteries Research Articles

Hybrid solid electrolyte with the combination of LATP ceramic and PEO polymer by a solvent-free procedure

The development of excellent performance solid-state electrolytes (SSEs) is essential for high-energy solid-state lithium batteries. Herein, solid state composite electrolyte consisting of NASICON particles and PEO-LiTFSI was prepared through a solvent-free procedure. The assembled LFP / PEO-LATP / Li all-solid-state battery can present an initial capacity of 153.8 mA h g−1 and exhibit excellent electrochemical stability with a high capacity retention ratio of 95% after 100 cycles at 60 °C. In addition, a small amount of ionic liquid (IL) was added into hybrid solid electrolyte (HSE) to enhance the interface contact and improved the room temperature performance. Surprisingly, the assembled LFP / HSE / Li battery exhibits a stable discharge capacity of 157.6 mA h g−1 at 25 °C when the content of IL is 3%. The capacity retention can be reached 97.8% over 150 cycles at 60 °C. All the results show that assembled cells with HSE revealed an improved electrochemical performance.

Fusing Ta-doped Li7La3Zr2O12 grains using nanoscale Y2O3 sintering aids for high-performance solid-state lithium batteries.

Solid-state lithium batteries have advantages of high energy density and usage safety and are considered as promising next-generation power sources. Among them, the garnet-type oxide electrolyte has become a widely studied inorganic electrolyte due to its high ionic conductivity and chemical stability. In this paper, nanoscale Y2O3 (NYO) particles are introduced as sintering aids for fabricating Ta-doped Li7La3Zr2O12 (LLZTO) ceramics, and the sintering effects of various NYO ratios on the properties of LLZTO are investigated. Among the samples, the LLZTO-5%NYO sample exhibits the highest ionic conductivity (7.39 × 10-4 S cm-1) and the lowest activation energy (0.17 eV). At various current densities, the polarization voltage of LLZTO-5%NYO is also the lowest without a short circuit. The full cells of LFP|LLZTO-5%NYO|Li exhibit a high capacity of 163.9 mA h g-1 with a high initial coulombic efficiency of 97.4%, and the capacity retention rate is up to 98.1% after 50 cycles. This work may inspire the development of analogous solid-state electrolytes and lithium batteries.

Improving the interfacial stability of ultrahigh-nickel cathodes with PEO-based electrolytes by targeted chemical reactions.

Benefiting from high energy density of ultrahigh-nickel cathode materials and good safety of PEO-based electrolytes, PEO-based ultrahigh-nickel solid-state lithium batteries (SLMBs) are considered to be new-generation energy storage devices. However, the incompatibility of ultrahigh-nickel cathode materials and PEO-based electrolytes is the main challenge due to serious interfacial side reactions. Therefore, the modification of the cathode/electrolyte interface is crucial. Herein, the residual lithium on the surface of LiNi0.9Co0.06Mn0.04O2 is utilized to construct an interfacial coating layer by reacting with H3BO3. The in situ formed xLi2O-B2O3 coating layer (LBO1-NCM) with high ionic conductivity can be regulated with different crystal structures during the sintering process. Besides, an all-solid-state three-electrode cell is fabricated, which verifies that the xLi2O-B2O3 coating can effectively stabilize the interface. Astonishingly, uneven Li anode deposition is observed in SLMBs, which is caused by the breakage of PEO molecular chains due to the strong oxidation of the cathode, while this crosstalk is also suppressed by the xLi2O-B2O3 coating layer. Consequently, Li|PEO|LBO1-NCM achieves a substantially improved electrochemical performance, exhibiting 90.5% of capacity retention after 100 cycles for the coin cell and 80.3% of capacity retention after 200 cycles for the pouch cell. Apparently, the targeted modification of interfaces should be paid as much attention as electrolyte optimization in SLMBs.

Safety concerns in solid-state lithium batteries: from materials to devices

The review focuses on potential safety issues in solid-state lithium batteries during electrolyte synthesis and battery operation/failure, and proposes recent innovations and future directions to inhibit thermal failure and hazardous product release.

The Influence of Organic-Inorganic Composite Solid Electrolytes on Electrochemical Performance in Solid-State Lithium Batteries

Lithium batteries, as the most closely watched secondary batteries, exhibit outstanding performance. Nonetheless, the formation of lithium dendrites significantly compromises their safety and hampers further development. To mitigate the impact of lithium dendrites on batteries, solid-state lithium batteries have emerged, with solid electrolytes being of paramount importance. Traditional solid electrolytes are categorized into polymers, oxides, and sulfides. However, the inherent limitations of these materials impede their effectiveness. This study proposes a novel solid electrolyte consisting of organic and inorganic materials, aiming to harness the collective benefits of the two electrolyte types to improve the electrochemical performance of solid electrolytes. Empirical data from experiments on composite solid electrolytes, incorporating polyethylene oxide (PEO) with Li6.4La3Zr1.4Ta0.6O12 (LLZTO) and Li10GeP2S12 (LGPS), reveal that these organic-inorganic composite solid electrolytes exhibit high ionic conductivity, reduced interface impedance, and an extensive electrochemical window. It demonstrates that organic-inorganic composite solid electrolytes combining polymers with oxides or sulfides can integrate the advantages of both, achieving electrolyte materials with superior electrochemical performance. Finally, the existing problems are discussed, and future research trends are anticipated.

Optimization strategy for metal lithium negative electrode interface in all-solid-state lithium batteries

Lithium metal is a perfect anode material for lithium secondary batteries because of its low redox potential and high specific capacity. In the future, solid-state lithium batteries constructed with embedded lithium anodes, solid-state electrolytes, and lithium metal anodes are anticipated to power electric cars, robots, high-end electronics, aircraft, and other relevant technological industries. However, as a result of the uneven deposition and dissolution of lithium during the charging and discharging process, a large number of dendritic dendrites form on the lithium-electrolyte contact surface and grow along the electrolyte’s direction, ultimately resulting in an internal short circuit that causes the battery to fail. Although the development of lithium dendrites can be substantially inhibited by the use of solid electrolytes with high Young’s modulus, long cycle and safety criteria are still not met. Furthermore, high interfacial resistance and interfacial interaction between lithium metal and solid electrolyte are issues brought on by the solid-solid contact between the two materials, which substantially impedes the creation and use of solid-state lithium-metal batteries. This paper first explains the growth principle of lithium dendrites. Then, the optimization strategy of the negative electrode interface is introduced. Finally, the future development trend of solid-state lithium batteries is overlooked.

A Review on Conventional to Bipolar Design of Anode Less All Solid-State Batteries

Large-scale energy storage technologies are becoming more and more necessary for the effective use of clean and sustainable energy sources. Solid-state lithium batteries (SSLBs) based on non- or less flammable...

Ferroelectric BiFeO3 modified PVDF-based electrolytes for high-performance lithium metal batteries

PVDF-based electrolytes are promising candidates for solid-state lithium batteries (SSLBs) due to their high safety, interface compatibility and electrochemical stability.

Recent advances in high-performance lithium-rich manganese-based materials for solid-state lithium batteries

The applications of high-performance LRMs in ASSBs can effectively overcome the low energy density and poor safety in the liquid batteries. Significant progresses are used to address challenges and promote the practical application of LRMs in ASSBs.

Janus in situ formed CoO/Li2CO3/LiF interlayer between LiCoO2 and Li6PS5Cl solid electrolytes boosting the 4.5 V performance of sulfide-based all-solid-state batteries

This study uses PVDF high-temperature treatment to modify LiCoO2 cathodes for solid-state lithium batteries, forming a CoO/Li2CO3/LiF coating that improves interfacial stability and reduces resistance, enhancing high-voltage performance.

Building continuous Li-ion transport channels from cathode to anode in solid-state lithium-metal batteries

Homogeneous Li+ transport channels through the electric core were built by surface modifications of both the solid-state electrolyte membrane and the binder phase in the cathode, thus improving the performance of solid-state lithium batteries.

Fluorinating All Interfaces Enables Super-Stable Solid-State Lithium Batteries by In Situ Conversion of Detrimental Surface Li2CO3.

Li-stuffed battery materials intrinsically have surface impurities, typically Li2CO3, which introduce severe kinetic barriers and electrochemical decay for a cycling battery. For energy-dense solid-state lithium batteries (SSLBs), mitigating detrimental Li2CO3 from both cathode and electrolyte materials is required, while the direct removal approaches hardly avoid Li2CO3 regeneration. Here, a decarbonization-fluorination strategy to construct ultrastable LiF-rich interphases throughout the SSLBs by in situ reacting Li2CO3 with LiPF6 at 60 °C is reported. The fluorination of all interfaces effectively suppresses parasitic reactions while substantially reducing the interface resistance, producing a dendrite-free Li anode with an impressive cycling stability of up to 7000h. Particularly, transition metal dissolution associated with gas evolution in the cathodes is remarkably reduced, leading to notable improvements in battery rate capability and cyclability at a high voltage of 4.5V. This all-in-one approach propels the development of SSLBs by overcoming the limitations associated with surface impurities and interfacial challenges.

Unravelling stability of current collectors in lithium bis(trifluoromethanesulfonyl)imide salt and polyethylene oxide electrolyte for solid-state lithium batteries

Recent interest in solid-state lithium batteries prevails in the battery community because of their superiority in terms of safety concerns. Many works have been reported for electrodes and electrolytes and their suitability for solid-state polymer electrolytes to adopt in lithium batteries. Herein, for the first time, we report on the electrochemical stabilities of Cu and Al current collectors in a polyethylene oxide (PEO)-based solid-state electrolyte containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. Our work on the electrochemical dynamic- and transient-mode polarization of these electrodes indicates that Cu metal undergoes Cu–O passivation below 3 V. The adhered Cu-F layer on the CuO passive layer may be beneficial to delay undesired reaction such as corrosion. And it is further confirmed that Al metal passivates stably even up to 5 V; namely, the Al surface forms double layers of the outer Al–F and inner Al–O layers. These F- and O-based layers are attributed to the combination of the Al and O from the reductively decomposed PEO and further progress of Al2O3 and HF (H+ + F− →HF), decomposed from the PEO (H+) and TFSI− (F−). Therefore, we verify that successful passivation on Cu and Al metal surfaces facilitates their suitability as current collectors for solid-state polymer lithium batteries.

Chemical and Electrochemical Interaction of Halide and Sulfide-Based Electrolytes in Solid-State Batteries

Introduction Conventional lithium-ion batteries (LIBs) have found widespread small and large applications. However, safety issues and capacity degradation of the cells, in general, can occur due to the use of toxic and flammable liquid electrolytes [1]. As one of the next-generation LIBs, solid-state lithium batteries (SSBs) have the potential to replace liquid electrolyte LIBs due to their safety and potentially high energy density [2]. The key component of SSBs is the solid-state electrolyte (SSE). Sulfide and halide-based solid electrolytes are among the hot topics in solid electrolyte research for SSBs. Despite the advantages of solid electrolytes, such as good compatibility with high-voltage cathode materials and soft fabrication. However, the poor chemical and electrochemical stability of sulfide and halide-based solid electrolytes towards Li metal has a critical problem that causes the degradation of the lithium/solid electrolyte interface due to the formation of side reaction components that leads to inhibiting lithium kinetics [3]. Results and Discussion Here, we have shown that a combination of halide and argyrodite (Li6PS5Cl) solid electrolytes can lead to the prevention of the formation of unfavorable interactions between solid electrolytes and lithium metal anode. The combination of halide and argyrodite (Li6PS5Cl) in the Li/Li symmetric cell can stabilize cycle life and increase the high critical current density (CCD) from C/20 to C/2 in comparison with the pure halide and argyrodite electrolytes. Furthermore, compared to the original halide and argyrodite electrolytes, a high initial coulombic efficiency and cycle life can be maintained when combined with a full Li/NCM cell. This approach to improving halide-based SSBs can provide a fairly simple and efficient strategy. Acknowledgements This project has received funding from the European Union's Horizon Europe programme for research and innovation under grant agreement No. 101069681 (HELENA project).

Interface Instability Analysis in Solid-State Lithium Batteries Using Advanced in Situ Methods

Solid-state lithium batteries are steadily gaining research interest due to their inherently safe design, high energy density and long life cycle. A polymer electrolyte is a key component of current battery technology and can enable the development of next-generation ultra-efficient solid-state lithium batteries. Despite the promise of high energy density, the development of polymer-based solid-state lithium batteries is hindered by interfacial challenges such as passivating layer formation and lithium dendrite infiltration [1-3]. Therefore, a deeper understanding of the interface chemistry and possible failure scenarios is essential for ensuring ideal battery performance. Advanced and in situ characterization methods are crucial for comprehending how these interfaces work with cell cycling and identifying responsible factors for cell failure [4].Here, by using in situ X-ray tomography, combined with XPS, SEM, and AES, we present the structural and chemical evolution of a lithium/PVDF-HFP-based polymer electrolyte interface over prolonged cell cycling at a higher temperature, from the pristine state up to cell failure. The electrolyte membrane, stacked between strips of metallic lithium under pressure, is scanned with this imaging technique while galvanostatic cycling. The in situ X-ray computed tomography provides in-depth 3D interface images and, non-invasively with accuracy and resolution, displays lithium penetration inside the electrolyte. A 3D reconstruction shows the structure of the electrolyte after cycling as a result of the lithium infiltration (Figure 1). Post-mortem XPS provides chemical information and shows an accumulation of lithium salts and organic compounds resulting from the degradation of membrane constituents during cycling. Impedance data reveal the degradation is followed by an increase in interfacial resistance. The higher-resolution SEM images and AES provide complementary data to the X-ray data. Together, these techniques contribute to a deeper comprehension of interfacial changes and provide the suggestions needed to overcome failure mechanisms and enhance the electrochemical performance.

Improved Lewis Acidity Using Ionic Liquid-Grafted Bimetallic Zr/Ti Uio-66 Fillers for Composite Solid Electrolytes

In recent years, solid-state lithium batteries have gained significant attention due to their high energy density and stability. However, challenges such as low ionic conductivity, non-homogeneous Li ion flux, and low interfacial compatibility of solid electrolytes still remain. Composite solid electrolytes (CSEs) have emerged as a potential solution to these issues, by combining an inorganic filler with a polymer matrix. To develop high-performance CSEs, extensive research has been conducted on inorganic active fillers with an abundance of Lewis acidic sites. The acidic sites of the filler can induce Lewis acid-base interactions, which can decrease the crystallinity of fillers by weakening the attraction between polymer segments and increasing chain mobility. Additionally, they increase the degree of dissociation of lithium salt, resulting in an increase in ionic conductivity. In terms of the concentration gradient of Li-ions, the free anion of lithium salt can be trapped by an acidic filler, thereby reducing the mobility and concentration of the anion. Finally, the acidic filler prevents the oxidation of ether oxygen groups in PEO, thus, improves its electrochemical stability. Furthermore, for increasing the ionic conductivity, inorganic filler should be an active filler capable of serving as Li-ion sources to the interfacial region between polymeric matrix and inorganic fillers, thereby facilitating Li-ion transport. Consequently, Li-ions can hop along the surface of active fillers. Therefore, in order to achieve high-performance CSEs with a polymer matrix, inorganic active fillers with an abundance of acidic sites have emerged as one of the most effective strategies for designing high performance fillers with good compatibility with the matrix. To address this technological need, in this work, we present a novel CSE based on a polyethylene oxide (PEO) matrix with a bimetallic (Zr/Ti) UiO-66-ionic liquid grafted filler (BUIL) that simultaneously modified the metal and ligand sites of UiO-66 MOF particles. The bimetallic structure of BUIL was prepared by replacing the metal sites of UiO-66 with Ti metal ions using the metal exchange method, resulting in the formation of more structural defects and an increase in the number of Lewis acid sites of filler. In addition, the pre-synthesized ionic liquids containing a -OH functional group (IL-OH), N-hydroxyhexyl-N’-methyl imidazolium bis(trifluoromethylsulfonyl)imide, were grafted when synthesizing UiO-66 with a ligand containing a -Br functional group. The BUIL filler functions as a high Lewis acid filler owing to its bimetallic structure and grafted ionic liquid. Also, to utilize BUIL as an active filler, lithium bis(trifluoromethanesulfonyl)imide/1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (IL, LiTFSI/EMIM-TFSI) was loaded into BUIL (IL@BUIL). In order to confirm the effect of Lewis acid filler interaction on PEO polymer matrix and lithium salt, various spectroscopic characterization methods were employed. As a result, CSEs containing IL@BUIL filler and PEO matrix exhibited markedly improved ionic conductivity, lithium-ion transference number, electrochemical stability, and long-cycle stability of Li metal electrode. After optimization, the ionic conductivity of CSEs at 30°C was enhanced to 0.458 mS cm-1, the lithium-ion transference number was raised to 0.668, and the electrochemical stability window was widened to 4.5 V. In addition, during a continuous plating/stripping test, the lithium metal symmetric cell of CSEs stably cycled for 500 h at a current density of 0.2 mA cm-2. Finally, LiFePO4/IL@BUIL/Li cell shows a capacity of 148 mA h g-1 at 1C.The present strategy of simultaneously modifying the metal and the ligand sites of MOF to improve the properties of CSEs can be used as a general platform for the design of a MOF filler in CSEs system, as well as a guideline for the next generation CSEs.

Striking a Balance between Carbon Mediated Cathode Degradation and SEI Engineering Towards Stable High-Performance Solid-State Batteries

Solid-state batteries (SSBs) can render a paradigm shift in battery safety and energy density. The promise hinges on integrating high-capacity alkali metal electrodes with state-of-the-art inorganic solid electrolytes and high-energy Li-ion cathodes. However, the development has been restricted, mainly owing to the limited understanding and partial overcoming of the interfacial electro-chemo-mechanical issues at the electrode-electrolyte interfaces, leading to inferior power capability, energy efficiency, and long-term stability of the cell.1 Sulfide-type solid electrolytes (SEs) like Li6PS5Cl, Li10GeP2S12, and Li3PS4 are promising for commercial SSB development, but they seem to suffer from interfacial stability issues with the high-energy NMC (LiNixCoyMnzO2) cathodes, particularly when a conductive carbon additive is employed, which is required for improved capacity and high current density operations. Earlier reports suggest that the carbon enables a faster electronic percolation pathway, leading to a quicker NMC-SE interfacial degradation over cycling. Parallelly, the reactive functional groups on the carbon surface may aggravate the decomposition pathway by reacting with the thiophosphate SEs.2–4 , 5 To shut down this conductive additive-led decomposition and to stabilize NMC-sulfide SE-based SSBs, often a protective coating of LiNbO3, LiZrO3, Li3PO4, etc., is applied on the NMC particles in addition to avoiding the use of carbon in the cathode composite. Relatively lesser-known approaches looked into the effect of modifying the conductive additive surface itself with a non-conductive polymer or insulator-type material to tame the degradation mechanism led by the electron percolation pathway.1,6–9 In this context, by thorough experimentation, we have established an in-depth understanding of carbon’s role in the NMC performance degradation process. This led to the reckoning that one of the insulating degradation products can be in situ generated with functionalized carbon as the conducting additive, rendering stable solid electrolyte interphase (SEI) during electrochemical cycling. We found that the controlled degradation kinetics with an optimally functionalized carbon material help achieve the required conductivity (low impedance) at the cathode for improved energy and power densities and a stable cathode SEI for durable SSB cycling. In conclusion, we present a novel and facile idea of engineering the conductive carbon additive for achieving high-capacity, long-life NMC-based SSBs without the complication of expensive coating strategies.Reference: Ding, Z., Li, J., Li, J. & An, C. Review-Interfaces: Key Issue to Be Solved for All-Solid-State Lithium Battery Technologies. (2020)Koerver, R. et al. Redox-active cathode interphases in solid-state batteries. J. Mater. Chem. A 5, 22750–22760 (2017).Walther, F. et al. Influence of Carbon Additives on the Decomposition Pathways in Cathodes of Lithium Thiophosphate-Based All-Solid-State Batteries. Chem. Mater. 32, 6123–6136 (2020).Walther, F. et al. Visualization of the Interfacial Decomposition of Composite Cathodes in Argyrodite-Based All-Solid-State Batteries Using Time-of-Flight Secondary-Ion Mass Spectrometry. Chem. Mater. (2019)Park, S. W. et al. Graphitic Hollow Nanocarbon as a Promising Conducting Agent for Solid-State Lithium Batteries. Small 15, (2019).Takada, K. et al. Interfacial modification for high-power solid-state lithium batteries. Solid State Ionics 179, 1333–1337 (2008).Banerjee, A., Wang, X., Fang, C., Wu, E. A. & Meng, Y. S. Interfaces and Interphases in All-Solid-State Batteries with Inorganic Solid Electrolytes. Chem. Rev. 120, 6878–6933 (2020).Zhang, Y. et al. Direct Visualization of the Interfacial Degradation of Cathode Coatings in Solid State Batteries: A Combined Experimental and Computational Study. Adv. Energy Mater. 10, 1903778 (2020).Randau, S. et al. On the Additive Microstructure in Composite Cathodes and Alumina-Coated Carbon Microwires for Improved All-Solid-State Batteries. Chem. Mater. 33, 1380–1393 (2021). Figure 1

The “Buffer Layer” an Improved Electrode-Electrolyte Interface for Solid-State Batteries

Solid-state lithium batteries are broadly accepted as promising candidates for application in the next generation of EVs as they should offer safer and higher-energy-density batteries. Nonetheless, their development is impeded by many challenges, including the resistive electrode–electrolyte interface originating from the removal of the liquid electrolyte that normally permeates through the porous cathode and insures efficient ionic conductivity through the cell. One way to tackle this challenge is by formulating composite cathodes containing solid ionic conductors in their structure but this approach will require the conductors to exhibit chemical stability, electrochemical stability, flexibility, adhesion and is therefore limited to some materials. Recently, Arkema developed a technology called buffering layer which allows to transform any conventional porous electrode into a catholyte. This organic layer has a very high ionic conductivity at room temperature, is compatible with all active materials and can be processed with conventional Gigafactory equipment. Moreover, this layer helps protect the solid ionic conductor from the cathode and anode materials. During this presentation, the manufacture and the electrochemical performance of this layer for different systems of cathode and anode will be discussed.

Robust-Dense Composite Cathode with Improved Three-Dimensional Ionic Percolation Network and Electrode/Electrolyte Interface for the Development of All-Solid-State Sodium Batteries

All solid-state sodium batteries (AS3Bs) attract immense attention due to their excellent energy and power density, cycle life and thermal security [1]. However, the practical realization of AS3Bs is greatly affected by low to moderate ionic conductivity of the solid electrolyte, unstable electrode/electrolyte interface and poor ion and electron transport between the cathode active materials [2,3]. The unstable electrode/electrolyte interface with point contact leads to huge charge transfer resistance, stress generation and the delamination of the electrode/electrolyte interface during electrochemical reactions. The ion percolation network in the cathode structure is also a critical part. Liquid electrolyte fills the pores present in the cathode and leads to a good Na+ percolation network; however, Na+ percolation cannot be possible in the case of AS3Bs due to the non-fluidity nature of solid electrolyte. This results in low capacity contribution from the cathode owing to fewer cathode active material utilization during electrochemical cycling [4]. Due to the above mentioned issues, the long-cycle stability of AS3Bs is poor.Here we have first prepared Mg doped Na1+3xZr2(SixP1-xO4)3 (NZSP-0.05Mg) with improved ionic conductivity (4.1 mS cm-1 25 ℃) by minimizing the secondary impurity phase. Further, we have utilized an innovative approach to develop a composite cathode by directly firing sodium vanadium fluoro phosphates (NVPF) with Na3.1Zr1.95Mg0.05Si2PO12 (NZSP-0.05Mg) solid electrolyte in the optimized size and weight ratio leading to the robust and dense structure with 3D ionic and electronic percolation network. Additionally, the pores present in the composite cathode is addressed by incorporating polymer electrolyte which further improves the ionic percolation network. The intimate contact between the solid electrolyte and the electrodes was further improved by using a composite solid electrolyte, and the full cell is fabricated by using NVPF composite cathode, composite solid electrolyte and Na metal. The cell delivers a discharge capacity of 103 mAh g-1 after 500 cycles with a Coulombic efficiency of 98 % at 0.1 C and shows excellent capacity retention of 67 mAh g-1 at 2C. The post-mortem XPS analysis confirms the electrochemical stability between the NVPF composite cathode and CSE as well as the Na metal and CSE. Our research provides a new prospective for the preparation of composite cathode and full cell design which can be utilized in solid state sodium and lithium batteries. This work can contribute to a safer battery with long cycle life.

(Invited) Achieving Extreme High Ion-Current Densities in Tailored Materials, Structures, and Interfaces

Rate capability is a limiting factor in solid oxide fuel cells (SOFCs), solid oxide electrolysis cells (SOECs), and oxide-based solid-state lithium (SSLiBs) and sodium (SSNaBs) batteries. In this presentation we will explain the roles of composition, structure, and interfaces in achieving extremely high current densities, and demonstrate SOFC/SOEC current densities of 5 mA/cm2 at 650°C, and SSNaB and SSLiB current densities of 30 mA/cm2 and 100 mA/cm2, respectively, at room temperature.