Lithium-ion batteries have had a profound impact on our daily life, but inherent limitations make it difficult for Li-ion chemistries to meet the growing demands for portable electronics, electric vehicles and grid-scale energy storage. Therefore, chemistries beyond Li-ion are currently being investigated and need to be made viable for commercial applications. The use of metallic Li is one of the most favoured choices for next-generation Li batteries, especially Li-S and Li-air systems. After falling into oblivion for several decades because of safety concerns, metallic Li is now ready for a revival, thanks to the development of investigative tools and nanotechnology-based solutions. In this Review, we first summarize the current understanding on Li anodes, then highlight the recent key progress in materials design and advanced characterization techniques, and finally discuss the opportunities and possible directions for future development of Li anodes in applications.

Reviving the lithium metal anode for high-energy batteries

The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Solid-state electrolytes are attracting increasing interest for electrochemical energy storage technologies. In this Review, we provide a background overview and discuss the state of the art, ion-transport mechanisms and fundamental properties of solid-state electrolyte materials of interest for energy storage applications. We focus on recent advances in various classes of battery chemistries and systems that are enabled by solid electrolytes, including all-solid-state lithium-ion batteries and emerging solid-electrolyte lithium batteries that feature cathodes with liquid or gaseous active materials (for example, lithium–air, lithium–sulfur and lithium–bromine systems). A low-cost, safe, aqueous electrochemical energy storage concept with a ‘mediator-ion’ solid electrolyte is also discussed. Advanced battery systems based on solid electrolytes would revitalize the rechargeable battery field because of their safety, excellent stability, long cycle lives and low cost. However, great effort will be needed to implement solid-electrolyte batteries as viable energy storage systems. In this context, we discuss the main issues that must be addressed, such as achieving acceptable ionic conductivity, electrochemical stability and mechanical properties of the solid electrolytes, as well as a compatible electrolyte/electrode interface. This Review details recent advances in battery chemistries and systems enabled by solid electrolytes, including all-solid-state lithium-ion, lithium–air, lithium–sulfur and lithium–bromine batteries, as well as an aqueous battery concept with a mediator-ion solid electrolyte.

Lithium battery chemistries enabled by solid-state electrolytes

Compared with lithium-ion batteries with liquid electrolytes, all-solid-state batteries offer an attractive option owing to their potential in improving the safety and achieving both high power and high energy densities. Despite extensive research efforts, the development of all-solid-state batteries still falls short of expectation largely because of the lack of suitable candidate materials for the electrolyte required for practical applications. Here we report lithium superionic conductors with an exceptionally high conductivity (25 mS cm−1 for Li9.54Si1.74P1.44S11.7Cl0.3), as well as high stability ( ∼0 V versus Li metal for Li9.6P3S12). A fabricated all-solid-state cell based on this lithium conductor is found to have very small internal resistance, especially at 100 ∘C. The cell possesses high specific power that is superior to that of conventional cells with liquid electrolytes. Stable cycling with a high current density of 18 C (charging/discharging in just three minutes; where C is the C-rate) is also demonstrated. The development of all-solid-state batteries requires fast lithium conductors. Here, the authors report a lithium compound, Li9.54Si1.74P1.44S11.7Cl0.3, with an exceptionally high conductivity and demonstrate that all-solid-state batteries based on the compound have high power densities.

High-power all-solid-state batteries using sulfide superionic conductors

Solid-state batteries have recently attracted great interest as potentially safe and stable high-energy storage systems. However, key issues remain unsolved, hindering full-scale commercialization.

A solid future for battery development

A thin coating layer between the cathode active materials (CAMs) and solid electrolytes (SEs) is indispensable for alleviating the reaction at the CAM/SE interface and thereby enhancing the reversible capacity of all-solid-state Li-ion batteries (ASSLIBs). It is well established that the interfacial resistance in the CAM/coating layer/SE is sensitive to post-annealing processes. However, the underlying mechanism remains unclear; the influence of the electrochemical/physicochemical phenomena on capacity degradation, particularly the impact of the annealing temperature, has not been adequately elucidated. Herein, we applied various annealing temperatures to LiNbO3-coated LiCoO2 (LNO-coated LCO) particles, and initially adopted a double-coating method to investigate the behaviour of the LCO/LNO/Li10GeP2S12 interfaces. We observed that the electronic conductivity of LNO-coated LCO increased with increasing annealing temperature, presumably because of the LNO segregation at the LCO surface and Co diffusion to the LNO layer, both of which occurred during the dynamic LNO phase change from amorphous (350 °C annealed state) to crystalline (700 °C annealed state). The increased electronic conductivity triggers the interfacial reaction between the LNO layer and Li10GeP2S12, which is the primary cause of reversible capacity loss, whereas the ionic conductivity in LNO has minimal effect on the reversible capacity at low C-rates. This study highlights the importance of having a suitable electronic conductivity in the coating layer to improve the performance of bulk-type ASSLIBs.

Annealing-induced evolution at the LiCoO2/LiNbO3 interface and its functions in all-solid-state batteries with a Li10GeP2S12 electrolyte

https://www.jstage.jst.go.jp/article/ajhs/5/0/5_104/_pdf

A Framework for Resilience Research in Parents of Children with Developmental Disorders

The structure changes and lithium intercalation properties in the surface region of Li4Ti5O12 were investigated using epitaxial Li4Ti5O12(111) film model electrodes. The discharge–charge measurements, which were conducted with 1 mol/dm3 LiPF6-containing propylene carbonate, revealed that a 23.8 nm-thick film exhibited a small capacity of 115 mA h/g compared to the theoretical value of 175 mA h/g. In situ neutron reflectometry and ex situ x-ray diffractometry and reflectometry indicated that an irreversible phase change had occurred in the 10-nm surface region of Li4Ti5O12 during the initial reaction processes. The level of deterioration of the surface structure was significantly reduced by decreasing the LiPF6 concentration; in addition, side reactions of the cell components with the electrolyte species, and their products, may be associated with the deterioration of the Li4Ti5O12 surface. The surface reactions have a significant impact on the capacity of lithium intercalation in nano-sized Li4Ti5O12.

Neutron reflectometry analysis of Li4Ti5O12/organic electrolyte interfaces: characterization of surface structure changes and lithium intercalation properties

A lithium conductor Li6.96Sn1.55Si1.71P0.8S12 with a cubic argyrodite-type structure in the Li2S–SnS2–SiS2–P2S5 system: Synthesis, structure, and electrochemical properties

Direct observation of the lithiation and de-lithiation in lithium batteries on the component and microstructural scale is still difficult. This work presents recent advances in MeV ion-beam analysis, enabling quantitative contact-free analysis of the spatially-resolved lithium content and state-of-charge (SoC) in all-solid-state lithium batteries via 3 MeV proton-based characteristic x-ray and gamma-ray emission analysis. The analysis is demonstrated on cross-sections of ceramic and polymer all-solid-state cells with LLZO and MEEP/LIBOB solid electrolytes. Different SoC are measured ex-situ and one polymer-based operando cell is charged at 333 K during analysis. The data unambiguously show the migration of lithium upon charging. Quantitative lithium concentrations are obtained by taking the physical and material aspects of the mixed cathodes into account. This quantitative lithium determination as a function of SoC gives insight into irreversible degradation phenomena of all-solid-state batteries during the first cycles and locations of immobile lithium. The determined SoC matches the electrochemical characterization within uncertainties. The presented analysis method thus opens up a completely new access to the state-of-charge of battery cells not depending on electrochemical measurements. Automated beam scanning and data-analysis algorithms enable a 2D quantitative Li and SoC mapping on the µm-scale, not accessible with other methods.

Kota Suzuki

Papers

Annealing-induced evolution at the LiCoO2/LiNbO3 interface and its functions in all-solid-state batteries with a Li10GeP2S12 electrolyte

A Framework for Resilience Research in Parents of Children with Developmental Disorders

Neutron reflectometry analysis of Li4Ti5O12/organic electrolyte interfaces: characterization of surface structure changes and lithium intercalation properties

A lithium conductor Li6.96Sn1.55Si1.71P0.8S12 with a cubic argyrodite-type structure in the Li2S–SnS2–SiS2–P2S5 system: Synthesis, structure, and electrochemical properties

Absolute Local Quantification of Li as Function of State-of-Charge in All-Solid-State Li Batteries via 2D MeV Ion-Beam Analysis