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

Considering the compositional complexity concept, novel solid electrolytes based on quaternary and quinary lithium superionic conductor (LISICON) systems were investigated for the development of highly ion-conducting materials. Phase identification indicated that even in highly complex compositions, relatively large Ti- and Ga-doping contents were difficult to achieve in the γ-Li3PO4 framework. Relatively low ionic conductivities (10–7 to 10–5 S cm–1) and high activation energies (0.44–0.53 eV) were confirmed compared to ternary LISICON systems, indicating a negligible positive effect of the compositional complexity. In addition, undesirable anti-site disorder occurred in the LISICON crystal, which was considered to limit fast ion conduction in the quaternary and quinary LISICON systems. A further systematic and detailed study is therefore required to accurately determine the effects of compositional complexity in the design of fast ion conductors. 

https://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.3c01765

Synthesis and Electrochemical Properties of Quaternary and Quinary γ-Li3PO4-Type Materials: Effects of Compositional Complexity in Lithium Superionic Conductors

Development of Energy Conversion/storage Materials Based on Crystal Defect Cores

発達性協調運動障害（DCD）は，協調運動技能の獲得や遂行に著しい困難を示す神経発達症である。本研究では，DCDにおける協調運動障害の神経学的な機序の解明を目指し，遺伝子多型に基づく脳内DA濃度と，運動反応抑制に関わる神経活動の両者が，協調運動機能に及ぼす影響を検討した。成人97名を対象に，DA関連遺伝子多型，運動反応抑制にかかわる事象関連電位および協調運動機能を評価した。その結果，脳内DA濃度の高い場合には，協調運動機能の低下が認められなかった。一方で，脳内DA濃度の低さと運動反応抑制にかかる神経活動の低下が重畳する場合に，バランス機能の低下が認められた。これらの結果は，複数の要因が重畳した場合に，協調運動障害が顕在化する可能性を示唆するものである。 

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Effects of Dopaminergic Neurotransmission and Neural Activity Involved in Motor Response Inhibition on Motor Coordination Function

Interfacial phenomena of oxide cathode/sulfide electrolytes are crucial for the improvement of energy density and cycle stability of all-solid-state batteries. Thin-film batteries provide a simple reaction field for mechanistic studies. We fabricated a model film battery consisted of LiCoO2 cathode, LiNbO3 buffer layer, amorphous Li3PS4 electrolyte, and Li metal anode by physical vapor deposition. Structural changes at the cathode-side interface were investigated by in situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) using Ar etching. The LiCoO2 lattice showed a reversible change under high voltage operation with the upper cutoff voltage of 4.5 V. A cathode electrolyte interphase (CEI) layer was formed at the interface by decomposition of LiNbO3 and Li3PS4. The ionic and electronic conductivities of the CEI layer could be crucial to improve the reaction resistance and the cycle stability of the oxide cathode/sulfide electrolyte interface.

Kota Suzuki

Papers

Synthesis and Electrochemical Properties of Quaternary and Quinary γ-Li3PO4-Type Materials: Effects of Compositional Complexity in Lithium Superionic Conductors

Development of Energy Conversion/storage Materials Based on Crystal Defect Cores

Effects of Dopaminergic Neurotransmission and Neural Activity Involved in Motor Response Inhibition on Motor Coordination Function

Characterization of Cathode/Sulfide Electrolyte Interface Using a Thin-Film Model Battery

AC Impedance Analysis of NCM523 Composite Electrodes in All-Solid-State Three Electrode Cells and Their Degradation Behavior