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Lithium metal batteries (LMBs) with inorganic solid-state electrolytes suffer from lithium dendrites propagation. Here, the authors demonstrate the production of stable lab-scale LMBs using an Ag-coated Li6.4La3Zr1.7Ta0.3O12 inorganic solid electrolyte in combination with a silver-carbon interlayer.

Conventional compositions of garnet solid electrolytes have limited access to the cubic phase for a high Li content of 7.0, which is beneficial for stability against Li metals. Here, the authors unlock the hidden chemical space via a high entropy strategy, enabling stable long-term battery cycling.

Abstract Solid‐state Li–metal batteries (based on solid‐state electrolytes) offer excellent safety and exhibit high potential to overcome the energy‐density limitations of current Li–ion batteries, making them suitable candidates for the rapidly developing fields of electric vehicles and energy‐storage systems. However, establishing close solid–solid contact is challenging, and Li‐dendrite formation in solid‐state electrolytes at high current densities causes fatal technical problems (due to high interfacial resistance and short‐circuit failure). The Li metal/solid electrolyte interfacial properties significantly influence the kinetics of Li–metal batteries and short‐circuit formation. This review discusses various strategies for introducing anode interlayers, from the perspective of reducing the interfacial resistance and preventing short‐circuit formation. In addition, 3D anode structural‐design strategies are discussed to alleviate the stress caused by volume changes during charging and discharging. This review highlights the importance of comprehensive anode/electrolyte interface control and anode design strategies that reduce the interfacial resistance, hinder short‐circuit formation, and facilitate stress relief for developing Li–metal batteries with commercial‐level performance.

Lithium-metal batteries (LMBs) have attracted intense interest but the instability issues limit its practical deployment. Here, the authors report a durable LMB with high energy density using a garnet-type solid electrolyte with a tailored Li-metal compatibility.

Rechargeable calcium batteries are promising multivalent battery systems but the lack of suitable electrodes hampers their development. Here the authors report a cathode derived from polyanion framework that demonstrates uncommonly stable and fast intercalation behaviours of calcium ions.

Graphite is a promising anode material for sodium-ion batteries but suffers from the high co-intercalation potential. Here, the authors examine the factors influencing this potential and tailor the stability of graphite intercalation compound, realizing high energy and power densities.

We introduce Na3V(PO4)2 as a new cathode material for Na-ion batteries for the first time. The structure of Na3V(PO4)2 was determined using X-ray diffraction and Rietveld refinement, and its high water stability was clearly demonstrated. The redox potential of Na3V(PO4)2 (∼3.5 V vs Na/Na+) was shown to be sufficiently high to prevent the side reaction with water (Na extraction and water insertion), ensuring its water stability in ambient air. Na3V(PO4)2 also exhibited outstanding power capability, with ∼79% of the theoretical capacity being delivered at 15C. First-principles calculation combined with electrochemical experiments linked this high power capability to the low activation barrier (∼433 meV) for the well-interconnected two-dimensional Na diffusion pathway. Moreover, outstanding cyclability of Na3V(PO4)2 (∼70% retention of the initial capacity after 200 cycles) was achieved at a reasonably fast current rate of 1C. [ABSTRACT FROM AUTHOR]

Here, we introduce Na3V(PO3)3N as a novel 4V-class and zero-strain cathode material for Na-ion batteries. Structural analysis based on a combination of neutron and X-ray diffraction (XRD) reveals that the Na3V(PO3)3N crystal contains three-dimensional channels that are suitable for facile Na diffusion. The Na (de)intercalation is observed to occur at ~4 V vs Na/Na+ in the Na cell via the V3+/V4+ redox reaction with ~67% retention of the initial capacity after over 3000 cycles. The remarkable cycle stability is attributed to the near-zero volume change (~0.24%) and unique centrosymmetric distortion that occurs during a cycle despite the large ionic size of Na ions for (de)intercalation, as demonstrated by ex situ XRD analysis and first-principles calculations. We also demonstrate that the Na3V(PO3)3N electrode can display outstanding power capability with ~84% of the theoretical capacity retained at 10C, even though the particle sizes are on the micrometer scale (>5 μm), which is attributed to its intrinsic three-dimensional open-crystal framework. The combination of this high power capability and extraordinary cycle stability makes Na3V(PO3)3N a new potential cathode material for Na-ion batteries. [ABSTRACT FROM AUTHOR]

The development of long-lasting and low-cost rechargeable batteries lies at the heart of the success of large-scale energy storage systems for various applications. Here, we introduce Fe- and Mn-based Na rechargeable battery cathodes that can stably cycle more than 3000 times. The new cathode is based on the solid-solution phases of Na4MnxFe3-x(PO4)2(P2O7) (x = 1 or 2) that we successfully synthesized for the first time. Electrochemical analysis and ex situ structural investigation reveal that the electrodes operate via a one-phase reaction upon charging and discharging with a remarkably low volume change of 2.1% for Na4MnFe2(PO4)(P2O7), which is one of the lowest values among Na battery cathodes reported thus far. With merits including an open framework structure and a small volume change, a stable cycle performance up to 3000 cycles can be achieved at 1C and room temperature, and almost 70% of the capacity at C/20 can be obtained at 20C. We believe that these materials are strong competitors for large-scale Na-ion battery cathodes based on their low costs, long-term cycle stability, and high energy density. [ABSTRACT FROM AUTHOR]

We investigate the mechanism of the intercalation-aided exfoliation of graphite using van der Waals force-corrected density functional theory (DFT) calculations. From a comparative study on various intercalation systems, we find that, depending on the intercalant species, the exfoliation energies vary significantly, not only due to the size of intercalants but also due to interactions with the host graphite. While it is generally perceived that an expanded interlayer distance with intercalants weakens the binding between graphene layers, as the van der Waals forces decrease, the calculations reveal that the intercalation of electronegative or electropositive intercalants (e.g., Li, K, F, Cl, and Br) result in a 1.5-5-fold higher exfoliation energy than pristine graphite due to additional binding forces from charge transfer between intercalants and graphene layers. Furthermore, we demonstrate that this additional binding force could be manipulated with cointercalation or neutral intercalants, which hints at effective exfoliation strategies with graphite intercalation compounds. This theoretical study broadens our understanding of the mechanism underlying graphite exfoliation and will facilitate development of more effective exfoliation strategies for other related layered materials. [ABSTRACT FROM AUTHOR]

Ion exchange is a ubiquitous phenomenon central to wide industrial applications, ranging from traditional (bio)chemical separation to the emerging chimie douce synthesis of materials with metastable structure for batteries and other energy applications. The exchange process is complex, involving substitution and transport of different ions under non-equilibrium conditions, and thus difficult to probe, leaving a gap in mechanistic understanding of kinetic exchange pathways toward final products. Herein, we report in situ tracking kinetic pathways of Li+/Na+ substitution during solvothermal ion-exchange synthesis of LixNa1.5-xVOPO4F0.5 (0 ≤ x ≤ 1.5), a promising multi-Li polyanionic cathode for batteries. The real-time observation, corroborated by first-principles calculations, reveals a selective replacement of Na+ by Li+, leading to peculiar Na+/Li+/vacancy orderings in the intermediates. Contradicting the traditional belief of facile topotactic substitution via solid solution reaction, an abrupt two-phase transformation occurs and predominantly governs the kinetics of ion exchange and transport in the 1D polyanionic framework, consequently leading to significant difference of Li stoichiometry and electrochemical properties in the exchanged products. The findings may help to pave the way for rational design of ion exchange synthesis for making new materials. [ABSTRACT FROM AUTHOR]