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The synthesis of LiNiO2 (LNO) typically involves oxidizing Ni(II) to Ni(III), thus leading to NiLi point-defect formation. Here, materials containing Ni(IV) in the form of overlithiated Li1+xNi1−xO2 (0 ≤ x ≤ 1/3) are converted into LNO. This method produces low defect-density samples at high temperatures, offering an attractive route toward coarse-grained particles that are naturally coated by the byproduct Li2O. In thiophosphate-based solid-state batteries, this kind of self-coating effect shows a direct correlation between residual lithium content and cycling performance. [ABSTRACT FROM AUTHOR]

Ni‐rich LiNixCoyMnzO2 cathode materials offer high practical capacities and good rate capability, but are notorious for being unstable at high state of charge. Here, a series of such layered oxides with nickel contents ranging from 88 to 100 mol% is fabricated by sodium‐to‐lithium ion exchange, yielding materials devoid of NiLi•${\mathrm{Ni}}_{{\mathrm{Li}}}^ \bullet $ substitutional defects. Examining the initial charge/discharge cycle reveals effects that are specifically caused by transition‐metal substitution, which would otherwise be obscured by changes in lithium‐site defect concentration. Lowering the nickel content helps to stabilize the high‐voltage regime, while simultaneously negatively affecting lithium diffusion. Operando X‐ray diffraction indicates mitigation of volume variation during cycling and transition toward solid‐solution behavior with sufficiently high cobalt and manganese contents, thus providing an explanation for the increased stability. The interplay between transition‐metal substitution, kinetic hindrance, and solid‐solution behavior may be a result of local inhomogeneities due to lithium‐vacancy pinning, which is further elucidated through density functional theory calculations. Overall, this work sheds new light on the effects of manganese and cobalt incorporation into the transition‐metal layer and their conjunction with NiLi•${\mathrm{Ni}}_{{\mathrm{Li}}}^ \bullet $ defects. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries offer an attractive alternative to lithium-based chemistries due to the lower cost and abundance of sodium compared to lithium. Using solid electrolytes instead of liquid ones in such batteries may help improve safety and energy density, but they need to combine easy processing with high stability toward the electrodes. Herein, we describe a new class of solid electrolytes that are accessible by room-temperature, aqueous synthesis. The materials exhibit a garnet-type zinc hexacyanoferrate framework with large diffusion channels for alkaline ions. Specifically, they show superionic behavior and allow for facile processing into pellets. We compare the structure, stability, and transport properties of lithium-, sodium-, and potassium-containing zinc hexacyanoferrates and find that Na2Zn3[Fe(CN)6]2 achieves the highest ionic conductivity of up to 0.21 mS/cm at room temperature. In addition, the electrochemical performance and stability of the latter solid electrolyte are examined in solid-state sodium-ion batteries. [ABSTRACT FROM AUTHOR]

The development of improved solid electrolytes (SEs) plays a crucial role in the advancement of bulk‐type solid‐state battery (SSB) technologies. In recent years, multicomponent or high‐entropy SEs are gaining increased attention for their advantageous charge‐transport and (electro)chemical properties. However, a comprehensive understanding of how configurational entropy affects ionic conductivity is largely lacking. Herein we investigate a series of multication‐substituted lithium argyrodites with the general formula Li6+x[M1aM2bM3cM4d]S5I, with M being P, Si, Ge, and Sb. Structure‐property relationships related to ion mobility are probed using a combination of diffraction techniques, solid‐state nuclear magnetic resonance spectroscopy, and charge‐transport measurements. We present, to the best of our knowledge, the first experimental evidence of a direct correlation between occupational disorder in the cationic host lattice and lithium transport. By controlling the configurational entropy through compositional design, high bulk ionic conductivities up to 18 mS cm−1 at room temperature are achieved for optimized lithium argyrodites. Our results indicate the possibility of improving ionic conductivity in ceramic ion conductors via entropy engineering, overcoming compositional limitations for the design of advanced electrolytes and opening up new avenues in the field. [ABSTRACT FROM AUTHOR]

Ceramic ion conductors play a pivotal role as electrolytes in solid‐state batteries (SSBs). Aside from the ionic conductivity, their (electro)chemical stability has a profound effect on the performance. Lithium thiophosphates represent a widely used class of superionic materials, yet they suffer from limited stability and are known to undergo interfacial degradation upon battery cycling. Knowledge of composition‐dependent properties is essential to improving upon the stability of thiophosphate solid electrolytes (SEs). In recent years, compositionally complex (multicomponent) and high‐entropy lithium argyrodite SEs have been reported, having room‐temperature ionic conductivities of σion>10 mS cm−1. In this work, various multi‐cationic and ‐anionic substituted argyrodite SEs are electrochemically tested via cyclic voltammetry and impedance spectroscopy, as well as under operating conditions in SSB cells with layered Ni‐rich oxide cathode and indium‐lithium anode. Cation substitution is found to negatively affect the electrochemical stability, while anion substitution (introducing Cl−/Br− and increasing halide content) has a beneficial effect on the cyclability, especially at high current rates. [ABSTRACT FROM AUTHOR]

Single crystal (SC) layered lithium metal oxides (LiNixCoyMnzO2, referred to as NCMs or NMCs) represent a new material design with unique benefits compared to their polycrystalline counterparts. However, preparation of SC-NCMs remains challenging, with methods such as molten salt synthesis being largely dependent on recipe-by-recipe reporting and no overarching conception of how to prepare desirable materials. For a model NCM, LiNiO2 (LNO), we use experimental design methodology to identify how the factors of salt selection, salt mixtures, and molar salt ratio affect the critical features of grain size, crystal defect content (), and particle size distribution. Herein, we identify that NaCl and KCl are salts which can be used to control particle size at relatively low defect content, while sulfate-containing salts are deleterious to quality LNO. The results of this work set out to provide a more comprehensive understanding of how others could prepare well-ordered SC-NCMs of specific particle size. [ABSTRACT FROM AUTHOR]

Lithiated oxides like Li[NixCoyMnz]O2 (x + y + z = 1) with high nickel content (x ≥ 0.8) can possess high specific capacity ≥200 mA h g−1 and have attracted extensive attention as perspective cathode materials for advanced lithium-ion batteries. In this work, we synthesized LiNi0.9Co0.1O2 (NC90) materials and studied their structural characteristics, electrochemical performance, and thermal behavior in Li-cells. We developed modified cationic-doped NC90 samples with greatly improved properties due to doping with Mo6+ and B3+ and dual doping via simultaneous modification with these dopants. The main results of the current study are significantly higher capacity retention, greatly reduced voltage hysteresis, and considerably decreased charge-transfer resistance of the Mo and Mo–B doped electrodes compared to the undoped ones upon prolonged cycling. We also revealed remarkable microstructural stability of the Mo-doped electrodes, whereas the undoped samples were unstable and exhibited networks of cracks developed upon cycling. Using density functional theory, we modeled the electronic structure of the undoped, Mo, B single-doped, and Mo–B dual-doped samples and established that the Ni-site is preferred over Co and Li sites. Additionally, density functional theory-based bonding strength calculations suggest that the dopants form strong bonds with oxygen, possibly reducing oxygen release from the cathode. An important finding is that B-dopant tends to segregate to the surface of NC90 similarly to that in NCM85 materials, as shown in our previous reports. In conclusion, this study presents a general approach for effectively stabilizing high-energy Ni-rich layered cathodes charged up to 4.3 V. [ABSTRACT FROM AUTHOR]

Protective coatings are required to address interfacial incompatibility issues in composite cathodes made from Ni‐rich layered oxides and lithium thiophosphate solid electrolytes (SEs), one of the most promising combinations of materials for high energy and power density solid‐state battery (SSB) applications. Herein, the preparation of conformal ZrO2 nanocoatings on a LiNi0.85Co0.10Mn0.05O2 (NCM85) cathode‐active material (CAM) by atomic layer deposition (ALD) is reported and the structural and chemical evolution of the modified NCM85 upon heat treatment—a post‐processing step often required to boost battery performance—is investigated. The coating properties are shown to have a strong effect on the cyclability of high‐loading SSB cells. After mild annealing (≈400 °C), the CAM delivers high specific capacities (≈200 mAh g−1 at C/10) and exhibits improved rate capability (≈125 mAh g−1 at 1C) and stability (≈78% capacity retention after 200 cycles at 0.5C), enabled by effective surface passivation. In contrast, annealing temperatures above 500 °C lead to the formation of an insulating interphase that negatively affects the cycling performance. The results of this study demonstrate that the preparation conditions for a given SE/CAM combination need to be tailored carefully and ALD is a powerful surface‐engineering technique toward this goal. [ABSTRACT FROM AUTHOR]