Wei Xia

Power delivery in all-solid-state lithium batteries (ASSLBs) is often pursued by maximizing the bulk ionic conductivity of cathode active materials (CAMs), while grain-boundary (GB) ion-transport barriers caused by lattice mismatch remain a major kinetic bottleneck. Here, we reveal that minimizing GB transport barriers, rather than simply enhancing intrinsic conductivity, unlocks ultrafast ion-transport in halide CAMs. Amorphization converts crystalline LiVCl4 into a conformal amorphous phase that preserves short-range V–Cl coordination while minimizing long-range ion-transport tortuosity. Despite lower bulk Li+ conductivity, amorphous LiVCl4 dramatically reduces GB-associated interfacial resistance and enables a catholyte-free cathode (CAM content: 90 wt %) to deliver a capacity of 74.3 mAh g–1 at 5 mA cm–2, compared with 10.2 mAh g–1 for the crystalline counterpart. Meanwhile, the ASSLB further operates across a wide temperature range from −30 to 60 °C and achieves 84.2% capacity utilization at an ultrahigh A-LiVCl4 areal loading of 53.4 mg cm–2. Coupled with amorphous LiTaOCl4, the ASSLB achieves 102.1 mAh g–1 at 20 mA cm–2 (∼75C) and retains 82.3% capacity after 16,000 cycles. These results establish amorphization-enabled conformal interfaces as a new paradigm for ultrahigh-power ASSLBs.

The decisive chemistry of iron-based halide cathodes─where lithium resides, how it evolves, and how disorder governs multielectron redox─has remained largely inaccessible, limiting the rational design of catholyte-free composite cathodes in all-solid-state lithium batteries. Here we make the lithium sublattice directly visible in paramagnetic LiFeCl3 using a 6Li solid-state NMR strategy combining high isotopic enrichment, optimized acquisition, and variable-temperature control. This method resolves and quantifies three Li+ environments, revealing that local Li/Fe disorder drives in-place Fe2+ reduction as the root cause of highly reversible intercalation-conversion chemistry. It further uncovers trace irreversible Fe0 species invisible to conventional spectroscopic and imaging techniques. Guided by this hidden degradation signature, optimization of the voltage window enables 85.9% capacity retention after 500 cycles with a 16.3% energy-density penalty, whereas full-depth cycling retains 68.6% after 100 cycles. Our work establishes lithium-resolved NMR as a platform linking disorder, hidden redox, and reversibility in paramagnetic cathodes.

O3-type layered positive electrode materials for sodium-ion batteries exhibit high specific energy but suffer from phase transitions during charge-discharge cycling, which generate significant lattice strain and compromise structural integrity. Using a model high-entropy positive electrode (Na_0.83Fe_0.22N_i0.18Cu_0.05Co_0.05Zn_0.075Li_0.025Mn_0.275Ti_0.05Sb_0.05Mg_0.025O₂), here we show, these phase transitions are conventionally kinetics-limited, occurring at states far removed from thermodynamic stability. By tailoring configurational entropy to regulate diffusion kinetics, we can delay the onset of phase transitions from kinetic barriers to thermodynamic stability, yielding an O3-type positive electrode with enhanced phase stability. Multiscale spatial resolution diffraction analysis reveals a reduction in internal stress due to suppressed kinetically driven early phase transitions. This advanced material achieves a high specific energy of 162.5 Wh/kg at the full‑cell total weight level at 0.1 C, retains 97.7% capacity at 5 C/1 C (650/130 mA/g), and maintains 90% capacity retention after 2300 cycles in Ah-level pouch cells, positioning it as a promising candidate for practical applications. The utilization of thermodynamically driven phase transition provides a promising alternative direction for preparing high performance layered sodium positive electrodes.

Solid‐state electrolytes (SSEs) inherently face a stability–conductivity trade‐off, whereby strategies that enhance moisture tolerance and oxidative stability often compromise Li ⁺ transport. Here, inspired by additive engineering in liquid electrolytes, we demonstrate that a similar concept can be translated into solid electrolytes. A solid‐additive engineering strategy is developed by incorporating oxide nanoparticles into halide SSEs, enabling stability regulation without sacrificing fast ion transport. Combined experimental characterizations and atomistic simulations reveal that a fraction of the additives participates in local interfacial reconstruction that generates disordered Li‐ion coordination environments, whereas the majority remains as chemically stable nanodomains within the electrolyte matrix. This cooperative structural regulation simultaneously enhances ionic conductivity, electrochemical stability, and moisture tolerance. Moreover, ASSBs exhibit markedly improved cycling reversibility and high‐voltage stability. Full cells incorporating such solid additives sustain stable operation over 3300 cycles at 1 C and retain considerable reversibility even at 4.8 V. The solid additive effect is further demonstrated across multiple halide electrolytes. These findings establish solid additive engineering as a general and cost‐effective strategy for overcoming the intrinsic stability–conductivity trade‐off in SSEs, providing new opportunities for the design of robust solid‐state battery chemistries.

Solid‐state electrolytes (SSEs) inherently face a stability–conductivity trade‐off, whereby strategies that enhance moisture tolerance and oxidative stability often compromise Li ⁺ transport. Here, inspired by additive engineering in liquid electrolytes, we demonstrate that a similar concept can be translated into solid electrolytes. A solid‐additive engineering strategy is developed by incorporating oxide nanoparticles into halide SSEs, enabling stability regulation without sacrificing fast ion transport. Combined experimental characterizations and atomistic simulations reveal that a fraction of the additives participates in local interfacial reconstruction that generates disordered Li‐ion coordination environments, whereas the majority remains as chemically stable nanodomains within the electrolyte matrix. This cooperative structural regulation simultaneously enhances ionic conductivity, electrochemical stability, and moisture tolerance. Moreover, ASSBs exhibit markedly improved cycling reversibility and high‐voltage stability. Full cells incorporating such solid additives sustain stable operation over 3300 cycles at 1 C and retain considerable reversibility even at 4.8 V. The solid additive effect is further demonstrated across multiple halide electrolytes. These findings establish solid additive engineering as a general and cost‐effective strategy for overcoming the intrinsic stability–conductivity trade‐off in SSEs, providing new opportunities for the design of robust solid‐state battery chemistries.

Recently, lithium‐metal‐halide (Li‐M‐X) superionic conductors have emerged as promising solid‐state electrolyte (SSEs) for all‐solid‐state lithium batteries (ASSLBs), owing to their high Li ⁺ conductivity, excellent compatibility with cathodes, and good mechanical deformability. However, many of these conductors exhibit chemical and electrochemical instability when in contact with the reductive anodes, which hinders the direct use of lithium metal as anodes with extraordinarily high specific capacities and limits the overall energy density of halide‐based ASSLBs. Therefore, enhancing the anode compatibility of halide SSEs has become a critical task in ASSLB development and has attracted broad research interest. Herein, the underlying mechanisms responsible for the instability of halide SSEs against the lithium anode are elucidated based on both experimental observations and theoretical calculations. Recent strategies and progress aimed at improving the compatibility of halide SSEs with lithium anodes are summarized. Moreover, the effects of pressure and volume changes on the interfacial compatibility between halide SSE and lithium metal are discussed. In addition, the current challenges and future research directions are analyzed, aiming to provide theoretical insights and guidance to support further advancements in Li‐M‐X type solid‐state electrolytes and all‐solid‐state lithium batteries.

The development of high-energy all-solid-state batteries is critically hindered by the electrochemical instability of solid electrolytes against high-voltage oxide positive electrodes. While fluorination is a promising strategy to enhance electrolyte stability, conventional methods are ineffective, resulting in insufficient fluorine content and a debilitating trade-off with ionic conductivity. Here, we report a solid-state anion-exchange strategy that overcomes these limitations by producing core-shell Li-fluoride/LiCl nanocomposite precursors. These precursors enable the synthesis of heavily fluorinated lithium-halide and lithium-sulfide electrolytes that combine high ionic conductivity with good oxidative stability. This stability originates from the formation of a robust, self-limiting LiF-rich interphase at the positive electrode. Consequently, an all-solid-state battery using a Li-rich oxide positive electrode achieves high performance, retaining over 77.5% capacity after 2000 cycles at a high rate of 3 C (1 C = 275 mA/g) and a 5.0 V cutoff. This anion-exchange approach is broadly applicable to other systems and establishes a versatile platform for designing advanced fluorinated materials for next-generation batteries.

All-solid-state batteries with inorganic solid electrolytes are a global trend in the development of next-generation energy storage devices, promising greatly simplified designs, increased energy density, and, perhaps most importantly, enhanced safety. Currently, the anion-mixed strategy for all-solid-state batteries is the mainstream for developing amorphous halide solid electrolytes, opening up good possibilities for creating conductors with high ionic conductivity and stability. Here, we show the structure evolution of amorphous solid electrolyte, Li_3xZrCl₄N_x (0.17 ≤ x ≤ 1), demonstrating ionic conductivities of up to 3.21 × 10^-3 S∙cm^-1 at 30°C, suggesting that the formation of nitrogen-containing frameworks is crucial for enhancing ionic conductivity. The structural evolution during the mechanochemical reaction, revealed by in situ time-resolved synchrotron X-ray diffraction, highlights the advantages of mixed-anion chemistry and clarifies the formation pathway of the dual-anion electrolyte. In addition, nitrogen incorporation into amorphous electrolyte provides enhanced mechanical deformability and leads to promising electrochemical performance over a wide temperature range. In particular, the dual-anion solid electrolyte maintains stable operation at lower temperatures when coupled with a LiIn negative electrode, highlighting the broader potential of anion-mixed design for all-solid-state batteries.

UCl₃-based halide solid electrolytes have garnered increasing interest for application in all-solid-state batteries, yet their structural characteristics, chemical composition, and ion transport mechanisms remain under debate. These uncertainties hamper their rational design and broader application. Taking PrCl₃ as a model system, we present a comprehensive structural investigation and reveal that foreign cations (e.g., Ta⁵⁺, Zr⁴⁺ and In³⁺) preferentially reside in amorphous matrix rather than substituting for Pr³⁺ in crystalline PrCl₃, owing to substantial mismatches in both ionic radii and coordination numbers. Importantly, the dominant pathway for fast Li⁺ conduction lies within the amorphous phase, rather than the PrCl₃ nanocrystals or their interfacial regions. Guided by these insights, Li_0.5Pr_0.455Ta_0.179Zr_0.06Cl₃ is rationally designed, realizing high ionic conductivity (3.10 mS cm⁻¹) and a low activation energy (0.236 eV). These improved ion-conducting properties enables battery with a capacity retention of 71.7% at 20 mA g^-1 and -20 °C, and a prolonged cycle life of 1350 cycles at 100 or 200 mA g^-1 and -10 °C. These results underscore the critical role of amorphous phase engineering in halide electrolytes and the potential of UCl₃-type systems for low-temperature all-solid-state batteries.

Lithium halide solid electrolytes have garnered significant attention owing to their high ionic conductivity and positive electrode compatibility. However, achieving target ionic conductivity typically requires high lithium concentration (>4.3 wt%) within optimal structure, which raises costs and exacerbates air sensitivity. Here, we leverage anion clusters to synthesize a series of amorphous halide electrolytes xLi₂SO₄-ZrCl₄, with optimal ionic conductivities of 1.5 mS cm^-1 at 30 °C and a significantly reduced lithium content of 2.4 wt%, alongside good air stability. Through neutron/synchrotron X-ray experiments, first-principles calculations and machine learning-accelerated molecular dynamics simulations, we reveal a disordered backbone of [Zr_aCl_4a(SO₄)]^2- (1 ≤ a ≤ 4) that enables fast Li-ion diffusion via under-coordinated oxygen sites. All-solid-state lithium batteries employing these electrolytes and LiNi_0.8Co_0.1Mn_0.1O₂ positive electrode exhibit 81.1% capacity retention after 1400 cycles at 1 C (60 min) and 30 °C. Our findings reveal anion-cluster chemistry as an approach that transforms solid electrolyte design for advanced batteries, bridging materials science with practical energy storage innovation.