Shou-Hang Bo

Existing alloy anodes suffer from high redox potentials and sluggish Li atomic kinetics, limiting the energy density and rate capability of all-solid-state lithium batteries (ASSLBs). Herein, we report a well-designed Li3Ga2 alloy anode that simultaneously delivers an ultralow Li deposition potential (0.007 V vs. Li+/Li) and fast Li atomic diffusion kinetics (2.0 × 10–8 cm2 s–1). The high Li atomic diffusivity primarily originates from moderate Li/Ga antisite mixing, stabilizing the anode-solid electrolyte interface and enabling a high critical current density of 24 mA cm–2 in ASSLBs. Coupled with a LiCoO2 cathode, the ASSLB delivers a high initial Coulombic efficiency of 96.5% and an ultralong cycle life of 2000 cycles at room temperature, with a high output voltage of 3.84 V, outperforming state-of-the-art alloy-based counterparts. A practical all-solid-state pouch cell employing the LiNi0.8Co0.1Mn0.1O2 cathode also delivers outstanding cycling stability. This work redefines alloy anode design principles through synergistic optimization of Li deposition potential and Li atomic diffusivity.

Sulfide solid-state electrolyte films that combine thinness, high ionic conductivity and large-area feasibility are needed to improve energy density and enable industrial-scale production of all-solid-state batteries. However, workable processing methods to integrate these critical features remain technically challenging. Herein, we demonstrate a quasi-dry process utilizing an organic additive (i.e., α-pinene), through which the fabricated sulfide electrolyte films successfully integrate all the aforementioned merits. α-Pinene is chemically compatible with Li_5.5PS_4.5Cl_1.5, improves film flexibility via stress dissipation, enhances ionic conductivity by promoting a more even distribution of the polytetrafluoroethylene binder, and facilitates film densification through lubrication. The resultant films with enhanced densification (porosity reduced from 12.24% to 7.78%) retain over 85% ionic conductivity of the pristine powder, exhibit an ionic conductivity of 4.79 mS/cm at 25 °C, with a thickness of 28 μm and lateral dimensions of 30 × 10 cm². The Li₄Ti₅O₁₂ | Li_5.5PS_4.5Cl_1.5 | LiNbO₃@LiNi_0.8Co_0.1Mn_0.1O₂ full cells present a capacity retention of 93% after 500 cycles at 1 C under 2 MPa. At the stack level, a 50 mAh pouch cell retains 83% capacity after 1000 cycles at 0.5 C under 2 MPa. This work proposes an additive-assisted quasi-dry process, paving a pathway for material-process optimization toward potentially scalable fabrication of all-solid-state batteries.

Atomistic modeling of solid-solid battery interfaces is essential for understanding electro-chemo-mechanical coupling, but the complex interfacial chemistry and heterogeneous environments pose major challenges for quantum-accurate, data-efficient modeling. Herein, we propose an approach of fine-tuning with integrated replay and efficiency (FIRE), a general framework for universal machine-learning interatomic potentials by combining efficient configurational sampling with a replay-argumented continual strategy, achieving quantum-level accuracy at moderate cost. Across six solid-solid battery interface systems, FIRE consistently achieves root-mean-square errors in energy below 1 meV/atom and in force near 20 meV/angstrom, marking an order-of-magnitude improvement over existing models while requiring only 10% of the original datasets. In addition, the fine-tuned model successfully reproduces key mechanical and electrochemical properties of the materials, in close agreement with experimental data. The FIRE offers a generalizable and data-efficient approach for developing accurate interatomic potentials across diverse materials, enabling predictive simulations beyond the reach of first-principles methods.

All-solid-state batteries frequently encounter mechanical instability due to the inherent brittleness and low elasticity of inorganic ceramic electrolytes, such as sulfides, oxides, and halides. These electrolytes struggle to accommodate the volumetric fluctuations of positive electrode materials during cycling, potentially leading to performance degradation and premature failure. To address this challenge, we propose a defect-based toughening approach for resilient halide solid electrolytes. By meticulously controlling the cooling rate during synthesis, we successfully increase the defect density within the electrolyte, enhancing its mechanical properties and mitigating the risk of mechanical failure. Mechanical property testing, high-resolution transmission electron microscopy characterization, and synchrotron radiation diffraction analysis reveal that the quenched material exhibit not only a higher Young’s modulus, rendering it less susceptible to deformation under stress and a higher capacity for energy absorption before plastic deformation or fracture due to its increased dispersed defect density. Consequently, it demonstrates better adaptability to the volumetric changes associated with the positive electrode material during battery cycling, effectively mitigating strain-induced material behavior. Here we show the effectiveness of defect-enhanced toughening strategies in optimizing the mechanical properties and microstructure of electrolyte materials, thereby enhancing the overall integrity of solid-state batteries without requiring modifications to their chemical composition.

The electrochemical plating of lithium metal is known to be nonuniform and complex, which can ultimately lead to short circuits and capacity degradation in lithium-metal batteries. These detrimental phenomena are extremely challenging to both predict and manage. Herein, we develop a fast photoacoustic imaging system based on microelectromechanical systems and can thus achieve a high temporal resolution of 0.45 ms per pixel. This system enables operando monitoring of the lithium-plating process under practical current densities, with a lateral resolution of 7.8 μm. We monitor a millimeter-scale region and simultaneously follow the height evolution of lithium metal across 1000 subregions using grid-based tracking. Careful statistical analysis of these growth patterns reveals that the lithium plating begins as a diffusion-controlled process but subsequently diverges into explosive, steady, and diminishing patterns at different locations. This variation likely arises from the spatially dependent lithium-ion diffusivity of the solid-electrolyte interphase formed at the lithium metal-liquid electrolyte interface, which ultimately leads to uneven lithium plating. These findings significantly advance our understanding of lithium-plating dynamics and motivate the development of strategies to mitigate the associated risks in lithium-metal batteries.

Alloy anodes hold promise for achieving dendrite-free all-solid-state lithium batteries (ASSLBs) by regulating lithium deposition behavior, leading to enhanced critical current density (CCD) and cycling stability. However, existing alloy anodes in ASSLBs fall short of practical requirements (CCD > 10 mA cm^-2), and key factors determining CCD remain unclear. Here, we propose a diffusion-controlled Li deposition model in which CCD critically depends on the competition between surface attachment and diffusion of incoming atoms. Multimodal characterizations validate that Li atomic diffusivity in the alloy anode is a key descriptor for the CCD and cycling stability of ASSLBs. Leveraging this insight, LiGa is chosen as the optimized alloy anode due to its high Li atomic diffusivity (∼3 × 10^-7 cm² s^-1), which enables a record-high CCD exceeding 50 mA cm^-2 and stable solid electrolyte-anode interface at a high current density of 3 mA cm^-2. ASSLBs pairing the LiGa anode with the LiNi_0.8Co_0.1Mn_0.1O₂ cathode and using Li₆PS₅Cl (LPSCl) solid electrolyte exhibit remarkable long-term cycling stability of 1000 cycles with 80% capacity retention under 25 °C and a stacking pressure of 1 MPa, outperforming state-of-the-art alloy anode-based counterparts. This work establishes a unified descriptor for the control of Li deposition, advancing practical ASSLB development.

Halide solid-state electrolytes are promising for next-generation all-solid-state lithium-ion batteries due to their high ionic conductivity and wide electrochemical windows. While most research focuses on close-packed crystal structures, nonclose-packed frameworks─exemplified by UCl₃-type structures─offer unique advantages in enhancing lithium-ion transport via reduced diffusion barriers. Here, we report a new family of UCl₃-type crystalline oxychloride electrolytes, Li_0.388+xLa_0.475Ta_0.238Cl_3-xO_x (0 ≤ x ≤ 0.388, LLTCO), synthesized via rapid high-energy shake milling. The material with an optimized composition (x = 0.15) exhibits high ionic conductivity above 2 mS cm^-1 at 30 °C, oxidative stability exceeding 5 V vs Li/Li⁺, and excellent mechanical compressibility. Moreover, the LLTCO-based Li-Li symmetric cells show a long cycle life, indicating their strong capacity to suppress lithium dendrite formation. Spectroscopy analyses reveal the successful incorporation of oxygen, which preferentially substitutes Cl^- around Ta⁵⁺ sites without compromising crystallinity, even at a high oxygen content. The oxygen incorporation further promotes the formation of Li environments with fast dynamics, accounting for the enhanced conductivity. All-solid-state batteries utilizing the optimized oxychloride electrolyte in conjunction with Ni-rich cathodes demonstrate enhanced reversible capacities compared to their undoped counterparts. This work highlights the benefits of nonclose-packed UCl₃-type oxychloride electrolytes, offering new design strategies for high-performance all-solid-state batteries.