Tianmu Lake Institute of Advanced Energy Storage Technologies (China)

Increasing the energy density of lithium-ion batteries (LIBs) raises safety risks. Understanding failure mechanisms, especially during abuse, is essential for improved battery design and management. In this study, multiscale characterization techniques are employed to systematically investigate the overcharge behavior (from 100% to 130% state of charge) of a 360 Wh kg-1 pouch cell with Ni-rich cathode and SiOx@Graphite anode. Further decoupling elucidates that the primary failure mechanism is the interfacial and structural degradation of the anode, including lithium plating on graphite, volume expansion and crack propagation in SiOx particles, and continuous reconstruction of the solid electrolyte interphase (SEI) film, which are further promoted by dissolved Ni ions (the Ni content on the anode increases from 0.005% to 0.268% after overcharging to 5.25 V) and by released oxygen species from the Ni-rich cathode. Ni ions (mainly as Ni2+) accumulate on Li-plating areas on graphite. These crosstalk reactions significantly influence the stability of both electrodes, causing severe phase transition (from LiC6 to LiC12 on the anode and from layered to rock-salt phase on the cathode), continuous electrolyte decomposition and harmful gas evolution, which accelerates full-cell failure. These findings can provide guidance for the optimization of battery safety management systems.

Severe performance decay is witnessed for fast-charging lithium-ion batteries due to tremendous kinetic barriers. Herein, high-entropy solvation configurations are achieved to diminish such kinetic limitations by inducing multiple salts into the electrolyte. Theoretical calculations combined with experimental characterizations confirm the enhanced entropy of the electrolyte, rendering the participation of several anionic groups and reducing the solvation strength between Li+ and solvent/anion species. Concurrently, inorganic-rich interphases are further identified via preferential oxidation/reduction of diverse multianions clusters, thus reducing the interphases impedance. The graphite/LiNi0.5Mn0.2Co0.3O2 full cell maintains 95.4% capacity retention over 650 cycles at 1 C and delivers a capacity of 82.3 mAh g–1 (45.2 mAh g–1 for routine batteries) at 5 C. Such kinetic performance ensures the safety without Li plating at fast charging, increasing the thermal failure onset temperature from 68.6 °C to 167.7 °C under deeply aging conditions. This electrolyte offers an opportunity to achieve safe and long-term fast-charging lithium-ion batteries.

Sluggish desolvation kinetics of Li ions cause poor lifespan of Li metal batteries at ultralow temperatures. Herein, the rapid desolvation process is achieved by reducing the change of Gibbs free energy (△G) at the electrode-electrolyte interfaces. The low desolvation barrier can be attained by higher entropy change (△S) and lower enthalpy change (△H). In the Gibbs-free-energy-driven electrolyte with multiple anions, the complex solvation structures are constructed, which release more group states during the desolvation process, thus increasing △S. The weak ion-dipole interaction of Li ion-solvent is designed to decrease △H. Hence, a lower desolvation barrier is realized. Besides, anion-induced solvation structure can form inorganic-rich solid electrolyte interphase. These synergistically enhance the plating kinetics and guide the uniform Li deposition at low temperatures. An impressive capacity retention of 95.5% can be maintained in Li||LiNi0.5Co0.2Mn0.3O2 cells with a high cathode loading of 3.0 mAh cm-2 after 210 cycles at -20°C. Even at an ultralow temperature of -40°C, the cells can stably operate for 220 cycles with a capacity retention of 87.7%. The Gibbs free energy regulation offers an innovative perspective for the design of low-temperature electrolytes with rapid interfacial kinetics.

Abstract All‐solid‐state Li metal batteries (ASSLMBs) with sulfide solid‐state electrolytes (SSEs) are anticipated to be the next‐generation energy storage technology, potentially providing high energy density meanwhile enhancing safety. However, the complicated solid–solid interface between SSEs and Li metal leads to contact issues and Li dendrite. In this contribution, a multifunctional hierarchical silicon and carbon (H–Si/C) structure design is proposed as an interlayer between SSEs and the Li metal. A homogeneous electron‐ion transport network is established through the Li–Si alloy formed by Si self‐lithiation and the nano‐carbon layer on the surface, achieving compact interfacial contact and Li dendrite‐free interlayer. The ASSLMBs assembled with H–Si/C interlayer exhibit 70.28% capacity retention after 800 cycles at 0.5C. In addition, the H─Si/C interlayers can efficiently match with the high‐loading cathode, maintaining a capacity retention of 80.9% after 200 cycles under an areal capacity of 3.4 mAh cm −2 , and working well even at the ultra‐high loading of 6.9 mAh cm −2 . This finding provides novel insights to understand the design principles of the anode interface and is crucial for achieving high safety and long lifespan for ASSLMBs.

Sulfide solid electrolytes are promising materials for next-generation all-solid-state lithium batteries due to their high ionic conductivity, mechanical properties, and compatibility with advanced electrodes like lithium metal. Recent advancements have focused on optimizing synthesis techniques, including both solid-phase and liquid-phase methods, alongside strategic doping modifications that enhance ionic conductivity and improve chemical stability. Despite these improvements, challenges remain, particularly in stabilizing interfaces between sulfide solid electrolytes and electrodes, as chemical reactivity leads to resistive layers and reduced battery performance. Efforts to address these challenges involve protective coatings, surface engineering, and advanced structural modifications. Additionally, sulfide solid electrolytes face environmental sensitivity, with exposure to air and moisture leading to degradation. To counter this, strategies such as hybrid electrolyte systems and surface treatments are being investigated to ensure long-term stability under various conditions. This review summarizes recent developments in sulfide solid electrolytes synthesis, doping modification, and interface engineering, while outlining future directions needed for the successful commercialization of all-solid-state lithium batteries, positioning sulfide-based electrolytes as key components for advancing battery safety, efficiency, and energy density.