Yan Li

Ethanol-aerosol-assisted roasting strategy: integrating selective Li recovery with in situ syngas generation.

Solid electrolyte interphase (SEI) dissolution in sodium‐ion batteries (NIBs) triggers electrolyte decomposition and gas evolution, resulting in capacity decay and safety issues. Lowering the solvation power of electrolyte mitigates SEI dissolution but decreases ionic conductivity. Here, we report a recessive solvent activation strategy, where the recessive solvent 1,2‐epoxy‐3,3,3‐trifluoropropane (TFPO) alone dissolves NaFSI only sparingly, but its solubility is greatly enhanced by the addition of an activating solvent, diethylene glycol diethyl ether (DEE). By harnessing the tunable solvation behavior of the DEE–TFPO system, we designed a weakly solvating electrolyte (WSE) containing 24 vol% DEE, far below the bulk‐solvent fractions typical of WSEs, and a high anion‐to‐DEE ratio. This low DEE content mitigates solvent‐induced SEI dissolution, while the high anion‐to‐DEE ratio promotes anion‐dominated solvation structure, forming a robust inorganic‐rich SEI. These effects preserve high ionic conductivity while overcome the challenge of SEI dissolution. The optimized electrolyte enabled hard carbon || NaMn _0.33 Fe _0.33 Ni _0.33 O ₂ full cells to retain 80.0% capacity after 500 cycles and 99.5% capacity in 1.0 Ah pouch cells after 230 cycles with suppressed gas release.

Solid electrolyte interphase (SEI) dissolution in sodium‐ion batteries (NIBs) triggers electrolyte decomposition and gas evolution, resulting in capacity decay and safety issues. Lowering the solvation power of electrolyte mitigates SEI dissolution but decreases ionic conductivity. Here, we report a recessive solvent activation strategy, where the recessive solvent 1,2‐epoxy‐3,3,3‐trifluoropropane (TFPO) alone dissolves NaFSI only sparingly, but its solubility is greatly enhanced by the addition of an activating solvent, diethylene glycol diethyl ether (DEE). By harnessing the tunable solvation behavior of the DEE–TFPO system, we designed a weakly solvating electrolyte (WSE) containing 24 vol% DEE, far below the bulk‐solvent fractions typical of WSEs, and a high anion‐to‐DEE ratio. This low DEE content mitigates solvent‐induced SEI dissolution, while the high anion‐to‐DEE ratio promotes anion‐dominated solvation structure, forming a robust inorganic‐rich SEI. These effects preserve high ionic conductivity while overcome the challenge of SEI dissolution. The optimized electrolyte enabled hard carbon || NaMn _0.33 Fe _0.33 Ni _0.33 O ₂ full cells to retain 80.0% capacity after 500 cycles and 99.5% capacity in 1.0 Ah pouch cells after 230 cycles with suppressed gas release.

Recycling of spent Li-ion batteries (LIBs) is an emerging global concern. Current recycling technologies generally include multiple purification operations and involve the use of lots of chemicals, which compromise their competitiveness in terms of both economic and environmental benefits. Herein, we propose a spray pyrolysis technology-based closed-loop for regenerating single-crystal cathodes from spent LIBs, which could simultaneously achieve the separation of Li and transition metals (TMs) and obtain high-quality precursors for the synthesis of single-crystal cathodes. As an exemplary study, spent LiCoO₂ is first converted into chlorides through a chlorination process. More than 95% of Li is selectively leached out by the “spray pyrolysis–water leaching” process. Simultaneously, the Co₃O₄ leaching residue could be directly used as a precursor for synthesizing high-performance single-crystal LiCoO₂, while the gaseous HCl produced in the pyrolysis process could be recycled in the chlorination process. Therefore, this closed-loop of Li, Co, and Cl holds great economic benefits as it gets rid of the complicated purification operations and precursor preparation processes (such as coprecipitation), opening a new avenue for LIBs recycling.

The inorganic-rich solid electrolyte interphase (SEI) has attracted wide attention due to its good compatibility with the lithium (Li) metal anode. Herein, a stable solvent-derived inorganic-rich SEI is constructed from a hydrofluoroether-diluted low-concentration electrolyte, which simultaneously possesses the merits of nonflammability and low cost (0.5 M LiPF₆). The addition of hydrofluoroether enhances the coordination strength between Li⁺ and solvents, altering the decomposition path of solvents to yield more Li₂O. The abundant Li₂O crystals endow the SEI with improved passivating ability and ion conductivity. The 30 μm Li|NCM523 (3.8 mAh cm^-2) batteries with solvent-derived Li₂O-rich SEI deliver 96.1% capacity retention after 200 cycles. Notably, a 1.1 Ah Li|NCA pouch cell delivers an energy density of 374 Wh kg^-1 and achieves 45 stable cycles. This study points out that tuning the decomposition of solvents provides a new approach to construct stable inorganic-rich SEI for practical Li-metal batteries.

Low-dimensional nanomaterials have attracted considerable attention for next-generation flexible energy devices owing to their excellent electrochemical properties and superior flexibility. Herein, uniform Tellurium nanotubes (Te NTs) were prepared through a facile hydrothermal method, and then a flexible and freestanding electrode was fabricated with Te NTs as active materials and a small amount of nanofibrillated celluloses (NFCs) as a flexible matrix through a vacuum filtration method without adding extra conductive carbon or a binder. The resulting Te-based electrode exhibits a high volumetric capacity of 1512 mAh cm⁻³ at 200 mA g⁻¹, and delivers admirable cyclic stability (capacity retention of 104% over 300 cycles) and excellent rate performance (833 mAh cm⁻³ at 1000 mA g⁻¹), which benefits from the unique structure and intrinsically superior conductivity of Te NTs. After bending 50 times, the Te-based electrode delivers a desirable volumetric capacity of 1117 mAh cm⁻³, and remains 93% of initial capacity after 100 cycles. The results imply that the Te-based electrode exhibits excellent electrochemical properties and superior flexibility simultaneously, which can serve as a potential candidate for the flexible lithium batteries.