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High‐voltage LiCoO2 (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li‐ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high‐voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li‐PVDF) coating under air atmosphere. Benefitting from the good film‐forming and strong adhesion ability of Li‐PVDF, the thus‐obtained LiF layer is uniform, dense, and conformal; therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high‐voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF‐modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g−1 at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high‐voltage LCO cathodes reported so far. [ABSTRACT FROM AUTHOR]

High interfacial resistance between electrodes and solid‐state electrolyte is the major cause for the failure of all‐solid‐state Li‐ion batteries. Spontaneous (electro)chemical reactions and poor Li‐ion diffusion at the interfaces are closely related to this increased impedance. Although introducing a coating layer can mitigate interfacial reactions and structural reconstruction, it may also lead to poor Li‐ion diffusion. Balancing this trade‐off therefore is crucial for the design of coating layer materials. In this study, the impact of the amorphous LiF (a‐LiF) coating layer on interfacial structural reconstruction and Li‐ion diffusion at the LiCoO2/Li6PS5Cl solid‐state interface is explicitly elucidated via machine‐learning‐assisted molecular dynamics (MD) simulations. It is found that the a‐LiF can effectively protect the P‐S tetrahedron local structures in Li6PS5Cl but cannot suppress the formation of side product S2 dimers. It is further discovered that once the a‐LiF coating exceeds a certain critical thickness, emergence of ordered local structures will inhibit Li‐ion diffusion. The simulations propose that the optimal thickness of the coating layer is around 1 nm. Overall, the work provides a microscopic understanding for effects of the a‐LiF coating layer on the structural and kinetic properties of cathode‐solid electrolyte interfaces and can guide the design of interfacial coating materials for solid‐state batteries. [ABSTRACT FROM AUTHOR]

Hard carbon (HC) is the most commonly used anode material in sodium‐ion batteries. However, the solid‐electrolyte‐interface (SEI) layer formed in carbonate ester‐based electrolytes has an imperceptible dissolution tendency and a sluggish Na+ diffusion kinetics, resulting in an unsatisfactory performance of HC anode. Given that electrode/electrolyte interface property is highly dependent on the configuration of Helmholtz plane, we filtrated proper solvents by PFBE (PF6− anion binding energy) and CAE (carbon absorption energy) and disclosed the function of chosen TFEP to reconstruct the Helmholtz plane and regulate the SEI film on HC anode. Benefiting from the preferential adsorption tendency on HC surface and strong anion‐dragging interaction of TFEP, a robust and thin anion‐derived F‐rich SEI film is established, which greatly enhances the mechanical stability and the Na+ ion diffusion kinetics of the electrode/electrolyte interface. The rationally designed TFEP‐based electrolyte endows Na||HC half‐cell and 2.8 Ah HC||Na4Fe3(PO4)2P2O7 pouch cell with excellent rate capability, long cycle life, high safety and low‐temperature adaptability. It is believed that this insightful recognition of tuning interface properties will pave a new avenue in the design of compatible electrolyte for low‐cost, long‐life, and high‐safe sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Degraded LiCoO2 cathode from retired Li‐ion batteries is urgently required to be recycled in a greener way for economic and environmental considerations. The coarse metallurgy technologies for Li/Co extraction with massive CO2 emission and energy consumption cannot satisfy the requirements of carbon neutralization. Herein, it is proposed that direct regeneration of degraded LiCoO2 cathode could be realized via 9‐fluorenone‐mediated Li supplementation and follow‐up structural restoration. The 9‐fluorenone‐lithium reagent is elaborately selected to compensate for the missing Li+ into lattice with targeted stoichiometry owing to its compatible redox potential of 1.95 V versus Li+/Li, which is located just between the reversible intercalation (3.8 V) and irreversible conversion (1.2 V) potentials of LiCoO2 electrode. Then, thermal energy‐driven structure reorganization enables Li/Co atoms to occupy the right sites, accomplishing desirable structure healing within a short annealing time of 4 h. The regenerated LiCoO2 cathode exhibits comparable Li‐storage capability to commercial LiCoO2, benefiting from the non‐destructive direct regeneration technology. In addition, the regeneration route is regarded as environmentally (0.13 kg CO2 kg−1 cell) and economically (10.07 $ kg−1 cell) superior to conventional recycling routes based on life‐cycle analysis. The precise surgery on spent LiCoO2 cathode provides a promising solution for the forthcoming retirement rush of Li‐ion batteries. [ABSTRACT FROM AUTHOR]

LiPF6 as a dominant lithium salt of electrolyte is widely used in commercial rechargeable lithium‐ion batteries due to its well‐balanced properties, including high solubility in organic solvents, good electrochemical stability, and high ionic conductivity. However, it suffers from several undesirable properties, such as high moisture sensitivity, thermal instability, and high cost. To address these issues, herein, we propose an electron‐donation modulation (EDM) rule for the development of low‐cost, sustainable, and electrochemically compatible LiNO3‐based electrolytes. We employ high donor‐number solvents (HDNSs) with strong electron‐donation ability to dissolve LiNO3, while low donor‐number solvents (LDNSs) with weak electron‐donation ability are used to regulate the solvation structure to stabilize the electrolytes. As an example, we design the LiNO3‐DMSO@PC electrolyte, where DMSO acts as an HDNS and PC serves as an LDNS. This electrolyte exhibits excellent electrochemical compatibility with graphite anodes, as well as the LiFePO4 and LiCoO2 cathodes, leading to stable cycling over 200 cycles. Through spectroscopy analyses and theoretical calculation, we uncover the underlying mechanism responsible for the stabilization of these electrolytes. Our findings provide valuable insights into the preparation of LiNO3‐based electrolytes using the EDM rule, opening new avenues for the development of advanced electrolytes with versatile functions for sustainable rechargeable batteries. [ABSTRACT FROM AUTHOR]