The practical applications of lithium-sulfur (Li-S) batteries are limited by the safety risks and rapid capacity loss attributed to Li-metal anodes. "Intercalation-conversion" Li-S batteries using prelithiated graphite anodes offer a safer, more practical alternative-but their progress is largely impeded by the complex graphite prelithiation process. Here, we report an in situ lithiation approach by stacking dry-processed graphite electrodes featuring simple fabrication, structural stability, and high-loading capability, onto Li-metal foil in the cells, accomplished during the initial discharge-charge process. The intimate contact within the hybrid Li-Graphite anode ensures efficient Li-ion transport, enabling complete stripping of the lithium metal and in situ lithiation of Graphite. This facilitates the subsequent intercalation chemistry at the anode and conversion chemistry at the cathode. With this configuration, by optimizing the N/P ratio, we achieve 100% utilization of lithium metal and highly reversible Li-ion intercalation/deintercalation. The proposed "intercalation-conversion" Li-S batteries exhibit significantly prolonged cycle life, achieving more than 15 times longer lifespan compared with conventional Li-S batteries. This strategy offers a versatile solution for the applications of battery systems employing Li-free cathodes. (c) 2026 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Employing thin Li films for contact prelithiation holds great promise for high-energy-density Li-ion batteries. However, it is challenging to obtain thin, uniform, and robust Li films with controllable areal capacity for practical battery assembly and manufacturing. Here, we report built-in thin Li films, by depositing Li on the separator or the copper (Cu) current collector via vacuum evaporation, to compensate for the initial Li loss in Liion batteries. The built-in strategy endows the thin Li films with robust substrates compatible with roll-to-roll processing, allows them to be directly assembled into batteries, and enables anode prelithiation during the subsequent resting stage. Moreover, we demonstrate that the thin Li films can be flexibly adjusted in thickness from submicrometer to micrometer, to achieve precise prelithiation in varied battery systems. The evaporated Li exhibits a high utilization efficiency of 97% and is almost completely consumed during prelithiation, leaving negligible residue that could interfere with Li+ or electron transport. The prelithiation effects of thin Li films are validated in full cells using low-Coulombic-efficiency Si/C anodes and dry-processed graphite anodes, respectively, exhibiting significant increases in energy density. Importantly for practical application, the fabricated thin Li films exhibit satisfactory air stability even under harsh conditions with 17% relative humidity.

To boost the practical energy density of lithium-sulfur batteries, replacing conventional solvating electrolytes with sparingly solvating ones has shown promise by enabling solid-state sulfur conversion and reducing electrolyte consumption. However, this approach often compromises sulfur redox kinetics. This study reports a new sulfur conversion pathway distinct from both traditional solvated and sparingly solvated mechanisms. Specifically, sulfur is converted into a mixture of solid and solvated lithium polysulfides (LPSs). Such a hybrid solid/solvating conversion pathway is achieved using a newly formulated moderately solvating electrolyte, accomplishing both lean-electrolyte operation and fast conversion kinetics for lithium-sulfur batteries. Methoxyacetonitrile (MAN) is selected as the solvent to formulate the moderately solvating electrolyte due to its high relative permittivity (21) that contributes to a high Li+ conductivity (11.7 mS cm-1 for 1M lithium bis(trifluoromethane sulfonyl)imide in MAN) and low donor number (14.6 kcal mol-1) that reduces the solubility to LPSs to 1/6 of that in mainstream solvating electrolytes. The as-formulated MAN electrolyte enables sulfur cathodes to operate at a low electrolyte-to-sulfur ratio of 2 mu L mg-1 and a low cathode porosity of 52%, displaying excellent prospects for boosting both gravimetric and volumetric energy density.

The proliferation of lithium-ion batteries results in a substantial accumulation of spent batteries. Traditional pyrometallurgical and hydrometallurgical processes require significant energy inputs, involve the use of hazardous chemicals, and generate large amounts of pollutants, making them inefficient for the economic environmental recycling of spent batteries. For the spent lithium cobalt oxide (LCO) cathodes, which lose electrochemical activity due to the structural damage, we demonstrated that LiF could serve as both a crack/ defect healer to repair the damaged structure and a structural stabilizer to consolidate the electrode/electrolyte interface and the reversibility of phase transitions. The density functional theory calculations revealed the presence of F atoms in the U-LCO crystal leads to a widened energy separation between the Co 3d and O orbitals, such an alteration effectively suppresses the activity of lattice oxygen and stabilizes the structure of LCO. The as-upcycled LCO cathode demonstrates significantly improved stability with an impressive capacity retention of 81.6 % after 260 cycles, surpassing those of the pristine LCO (62.3 %) and normally regenerated LCO (35.6 %). Moreover, the recycling process only involves a solid sintering procedure, leading to a reduced carbon footprint by 73.1 % and 64.1 %, and increased benefits by 62.2 % and 47.7 %, as compared with the pyro and hydro methods, respectively. The as-proposed upcycling strategy provides a practical and efficient solution for the closed-loop development of LCO batteries.

The cobalt-free layered oxide cathode of LiNi0.65Mn0.35O2 is promising for high-energy-density lithium-ion batteries (LIBs). However, under high-voltage conditions, severe side reactions between the Co-free cathode and electrolyte, as well as grain boundary cracks and pulverization of particles, hinder its practical applications. Herein, an electrolyte regulation strategy is proposed by adding fluoroethylene carbonate (FEC) and LiPO2F2 as electrolyte additives in carbonate-based electrolytes to address the above issues. As a result, a homogeneous and dense organic-inorganic hybrid cathode electrolyte interface (CEI) film is formed on the cathode surface. The CEI film consists of C-F, LiF, Li2CO3, and LixPOyFz species, which is proven to be highly conductive and effective in suppressing structure damage and alleviating the interfacial reactions between the cathode and electrolyte. With such a CEI film, the interfacial stability of the Co-free cathode and the high-voltage cycling performance of Li||LiNi0.65Mn0.35O2 are greatly improved. A reversible capacity of 155.1 mAh g-1 and a capacity retention of 81.3% over 150 cycles are attained at a 4.8 V charge cutoff voltage with the tamed electrolyte, whereas the cell without the additives only retains 76.1% capacity retention. Therefore, our work demonstrates the synergistic effect of FEC and LiPO2F2 in stabilizing the interface of Co-free cathode materials and provides an alternative strategy for the electrolyte design of high-voltage LIBs.

Solid electrolyte interface (SEI) is arguably the most important concern in graphite anodes, which determines their achievable Coulombic efficiency (CE) and cycling stability. In spent graphite anodes, there are already-formed (yet loose and/or broken) SEIs and some residual active lithium, which, if can be inherited in the regenerated electrodes, are highly desired to compensate for the lithium loss due to SEI formation. However, current graphite regenerated approaches easily destroy the thin SEIs and residue active lithium, making their reuse impossible. Herein, this work reports a fast-heating strategy (e.g., 1900 K for ≈150 ms) to upcycle degraded graphite via instantly converting the loose original SEI layer (≈100 nm thick) to a compact and mostly inorganic one (≈10-30 nm thick with a 26X higher Young's Modulus) and still retaining the activity of residual lithium. Thanks to the robust SEI and enclosed active lithium, the regenerated graphite exhibited 104.7% initial CE for half-cell and gifted the full cells with LiFePO4 significantly improved initial CE (98.8% versus 83.2%) and energy density (309.4 versus 281.4 Wh kg-1), as compared with commercial graphite. The as-proposed upcycling strategy turns the "waste" graphite into high-value prelithiated ones, along with significant economic and environmental benefits.

Using Li2S cathodes instead of S cathodes presents an opportunity to pair them with Li-free anodes (e.g., graphite), thereby circumventing anode-related issues, such as poor reversibility and safety, encountered in Li-S batteries. However, the moisture-sensitive nature of Li2S causes the release of hazardous H2S and the formation of insulative by-products, increasing the manufacturing difficulty and adversely affecting cathode performance. Here, Li4SnS4, a Li+ conductor that is air-stable according to the hard-soft acid-base principle, is formed in situ and uniformly on Li2S particles because Li2S itself participates in Li4SnS4 formation. When exposed to air (20% relative humidity), the protective Li4SnS4 layer maintains its components and structure, thus contributing to the enhanced stability of the Li2S@Li4SnS4 composite. In addition, the Li4SnS4 layer can accelerate the sluggish conversion of Li2S because of its favorable interfacial charge transfer, and continuously confine lithium polysulfides owing to its integrity during electrochemical processes. A graphite-Li2S pouch cell containing a Li2S@Li4SnS4 cathode is constructed, which shows stable cyclability with 97% capacity retention after 100 cycles. Hence, combining a desirable air-stable Li2S cathode and a highly reversible Li-free configuration offers potential practical applications of graphite-Li2S full cells.

The recycling of graphite from spent lithium-ion batteries (LIBs) is overlooked due to its relatively low added value and the lack of efficient recovering methods. To reuse the spent graphite anodes, we need to eliminate their useless components (mainly the degraded solid electrolyte interphase, SEI) and reconstruct their damaged structure. Herein, a facile and efficient strategy is proposed to recycle the spent graphite on the basis of the careful investigation of the composition of the cycled graphite anodes and the rational design of the regeneration processes. The regenerated graphite, which is revitalized by calcination treatment and acid leaching, delivers superb rate performance and a high specific capacity of 370 mAh g−1 (∼99% of its theoretical capacity) after 100 cycles at 0.1C, superior to the commercial graphite anodes. The improved electrochemical performance could be attributed to unchoked Li+ transport channels and enhanced charge transfer reaction due to the effective destruction of the degraded SEI and the full recovery of the damaged structure of the spent graphite. This work clarifies that the electrochemical performance of the regenerated graphite could be deteriorated by even a trace amount of the residual “impurity” and provides a facile method for the efficient regeneration of graphite anodes.

The sustainable development of lithium iron phosphate (LFP) batteries calls for efficient recycling technologies for spent LFP (SLFP). Even for the advanced direct material regeneration (DMR) method, multiple steps including separation, regeneration, and electrode refabrication processes are still needed. To circumvent these intricacies, new regeneration methods that allow direct electrode reuse (DER) by rejuvenating SLFP electrodes without damaging its structure are desired. Here, a 0.1 M lithium triethyl borohydride/tetrahydrofuran solution, which has the proper reductive capability to reduce Fe 3+ in SLFP to Fe 2+ without alloying with the aluminum current collector, is selected as the lithiation/regeneration reagent to restock the Li loss and regenerate SLFP electrodes. By soaking the SLFP electrodes in the lithiation solution, we successfully rejuvenated the crystal structure and electrochemical activity of SLFP electrodes with structural integrity within only 6 minutes at room temperature. When being directly reused, the regenerated LFP electrodes deliver a high specific capacity of 162.6 mAh g −1 even after being exposed to air for 3 months. The DER strategy presents significant economic and environmental benefits compared with the DMR method. This research provides a timely and innovative solution for recycling spent blade batteries using large-sized LFP electrodes, boosting the closed-loop development of LFP batteries.

Lithium (Li) metal electrodes show significantly different reversibility in the electrolytes with different salts. However, the understanding on how the salts impact on the Li loss remains unclear. Herein, using the electrolytes with different salts (e.g., lithium hexafluorophosphate (LiPF6), lithium difluoro(oxalato)borate (LiDFOB), and lithium bis(fluorosulfonyl)amide (LiFSI)) as examples, we decouple the irreversible Li loss (SEI Li+ and "dead" Li) during cycling. It is found that the accumulation of both SEI Li+ and "dead" Li may be responsible to the irreversible Li loss for the Li metal in the electrolyte with LiPF6 salt. While for the electrolytes with LiDFOB and LiFSI salts, the accumulation of "dead" Li predominates the Li loss. We also demonstrate that lithium nitrate and fluoroethylene carbonate additives could, respectively, function as the "dead" Li and SEI Li+ inhibitors. Inspired by the above understandings, we propose a universal procedure for the electrolyte design of Li metal batteries (LMBs): (i) decouple and find the main reason for the irreversible Li loss; (ii) add the corresponding electrolyte additive. With such a Li-loss-targeted strategy, the Li reversibility was significantly enhanced in the electrolytes with 1,2-dimethoxyethane, triethyl phosphate, and tetrahydrofuran solvents. Our strategy may broaden the scope of electrolyte design toward practical LMBs.

In conventional lithium-ion batteries (LIBs), active lithium (Li) ions, which function as charge carriers and could only be supplied by the Li-containing cathodes, are also consumed during the formation of the solid electrolyte interphase. Such irreversible Li loss reduces the energy density of LIBs and is highly desired to be compensated by prelithiation additives. Herein, lithium selenide (Li2Se), which could be irreversibly converted into selenide (Se) at 2.5-3.8 V and thus supplies additional Li, is proposed as a cathode prelithiation additive for LIBs. Compared with previously reported prelithiation reagents (e.g., Li6CoO4, Li2O, and Li2S), the delithiation of Li2Se not only delivers a high specific capacity but also avoids gas release and incompatibility with carbonate electrolytes. The electrochemical characterizations show that with the addition of 6 wt % Li2Se to the LiFePO4 (LFP) cathodes, a 9% increase in the initial specific capacity in half Li||LFP cells and a 19.8% increase in the energy density (based on the total mass of the two electrodes' materials) could be achieved without sacrificing the other battery performance. This work demonstrates the possibility to use Li2Se as a high-efficiency prelithiation additive for LIBs and provides a solution to the high-energy LIBs.

We introduce a facile strategy to greatly improve the electrochemical reversibility of cobalt-free cathode material by doping trace quantity of aluminum (Al) in LiNi0.65Mn0.35O2. X-ray diffraction and X-ray photoelectron spectroscopy results reveal that Al doping reduces the cation disorder consequently and hence increases structural stability. Electrochemical measurements show that rate capability and cycling stability are remarkably enhanced by Al doping. Al-doped LiNi0.65Mn0.35O2 exhibits the optimized electrochemical performance with a capacity retention of 94.2% after 200 cycles at 2 C in voltage range of 2.75-4.2 V in cylindrical full cell, demonstrating that Al-doped cathode exhibits enhanced cyclability, reduced polarization and high-rate capability during charge/discharge process. Moreover, the full cell shows good low-temperature performance with more than 70% capacity retention at -20 degrees C. The improved performances can be ascribed to the enhanced stability in layered structure of the Co-free material by the support of doped Al ions.

The exponential growth of "3C" (computer, communication, and consumer electronics) market generates an ever-increasing demand on recycling materials from the end-of-life LiCoO2 (LCO) batteries with ecological and efficient methods. Herein, we present a direct and scalable approach to recycle the degraded LCO by healing and stabilizing their damaged structure via solid reactions. The as-proposed approach constructs a protective layer onto the regenerated LCO particles to suppress the O3 to H1-3 phase transition at 4.55 V. Benefiting from the unique design, superb electrochemical performance was achieved for the regenerated LCO, exhibiting a high specific capacity retention of 85.9% after 100 cycles with a charging cut-off voltage of 4.6 V and a superb rate capability, which are even superior to those of the pristine commercial LCO. In addition, compared with the LCO production with raw chemicals, the as-proposed healing-stabilizing strategy reduces the total energy consump-tion by 68.5%, bringing noteworthy economic and environmental benefits. This work provides not only new understandings to stabilize LCO at high voltage, but also a practical solution to the closed-loop development of LCO batteries.

Recruiting anions from electrolyte additives into the lithium ion solvation structure is a promising strategy for the construction of long‐lifespan Li‐metal batteries (LMBs). However, inadequate understanding of the anion‐involved Li + solvation hinders the finding of new anion additives. Herein, using NO 3 − as an example, the effects of the newly‐introduced anion on the Li + solvation structure are investigated. It is demonstrated that the added NO 3 − reduces the electrostatic potential of the Li + solvation cluster, especially for solvated solvents, which improves electrolyte stability against the Li anode. However, such a conclusion is not universal for all anion additives. It is also confirmed that the anions with higher binding energy and smaller ion size are more apt to improve the Li stability and reversibility. Based on the above understanding, a new selection principle based on anion selection coefficient (the rate of the anion size to the binding energy toward Li + , unit: Å 3 eV −1 ) is proposed, and with which a new hexafluorosilicate anion is found to be beneficial to LMBs.

Ionic conductivity is a critical factor affecting the electrochemical performance of double layer capacitor. Therefore, additional ion transport channels are introduced by using Nafion as binder in electrode. In this study, carbonized maple as active substance was mixed with binder of Nafion or PVDF to form electrodes. The electrode structures were obtained by scanning electron microscopy and N-2 adsorption-desorption isotherms with the aim of clarifying negligible differences in the microstructure and binding strength of electrodes with different binders. Furthermore, the two electrodes with different binders tested in KOH exhibited similar electrochemical properties. However, in H2SO4 electrolyte, the electrode containing Nafion showed a much higher specific capacitance than that of electrode using PVDF binder. To directly prove the high ionic conductivity of Nafion electrode, concentration battery was constructed using the two electrodes as separators to investigate their liquid junction potential. This study focused on the ionic conduction in electrodes, which could provide suggestions for electrode design, especially for the utilization of commercial supercapacitors.