Lithium Salts Research Articles

Ring Expansion via One-Pot Conversion of Lactone Acetals to Cyclic Enones. Synthesis of (±)-1-epi-Xerantholide.

Baeyer-Villiger oxidation of α-alkoxy ketones 1 provides lactone acetals 2, which react with the lithium salts of dimethyl(alkyl) phosphonates in the presence of LaCl3·2LiCl to provide cyclic enones 3 in good to excellent yields after treatment with dilute aqueous potassium carbonate. Thus, five-, six-, and seven-membered lactones are converted to five-, six-, and seven-membered cyclic enones. The utility of this two-step ring expansion method is demonstrated in the synthesis of (±)-1-epi-xerantholide from 5-methyl-2-cyclohexen-1-one.

Unprecedented cubic mesomorphic behaviour of crown-ether functionalized amphiphilic cyclodextrins.

Amphiphilic supramolecular materials based on biodegradable cyclodextrins (CDs) have been known to self-assemble into different types of thermotropic liquid crystals, including smectic and hexagonal columnar mesophases. Previous studies on amphiphilic CDs bearing 14 aliphatic chains at the primary face and 7 oligoethylene glycol (OEG) chains at the secondary face showed that the stability of the mesophase can be rationally tuned through implemation of terminal functional groups to the OEG chains. Here, we report the syntheses of first examples of crown ether-functionalized amphiphilic cyclodextrins that unexpectedly form thermotropic bicontinuous cubic phases. This constitutes the first reported examples of cyclodextrins forming such phases, which are potentially capable of 3D ion transport. Lithium composites were made to assess lithium conduction in the material. XRD revealed the added lithium salt destabilizes the cubic phase in favour of the smectic phase. Solid-state NMR studies showed that these materials conduct lithium ions with a very low activation energy.

Influence of H-bonding on the crystalline structures and ferroelectric and piezoelectric properties of novel nanogenerators of the lithium salt of 6-amino hexanoic acid incorporated poly(vinylidene fluoride) composites.

The lithium salt of 6-amino hexanoic acid (Li-AHA) was melt-mixed with poly(vinylidene fluoride) (PVDF), wherein the Li-AHA concentration was varied between 1-15 wt% with the aim of establishing hydrogen bonding between the NH2 functionality of Li-AHA and the -CF2 moieties of PVDF. This was followed by compression-moulding as well as solution-casting to make PVDF/Li-AHA composite thin films. FTIR analysis established interactions between the -CF2 groups in PVDF with amine functional moieties of Li-AHA. Moreover, FTIR analysis estimated that the solution-cast PVDF/Li-AHA composite of 15 wt% Li-AHA exhibited the highest polar phase fraction of ∼60%. Furthermore, ferroelectric analysis showed that the solution-cast PVDF/Li-AHA composite of 15 wt% Li-AHA exhibited the highest remnant polarization of 0.07 μC cm-2 (at 50 Hz, 1000 V) from the polarization versus electric field loop. Finally, energy harvester devices were fabricated using compression-moulded and solution-cast PVDF/Li-AHA composite films, in which a maximum output voltage of ∼110 V was obtained in the solution-cast PVDF/Li-AHA composite of 15 wt% Li-AHA. The devices also displayed a maximum power density of 75 μW cm-2 and 85 μW cm-2 for those fabricated via compression-moulding and solution-casting, respectively. Three different capacitors were efficiently charged by the tapping of the devices made from solution-cast and compression-moulded composite films of 15 wt% Li-AHA. An interrelationship between processing, structure and properties was successfully established in the PVDF/Li-AHA composites with greatly enhanced piezoelectric properties.

Cationic Covalent Organic Framework-Modified Polypropylene Separator for High-Performance Lithium Metal Batteries.

As an important component of lithium batteries, the wettability and thermal stability of the separator play a significant role in cell performance. Despite the availability of numerous commercial separators, issues such as low ion selectivity and poor thermal stability continue to limit the efficiency and reliability of the batteries. Herein, two cationic covalent organic frameworks (Br-COF and TFSI-COF) with abundant imidazole cationic groups were designed to modify commercial polypropylene (PP) separators. The strong lithium-ion affinity of the cationic COF enables the effective dissociation of lithium salt ion clusters, simplifying the solvent structure of lithium ions to promote lithium ions transport. Additionally, solvent anions can be anchored to the cationic COF by electrostatic interactions, reducing side reactions on the lithium metal anode surface to form a favorable SEI layer, which can effectively inhibit the growth of lithium dendrites. The rapid dissociation of anions in lithium salts with some organic solvents and cationic COFs was revealed by a molecular dynamics simulation. A LiF-rich SEI layer on the lithium metal anode surface was formed, which can speed up Li+ transport at interfaces, leading to consistent lithium deposition and outstanding battery performance. The ordered porous structure of the cationic COF provides interconnected and continuous channels, improving the wettability between the liquid electrolyte and separators, which is conducive to ion transport. When paired with a LiFePO4 cathode and electrolyte (1.0 M LiTFSI in DEC: EC: DMC = 1:1:1), the LiFePO4/TFSI-COF@PP/Li cell demonstrates a prominent cycling capacity of 148.0 mAh g-1 at 0.5 C with a Coulombic efficiency of 98.0% in the first cycle, and the capacity retention is 82.0% after 100 cycles, showing good cycling stability. Thus, this investigation provides inspiration for the expansion of cationic COF-modified separators for next-generation lithium metal batteries.

Boosting Fast Charging of Lithium-Metal Batteries via Weak Interactions Between Non-Solvating Solvents and Anions in High-Safety Eutectic Electrolytes.

Proper design of the solvation structure is crucial for the development of lithium metal batteries (LMBs). In this paper, the use of 1,2-Dimethoxyethane (DME) as a non-solvating cosolvent in amide-based eutectic electrolytes is proposed to address challenges related to high viscosity, high polarization, and low conductivity, thus enhancing the compatibility with lithium metal anodes. Through physical characterization combined with simulation calculations the existence of a weak interaction between DME and anions is confirmed, which promotes the dissociation of lithium salts and increases the Li+ transference number and diffusion coefficient, thus improving the fast charging performance of eutectic electrolytes. In addition, stable SEI layer enriched with inorganic components is formed during the cycling process, resulting in uniform and dense lithium deposition. The fast charging performance of the cell can be effectively improved by utilizing the interaction between anions and solvents. The LiFePO4 (LFP)||Li cell has a capacity retention of 97% after 1200 cycles at 5 C and also performs well at high temperature of 50°C. Overall, the use of a non-solvating cosolvent in eutectic electrolytes presents a promising and innovative approach for enhancing electrolyte performance in LMBs.

The superior growth of Kluyveromyces marxianus at very low potassium concentrations is enabled by the high-affinity potassium transporter Hak1.

The non-conventional yeast Kluyveromyces marxianus has recently emerged as a promising candidate for many food, environment and biotechnology applications. This yeast is thermotolerant and has robust growth under many adverse conditions. Here, we show that its ability to grow under potassium-limiting conditions is much better than that of Saccharomyces cerevisiae, suggesting a very efficient and high-affinity potassium uptake system(s) in this species. The K. marxianus genome contains two genes for putative potassium transporters: KmHAK1 and KmTRK1. To characterise the products of the two genes, we constructed single and double knock-out mutants in K. marxianus and also expressed both genes in an S. cerevisiae mutant, that lacks potassium importers. Our results in K. marxianus and S. cerevisiae revealed that both genes encode efficient high-affinity potassium transporters, contributing to potassium homeostasis and maintaining plasma-membrane potential and cytosolic pH. In K. marxianus, the presence of HAK1 supports growth at low K+ much better than that of TRK1, probably because the substrate affinity of KmHak1 is about tenfold higher than that of KmTrk1, and its expression is induced approx. eightyfold upon potassium starvation. KmHak1 is crucial for salt stress survival in both K. marxianus and S. cerevisiae. In co-expression experiments with ScTrk1 and ScTrk2, its robustness contributes to an increased tolerance of S. cerevisiae cells to sodium and lithium salt stress.

A novel multifunctional naphthalene triazole columnar liquid crystal: synthesis, self-assembly and application in silicon solar cells

Herein, click reaction was used as a crucial step to effectively synthesize a new multifunctional naphthalene triazole columnar liquid crystal ICm/n. The properties of liquid crystal and gel in ICm/n were investigated using POM, DSC, XRD and SEM. ICm/n can self-assemble into square columnar liquid crystals in their pure state and form organogels in N,N-dimethylformamide (DMF). In addition, ICm/n can be used as a Fe3+ chemosensor. Interestingly, the addition of lithium salts has a significant impact on the self-assembly, molecular dynamics and ionic conductivity of the compounds, thus potentially providing nanostructured LC electrolytes with continuous substrate ionic conductivity. Additionally, the use of ICm/n as a dopant in the poly (3,4-ethylenedioxythiophene): polystyrene (PEDOT: PSS) hole injection layer greatly enhanced the photoelectric conversion efficiency (PCE) of Si/PEDOT: PSS heterojunction solar cells, boosting it from 2.08% to 8.10%. The current work offers a novel method for creating liquid crystal (LC) materials with several uses for naphthalene triazoles.

Triple Salts Electrolyte for High Cyclability and High Capability in Practical Safe Nickel-Rich Batteries

The pursuit of extended driving ranges of electric vehicles has spurred the use of nickel-rich layered cathodes, yet raised safety concerns. Existing ethylene carbonate-free electrolytes improve safety but compromise electrochemical performances due to the delicate balance between anode interphases. We introduce a novel electrolyte composed of propylene carbonate (PC) and triple lithium salts, which synergistically reinforces both cathode and anode interfaces. PC's low kinetic reactivity with LiNi0.8Mn0.1Co0.1O2 (NCM811) at the cathode minimizes heat generation and oxygen evolution. To stabilize the anode, bis(fluorosulfonyl)imide (FSI-) anions are integrated to construct an anion-driven interface, while difluoro(oxalato)borate (DFOB-) is added to lower PC's de-solvation energy and prevent co-intercalation. NCM811/Graphite pouch cells utilizing this electrolyte show enhanced safety, cyclability, and rate capability, surviving 60minutes at 180℃ without incident. Post-mortem analysis reveals suppressed parasitic reactions and the formation of a robust solid electrolyte interphase (SEI). This research offers a critical framework for the design of electrolytes tailored for high-energy lithium-ion batteries.

Li‐ion Exchange‐Driven Interfacial Buffer Layer for All‐Solid‐State Lithium Metal Batteries

AbstractThe goal of achieving batteries with high energy density and high safety profile has been a driving force in developing all‐solid‐state lithium metal batteries (ASSLMBs). However, the complex issues arising from the interfacial interaction between lithium anode/cathode and solid‐state electrolytes (SSE) have hindered the progress of ASSLMBs. This study presents a strategy for constructing an organic/inorganic buffer layer via employing Li‐ion exchanging chemistry of H1.6Mn1.6O4 (HMO) with a flexible matrix of polyethylene oxide (PEO). The buffer layer shows a remarkable ion conductivity of 3.21 × 10−4 S cm−1 at 25 °C originating from the exceptional Li+‐H+ ion exchange capability of HMO. This PEO/HMO buffer layer not only establishes an intimate physical contact between the Li anode/cathode and the SSE but also functions as a dynamic Li+ transfer station to facilitate Li+ movement through the interfaces improving interfacial stability. By pairing with cathodes of LiFePO4 (LFP) and LiNi0.8Co0.1Mn0.1O2 (NCM811), the ASSLMBs feature high‐rate capability and stable cycling performance with low polarization. This marks the utilization of HMO as a superior interfacial material to replace conventional lithium salts, with improved ion transport, decreased polarization, and enhanced overall performances. This constitutes a significant advancement toward the next‐generation energy storage solutions for ASSLMBs.

Operando Fabricated Quasi-Solid-State Electrolyte Hinders Polysulfide Shuttles in an Advanced Li-S Battery

Lithium-sulfur (Li-S) batteries are a promising option for energy storage due to their theoretical high energy density and the use of abundant, low-cost sulfur cathodes. Nevertheless, several obstacles remain, including the dissolution of lithium polysulfides (LiPS) into the electrolyte and a restricted operational temperature range. This manuscript presents a promising approach to addressing these challenges. The manuscript describes a straightforward and scalable in situ thermal polymerization method for synthesizing a quasi-solid-state electrolyte (QSE) by gelling pentaerythritol tetraacrylate (PETEA), azobisisobutyronitrile (AIBN), and a dual salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium nitrate (LiNO3)-based liquid electrolyte. The resulting freestanding quasi-solid-state electrolyte (QSE) effectively inhibits the polysulfide shuttle effect across a wider temperature range of −25 °C to 45 °C. The electrolyte’s ability to prevent LiPS migration and cluster formation has been corroborated by scanning electron microscopy (SEM) and Raman spectroscopy analyses. The optimized QSE composition appears to act as a physical barrier, thereby significantly improving battery performance. Notably, the capacity retention has been demonstrated to reach 95% after 100 cycles at a 2C rate. Furthermore, the simple and scalable synthesis process paves the way for the potential commercialization of this technology.

Ion specificity on cysteine tripeptides in aqueous environments revealed by molecular simulation

Molecular dynamics simulations were conducted to investigate the interactions of cysteine tripeptides with ions and water molecules in solutions of salts (MA, M = Li+ and Cs+, A = halide ions). The results revealed that as the anion size increases, cations aggregate more easily around the tripeptide, irrespective of capping. Radial distribution function (RDF) analysis showed direct interactions between F− and tricysteine, whereas Cl−, Br−, and I− exhibited indirect binding. Comparison between Li+ and Cs+ systems indicated that the smaller Li+ ions tend to distribute more around the tripeptide, engaging in direct interactions, whereas Cs+ ions interact indirectly, mediated by water molecules. Interaction energy analysis demonstrated that in lithium salt solutions, the total energy of anions with tricysteine decreased with anion size for both capped and uncapped systems. In cesium salt solutions, the anionic I− had the strongest interaction with cysteine tripeptides, and the cationic Cs+ interaction with tripeptides peaked in the CsI solution. The results highlight differences in ionic interactions depending on the anion-cation correlations of different salts.

Enhancing the electrochemical properties of polyethylene oxide solid-state electrolytes based on a small nano-sized UiO-66 metal-organic framework

Metal-organic frameworks (MOFs) have garnered significant attention in the field of Lithium-ion batteries due to their porous periodic network properties. However, this is a challenge to design high-performance solid-state electrolytes reasonably. Herein, a small nano-sized MOF Small-UiO-66 is reported, which has high surface area and mesoporous properties that can effectively inhibit PEO matrix crystallization. The presence of Small-UiO-66 accelerates the dissociation of lithium salts, which disrupts the ordered arrangement of the PEO chain segments. The abundant Lewis acidic sites on the surface of Small-UiO-66 facilitate the construction of abundant Li+ transport channels and promote Li+ conduction. Furthermore, the smaller nano-sized increase the interfacial wettability with lithium metal, which promotes the uniform diffusion of Li+ and inhibits the growth of lithium dendrites. The results indicate that 0.1 Zr-CSE exhibits high ionic conductivities of 6.94 × 10−4 S/cm at 60 °C. Based on 0.1 Zr-CSE, the Li||Li symmetric cell can operate stably for 1200 h at a current density of 0.1 mA/cm2, and the LFP||Li cell also achieves a high initial capacity of 147.65 mAh·g−1 at current densities of 0.5C. This work presents a novel approach for preparing high-performance solid-state Lithium-ion batteries using MOFs as fillers for polymer solid-state electrolytes.

Electrolytes for High-Safety Lithium-Ion Batteries at Low Temperature: A Review.

As the core of modern energy technology, lithium-ion batteries (LIBs) have been widely integrated into many key areas, especially in the automotive industry, particularly represented by electric vehicles (EVs). The spread of LIBs has contributed to the sustainable development of societies, especially in the promotion of green transportation. However, the high demand for battery performance and safety in these fields has made the high viscosity, volatility, and potential leakage inherent in traditional organic liquid electrolytes a constraint on their further expansion. Especially at low temperature, the increased viscosity of the electrolyte, reduced solubility of lithium salts, crystallization or solidification of the electrolyte, increased resistance to charge transfer due to interfacial by-products, and short-circuiting due to the growth of anode lithium dendrites all affect the performance and safety of LIBs. Therefore, improving the safety performance of LIBs under low-temperature environments has become a focus of current research. This paper primarily reviews the progress made in utilizing different types of electrolytes in LIBs to enhance safety and optimize low temperature performance and discusses the current research progress as well as the future development direction of the field.

Unrevealing Lithium Repositioning in the Hallmarks of Cancer: Effects of Lithium Salts (LiCl and Li2CO3) in an In Vitro Cervical Cancer Model.

Lithium, a natural element, has been employed as a mental stabilizer in psychiatric treatments; however, some reports indicate it has an anticancer effect, prompting the consideration of repurposing lithium for cancer treatment. The potential anticancer use of lithium may depend on its form (salt type) and the type of cancer cells targeted. Little is known about the effects of Li2CO3 or LiCl on cancer cells, so we focused on exploring their effects on proliferation, apoptosis, migration, and cell cycle as part of the hallmarks of cancer. Firstly, we established the IC50 values on HeLa, SiHa, and HaCaT cells with LiCl and Li2CO3 and determined by crystal violet that cell proliferation was time-dependent in the three cell lines (IC50 values for LiCl were 23.43 mM for SiHa, 23.14 mM for HeLa, and 15.10 mM for HaCaT cells, while the IC50 values for Li2CO3 were 20.57 mM for SiHa, 11.52 mM for HeLa, and 10.52 mM for HaCaT cells.) Our findings indicate that Li2CO3 and LiCl induce DNA fragmentation and caspase-independent apoptosis, as shown by TUNEL, Western Blot, and Annexin V/IP assay by flow cytometry. Also, cell cycle analysis showed that LiCl and Li2CO3 arrested the cervical cancer cells at the G1 phase. Moreover, lithium salts displayed an anti-migratory effect on the three cell lines observed by the wound-healing assay. All these findings imply the viable anticancer effect of lithium salts by targeting several of the hallmarks of cancer.

Bimetal Fluorides with Adjustable Vacancy Concentration Reinforcing Ion Transport in Poly(ethylene oxide) Electrolyte.

The poor ambient ionic transport properties of poly(ethylene oxide) (PEO)-based SPEs can be greatly improved through filler introduction. Metal fluorides are effective in promoting the dissociation of lithium salts via the establishment of the Li-F bond. However, too strong Li-F interaction would impair the fast migration of lithium ions. Herein, magnesium aluminum fluoride (MAF) fillers are developed. Experimental and simulation results reveal that the Li-F bond strength could be readily altered by changing fluorine vacancy (VF) concentration in the MAF, and lithium salt anions can also be well immobilized, which realizes a balance between the dissociation degree of lithium salts and fast transport of lithium ions. Consequently, the Li symmetric cells cycle stably for more than 1400 h at 0.1 mA cm-2 with a LiF/Li3N-rich solid electrolyte interphase (SEI). The SPE exhibits a high ionic conductivity (0.5 mS cm-1) and large lithium-ion transference number (0.4), as well as high mechanical strength owing to the hydrogen bonding between MAF and PEO. The corresponding Li//LiFePO4 cells deliver a high discharge capacity of 160.1 mAh g-1 at 1 C and excellent cycling stability with 100.2 mAh g-1 retaining after 1000 cycles. The as-assembled pouch cells show excellent electrochemical stability even at rigorous conditions, demonstrating high safety and practicability.

A Super-Ionic Solid-State Block Copolymer Electrolyte.

Polymer solid-state electrolytes offer great promise for battery materials with high energy density, mechanical stability, and improved safety. However, their low ion conductivities have so far limited their potential applications. Here, it is shown for poly(ethylene oxide) block copolymers that the super-stoichiometric addition of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) as lithium salt leads to the formation of a crystalline PEO block copolymer phase with exceptionally high ion conductivities and low activation energies. The addition of LiTFSI further induces block copolymer phase transitions into bi-continuous Fddd and gyroid network morphologies, providing continuous 3D conduction pathways. Both effects lead to solid-state block copolymer electrolyte membranes with ion conductivities of up to 1·10-1Scm-1 at 90°C, decreasing only moderately to 4·10-2Scm-1 at room temperature, and to >1·10-3Scm-1 at -20°C, corresponding to activation energies as low as 0.19eV. The co-crystallization of PEO and LiTFSI with ether and carbonate solvents is observed to play a key role to realize a super-ionic conduction mechanism. The discovery of PEO super-ionic conductivity at high lithium concentrations opens a new pathway for fabrication of solid polymer electrolyte membranes with sufficiently high ion conductivities over a broad temperature range with widespread applications in electrical devices.

Rare Gold-Catalyzed 4-exo-dig Cyclization for Ring Expansion of Propargylic Aziridines toward Stereoselective (Z)-Alkylidene Azetidines, via Diborylalkyl Homopropargyl Amines.

We report an uncommon 4-exo-dig cyclization of N-tosyl homopropargyl amines, catalyzed by [AuCl(PEt3)]/AgOTf, to prepare stereoselective (Z)-2-alkylidene-1-tosylazetidine compounds. The reaction outcome contrasts with the gold-catalyzed cyclization of N-tosyl homopropargyl amines containing a methyl group at the propargylic position that provides substituted 2,3-dihydropyrroles via a 5-endo-dig mechanism. The access to N-tosyl homopropargyl amines is possible by the regioselective nucleophilic attack of α-diboryl alkylidene lithium salts to propargylic aziridines.

Synergistic Enhancement of Biaxial Stretching and Multilayer Composites in All-Solid-State Polymer Electrolytes.

As an important component of lithium-ion batteries, all-solid-state electrolytes should possess high ionic conductivity, excellent flexibility, and relatively high mechanical strength. All-solid-state polymer electrolytes (ASSPEs) based on polymers seem to be able to meet these requirements. However, pure ASSPEs have relatively low ionic conductivity, and the addition of inorganic fillers such as lithium salts will reduce their flexibility and mechanical strength. To address the above issues, in this paper, the solvent-free method was used to prepare a poly(vinylidenefluoride-co-hexafluoropropylene)/lithium bis(trifluoromethanesulfonyl) imide/poly(ethylene oxide) all-solid-state polymer electrolyte, which was then subjected to 4 × 4 magnification synchronous bidirectional stretching. Subsequently, it was multilayered with PEO-based composite polymer electrolytes to obtain multilayered composite polymer electrolytes (MCPEs). Bidirectional stretching provides superior in-plane and out-of-plane mechanical properties to MCPEs by inducing molecular chain orientation, which suppresses the growth of lithium dendrites. Concurrently, it facilitates the formation of the β-crystal form of PVDF-HFP, thereby weakening the ion solvation effect and reducing the lithium-ion migration energy barrier. Multilayered compounding improves the interfacial contact between MCPEs and electrodes, thereby reducing the interfacial impedance. Experiments have demonstrated that the MCPEs prepared in this paper exhibit high ionic conductivity at room temperature (1.83 × 10-4 S cm-1), low interfacial resistance (547 Ω cm-2), excellent mechanical properties (26 MPa), and excellent cycling rate performance (a capacity retention rate of 90% after 110 cycles at 0.1 C), which can meet the performance requirements of lithium-ion batteries for ASSPEs.

A method for deriving oligomers from sulfamide monomer and their application as electrolytes

This paper describes the development of a method of catalytic polymerization that was then applied to synthesize sulfate-based oligomers from sulfamide. Two molecules, copper triflate and copper acetate, catalyzed the formation of oligomers with diol monomers. Two oligomers were identified as products of the reactions. Oligomers with sulfate incorporated in the backbone proved to have an ability for ion diffusion. When the oligomers were doped with lithium salt, anion transportation was predominant, as shown by solid-state NMR. The lithium ion was found to be strongly bonded to the backbone, while the anion was highly mobile. To corroborate this finding, we conducted molecular dynamics (MD) simulations, which revealed the structural characteristics and static properties of two electrolytes containing LiTFSI and two different polyethylene oxide oligomers. Interactions between the anion and cation were analyzed through computation of the radial distribution function (RDF) and the spatial distribution function (SDF). Our findings indicate that while the anion presents weak interactions with the polymer chain, the cation interacts strongly with the oligomer backbone.

A novel technology for lithium extraction through low-temperature synergistic roasting of α-spodumene with lepidolite

α-Spodumene and lepidolite have garnered significant attention because of the booming market of lithium (Li) salts. However, α-spodumene requires a high-temperature phase transition step at ≥1050 °C, and lepidolite needs a large amount of sulfate to extract Li. The economic and environmental benefits of these processes need to be improved. Herein, an innovative scheme, low-temperature synergistic roasting of α-spodumene with lepidolite, was proposed to efficiently extract Li. The conditions for phase transition roasting, acid baking, and water leaching were sequentially optimized. The mechanisms underlying the synchronous phase transition of α-spodumene and lepidolite were studied using various characterization methods. Results indicated that lepidolite lowers the transition temperature of spodumene from the α-phase to the β-phase by 150 °C. During the synergistic roasting, fluorine escapes from the lepidolite lattice and attacks SiO, AlO, and LiO bonds within the α-spodumene lattice. Under optimal conditions, 97.60 % of the Li was extracted, while the leaching ratios of Na, K, Al, and Si were only 50.96 %, 10.96 %, 5.75 %, and 0.30 %, respectively. Current scheme is a promising low-carbon technology that synchronously achieves the low-temperature phase transition of α-spodumene and additive-free Li extraction from lepidolite, offering superior economics, environmental benefits, and practicality compared with the existing methods.