Silicon-based anodes, as key high-energy-density anode materials for lithium-ion batteries, face limitations in practical application due to long-term calendar aging. This study systematically investigates the calendar aging behavior of commercial pouch cells with varying silicon oxide (SiO_x) contents under storage conditions of 100% state of charge (SOC) and 40 °C. Experimental results demonstrate that increasing SiO_x content significantly in SiO_x-graphite (SG) accelerates capacity degradation. The pouch cells with an anode capacity of 1000 mAh·g⁻¹ (SG-1000) retained only 10% of their original capacity after 4 weeks of storage, while pure graphite (Gr) counterparts maintained 75%. By employing in-situ ultrasonic scanning technology, we achieved high-resolution, non-destructive visualization of internal gas evolution, confirming that SiO_x particles intensify interfacial side reactions. Multiscale characterization reveals a unique “lithium migration-solid electrolyte interphase (SEI) destruction-side reaction” vicious cycle mechanism in SG anodes. The electrochemical potential difference between lithiated graphite and SiO_x drives spontaneous lithium migration from graphite to SiO_x particles, causing excessive volume expansion and repeated SEI rupture. This process is further exacerbated by the SiO_x-promoted LiPF₆ hydrolysis cycle, which generates HF and yields a porous, unstable interface. A polyurethane (PCL)-based polymer electrolyte (PCL-2-isocyanatoethyl methacrylate (IEM)) was developed via in-situ polymerization. This highly elastic polymer network effectively suppresses SiO_x volume expansion and interrupts the Li⁺ migration pathways. Consequently, the capacity retention of SG-650 (1000 mAh·g⁻¹) cells improved from 64% to 77%, with gassing effectively suppressed. This work provides critical insights into the calendar aging of SiO_x-based anodes and offers a robust strategy for extending the life-cycle of high-energy-density pouch cells.

Lithium iron phosphate (LFP) offers excellent structural and performance stability derived from the (PO₄)³⁻ polyanionic structure, which is beneficial for long-term usage. However, this inherent stability also comes along with intrinsically poor ionic and electronic conductivities, which have been notoriously plaguing its high-rate performance and broader applications. Here, we present a gas-assisted transient synthesis (GATS, ~ 30 s) of LFP with controllable oxygen vacancies (O_v) for enhanced rate performance yet without sacrificing structural integrity or cycling stability. Benefited by the ultrafast heating and a higher synthesis temperature, we revealed that the LFP synthesis in GATS followed an interface reaction mechanism (rapid core shrinking) with a low activation energy (E_a), thus reducing the synthesis time from ~ 16.5 h in tube furnace heating (TFH, often nuclei-growth mechanism) to merely seconds. The optimized LFP sample demonstrates an 8-fold enhancement in ionic conductivity and a 12-fold increase in electronic conductivity compared to LFP obtained by TFH and attains exceptional cycling stability even at high rates of 10 C, as evidenced by a higher capacity retention of 93.8% (vs. 63.6% of commercial LFP) after 1000 cycles. Our strategy offers a kinetic pathway for rapid synthesis and structural engineering of LFP, thus unlocking its potential for broader energy storage applications.

Lithium-ion batteries (LIBs) have emerged as the predominant electrochemical energy storage devices in contemporary applications. However, the uncontrollable lithium (Li) plating on graphite (Gr) anodes and the structural deterioration of LiNi_0.5Co_0.2Mn_0.3O₂ (NCM523) cathodes in conventional carbonate electrolytes—particularly at high operating voltages and elevated temperatures—are the primary factors contributing to capacity decay and short circuits in LIBs. Herein, we elucidate the regulation of the lithium hexafluorophosphate (LiPF₆) decomposition pathway with a 1.15 M LiPF₆ by incorporating trace dual-unsaturated additives, 0.5 wt.% vinylene carbonate (VC) and 0.3 wt.% prop-1-ene-1,3-sultone (PES), resulting in LiF-enriched cathode electrolyte interphase and polymeric C–F and S–F species. The influences of the VC and PES serve to deactivate the Lewis acid phosphorus pentafluoride (PF₅), thereby impeding the formation of the byproduct Li_xPOF_y. Furthermore, the radical copolymerization of VC with PES through electrochemical initiation engenders a spatially adaptable polymeric solid electrolyte interphase on the Gr anode, significantly mitigating Li plating during cycling. Consequently, Gr|NCM523 pouch cells containing 0.5% VC and 0.3% PES additives exhibit a remarkable capacity retention of 97.54% after 500 cycles at 45 °C. This work offers a new insight into tuning the interphasial chemistry of anode/cathode at elevated temperatures through strategic dual-unsaturated electrolyte additives.

With increasing application demands of electronics and electric vehicles, the energy density of lithiumion batteries (LIBs) is expected to be higher and higher. The silicon-based anode materials have triggered global research interest due to low operating voltage and high specific capacity. However, for the Si-based anode, the large volume change during cycling causes cracking and pulverization of Si particles, leading to the sluggish kinetics and poor cycle life. In this work, fluoroethylene carbonate (FEC) and lithium bis(fluorosulfonyl)imide (LiFSI) are used as synergistic functional additives to enhance the performance of silicon–carbon (Si–C) composite anode in pouch cell. The properties of solid electrolyte interphase (SEI) formed on the surface of Si–C composite anode have been systematically investigated. The images of different electrolytes infiltration and gas production after formation are analyzed with ultrasonic transmission scanning technique. DFT calculations are used to illustrate the mechanism. All date collection is at pouch cell level, which is more persuasive.

The application of solid polymer electrolytes (SPEs) is severely impeded by the insufficient ionic conductivity and low Li⁺ transference numbers (t_Li⁺). Here, we report an iodine-driven strategy to address both the two long-standing issues of SPEs simultaneously. Electronegative iodine-containing groups introduced on polymer chains effectively attract Li⁺ ions, facilitate Li⁺ transport, and promote the dissociation of Li salts. Meanwhile, iodine is also favorable to alleviate the strong O−Li⁺ coordination through a Lewis acid–base interaction, further improving the ionic conductivity and t_Li⁺. As a proof of concept, an iodinated single-ion conducting polymer electrolyte (IPE) demonstrates a high ionic conductivity of 0.93 mS cm⁻¹ and a high t_Li⁺ of 0.86 at 25 °C, which is among the best results ever reported for SPEs. Moreover, symmetric Li/Li cells with IPE achieve a long-term stability over 2600 h through the in-situ formed LiF-rich interphase. As a result, Li−S battery with IPE maintains a high capacity of 623.7 mAh g⁻¹ over 300 cycles with an average Coulombic efficiency of 99%. When matched with intercalation cathode chemistries, Li/IPE/LiFePO₄ and Li/IPE/LiNi_0.8Mn_0.1Co_0.1O₂ solid-state batteries also deliver high-capacity retentions of 95% and 97% at 0.2 C after 120 cycles, respectively.

A highly sensitive and selective electrochemical chiral sensor was developed based on the competitive supramolecular interaction of carbon nanofibers (CNFs) embedded sulfobutyl ether-β-cyclodextrin (SBE-β-CD) with optically active cationic drugs at glassy carbon electrode (GCE). The difference in intermolecular hydrogen bonding/stability constant/enantioselectivity coefficient and Gibbs free energy of anionic host SBE-β-CD with enantiomers of amlodipine (R-/S-AML), clenbuterol (R-/S-CBL) and metoprolol (R-/S-MET) as a guest paved the way for efficient discrimination. The proposed sensing platform (CNFs-SBE-β-CD/GCE) could recognize the aforementioned enantiomers based on the discernible difference of peak potential (S/R-AML (ΔE_p = 135 mV), R/S-MET (ΔE_p = 99 mV) and R/S-CBL (ΔE_p = 111 mV). The binding mechanisms and thermodynamic study of the enantiospecific behavior have been investigated using the host-guest chemistry approach inside the nanocavity and results suggest that S-AML, R-MET, and R-CBL show stronger stability constants than their antipodes. Formation of the diastereomeric complex was taken as a measure of enantioselectivity and experimental results indicated that anionic SBE-β-CD is a better chiral ligand than neutral cyclodextrins. The fabricated sensor could be a useful low-cost electrochemical tool for molecular recognition of a variety of cationic species not only of drugs but also from other sources.