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Polyoxometalates (POMs)‐based materials, with high theoretical capacities and abundant reversible multi‐electron redox properties, are considered as promising candidates in lithium‐ion storage. However, the poor electronic conductivity, low specific surface area and high solubility in the electrolyte limited their practical applications. Herein, a double‐shelled hollow PMo12−SiO2@N−C nanofiber (PMo12−SiO2@N−C, where PMo12 is [PMo12O40]3−, N−C is nitrogen‐doped carbon) was fabricated for the first time by combining coaxial electrospinning technique, thermal treatment and electrostatic adsorption. As an anode material for LIBs, the PMo12−SiO2@N−C delivered an excellent specific capacity of 1641 mA h g−1 after 1000 cycles under 2 A g−1. The excellent electrochemical performance benefited from the unique double‐shelled hollow structure of the material, in which the outermost N−C shell cannot only hinder the agglomeration of PMo12, but also improve its electronic conductivity. The SiO2 inner shell can efficiently avoid the loss of active components. The hollow structure can buffer the volume expansion and accelerate Li+ diffusion during lithiation/delithiation process. Moreover, PMo12 can greatly reduce charge‐resistance and facilitate electron transfer of the entire composites, as evidenced by the EIS kinetics study and lithium‐ion diffusion analysis. This work paves the way for the fabrication of novel POM‐based LIBs anode materials with excellent lithium storage performance. [ABSTRACT FROM AUTHOR]

To enhance the model estimation performance and minimize the possibility of overfitting, we propose a statistical optimization strategy of healthy features (HFs) for estimating the state-of-health (SOH) of lithium-ion batteries (LIBs). Firstly, a series of initial HFs were extracted from the voltage, current, temperature, incremental capacity (IC) curves, and differential thermal voltammetry (DTV) curves according to the battery characteristics. Secondly, the six statistical features (i.e., mean, median, lower quartile, range, upper quartile, and standard deviation) of the initial HFs for each charge cycle were calculated. Thirdly, to minimize the impact of redundant features and noise, the optimal HF set was identified by a comparative analysis among different combinations of the six statistical features. Thus, the battery SOH can be estimated using the dual-kernel Gaussian process regression (GPR), which improves the estimation accuracy and generalization ability of the single-kernel GPR. To prevent estimation errors due to manual adjustments, the GPR hyperparameters were optimized via the northern goshawk optimization (NGO) algorithm. Experiments were conducted on the NASA and Oxford datasets, with most estimation errors below 1%. Experimental results demonstrate the lightweight NGO-Dualkernel-GPR model, by incorporating the statistical feature optimization strategy, achieves exceptional SOH estimation performance for different LIBs. [ABSTRACT FROM AUTHOR]

Recently, it has become very important to develop cost‐effective anode materials for the large‐scale use of lithium‐ion batteries (LIBs). Polyoxometalates (POMs) have been considered as one of the most promising alternatives for LIB electrodes owing to their reversible multi‐electron‐transfer capacity. Herein, Keggin‐type [PMo12O40]3− (donated as PMo12) clusters are anchored onto a 3D microporous carbon framework derived from ZIF‐8 through electrostatic interactions. The PMo12 clusters can be immobilized steadily and uniformly on the carbon framework, which provides enhanced electrical conductivity and high stability. Compared with PMo12 itself, the as‐prepared novel 3D Carbon‐PMo12 composite displays a significantly improved Li‐ion storage performance as an LIB anode, with excellent reversible specific capacity and rate capacity, as well as high cycling performance (discharge capacity of 985 mA h g−1 after 200 cycles), which are superior to other POM‐based anode materials reported so far. The high performance of the Carbon‐PMo12 composite can be attributed to the 3D conductive network with fast electron transport, high ratio of pseudocapacitive contribution, and evenly distributed PMo12 clusters with reversible 24‐electron transfer capacity. This work offers a facile way to explore novel LIB anodes consisting of electroactive molecule clusters. [ABSTRACT FROM AUTHOR]

Keywords: anode material; carbon-based material; double-shelled hollow structure; lithium-ion batteries; polyoxometalates EN anode material carbon-based material double-shelled hollow structure lithium-ion batteries polyoxometalates 13278 13278 1 09/22/21 20210920 NES 210920 B Excellent lithium storage b is achieved by the double-shelled hollow PMo SB 12 sb -SiO SB 2 sb @N-C anode material. Anode material, carbon-based material, double-shelled hollow structure, lithium-ion batteries, polyoxometalates Cover Feature: Double-Shelled Hollow SiO2@N-C Nanofiber Boosts the Lithium Storage Performance of [PMo12O40]3- (Chem. Eur. J. 53/2021). [Extracted from the article]

Polyoxometalates (POMs)‐based materials, with high theoretical capacities and abundant reversible multi‐electron redox properties, are considered as promising candidates in lithium‐ion storage. However, the poor electronic conductivity, low specific surface area and high solubility in the electrolyte limited their practical applications. Herein, a double‐shelled hollow PMo12−SiO2@N−C nanofiber (PMo12−SiO2@N−C, where PMo12 is [PMo12O40]3−, N−C is nitrogen‐doped carbon) was fabricated for the first time by combining coaxial electrospinning technique, thermal treatment and electrostatic adsorption. As an anode material for LIBs, the PMo12−SiO2@N−C delivered an excellent specific capacity of 1641 mA h g−1 after 1000 cycles under 2 A g−1. The excellent electrochemical performance benefited from the unique double‐shelled hollow structure of the material, in which the outermost N−C shell cannot only hinder the agglomeration of PMo12, but also improve its electronic conductivity. The SiO2 inner shell can efficiently avoid the loss of active components. The hollow structure can buffer the volume expansion and accelerate Li+ diffusion during lithiation/delithiation process. Moreover, PMo12 can greatly reduce charge‐resistance and facilitate electron transfer of the entire composites, as evidenced by the EIS kinetics study and lithium‐ion diffusion analysis. This work paves the way for the fabrication of novel POM‐based LIBs anode materials with excellent lithium storage performance. [ABSTRACT FROM AUTHOR]

Aiming at enhancing cyclic stability and fast charging performance of lithium-ion batteries (LIBs), a sandwich structured composite with a buffer layer of porous silicon (Si) between the carbon layer and SnO 2 layer (C/Si@SnO 2) was developed by using ball milling. The results showed that the Si layer with plenty of mesoporous and cracks was coated successfully and the introduction of Si increased the disordered structure of SnO 2 , including the expansion of interlayer spacing, the emergence of Sn and SiOx indicated the reaction between Si and SnO 2 occurred during the ball milling process, while the generation of Si-O-Sn and Si-O-C bonds formed by Si integration connected the three components with intimate interfaces. Used as an anode for LIBs, the C/Si@SnO 2 electrode performed a favorable discharge capacity (919.21 mAh·g−1 at 0.1 A·g−1), the ultra-long cyclability after 1000 and 2000 cycles, impressive rate performance (269.87 mAh·g−1 at 5 A·g−1), and fast charging capability accompanying discharge capacity of 805.57 mAh·g−1 at 0.2 A·g−1 and charge capacity of 400.55 mAh·g−1 at 2 A·g−1. In addition, the electrochemical impedance spectroscopy analysis showed that the graphitic carbon layer and porous Si layer improved the rapid Li+ diffusion and transportation, which was beneficial to fast charging in LIBs. Our work provided a facile and green ball milling method to construct porous sandwich structured metal oxide/C composites with the introduction of Si, which can effectively increase the disordered structure of composite and also open up a new scheme of Si materials as an anode in the field of fast charging for LIBs. [Display omitted] • Ball milling of Si and SnO 2 resulted in disordered SnO 2. • Si layer with mesoporous and cracks provided a buffer zone for SnO 2. • Si-O-Sn and Si-O-C bonds enhanced ultra-long cyclic stability of C/Si@SnO 2. • Graphitic carbon layer conductive to conductivity and improved anodic stability. • The capacity retention of 87% was achieved in fast charging after 500 cycles. [ABSTRACT FROM AUTHOR]

Silicon (Si) as anode material has a very high theoretical specific capacity for lithium-ion batteries (LIBs), but there are serious problems such as volume expansion and poor conductivity. Even though abundant carbon-silicon composite has been designed to alleviate these problems, the unstable carbon-silicon interface makes it hard to present high-performance. Herein, we created a core-shell structure (RH-Si/SiO x @C) that had a robust carbon-silicon interface with Si–C, Si–O–C, and Si–N bonding between rice husk-derived silicon nanoparticles (Si NPs) and pitch-derived soft carbon induced by 1-butyl-3-methyl-imidazole acetate ([BMIm]Ac). The pitch-derived soft carbon was evenly coated on the Si NPs and supplied outstanding electrical conductivity, while the oxygen of pitch and [BMIm]Ac caused SiO x growth on the Si NPs surface to buffer expansion. RH-Si/SiO x @C electrode demonstrated extraordinary long-term cycling performance for LIBs. After going through 1000 cycles at 2 A g−1, it still possessed 89.78% retention and kept 622 mAh g−1. When the test current was applied to 3 A g−1, it maintained a 357 mAh g−1 specific capacity with 60.16% retention. RH-Si/SiO x @C has a lot of promise for high-energy-density LIBs because of its outstanding electrochemical performance and easy fabrication procedures. [Display omitted] • Ionic liquids built robust C/Si interfaces by Si–O–C, Si–C, and Si–N bonds. • A homogenous coating of soft carbon increased electric conductivity. • The RH-Si/SiOx@C shows excellent long-term cycle performance. [ABSTRACT FROM AUTHOR]