Controlled Synthesis of Triangular Submicron-Sized CeO2 and Its Polishing Performance.

CeO2 is widely used in the field of chemical-mechanical polishing for integrated circuits. Morphology, particle size, crystallinity, and Ce3+ concentration are crucial factors that affect polishing performance. In this study, we successfully synthesized two novel triangular CeO2 abrasives with similar particle sizes (600 nm) but different morphologies and Ce3+ concentrations using a microwave-assisted hydrothermal method with high-concentration raw materials, and no surfactants or template agents were added. It is generally believed that CeO2 with a higher Ce3+ concentration leads to better polishing performance. However, the results of polishing indicate that CeO2 synthesized at 200 °C, despite its lower Ce3+ concentration, demonstrates outstanding polishing performance, achieving a polishing rate of 324 nm/min, and the Sa of Si wafers decreased by 3.6% after polishing. This suggests that, under similar particle size conditions, the morphology of CeO2 plays a dominant role in the mechanical effects during the polishing process. Additionally, compared to commercial polishing slurries, the synthesized samples demonstrated better polishing performance. This indicates that, in CMP, the pursuit of smaller spherical abrasives may not be necessary. Instead, the appropriate shape and particle size can better balance the material removal rate and surface roughness.

Gradual gradient distribution composite solid electrolyte for solid-state lithium metal batteries with ameliorated electrochemical performance.

Composite solid electrolytes (CSEs) have emerged as promising contenders for tackling the safety concerns associated with lithium metal batteries and attaining elevated energy densities. Nonetheless, augmenting ion conductivity and curtailing the growth of lithium dendrites within the electrolyte remain pressing challenges. We have developed CSEs featuring a unique structure, in which Li6.4La3Zr1.4Ta0.6O12 (LLZTO) is distributed in a gradient decline from the center to both sides (GCSE). This distinctive arrangement encompasses heightened polymer content at the edges, thereby enhancing the compatibility between CSEs and electrode materials. Concurrently, the escalated LLZTO content at the center functions to impede the proliferation of lithium dendrites. The uniform gradient distribution state facilitates the consistent and rapid transport of lithium ions. At room temperature, GCSE exhibits an ionic conductivity of 1.5 × 10-4 S cm-1, with stable constant current cycling of lithium for over 1200 h. Furthermore, CR2032 coin batteries with a LiFePO4 (LFP)|GCSE|Li configuration demonstrate excellent rate performance and cycling stability, yielding a discharge capacity of 120 mA h g-1 at 0.5C and retaining 90 % capacity after 200 cycles at 60 °C. Flexible solid electrolytes with gradient structures offer substantial advantages in dealing with ion conductivity and inhibition of lithium dendrites, thereby expected to propel the practical application of lithium metal batteries.

Misplaced Intuitions in Interventions to Reduce Attractiveness-Based Discrimination.

Individuals and organizations are increasing efforts to address discrimination. Nonexperts may lack awareness of, or are resistant to, scientifically informed strategies for reducing discrimination, instead relying on intuition. Five studies investigated the accuracy of nonexperts' intuitions about reducing discrimination concerning physical attractiveness. In Studies 1a to 1c (N = 902), participants predicted the effectiveness of six interventions to reduce attractiveness-based favoritism on a judgment task. Studies 2a and 2b (N = 6,292) investigated the effectiveness of these interventions. Although two interventions reduced discrimination, intuitions were poorly aligned with actual results; fewer than 1% of participants identified the combination of interventions that did, versus did not, impact judgment, and responses were more likely to be below than above chance when predicting each intervention's effectiveness. Although follow-up work should investigate the accuracy of intuition in other forms of discrimination, these results further stress the need for greater development and adoption of evidence-based strategies for combating discrimination.

A cycling robust network binder for high performance Si-based negative electrodes for lithium-ion batteries.

Silicon has been a pivotal negative electrode material for the next generation lithium-ion batteries due to its superior theoretical capacity. However, commercial application of Si negative electrodes is seriously restricted by its fast capacity fading as a result of severe volume changes during the process of charge and discharge. A novel functional binder is essential to resolve this conflict. In this work, we have proposed a composite of carboxymethyl cellulose (CMC) and cationic polyacrylamides (CPAM) as an effective network binder to improve the electrochemical performance of Si-based negative electrodes in lithium-ion batteries. The CMC-CPAM composite binder is cross-linked physically through reversible electrostatic interaction. Unlike common covalent cross-linked binders, the network structure of it forms spontaneously at room temperature, which makes it self-healing. Besides, benefits from the use of high molecular CPAM, the CMC-CPAM network binder exhibits excellent mechanical and adhesive strength, which makes it robust enough to tolerate the volume change of Si. As a result, the Si electrode with the self-healing CMC-CPAM composite binder shows an excellent cycling stability than the covalent cross-linked CMC-polyacrylic acid (PAA) and linear CMC binders, with a capacity of 1906.4 mAh·g-1 remaining after 100 cycles. Moreover, the cycling performance of retaining 78% of the initial capacity after 350 cycles is achieved based on the commercial Si@C/graphite negative electrode using the self-healing CMC-CPAM network binder with a very high mass loading (~4 mg·cm-2).

Effect of particle size distribution on the electrochemical performance of micro-sized silicon-based negative materials.

Si has been extensively examined as a potential alternative to carbonaceous negative materials, because it shows exceptional gravimetric capacity and abundance. In recent years, the strategy of using nano-structured silicon materials as building blocks to build micro-sized silicon-based materials has been widely studied. In this work, a commercialized and benchmark micro-sized silicon-based material (denoted as SiO x /C) is used as research target and three groups of materials with different particle size distributions (PSDs) were obtained by simply mechanical sieving. The effects of PSD on the electrochemical performance and electrode structure of micro-sized silicon-based negative electrodes are discussed. The optimized selection of micro-sized active material PSD presents a comprehensive way for developing and characterizing Si-based negative electrodes for practicable high-energy LIBs. In this case, the optimized SiO x /C composite electrode with a particle size of 22.7 µm and narrow PSD shows enhanced cycling stability with a high capacity retention of 84.31% over 100 cycles.

Correction: Effect of particle size distribution on the electrochemical performance of micro-sized silicon-based negative materials.

[This corrects the article DOI: 10.1039/C8RA00539G.].

Formation of Si nanowires by the electrochemical reduction of SiO2 with Ni or NiO additives.

Various morphologies of silicon nanowires (SiNWs) were successfully prepared by the electrochemical reduction of silica mixed with different additives (Au, Ag, Fe, Co, Ni, and NiO, respectively). Straight SiNWs were extensively obtained by the electro-reduction of porous Ni/SiO2 blocks in molten CaCl2 at 900 °C. The SiNWs had a wide diameter distribution of 80 to 350 nm, and the Ni-Si droplets were found on the tips of the nanowires. The growth mechanism of SiNWs was investigated, which could reveal that the nano-sized Ni-Si droplets formed at the Ni/SiO2/CaCl2 three-phase interlines. Based on the mechanism proposed, NiO particles with sub-micrometer size were selected as the additive, and straight SiNWs with diameters of 60 to 150 nm were also prepared via the electrochemical process.

Improving the Cycling Stability of Si/Ni Negative Composite Through Introducing the SiOC Skeleton.

A Si/Ni/SiOC (SNS) composite structure with high efficiency and long-term cycling stability was synthesized by a cost-effective and scalable method. In this structure, a SiOC net with favorably physical and chemical stability acts as a skeleton to support and segregate Si-Ni mixed powders. The electrochemical performance of Si-Ni as a negative for Li-ion battery had been largely improved through introducing a stable SiOC skeleton structure as buffer base. Compared with Si-Ni mixed powders, the SNS composite negative exhibits excellent long-term cycling stability and capacity. Such SNS composite negative shows excellent cycling stability with a specific capacity of 505.5 mA· h · g(-1) and 84% capacity retention over 25 cycles at 0.2 C rate, which has the perspective application in the future high energy density li-ion batteries. In the meantime, the design and fabrication of this structure has the potential to provide a way for the other functional composite materials in the semiconductive field.

Electrochemical preparation of silicon nanowires from nanometre silica in molten calcium chloride.

Here we report Si nanowire growth by electrochemical reduction of nanometre silica in molten CaCl2; to our knowledge, this is the first report of an electrochemical route that provides crystalline Si nanowires in large quantities.