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1. Thermal properties of field‐assisted‐sintered SiCN–Y ₂ O ₃ composites

   https://doi.org/10.1111/ijac.14265  

   Zhang, Zhao; Li, Quan; Maiti, Sanat Chandra; Shen, Xingchen; He, Jian; Peng, Fei; Bordia, Ranjendra K. (March 2023, International Journal of Applied Ceramic Technology)

   Abstract Polymer‐derived amorphous SiCN has excellent high‐temperature stability and properties. To reduce the shrinkage during pyrolysis and to improve the high‐temperature oxidation resistance, Y₂O₃was added as a filler. In this study, polymer‐derived SiCN–Y₂O₃composites were fabricated by mixing a polymeric precursor of SiCN with Y₂O₃submicron powders in different ratios. The mixtures were cross‐linked and pyrolyzed in argon. SiCN–Y₂O₃composites were processed using field‐assisted sintering technology at 1350°C for 5 min under vacuum. Dense SiCN–Y₂O₃composite pellets were successfully made with relative density higher than 98% and homogeneous microstructure. Due to low temperature and short time of the heat‐treatment, the grain growth of Y₂O₃was substantially inhibited. The Y₂O₃grain size was ∼1 μm after sintering. The composites’ heat capacity, thermal diffusivity, and thermal expansion coefficients were characterized as a function of temperature. The thermal conductivity of the composites ceramics decreased as the amount of amorphous SiCN increased and the coefficient of thermal expansion (CTE) of the composites increased with Y₂O₃content. However, the thermal conductivity and CTE did not follow the rule of mixture. This is likely due to the partial oxidation of SiCN and the resultant impurity phases such as Y₂SiO₅, Y₂Si₂O₇, and Y_4.67(SiO₄)₃O. 

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2. Enhanced Electrochemical Performance of LiNi _0.8 Co _0.1 Mn _0.1 O ₂ with SiO ₂ Surface Coating Via Homogeneous Precipitation

   https://doi.org/10.1002/celc.202101230  

   Dou, Lintao; Hu, Pu; Shang, Chaoqun; Wang, Heng; Xiao, Dongdong; Ahuja, Utkarsh; Aifantis, Katerina; Zhang, Zhanhui; Huang, Zhiliang (November 2021, ChemElectroChem)

   Abstract Ni‐rich LiNi_0.8Co_0.1Mn_0.1O₂(NCM811) has been considered as a promising cathode material for high energy density lithium‐ion batteries. However, it experiences undesirable interfacial side‐reactions with the electrolyte, which lead to a rapid capacity decay. In this work, a homogeneous precipitation method is proposed for forming a uniform silicon dioxide (SiO₂) coating on the NCM811 surface. The strong Si−O network provided a stable protective layer between the NCM811 active material and electrolyte to improve the electrochemical stability. As a result, the NCM811@SiO₂cathode showed superior cycling stability (84.9 % after 100 cycles at 0.2 C) and rate capability (142.7 mA h g⁻¹at 5 C) compared to the pristine NCM811 cathode (56.6 % after 100 cycles, 127.9 mA h g⁻¹at 5 C). Moreover, the SiO₂coating effectively suppressed voltage decay and pulverization of the NCM811 particles during long term cycling. This uniform coating technique offers a viable approach for stabilizing Ni‐rich cathode materials for high‐energy density lithium‐ion batteries. 

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3. High‐Performance Solar Blind UV Photodetectors Based on Single‐Crystal Si/β‐Ga ₂ O ₃ p‐n Heterojunction

   https://doi.org/10.1002/admt.202100254  

   Zheng, Yixiong; Hasan, Md_Nazmul; Seo, Jung‐Hun (April 2021, Advanced Materials Technologies)

   Abstract In this study, Si/β‐Ga₂O₃solar‐blind photodetectors (PDs) have been demonstrated via micro‐transfer printing of a single crystalline Si pillar on β‐Ga₂O₃. Unlike other previous approaches for β‐Ga₂O₃based heterojunction, this new single crystalline p‐n Si/β‐Ga₂O₃heterojunction has a particle‐free heterointerface and does not show any sign of internal strain after the heterogeneous integration that is confirmed by Raman spectroscopy. As a result, PDs exhibit extremely high photoresponsivity (748 A W⁻¹), quantum efficiency (3.67 × 10⁵%), and UV/visible rejection ratio (≈10⁵) under UV light illumination. This result is believed to provide a viable route for the realization of high‐performance solar‐blind photodetection systems, which form some of the most indispensable and important components in high‐performance next‐generation security, biomedical, and environmental monitoring systems. Also, the unique heterogeneous integration method allows us to realize a variety of β‐Ga₂O₃based heterostructures that can further enhance the optical performances of β‐Ga₂O₃based PDs. 

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4. Zn(Cu)Si _{2+ x} P ₃ Solid Solution Anodes for High‐Performance Li‐Ion Batteries with Tunable Working Potentials

   https://doi.org/10.1002/adfm.201903638  

   Li, Wenwu; Liao, Jun; Li, Xinwei; Zhang, Lei; Zhao, Bote; Chen, Yu; Zhou, Yucun; Guo, Zaiping; Liu, Meilin (June 2019, Advanced Functional Materials)

   Abstract Si‐based anodes with a stiff diamond structure usually suffer from sluggish lithiation/delithiation reaction due to low Li‐ion and electronic conductivity. Here, a novel ternary compound ZnSi₂P₃with a cation‐disordered sphalerite structure, prepared by a facile mechanochemical method, is reported, demonstrating faster Li‐ion and electron transport and greater tolerance to volume change during cycling than the existing Si‐based anodes. A composite electrode consisting of ZnSi₂P₃and carbon achieves a high initial Coulombic efficiency (92%) and excellent rate capability (950 mAh g⁻¹at 10 A g⁻¹) while maintaining superior cycling stability (1955 mAh g⁻¹after 500 cycles at 300 mA g⁻¹), surpassing the performance of most Si‐ and P‐based anodes ever reported. The remarkable electrochemical performance is attributed to the sphalerite structure that allows fast ion and electron transport and the reversible Li‐storage mechanism involving intercalation and conversion reactions. Moreover, the cation‐disordered sphalerite structure is flexible to ionic substitutions, allowing extension to a family of Zn(Cu)Si_2+xP₃solid solution anodes (x= 0, 2, 5, 10) with large capacity, high initial Coulombic efficiency, and tunable working potentials, representing attractive anode candidates for next‐generation, high‐performance, and low‐cost Li‐ion batteries. 

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5. Interface Engineering V ₂ O ₅ Nanofibers for High‐Energy and Durable Supercapacitors

   https://doi.org/10.1002/smll.201901747  

   Bi, Wenchao; Wang, Jichao; Jahrman, Evan P.; Seidler, Gerald T.; Gao, Guohua; Wu, Guangming; Cao, Guozhong (June 2019, Small)

   Abstract A local electric field is induced to engineer the interface of vanadium pentoxide nanofibers (V₂O₅‐NF) to manipulate the charge transport behavior and obtain high‐energy and durable supercapacitors. The interface of V₂O₅‐NF is modified with oxygen vacancies (Vö) in a one‐step polymerization process of polyaniline (PANI). In the charge storage process, the local electric field deriving from the lopsided charge distribution around Vö will provide Coulombic forces to promote the charge transport in the resultant Vö‐V₂O₅/PANI nanocable electrode. Furthermore, an ≈7 nm porous PANI coating serves as the external percolated charge transport pathway. As the charge transfer kinetics are synergistically enhanced by the dual modifications, Vö‐V₂O₅/PANI‐based supercapacitors exhibit an excellent specific capacitance (523 F g⁻¹) as well as a long cycling lifespan (110% of capacitance remained after 20 000 cycles). This work paves an effective way to promote the charge transfer kinetics of electrode materials for next‐generation energy storage systems. 

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