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For Si/C anodes, achieving excellent performance with a simple fabrication process is still an ongoing challenge. Herein, we report a green, facile and scalable approach for the in situ synthesis of Si@C anodes during the electrode manufacturing process by partially carbonizing Si nanoparticles (Si NPs) and dual polymers at a relatively low temperature. Due to the proper mass ratio of the two polymer precursors and proper carbonization temperature, the resultant Si-based anode demonstrates a typical Si@C core–shell structure and has strong mechanical properties with the aid of dual-interfacial bonding between the Si NPs core and carbon shell layer, as well as between the C matrix and the underlying Cu foil. Consequently, the resultant Si@C anode shows a high specific capacity (3458.1 mAh g−1 at 0.2 A g−1), good rate capability (1039 mAh g−1 at 4 A g−1) and excellent cyclability (77.94% of capacity retention at a high current density of 1 A g−1 after 200 cycles). More importantly, the synthesis of the Si@C anode is integrated in situ into the electrode manufacturing process and, thus, significantly decreases the cost of the lithium-ion battery but without sacrificing the electrochemical performance of the Si@C anode. Our results provide a new strategy for designing next-generation, high-capacity and cost-effective batteries. [ABSTRACT FROM AUTHOR]

Porous silicon (PSi) has become one of the current hotspots in lithium-ion anode materials research. However, due to their large volume change in the charge and discharge processes, which results in poor electrochemical performance, the material's practical value is significantly impacted. In this study, PSi@poly(3,4-ethylenedioxythiophene) (PSi@PEDOT) composites were prepared by coating porous micron Si etched from the commercial Al–Si alloy with a conductive polymer synthesized via the in situ polymerization of 3,4-ethylenedioxythiophene (EDOT). The PEDOT shell not only ensures the conductive network in the composite material but also inhibits Si volume expansion. In addition, the pores inside the PSi material's core layer provide space gaps to buffer Si volume expansion, which can effectively improve its cycling stability and rate performance. Electrochemical test results show that the PSi@PEDOT-2 composite with mass ratio of 1.5:1 exhibits the best cycling stability. The initial discharge capacity is 1338.62 mAh g−1 at a current density of 0.5 A g−1, and the postcapacity retention rate is 70.3% after 200 cycles. Further, the preparation method may be used as an approach for preparing high-performance Si-based anode materials. [ABSTRACT FROM AUTHOR]

The mediocre capacitive performance of carbon cathode has seriously hampered the advancement of lithium ion capacitors (LICs). The guideline for high-performance capacitive carbon cathode is still lacking. In this study, the desired microstructure of carbon cathode that suitable for LiPF 6 -contained electrolyte is calculated by using density functional theory. Results suggest that only the pore sizes more than 2.18 nm can accommodate the solvated P F 6 - ions. Experimental results confirm that the capacitive performance of the synthesized activated polyaniline-derived carbon (APDC) can be significantly promoted as the pore size was more than 2 nm. Especially, the APDC-700-based electrode demonstrates outstanding electrochemical performance with high capacitance (247 F g-1 at 0.1 A g-1) and good rate capability (156 F g-1 at 10 A g-1), owing to the appropriate pore size and high N content in carbon matrix. The APDC-700-based LIC device can deliver an ultra-high energy density of 300.3 Wh kg-1 at 318 W kg-1, as well as good cycling stability over 10 000 cycles. This well-designed work will be conducive to deeply understand the performance improvement of capacitive carbon cathode in LiPF 6 electrolyte and provides guidelines for designing advanced LIC devices. [Display omitted] • P F 6 - ion mainly exists in the form of P F 6 - E C 6 in EC/DMC/DEC solvents. • The carbon with pore size more than 2.18 nm can accommodate the P F 6 - E C 6 species. • APDC-700 cathode delivers a high capacitance of 247 F g-1 in LiPF 6 electrolyte. • Good performance of APDC-700 is due to the suitable pore size and high N content. • APDC-700-based LIC device deliver an ultra-high energy density of 300.3 Wh kg-1. [ABSTRACT FROM AUTHOR]

Binary metal oxides have been proved to possess better pseudocapacitive performance than single metal oxide analogies. Substitution of toxic and high-cost ions (Co and Mo) in binary metal oxides with low-cost and environmentally-friendly ions (Ni and Mn) is of great economic and environmental importance. In this paper, murdochite-type binary metal oxides (i.e., Ni 6 MnO 8) and binary metal oxides@carbon nanotubes (i.e., Ni 6 MnO 8 @CNTs) core-shell structure were synthesized via a facile hydrothermal approach followed by a calcination process. Electrochemical measurement results indicated that the synthesized Ni 6 MnO 8 @CNT core-shell structure showed a high specific capacitance of 1213 F g−1 at 1 A g−1 with two times capacitance value of Ni 6 MnO 8 at same current density. Even at the high current density of 20 A g−1, the Ni 6 MnO 8 @CNT core-shell structure can still deliver a high capacitance value of 711 F g−1, which value is also much higher than that of Ni 6 MnO 8 at the current density of 1 A g−1. With the prepared Ni 6 MnO 8 @CNT hybrid as positive electrode and activated-polyaniline-derived-carbon as negative electrode, an asymmetric supercapacitor cell (ASC) was successfully assembled. The assembled ASC device exhibited excellent pseudocapacitive performance with a high specific capacitance of 154 F g−1 at 1 A g−1 and a high energy density of 58.2 Wh kg−1 at a power density of 831.4 W kg−1. Even at a high power density of 16.6 kW kg−1, the ASC device can still deliver a high energy density of 23.1 Wh kg−1, suggesting the promising applications of Ni 6 MnO 8 @CNT hybrid in supercapacitors. [ABSTRACT FROM AUTHOR]