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Tremendous efforts have been made to improve the electrochemical performance of the lithium-sulfur batteries. However, challenges remain in achieving fast electronic and ionic transport while accommodate the significant cathode volumetric change. On the other hand, the severe capacity decay mainly attributed to polysulfide shuttle also hampers the practical applications. Here, we report a simple, low-cost, and eco-friendly method for the one-step preparation of a binder-free S-C composite cathode by plasma dissociation of CS2 containing gases at room-temperature. The key issue of polysulfide shuttle effect in Li-S batteries is also effectively resolved just by the introduction of N2 into the precursor gases. The electrode exhibits a high reversible capacity of ~600 mAh/g of the total hybrid of S + C at 100 mA/g after 100 cycles with an excellent initial coulombic efficiency of nearly 100%. The cells also demonstrate along cycle life and an extremely high capacity of ~306 mAh/g even after 300 cycles at 1 A/g with a high coulombic efficiency of about 100%. The proposed method will open the way for the plasma applications in facile preparation of Li-S batteries and the improvement of its electrochemical performance.

The effect of the chemical component and microstructure, not to mention their facile modification, of the coating/wrapping carbon layer on the electrochemical performance of the Si/C composite anode in lithium ion batteries (LIBs) hasn’t been actively explored although Si/C has been recognized as one of the most promising route for the high energy density LIBs. Herein we propose a novel nitrogen-plasma doping route to modify the top carbon film in an elaborately constructed layered Si/C composite anode. The electrochemical performance, e.g., the initial coulombic efficiency (CE), cycle stability and specific capacity of the composite anode is drastically improved by this plasma processing due to the increased kinetics of lithium ions. By means of the appropriate adjustment of the N doping ratio and N chemical configuration in the carbon layer through a N2/H2 plasma processing, the lithium diffusion rate in the composite anode was memorably increased as the pseudocapacitance effects promoted. The optimized Si/C composite exhibits a high capacity of 1120.7 mA h g−1 and an initial CE of 80.8% at the current of 2 A g−1 after a long cycle of 1500, increasing by ~40% of specific capacity and ~29% of the initial CE.

Transition metal vanadates have attracted much attention for high capacity anodes of lithium ion batteries (LIBs). However, they have obvious drawbacks (short cycle-lives and low rate performance) because of the intrinsically low electronic conductivity and serious volume variation during Li-ion desorption and insertion. In particular, pure Co3V2O8 micro-pencils (pCVO MPs) have a stable and regular crystal structure, large tap density and uniform grain size, but, unfortunately, they have not exhibited expected electrochemical performance. Herein, we report the successful preparation of reduced graphene oxide coated Co3V2O8 micro-pencils (rGO@CVO MPs) through a facile approach combining hydrothermal synthesis with thermal reduction. When tested as anodes for LIBs, rGO@CVO MPs exhibit superior electrochemical performance compared to that of pure Co3V2O8 micro-pencils (pCVO MPs). The anodes of rGO@CVO MPs show a high reversible capacity of 760 mA h g−1 over 200 cycles at 200 mA g−1, and 500 mA h g−1 can remain after 500 cycles at 1000 mA g−1, with an increase in 200 mA h g−1 in contrast to the pCVO MPs. It is consequently demonstrated that the composite material (rGO@CVO MPs) is a promising anode material for LIBs.

Graphene aerogels (GAs) have attracted extensive interest in diverse fields, owing to their ultrahigh surface area, low density and decent electrical conductivity. However, the undesirable thermal conductivity of GAs may limit their applications in energy storage devices. Here, we report a facile hydrothermal method to modulate both the electrical and thermal properties of GAs by including bulk molybdenum disulfide (MoS2). It was found that MoS2 can help to reduce the size of graphene sheets and improve their dispersion, leading to the uniform porous micro-structure of GAs. The electrical measurement showed that the electrical conductivity of GAs could be decreased by 87% by adding 0.132 vol % of MoS2. On the contrary, the thermal conductivity of GAs could be increased by ~51% by including 0.2 vol % of MoS2. The quantitative investigation demonstrated that the effective medium theories (EMTs) could be applied to predict the thermal conductivity of composite GAs. Our findings indicated that the electrical and thermal properties of GAs can be tuned for the applications in various fields.

DLC coated 2024 aluminum alloy samples having four different intermediate layers prepared by different plasma-based ion implantation modes. The composition and structures of DLC coated samples were investigated by X-ray photoelectron spectroscopy (XPS), laser Raman spectroscopy and glancing angle X-ray diffraction (GXRD). Knoop micro-hardness and nano-hardness of the layers had been measured too. The tribological behaviors of these samples were investigated by ball on disk frictional tester and scanning electron microscopy (SEM). Results show that the stable friction coefficients of these four samples are nearly same and about 0.1, but the sliding cycles of holding stable friction coefficient are different, they increase according to the order of samples (a)–(d) sequentially. For these four samples, whether the loading was 1 or 20 N, the stable friction coefficient is nearly same, but the sliding cycles of holding stable friction coefficient are different, while the cycles of holding stable friction coefficient as loading 20 N are less than as loading 1 N for same sample. The wear rate of the samples decreases according to the order of samples (a)–(d) sequentially. The SEM morphologies of the worn tracks are dependent on the intermediate layer structures and friction test conditions, the characters of the wear are rubbing, abrasive wear and delamination wear, but for samples (a) and (b) a slight adhesive wear appears as loading 20 N.

The composition depth profiles, structure and ball-on-disk frictional characteristics of aluminum alloys 2024 plasma-based ion implanted with nitrogen, titanium and nitrogen then acetylene were investigated. The layers implanted with nitrogen then with nitrogen and titanium and finally with acetylene included three zones: a top DLC (diamond-like caron) zone, a C, Ti and N coexisting intermediate zone which undergoes chemical changes forming TiC, Ti(C,N), TiN,Ti,Al)N and AlN second phases, and the bottom zone of the substrate. The micro-hardness and nano-hardness of these layers are HK7.8 GPa and 22 GPa, respectively. The layers showed loser friction coefficient and higher wear resistance. The Raman spectra for worn tracks after sliding for different numbers of cycles showed that when the loading was JN after sliding 10,000 cycles, a slight graphitization phenomenon of the DLC film is found. If the loading was 20 N. the graphitization phenomenon of the DLC film is more obvious after sliding 2000 cycles. The SEM morphologies of the wear tracks showed that when the load was 1N, after sliding 7200 cycles the wear is from rubbing and abrasive wear. When the load was 20 N, after sliding 2000 cycles, delamination wear is dominam.