A high power density electrode with ultralow carbon via direct growth of particles on graphene sheets

The application of lithium ion batteries in high power applications such as hybrid electric vehicles and electric grid systems critically requires drastic improvement in the electronic conductivity using effective materials design and strategies. Here, we demonstrate that the growth of a multi-component structure of composition LiTi2(PO4)(3) [LTP] on a reduced graphene oxide (rGO) surface via a facile synthetic strategy could achieve an ultrahigh rate capability with the total carbon content as low as 1.79 wt%. The rGO-LTP hybrid material has been prepared using a two-step approach, where the growth of TiO2 nanoparticles on the graphene oxide surface is followed by the high temperature growth of LTP on graphene sheets and simultaneous thermal reduction of graphene oxide. The LTP particles are densely packed within the ripples of rGO and form a compact, well-connected graphene network requiring no additional conductive carbon to facilitate fast electron transport from active materials to the current collector. Here, graphene not only acts as a stable conductive substrate but also helps to control the size of the formed particles. The rGO-LTP hybrid as a cathode in lithium ion batteries achieves an ultrahigh specific power of 10 000 W kg(-1) at a specific energy of 210 W h kg(-1), which corresponds to a charge and discharge time of 36 s and also retains 92% of the initial capacity after 100 cycles at a 10 C charge-discharge rate. Such an excellent performance is attributed to the multifunctional roles performed by rGO such as controlling the particle size, enhancing the electronic conductivity through a highly conductive network and rendering stability during cycling. This provides an effective design strategy for growing complex hybrid materials on graphene and engineering graphene nanosheets for advanced energy storage applications.close8

Nanocrevasse-Rich Carbon Fibers for Stable Lithium and Sodium Metal Anodes

Metallic lithium (Li) and sodium (Na) anodes have received great attention as ideal anodes to meet the needs for high energy density batteries due to their highest theoretical capacities. Although many approaches have successfully improved the performances of Li or Na metal anodes, many of these methods are difficult to scale up and thus cannot be applied in the production of batteries in practice. In this work, we introduce nanocrevasses in a carbon fiber scaffold which can facilitate the penetration of molten alkali metal into a carbon scaffold by enhancing its wettability for Li/Na metal. The resulting alkali metal/carbon composites exhibit stable long-term cycling over hundreds of cycles. The facile synthetic method is enabled for scalable production using recycled metal waste. Thus, the addition of nanocrevasses to carbon fiber as a scaffold for alkali metals can generate environmentally friendly and cost-effective composites for practical electrode applications