Xueliang Li

Efficient and stable perovskite solar cells based on functional graphene-modified P3HT hole-transporting layer

Organic–inorganic perovskite solar cells have recently emerged at the forefront of photovoltaics research. With the focus mainly on efficiency, the aspect of mobility and stability has so far not been thoroughly addressed. In this paper, we identify mobility as a fundamental weak point of perovskite solar cells, and demonstrate a facile approach to enhance the hole mobility and conductivity by introducing the highly dispersed graphene in P3HT as the hole transporting layer. With this composite structure, we achieve power conversion efficiencies of up to 13.82%. Moreover, we observe excellent stability based on the P3HT/graphene layer due to its good hydrophobicity.

CuS quantum dot modified carbon aerogel as an immobilizer for lithium polysulfides for high-performance lithium–sulfur batteries

CuS quantum dot (QD) modified carbon aerogels were successfully prepared via a facile and scalable method to encapsulate sulfur and polysulfides into the hierarchical porous channel of lithium–sulfur batteries. The surface morphologies and microstructures of the CuS QD modified composites and their electrochemical performances are investigated in detail. The modified 3D interconnected porous CA with excellent conductivity and high specific surface can effectively facilitate electron and ion transfer. The well-distributed CuS QDs further provide abundant active adsorption sites to anchor sulfur particles and polysulfides. As a result of the synergistic effect of CuS QD and hierarchical mesoporous carbon, the composite delivers a high initial capacity of 1318 mA h g−1 at a current rate of 0.2C and retains 1073 mA h g−1 after 100 cycles. Furthermore, the high conductive CuS QD modified composite provides a stabilized capacity of over 840 mA h g−1 for over 500 cycles with only 0.05% decay per cycle at 0.5C.

An ultrafine V2O3 modified hierarchical porous carbon microsphere as a high performance cathode matrix for lithium–sulfur batteries

An ultrafine V2O3 modified carbon microsphere (VCM) was effectively prepared by a facile wet impregnation method and used as a cathode matrix for lithium–sulfur batteries. This resulting composite presents hierarchical porous frameworks of mesopores together with micropores, effectively restrains soluble polysulfides and enhances mass transport. Moreover, V2O3 modification in this mono-dispersed microsphere material can trap polysulfides and mitigate loss of active materials by chemical adsorption. The S/VCM nanocomposites show a high initial discharge capacity of 1177 mA h g−1 at 0.5C and an excellent cycling performance with 921 mA h g−1 after 100 cycles. And it still maintains higher rate capacities of 843 and 719 mA h g−1 at 1C and 2C, respectively, after 100 cycles. These improved electrochemical performances are attributed to the synergistic effects of hierarchical pores and uniformly dispersed vanadium trioxide.

Carbon nitride based mesoporous materials as cathode matrix for high performance lithium–sulfur batteries

A facile silica template nanocasting method was adopted to effectively synthesize mesoporous carbon nitride (MCN) based materials as cathode matrixes for advanced lithium/sulfur (Li/S) batteries. The materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The MCN/S composite cathode displays excellent electrochemical performance with initial discharge capacities of 1284.5 and 1107.1 mA h g−1 for 66.7 wt% active material at 0.1 and 0.5C, respectively. And it presents good rate performance and stability with remaining discharge capacity of 828.4 mA h g−1 after 100 cycles at 0.5C. The excellent performances are mainly attributed to the crosslink mesoporous structure and the strong chemical interaction between sulfur and carbon–nitrogen framework, which not only can provide polysulfides reservoirs and transport channels for the transportation of ions and electrons within MCN/S, but also is beneficial to restrain polysulfides migration.

In situ synthesis of porous SnO2 nanospheres/graphene composite with enhanced electrochemical performance

A large diameter porous SnO2 nanospheres/graphene composite (p-SNG) was synthesized by a one-pot in situ hydrothermal method for the first time. XRD studies and FE-SEM, TEM images indicate that the porous SnO2 nanospheres with diameters of about 200 nm are distributed on the graphene nanosheets (GNS) uniformly. In comparison with the bare SnO2 nanospheres, the as-synthesized p-SNG exhibited enhanced initial charge and discharge capacity, superior cycle performance and rate performance. Electrochemical measurements demonstrated that the p-SNG composite delivered a reversible discharge capacity of 921.5 mA h g−1 at a current density of 400 mA g−1 after 50 cycles and a rate performance of 802.9 mA h g−1 at a high current density of 1600 mA g−1.