Ultrathin dual phase nanosheets consisting of alternating spinel Li4Ti5O12 (LTO) and rutile TiO2 (RT) lamellas are synthesized through a facile and scalable hydrothermal method, and the formation mechanism is explored. The thickness of constituent lamellas can be controlled exactly by adjusting the mole ratio of Li:Ti in the original reactants. Alternating insertion of the RT lamellas significantly improves the electrochemical performance of LTO nanosheets, especially at high charge/discharge rates. As anodes in lithium-ion batteries (LIBs), the dual phase nanosheet electrode with the optimized phase ratio can deliver stable discharge capacities of 178.5, 154.9, 148.4, 142.3, 138.2, and 131.4 mA h g–1 at current densities of 1, 10, 20, 30, 40, and 50 C, respectively. Meanwhile, they inherit the excellent cyclic stability of pure spinel LTO and exhibit a capacity retention of 93.1% even after 500 cycles at 50 C. Our results indicate that the alternating nanoscaled lamella structure is a good alternative to facilitate the transfer of both the Li ions and electrons into the spinel LTO, giving rise to an excellent cyclability and fast rate performance. Therefore, the newly prepared carbon-free LTO-RT nanosheets with high safety provide a new opportunity to develop high-power anodes for LIBs.Keywords: dual phase; hydrothermal method; lithium titanate; lithium-ion batteries; rutile titanium oxide;

Hierarchical porous architectures assembled by ultrathin mesoporous nanosheets are attractive for electrochemical energy storage. Herein, we present a facile and scalable strategy where two ultrathin mesoporous NiCoO2 sheets (∼2 nm) are anchored on both sides of a rGO sheet to form an ultrathin sandwich nanosheet (∼6 nm) using a chemical co-precipitation method. The sandwich nanosheets are randomly wrinkled, thus the framework built up by such sheets is porous and has a high specific surface area. The high quality rGO endows the composite with excellent conductivity. And the firm adhesion between the NiCoO2 sheet and flexible rGO also guarantees the integration of the electrode during electrochemical cycling. The electrochemical tests on the electrode made by such ultrathin sandwich nanosheets validate that the strategy is effective to obtain high performance electrodes for supercapacitors and lithium ion batteries. As an electrode of a lithium ion battery, it shows excellent cycling performance with a specific capacity close to 998 mA h g−1 at a current density of 0.1 A g−1; and as an electrode of a supercapacitor, capacitance retention of 87.6% is achieved over 2000 cycles at a constant current density of 20 A g−1.

A new smelting method to synthesize high-nitrogen nickel-free austenitic stainless steel was suggested. The synthesized steel completely consists of austenite and represents more brilliant anti-corrosion ability both in salt solution and sulfuric acid solution. The brilliant anti-corrosion ability is retained even after severe cold-rolling deformation, which ensures its workability in practice. The potentiodynamic polarization curves, electrochemical impedance spectroscopy, and passivating treatment were used to characterize its corrosion properties and uncover its corrosion mechanism in salt solution. X-ray photoelectron spectroscopy was used to clarify the mechanism of passivation. The results demonstrate that the steel has a more uniform and thicker passive film than traditional stainless steel due to the cooperation of nitrogen and chromium.

Recently, hydroxyl-carbonates have drawn increasing interest in energy storage because of their special layered structure and pseudocapacitive character. In this work, a novel open architecture based on reduced graphene oxide and ultra-fine single-crystal Co2(CO3)(OH)2 nanowires (designed as rGO/Co2(CO3)(OH)2) is synthesized via mutual electrostatic interactions benefiting from their intrinsic opposite charges. Taking advantage of the high conductivity of rGO, the ultra-fine diameter of the nanowires, and the open network of the architecture, the rGO/Co2(CO3)(OH)2 electrode exhibits high specific capacitance (998 F g−1 at 1 A g−1 and 727 F g−1 at 20 A g−1) with excellent rate capability and stability (98.3% capacitance retention after 4000 cycles). An asymmetric supercapacitor fabricated by using it as the positive electrode and activated carbon as the negative electrode has demonstrated high energy/power density (26.7 W h kg−1 at 751 W kg−1 and 13.1 W h kg−1 at 15362 W kg−1) and outstanding cycle stability (10000 times with only 5.4% loss).

Hierarchical porous architectures assembled by ultrathin mesoporous nanosheets are attractive for electrochemical energy storage. Herein, we present a facile and scalable strategy where two ultrathin mesoporous NiCoO2 sheets (∼2 nm) are anchored on both sides of a rGO sheet to form an ultrathin sandwich nanosheet (∼6 nm) using a chemical co-precipitation method. The sandwich nanosheets are randomly wrinkled, thus the framework built up by such sheets is porous and has a high specific surface area. The high quality rGO endows the composite with excellent conductivity. And the firm adhesion between the NiCoO2 sheet and flexible rGO also guarantees the integration of the electrode during electrochemical cycling. The electrochemical tests on the electrode made by such ultrathin sandwich nanosheets validate that the strategy is effective to obtain high performance electrodes for supercapacitors and lithium ion batteries. As an electrode of a lithium ion battery, it shows excellent cycling performance with a specific capacity close to 998 mA h g−1 at a current density of 0.1 A g−1; and as an electrode of a supercapacitor, capacitance retention of 87.6% is achieved over 2000 cycles at a constant current density of 20 A g−1.