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We introduce a “gelating-cutting” strategy to improve specific areal capacity and cycle life for Li-O 2 cathode. Conventional Li-O 2 cathode with liquid electrolyte is gelated with highly elastic crosslinked polymer and cut into 50–200 µm granules. The gaps between the packed gel granules efficiently induce oxygen to the inner part of the cathode, leading to even Li 2 O 2 growth in thick cathode. Meanwhile, the elasticity of the polymer chain helps to keep good contact between carbon and Li 2 O 2 nanoparticles, which facilitates the electron transfer and improves the cyclability. Without any catalyst, the granular gel cathode is able to run 170 cycles at a fixed capacity of 1000 mA h g carbon −1 , or maintains a specific capacity higher than 10,500 mA h g carbon −1 (12.6 mA h cm −2 ) during 11 cycles of full discharge-charge. Since good contact is the precondition to any electrochemical reaction, our strategy is a general way to enhance the performance of Li-O 2 cathodes. [ABSTRACT FROM AUTHOR]

This study reported the significant influence of Ta on hydrogen-induced cracking of pipeline steels. It was found that with decreasing TaC size, the hydrogen diffusivity of steels was decreased, as the hydrogen trapping of TaC is surface-dominant. Ta inhibited crack initiation through deep H-traps provided by small semi-coherent/incoherent TaC (<35 nm), whilst trigger cracks directly at incoherent TaC/α-Fe interfaces when TaC > ~223 nm. Moreover, Ta suppressed crack propagation as it increased effective H-trap densities, optimized crystallographic characteristics (changing the proportions of Σ3, Σ11, Σ17 and high-angle grain boundaries), and inhibited H-dislocation interaction, which was more pronounced when TaC was smaller. [Display omitted] • Ta markedly changed the HIC resistance and its influence depended on TaC size. • Ta has different functions in crack initiation and propagation of HIC. • The critical TaC size for crack initiation at the TaC/matrix interface was ~223 nm. • Ta impeded crack growth via changing crystallographic features, H traps and HELP. • The hydrogen trapping of semi/in-coherent TaC precipitates is interface-dominant. [ABSTRACT FROM AUTHOR]