锂/空气电池非贵金属催化剂研究进展

锂/空气电池理论能量密度高、体积小、质量轻、价格低、无污染,是极具应用前景的二次电池。本文首先简要介绍了锂/空气电池的基本结构、原理和种类,随后重点讨论了近年来用于锂/空气电池的非贵金属催化剂的研究进展。这些催化剂主要包括过渡金属氧化物、过渡金属氮化物、碳材料以及过渡金属大环化合物等。最后认为,材料化学、纳米技术等学科的发展以及催化机理的阐明对发展高性能的锂/空气电池非贵金属催化剂起至关重要的作用。

以聚磷腈为电解质的锂/空气电池

以复配高氯酸锂的聚磷腈电解质涂覆锂阳极,制备了结构分别为Li|聚磷腈电解质|含水凝胶|石墨(结构①)、Li|聚磷腈电解质|蒙脱石|含水凝胶|石墨(结构②)及Li|聚磷腈电解质|蒙脱石|石墨(结构③)的锂/空气电池。结构②的电池以0.1 mA/cm2恒流放电,可放电60 h,放电比容量达400 mAh/g(以锂片计)。在放电过程中,锂表面的氧化膜先增厚,再变薄,又增厚,在放电结束时,膜厚可达一定值,其中结构②的电池的膜最薄,为0.127 mm。

锂燃料电池的研究进展

高容量电池一直是研究的热点,锂燃料电池可能会突破电池体系的能量瓶颈。理论上,锂燃料电池的比能量高达11 140 W h/kg,高出现有商品电池体系1～2个数量级。但目前仍有不少问题需要解决,如寻找适用的电解质和空气电极。根据所用电解质的不同,将锂燃料电池分为三类:水溶性电解质电池、有机电解质电池和多相电解质电池。分别讨论了它们的优缺点和需要解决的难题,并综述了其研究进展。

α-MnO_2 nanoneedle-based hollow microspheres coated with Pd nanoparticles as a novel catalyst for rechargeable lithium-air batteries

The hollow α-MnO2 nanoneedle-based microspheres coated with Pd nanoparticles were reported as a novel catalyst for rechargeable lithium-air batteries. The hollow microspheres are composed ofα-MnO2 nanoneedles. Pd nanoparticles are deposited on the hollow microspheres through an aqueous-solution reduction of PdCl2 with NaBH4 at room temperature. The results of TEM, XRD, and EDS show that the Pd nanoparticles are coated on the surface ofα-MnO2 nanoneedles uniformly and the mass fraction of Pd in the Pd-coated α-MnO2 catalyst is about 8.88%. Compared with the counterpart of the hollow α-MnO2 catalyst, the hollow Pd-coated α-MnO2 catalyst improves the energy conversion efficiency and the charge-discharge cycling performance of the air electrode. The initial specific discharge capacity of an air electrode composed of Super P carbon and the as-prepared Pd-coatedα-MnO2 catalyst is 1220 mA＆#183;h/g （based on the total electrode mass） at a current density of 0.1 mA/cm2, and the capacity retention rate is about 47.3% after 13 charge-discharge cycles. The results of charge-discharge cycling tests demonstrate that this novel Pd-coatedα-MnO2 catalyst with a hierarchical core-shell structure is a promising catalyst for the lithium-air battery.

Effect of Magnetic Field on Properties of AuPt Particles Magneto- electrodeposited on Carbon Paper

AuPt nano particles are bi-functional catalysts for Oxygen Reduction Reaction （ORR） and Oxygen Evolution Reaction （OER） that were taken place on air electrodes in lithium air batteries. Magnetic field has been applied during electrodeposition for the preparation of AuPt particles. With the increase of the magnetic flux density under constant current density, the grain size decreases from - 1μm to 200nm and the activity of the AuPt catalyst increases. The magnetic field oriented vertical to the electric field has a promotion effect on increasing the catalytic ability of AuPt/carbon electrode. By pulse plating, the grain size decreases to about 100nm. By adjusting parameters of the electric field and the magnetic field, controllable in-situ preparation of AuPt catalyst with various morphology and catalytic activity could be achieved.

Amorphous CoSnO_3@rGO nanocomposite as an efficient cathode catalyst for long-life Li-O_2 batteries

An amorphous CoSnO3@rGO nanocomposite fabricated using a surfactant‐assisted assembly method combined with thermal treatment served as a catalyst for non‐aqueous lithium‐oxygen(Li‐O2)batteries.In contrast to the specific surface area of the bare CoSnO3 nanoboxes(104.3 m2 g–1),the specific surface area of the CoSnO3@rGO nanocomposite increased to approximately 195.8 m2 g–1 and the electronic conductivity also improved.The increased specific surface area provided more space for the deposition of Li2O2,while the improved electronic conductivity accelerated the decomposition of Li2O2.Compared to bare CoSnO3,the overpotential reduced by approximately 20 and 60 mV at current densities of 100 and 500 mA g?1 when CoSnO3@rGO was used as the catalyst.A Li‐O2 battery using a CoSnO3@rGO nanocomposite as the cathode catalyst cycled indicated a superior cyclic stability of approximately 130 cycles at a current density of 200 mA g–1 with a limited capacity of 1000 mAh g–1,which is 25 cycles more than that of the bare amorphous CoSnO3 nanoboxes.

Solvation structure and dynamics of Li and LiO_(2)and their transformation in non-aqueous organic electrolyte solvents from first-principles simulations

Density functional theory calculations together with ab initio molecular dynamics(AIMD)simulations have been used to study the solvation,diffusion and transformation of Li^(+)and LiO_(2)upon O_(2)reduction in three organic electrolytes.These processes are critical for the performance of Li-air batteries.Apart from studying the structure of the solvation shells in detail,AIMD simulations have been used to derive the diffusivity and together with the Blue Moon ensemble approach to explore LiO_(2)formation from Li^(+)and O_(2)−and the subsequent disproportionation of 2LiO_(2)into Li_(2)O_(2)+O_(2).By comparing the results of the simulations to gas phase calculations,the impact of electrolytes on these reactions is assessed which turns out to be more pronounced for the ionic species involved in these reactions.