中文摘要：

利用 NaBH4溶液还原 PdCl2的方法在具有纳米刺状表面的α-MnO2中空微球上沉积 Pd，制备一种α-MnO2/Pd 核壳型复合催化剂作为新一代可充锂-空气电池的催化剂。TEM、XRD 和 EDS 等方法的分析结果表明，在催化剂中纳米Pd颗粒均匀地分布在刺状α-MnO2中空微球表面，Pd在催化剂中的质量分数约为8.88%。充放电测试结果表明，与纳米刺状的α-MnO2中空微球催化剂相比，α-MnO2/Pd 复合催化剂提高了空气电极的能量转化效率和充放电循环性能。由 Super P 碳材料和所制备的α-MnO2/Pd 复合催化剂所构成的空气电极在0.1 mA/cm2电流密度下的首次放电比容量可以达1220 mA＆#183;h/g，经13次充放电循环后的容量保持率为47.3%。该纳米刺状α-MnO2/Pd核壳型复合催化剂是一种有前途的空气电池催化剂。

英文摘要：

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.