多孔Co_(3)O_(4)纳米纤维用于锂-空气电池高性能正极催化剂

Porous Co_(3)O_(4)nanofibers applied as an efficient cathode catalyst for Li-air batteries

采用静电纺丝技术结合高温煅烧方法,以乙酰丙酮钴(Co(C5H7O2)3)为前驱物,制备了由Co_(3)O_(4)纳米颗粒组成的多孔纳米纤维(Co_(3)O_(4)NFs),其比表面积高达83 m^(2)·g^(−1),并将制得的多孔Co_(3)O_(4)NFs用于锂-空气电池催化剂。多孔Co_(3)O_(4)NFs为电池反应提供了充足的活性位点及反应物的传输通道,有利于电池反应的顺利进行,使电池的放电容量得到极大地提高。另外,Co_(3)O_(4)催化剂的加入提高了电极的催化活性,较大程度降低了电池的过电位。值得注意的是,Co_(3)O_(4)催化剂的加入同时调控了锂-空气电池放电产物Li_(2)O_(2)的形貌,得到的放电产物Li_(2)O_(2)尺寸更小,在电极表面分布更为均匀,该形态的Li_(2)O_(2)在充电过程中更容易被分解,有利于提高电池的充电效率,同时电极的体积效应也可得到极大缓解。得益于以上优势,基于多孔Co_(3)O_(4)NFs/炭黑Super P(Co_(3)O_(4)NFs/SP)正极的锂-空气电池的电化学性能得到较大提高,50 mA·g^(−1)电流密度下Co_(3)O_(4)NFs/SP的放电容量高达10600 mA·h·g^(−1),电池可实现100次的充放电循环。

Porous Co_(3)O_(4)nanofibers(Co_(3)O_(4)NFs)composed with nanoparticles were fabricated by combining electrostatic spinning with subsequent calcination technology adopting Co(C5H7O2)3 as the precursor.The prepared porous Co_(3)O_(4)NFs with specific surface area is up to 83 m^(2)·g^(−1),which can be successfully used as an efficient catalyst in Li-air battery.Porous Co_(3)O_(4)NFs provide sufficient active sites and transport channels for the battery reaction,which is favorable for the battery reaction and greatly improves the discharge capacity of the battery.In addition,the addition of Co_(3)O_(4)catalyst also greatly promotes the catalytic activity of the cathode and reduces the over-potential of the Li-air battery.Significantly,with the addition of Co_(3)O_(4)catalyst,the morphology of discharge product Li_(2)O_(2)can also be regulated.Li_(2)O_(2)with smaller size are uniformly distributed on the surface of cathode,which is more likely to be decomposed during the subsequent charging process.Additionally,the volume effect of the electrode is greatly alleviated.Because of the above-mentioned advantages,the electrochemical performances of porous Co_(3)O_(4)NFs/Super P carbon(Co_(3)O_(4)NFs/SP)-based Li-air battery have been greatly improved.The discharge capacity of Co_(3)O_(4)NFs/SP is up to 10600 mA·h·g^(−1)at the current density of 50 mA·g^(−1),and 100 continuous dischargecharge cycles can be achieved.