Dual-functional 3D carbon fibers decorated with Co nanoparticles and Co-Nx sites for rechargeable aprotic Li-O2 batteries
Dual-functional 3D carbon fibers decorated with Co nanoparticles and Co-Nx sites for rechargeable aprotic Li-O2 batteries
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DOI：
10.1039/d2nj00970f
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发表时间：
2022-05-10
影响因子：
3.3
通讯作者：
Xin, Xing
中科院分区：
文献类型：
--
作者：
He, Lingyan;Shi, Kaiyuan;Xin, Xing
在所有现有的可充电电池系统中，质子惰性Li-O-2电池具有极高的理论能量密度。因此，它们被认为是最有潜力的下一代储能设备之一。然而，在正极侧的锂（Li）枝晶和在负极侧的缓慢的氧还原反应（ORR）和析氧反应（OER）动力学极大地限制了Li-O-2电池的实际应用。因此，我们提出了一种双功能的碳纳米纤维骨架，在其上修饰Co纳米颗粒和Co-N-x位，以改善Li-O-2电池的正极和负极的电化学行为。Co纳米颗粒和Co-N-x中心的协同作用可以将碳纤维从疏锂转变为亲锂，这有利于降低锂金属阳极处的极化和缓和枝晶的形成。此外，Co纳米颗粒和Co-N-x位作为活性位可以促进阴极侧的ORR和OER过程（尤其是OER过程）。相应地，由Co/CNF-750阴极和Co/CNF-750夹层改性的Li金属阳极组成的Li-O-2电池显示出1.004V的低放电-充电间隙和在500 mA·h·g（-1）的限制容量下在200 mA·g（-1）的160次循环的长循环寿命。本工作为锂氧电池的应用提供了一种有效的同时处理氧阴极和锂阳极势垒的策略。
Aprotic Li-O-2 batteries possess extremely high theoretical energy density among all existing rechargeable battery systems. Thus, they are considered one of the most potential next-generation energy storage devices. Nevertheless, the lithium (Li) dendrites at the anodic side and the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics at the cathodic side of Li-O-2 batteries greatly limit their practical applications. Herein, we put forward a dual-functional carbon nanofibrous skeleton decorated with Co nanoparticles and Co-N-x sites to ameliorate the electrochemical behavior of both anode and cathode in Li-O-2 batteries. The synergistic effect of Co nanoparticles and Co-N-x sites could convert carbon fibers from lithiophobic to lithiophilic, which is beneficial to decrease polarization and moderate the dendritic formation at the Li metal anode. Moreover, Co nanoparticles and Co-N-x sites as active sites can promote the ORR and OER processes (especially the OER process) at the cathodic side. Accordingly, Li-O-2 batteries composed of Co/CNF-750 cathodes and Co/CNF-750 interlayer-modified Li metal anodes displayed a low discharge-charge gap of 1.004 V and long cycle life of 160 cycles under a limited capacity of 500 mA h g(-1) at a current density of 200 mA g(-1). This work offers an effective strategy to simultaneously deal with barriers both in the O-2 cathode and Li anode for the application of Li-O-2 batteries.