Nitrogen-Doped Holey Graphene for High-Performance Rechargeable Li–O₂ Batteries

Abstract

Li−air batteries represent cutting edge electrochemical energy storage devices, but their practical applications have been precluded by the high cathode cost, the low discharge/charge efficiency, and/or the short battery lifetime. Here, we developed a low-cost, but very efficient, air electrode from porous nitrogen-doped holey graphene for rechargeable nonaqueous Li−O 2 cells. The resultant Li−O 2 cell can deliver a high round-trip efficiency (85%) and a long cycling life (>100 cycles) under controlled discharge/charge depths or a high capacity of 17 000 mAh/g under the full discharge/charge condition, superior to most other carbonaceous air cathodes. The observed superb performance for the air electrode based on the nitrogen-doped holey graphene can be attributed to its efficient metal-free catalytic activity and threedimensional mass transport pathway. Therefore, this work represents a new approach to low-cost, efficient, metal-free, binder-free, and hierarchically porous air electrodes useful for energy conversion and storage from N-doped holey graphene.

Holey 2D Nanomaterials for Electrochemical Energy Storage

“…[63,64] Yet, there still remains a critical challenge in realizing complete conversion of the discharge product Li 2 O 2 with minimal overpotential on charge. The precipitation of Li 2 O 2 on the carbonaceous electrode tend to block the oxygen pathway and limit the capacity of the Li-air batteries, thus it is critically urgent to design the air electrode by both creating microporous channels for fast oxygen diffusion and generating nanoporous structure for catalyzing the LiO 2 reactions.…”

“…Shui et al doped holey graphene with nitrogen (N-HGr) via thermal annealing under NH 3 gas. [64] The authors adopted a vacuum-filtration method to fabricate the resultant N-HGr with www.advenergymat.de porous structural features (Figure 13a,b) into the hierarchically porous air electrode. Transport of three major components, including electrolyte, oxygen, and electron, has been greatly improved in the hierarchically porous electrode, and additionally the N-doping brought a plenty of active sites and improved electrical conductivity.…”

Recent Progress in Electrocatalyst for Li‐O2 Batteries

“…With years going forward, another work of typical significance is also reported from the same research group in 2016. [58] An efficient cathode with porous nitrogen-doped holey graphene is developed (Figure 3b). Benefiting from the efficient metal-free catalytic activity brought by nitrogen doping and three dimensional mass transport pathway, the resultant Li-O 2 cell can deliver a high round-trip efficiency (85%) and a long cycling life (>100 cycles) under controlled discharge/charge depths or a high capacity of 17 000 mA h g −1 under the full discharge/charge condition, superior to most other carbonaceous cathodes.…”

Carbon-Based Metal-Free Electrocatalysis for Energy Conversion, Energy Storage, and Environmental Protection

“…The introduction of N species into onion-like carbons can modify electron distributions to facilitate oxygen chemisorption, leading to enhanced ORR and OER kinetics, energy output, and recharging characteristics of Li-O 2 batteries [166]. N-doping of graphene has also been demonstrated to facilitate the nucleation of Li 2 O 2 clusters, again leading to improved electrochemical performances [9]. Li-air batteries based on N-doped CNTs with uniform distributions of nitrogen species ensure large numbers of nucleation sites and high dispersion of discharge products, enhancing discharge capacities [173].…”

“…Because of high abundance, high electrical conductivity, structure tunability at the atomic level, high selectivity, strong tolerance to acidic/alkaline conditions, and eco-friendliness [4,5], many nanostructured carbon materials have been developed as metal-free catalysts with impressive electrocatalytic performances for ORR, HER, OER, and/or CO 2 RR, key reactions involved in energy conversion/storage and environmental protection processes [3,[6][7][8][9]. The electrocatalytic performances of metal-free carbon-based catalysts were further found to be tuneable through the regulation of the nanoparticles size, macrostructures, and electrode architectures, along with the introduction of heteroatoms (doping) and defects [8,9].…”