Pseudocapacitive Lithium Storage in Three‐Dimensional Cobalt‐Doped MnO/Nitrogen‐Doped Reduced Graphene Oxide Aerogels as High‐Rate Anode Material

Abstract

Structural design and modification are effective measures to improve the lithium storage performance of electrode materials. Herein, three‐dimensional (3D) porous Co‐doped MnO/nitrogen‐doped reduced graphene oxide aerogels (Co−MnO/NG‐G) have been prepared by successive self‐assembly processes, including the self‐assembly nucleation of Co−MnO on GO in H2O/N,N‐Dimethylformamide (DMF) mixed solvent, and the 3D reduction‐assembly of hydrogels accompanied with nucleation‐inducing growth of Co−MnO nanocrystals. Due to high‐efficient electron/ion transport channels dating from the novel 3D porous microstructure and improved electron/ion conductivity deriving from doping MnO with Co, the 3D Co−MnO/NG‐G electrode demonstrates high pseudocapacitive lithium storage behavior with 88.3 % at 2 mV s−1. As an anode in lithium‐ion battery, the 3D Co−MnO/NG‐G shows a high capacity of 982.8 mAh g−1 at 0.5 A g−1 after 100 cycles, outstanding rate capability with 424.0 mAh g−1 at 8 A g−1, as well as superior cycle stability with 508.9 mAh g−1 after 800 cycles at 4 A g−1. This work demonstrates that the synergistic strategy between cation doping and 3D porous channels for electron/ion transport is an effective way to design high‐rate anode materials.

Self‐Assembled Three‐Dimensional Graphene Aerogel with an Interconnected Porous Structure for Lithium‐Ion Batteries

“…The Li + diffusion coefficients (D) of 3DGA and GP can be obtained from the following formula [Eq. (1)]: [61] D ¼ 0:5 ðRT=An 2 F 2 s w CÞ 2 (1)…”

“…[4] Intensive investigations have been conducted to solve the above issue. Carbon-based materials such as carbon nanofibers, [5][6][7][8] carbon nanotubes, [9,10] and graphene [2,[11][12][13][14] have obtained growing attention owing to their excellent electronic conductivities. In comparison with other investigated carbon materials, graphene is a more promising material for LIBs owing to its fast charge transfer kinetics, high specific surface area, good mechanical property and excellent thermodynamic stability.…”

“…Lithium‐ion batteries (LIBs) as power sources are highly demanded in electric vehicles, large‐scale energy storage systems and portable electronic products in virtue of large energy density, long cycle life and environmental benignity . However, the relatively slow diffusion and intercalation of lithium ions limit the power densities of LIBs, and the low electronic conductivities of electrode materials also directly decrease the charge transfer rate, thus restricting the performance of large current charging and discharging .…”

Rational design of 3D net-like carbon based Mn3O4 anode materials with enhanced lithium storage performance

“…At the low frequency, the more vertical straight line of the Mn 3 O 4 /CP composite than that of the pure Mn 3 O 4 , indicates the faster Li + diffusion rate in the Mn 3 O 4 /CP electrodes. 61 The corresponding fitted electric circuit is shown in Fig. 6e.…”