A Co‐Doped MnO₂ Catalyst for Li‐CO₂ Batteries with Low Overpotential and Ultrahigh Cyclability

Abstract

energy density and good cycle stability is believed as a promising strategy to solve this issue. For example, Li-CO 2 batteries which have been developed on the basis of Li-O 2 batteries have recently attracted attention. This battery system not only offers a high energy density for electrochemical energy storage but also alleviates the greenhouse effect by capturing CO 2 . [5] More recently, Li-CO 2 batteries have been attempted as new energy carriers to store renewable energy, in which Li 2 CO 3 is the main discharge product: 4Li + 3CO 2 + 4e − ↔ 2Li 2 CO 3 + C (E 0 = 2.80 V vs Li/Li). [6][7][8] Unfortunately, this incipient prototype battery can only run about ten cycles. The main bottlenecks are related to two aspects. First, the insert decomposition of Li 2 CO 3 discharge product is prone to adhere on the cathode surface, and then remarkably reduces the capacity. [8] Second, the aggregation of Li 2 CO 3 product will block the channels of gas diffusion and reduce the conductivity of electrode, resulting in a very high charge potential (>4.3 V). [6] In this regard, a cathode with a high surface area which could promote the reversibility of the Li 2 CO 3 discharge product is desirable to accelerate the practical applications of Li-CO 2 batteries. [9] Akin to the development of Li-O 2 batteries, there are two approaches to improve the electrochemical properties of the cathodes. On the one hand, the direct optimization of cathode structures has been regarded as a simple method to improve the properties of Li-CO 2 batteries. For instance, Zhou et al. [10,11] successfully examine graphene and carbon nanotubes (CNTs) as the cathodes, in which Li-CO 2 batteries operate for 20 cycles with an overpotential of 1.78 V at 50 mA g −1 under a limitative capacity of 1000 mA h g −1 . Dai et al. [12] design two graphenebased materials with defective structures for Li-CO 2 batteriesholey graphene and B,N-co-doped holey graphene, which show a cycling lifetime of over 200 cycles at 1 A g −1 , but suffer from a large overpotential (about 1.8 V at 1 A g −1 ). Liu et al. [13] first introduce CNTs which decorated with RuO 2 as cathode materials for Li-CO 2 batteries, which can deliver a high specific capacity together with a lower overpotential.On the other hand, the development of new catalysts is another effective method to enhance the electrochemical properties of Li-CO 2 batteries. For example, the cobalt-titanium-layered oxide-RuO 2 composite with a low over-potential of 0.6 V has Li-CO 2 batteries can not only capture CO 2 to solve the greenhouse effect but also serve as next-generation energy storage devices on the merits of economical, environmentally-friendly, and sustainable aspects. However, these batteries are suffering from two main drawbacks: high overpotential and poor cyclability, severely postponing the acceleration of their applications. Herein, a new Co-doped alpha-MnO 2 nanowire catalyst is prepared for rechargeable Li-CO 2 batteries, which exhibits a high capacity (8160 mA h g −1 at a current density of 100 mA g ...

Correlating Catalyst Design and Discharged Product to Reduce Overpotential in Li‐CO2 Batteries

“…Ge et al reported on Co-doped α-MnO 2 nanowires used as catalysts for Li-CO 2 batteries. [13] α-MnO 2 interstitial sites were successfully doped with Co, whose concentration directly impacted electronic conductivity where the bandgap was shortened and an impurity band was formed in α-MnO 2 . Enhanced electrical transport and optimized hierarchical channel structures enable Co-doped α-MnO 2 catalysts to exhibit a high capacity of 8160 mA h g −1 , a low overpotential of about 0.73 V, and long cycle life of >500 cycles at 100 mA g −1 .…”

Advanced Electron Energy Loss Spectroscopy for Battery Studies

“…For the Lirich layered cathodes, EELS has been applied to investigate the injection of the oxygen vacancies into the bulk lattice, which is responsible for the layered-to-spinel phase transformation. [53b] Ex situ EELS has also been utilized to identify the transition products in the charge-discharge process of the metal-gas batteries, such as the Li-O 2 , [55] Li-CO 2 , [56] Na-CO 2 , [57] Li-CO 2 / O 2 , [58] Na-O 2 , [59] Na-N 2 , [60] etc. Combing the environmental TEM and the probe-type electrochemical solid-state open cell, Huang and co-workers conducted the first in situ TEM/EELS study of a Na-O 2 battery (Figure 6b).…”

Recent Advances in Lithium–Carbon Dioxide Batteries

“…The superior performance of the Co/α-MnO 2 composite was ascribed to the Co interstitial doping (Figure 11b) and highly conductive hierarchical channels of the MnO 2 NW network. [105] A CNT-supported MnO 2 composite has also been demonstrated as an efficient cathode catalyst in Li-CO 2 cells. [106] The electrochemical performance of Li-CO 2 cells with the MnO 2 /CNT catalyst is comparable with other types of Mn-based catalysts.…”