Exploiting Synergistic Effect by Integrating Ruthenium–Copper Nanoparticles Highly Co‐Dispersed on Graphene as Efficient Air Cathodes for Li–CO₂ Batteries

Abstract

is inevitable in Li-CO 2 batteries, [11,12] Li-CO 2 /O 2 batteries, [8,13] and even Li-air batteries. [14] Exception is that the discharge products could be different without the generation of Li 2 CO 3 under specific conditions including protected anodes and effective electrolytes. [15,16] Li 2 CO 3 decomposes to CO 2 when the potential is higher than 3.8 V versus Li/Li + . Notably, O 2 evolution is not detected, as is expected according to the decomposition reaction 2Li 2 CO 3 → 4Li + + 4 e -+ 2CO 2 + O 2 . Instead, superoxide radicals or "nascent oxygen" form during the self-decomposition of Li 2 CO 3 . [12,17] More accurate verification was performed through chemical probes, which qualitatively detected the existence of singlet oxygen ( 1 O 2 ). [18] Parasitic reactions of electrolytes and catalyst degradation were then induced by Li 2 CO 3 oxidation. [12,18] Therefore, efficient air cathodes are expected to change this situation.The introduction of metal nanoparticles could limit side reactions and promote the interaction between Li 2 CO 3 and C. [11,[19][20][21] Beyond this, metal-organic frameworks or surface modified carbon materials also brought unexpected electrochemical performance. [22,23] Therefore, catalysts play important roles in Li-CO 2 batteries. [24][25][26][27][28][29] As mentioned above, self-decomposition of Li 2 CO 3 induced a series of parasitic reactions, and further influenced the stability of catalysts during the operation of Li-CO 2 batteries. Only by clarifying the changes of catalysts in this process can we design more stable Li-CO 2 batteries. In previous reports, mono metal catalysts (Ru, Cu, Au, and Ni) exhibited outstanding activity toward Li-CO 2 batteries and revealed some changes in electrochemical processes. [19][20][21] Nevertheless, there exist shortcomings with mono metal catalysts from materials preparation to electrochemical processes. First, for example, the preparation for monodispersed Ru nanoparticles was often achieved under mild experimental conditions without the generation of stable crystal surfaces, further affecting catalytic activity in Li-CO 2 batteries. [21,30] Second, the incompatibility between the discharge products and mono metal nanomaterials might lead to severe agglomeration and dropping during long cycles. [20,31] In this work, we designed a composite of ruthenium-copper nanoparticles highly co-dispersed on graphene (Ru-Cu-G), and this composite cathode endows Li-CO 2 batteries with low overpotential and excellent cyclability through their synergistic Li-CO 2 batteries are attractive electrical energy storage devices; however, they still suffer from unsatisfactory electrochemical performance, and the kinetics of CO 2 reduction and evolution reactions must be improved significantly. Herein, a composite of ruthenium-copper nanoparticles highly co-dispersed on graphene (Ru-Cu-G) as efficient air cathodes for Li-CO 2 batteries is designed. The Li-CO 2 batteries with Ru-Cu-G cathodes exhibit ultra-low overpotential and can be operated for 100 cycles with ...

Towards a High‐Performance Lithium‐Metal Battery with Glyme Solution and an Olivine Cathode

“…2.25 g cm −3 for graphite) . Accordingly, lithium‐metal batteries with ultrahigh energy densities, including Li‐sulfur and Li‐air cells, have become a popular research topic. Analogously to graphite, meanwhile with different features and magnitude, the lithium metal anode is thermodynamically unstable in most electrolyte solutions, thereby requiring an adequate solid electrolyte interphase (SEI) layer to kinetically prevent parasitic reactions, which affect anode, electrolyte and cycling performance, and possibly limit hazardous dendritic growth .…”

Tuning electronic and composition effects in ruthenium-copper alloy nanoparticles anchored on carbon nanofibers for rechargeable Li-CO2 batteries

“…The resulting PdCu catalyst demonstrated superb round-trip efficiency of ~80% and cyclic stability for Li-O2 batteries, which is ascribed to the weak LiO2 adsorption strength caused by electron transfer from Cu to top-layer Pd atoms on the surface. More recently, the phase separated Ru-Cu nanoparticles on graphene was reported by Zhang et al for improving Li-CO2 battery performance [40]. Benefitting from synergistic effect between individual Ru and Cu nanoparticles, the Li-CO2 batteries exhibited low overpotential and long cycle life.…”

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

“…e) Cutoff voltages of the different samples under a controlled capacity of 1000 mA h g −1 at 100 mA g −1 . f) Comparison of cycle performance and charge/discharge voltage gap among Li‐CO 2 batteries reported so far …”

“…As summarized in Figure f, the cycling performance of Li‐CO 2 batteries with the Co 0.2 Mn 0.8 O 2 /CC cathode is the best among all the Li‐CO 2 batteries reported so far. Simultaneously, the overpotential of the Co 0.2 Mn 0.8 O 2 /CC cathode is the lowest (≈0.73 V), which overwhelms the majority of other catalysts …”