Promoting the Performance of Li–CO2 Batteries via Constructing Three-Dimensional Interconnected K+ Doped MnO2 Nanowires Networks

Abstract

Nowadays, Li–CO2 batteries have attracted enormous interests due to their high energy density for integrated energy storage and conversion devices, superiorities of capturing and converting CO2. Nevertheless, the actual application of Li–CO2 batteries is hindered attributed to excessive overpotential and poor lifespan. In the past decades, catalysts have been employed in the Li–CO2 batteries and been demonstrated to reduce the decomposition potential of the as-formed Li2CO3 during charge process with high efficiency. However, as a representative of promising catalysts, the high costs of noble metals limit the further development, which gives rise to the exploration of catalysts with high efficiency and low cost. In this work, we prepared a K+ doped MnO2 nanowires networks with three-dimensional interconnections (3D KMO NWs) catalyst through a simple hydrothermal method. The interconnected 3D nanowires network catalysts could accelerate the Li ions diffusion, CO2 transfer and the decomposition of discharge products Li2CO3. It is found that high content of K+ doping can promote the diffusion of ions, electrons and CO2 in the MnO2 air cathode, and promote the octahedral effect of MnO6, stabilize the structure of MnO2 hosts, and improve the catalytic activity of CO2. Therefore, it shows a high total discharge capacity of 9,043 mAh g−1, a low overpotential of 1.25 V, and a longer cycle performance.

Freestanding MXene–MnO2 Films for Li–CO2 Cathodes with Low Overpotential and Long-Term Cycling

“…Moreover, the Ti 3 C 2 –0.1MnO 2 film cathode delivers a higher discharge capacity at 100 mA g –1 , while those of MnO 2 -based cathodes are only 2757 mA h g –1 (Figure e). As summarized in Figure f, the recycling behavior of Li–CO 2 batteries with the Ti 3 C 2 –0.1MnO 2 film cathode is the best among the Mn oxide-based materials, as cathodes for Li–CO 2 battery literature surveyed. − In addition, the specific capacities of the first five turns of the Ti 3 C 2 –0.1MnO 2 film cathode catalyst for current densities of 200 and 500 mA g –1 are shown in Figure S8c,f, respectively. Figure g presents the cycling galvanostatic discharge/recharge curves of the hybrid Ti 3 C 2 –0.1MnO 2 film cathode with the fixed capacity of 1000 mA h g –1 at a current density of 100 mA g –1 , and it maintains a stable terminal discharge voltage above 2.0 V after 220 cycles.…”

Recent progress of transition metal-based catalysts as cathodes in O2/H2O-involved and pure Li–CO2batteries

“…In 2021, Tang et al synthesized K + -doped α-MnO 2 nanowires with 3D interlinked networks to enhance the adsorption of intermediates and the decomposition of Li 2 CO 3 . 82 The relatively high doping amount of K + in the primary structure of MnO 2 could induce the charge reordering of Mn 3+ /Mn 4+ and enhance the octahedral influence of MnO 6 . More importantly, the as-formed K–O bonds could stabilize the nanostructure of the MnO 2 hosts, inhibit the dissolution of active Mn monomer, and provide ion transport channels and active sites for the CO 2 RR and CO 2 ER.…”

In Situ/Operando Characterization Techniques: The Guiding Tool for the Development of Li–CO2 Battery

“…Most reports have mentioned the formation of Li 2 CO 3 on discharging the Li-CO 2 battery, establishing it as one of the main discharge products. [11,[68][69][70] Li 2 CO 3 needs to be decomposed by providing an external potential (the charging step) to recharge the battery. However, due to the thermodynamic stability of Li 2 CO 3 ((∆ f G 0 = −1132.12 kJ mol −1 )), a high potential is required for its decomposition.…”