Using Hemoglobin as a Performance Enhancer in Rechargeable Lithium–Oxygen Batteries

Abstract

We demonstrate here that hemoglobin, a biological oxygen binder/transporter, can be used as a performance-enhancing additive in nonaqueous lithium–oxygen batteries. In a fashion similar to the way hemoglobin binds and transports oxygen in the human blood, it can bind and transport oxygen in the electrolyte solution in a conventional lithium–oxygen battery. Binding and transport of oxygen into the soluble electrolyte phase enhance the efficiency of oxygen reduction reactions (ORRs) occurring at the air cathode by preventing the accumulation of solid insulating discharge products at the cathode site. We observe stable galvanostatic cycling, high specific capacity, and low polarization in the cell in the presence of hemoglobin. Electrochemical impedance spectroscopy indicates low interfacial resistance even after several rounds of galvanostatic charge–discharge cycles. We thus propose the use of oxygen-binding natural biomolecules as possible redox mediators for energy-harvesting systems utilizing oxygen electrochemistry in the future.

Using a Heme‐Based Nanozyme as Bifunctional Redox Mediator for Li−O2 Batteries

“…However, there is almost no promotion in specific capacity and discharge/charge voltage gap during deep‐discharge operation in polydopamine or cerium triflate‐involved systems . Moreover, as for hemoglobin or heme, natural enzymes possess intrinsic limitations of poor stability, high cost and sensitivity to harsh environments …”

“…One the one hand, the aggressive superoxide radicals are scavenged by Zn‐TCPP(Fe) nanozymes efficiently, which is beneficial for the enhanced stability of electrolyte and cathode during the battery operation. On the other hand, the Zn‐TCPP(Fe) nanozymes can act as superoxide and electron carriers between the cathode and Li 2 O 2 , serving as effective ORR/OER redox mediators in Li‐O 2 batteries .…”

“…By contrast, soluble catalysts dissolved in electrolyte have been introduced as more fascinating candidates, which present superior performance owning to the sufficient contact area between liquid additives and solid products and their high utilization efficiency . In particular, some electrolyte additives have been reported to serve as superoxide radical scavengers in Li‐O 2 batteries, such as polydopamine, cerium triflate, hemoglobin and so on . As residual superoxide radicals are scavenged, the deposition of irreversible byproducts is alleviated and improved cycling stability is achieved.…”

“…[12,13] Moreover, as for hemoglobin or heme, natural enzymes possess intrinsic limitations of poor stability, high cost and sensitivity to harsh environments. [14,16] Nanomaterials with enzyme-like catalytic activities, known as nanozymes, can be used as stable and durable mimics to natural enzymes with highly catalytic activity. [17] Zhang's group has synthesized a series of archetypical metal-organic framework (MOF) nanosheets with intrinsic heme-like active sites to mimic peroxidases, which exhibit higher peroxide sensitivity compared with natural heme proteins.…”

“…[16] Subsequently, Bhattacharyya et al have revealed that heme is not a suitable redox mediator with lesser stability during cycling in LiÀ O 2 batteries. [14] In particular, the Zn-TCPP(Fe) nanozymes composed of heme-like ligands, possess characteristics of highly catalytic activity and superior robustness. [19] The specific reaction mechanism of LiÀ O 2 batteries with Zn-TCPP (Fe) nanozymes can be summarized in Equations (1)-(7):…”