Simple and Effective Gas-Phase Doping for Lithium Metal Protection in Lithium Metal Batteries

Increasing demands for advanced lithium batteries with higher energy density have resurrected the use of lithium metal as an anode, whose practical implementation has still been restricted, because of its intrinsic problems originating from the high reactivity of elemental lithium metal. Herein, we explore a facile strategy of doping gas phase into electrolyte to stabilize lithium metal and suppress the selective lithium growth through the formation of stable and homogeneous solid electrolyte interphase (SEI) layer. We find that the sulfur dioxide gas additive doped in electrolyte significantly improves both chemical and electrochemical stability of lithium metal electrodes. It is demonstrated that the cycle stability of the lithium cells can be remarkably prolonged, because of the compact and homogeneous SEI layers consisting of Li–S–O reduction products formed on the lithium metal surface. Simulations on the lithium metal growth process suggested the homogeneity of the protective layer induced by the gas-phase doping is attributable for the effective prevention of the selective growth of lithium metal. This study introduces a new simple approach to stabilize the lithium metal electrode with gas-phase doping, where the SEI layer can be rationally tunable by the composition of gas phase

Roll-to-Roll Laser-Printed Graphene–Graphitic Carbon Electrodes for High-Performance Supercapacitors

Carbon electrodes including graphene and thin graphite films have been utilized for various energy and sensor applications, where the patterning of electrodes is essentially included. Laser scribing in a DVD writer and inkjet printing were used to pattern the graphene-like materials, but the size and speed of fabrication has been limited for practical applications. In this work, we devise a simple strategy to use conventional laser-printer toner materials as precursors for graphitic carbon electrodes. The toner was laser-printed on metal foils, followed by thermal annealing in hydrogen environment, finally resulting in the patterned thin graphitic carbon or graphene electrodes for supercapacitors. The electrochemical cells made of the graphene–graphitic carbon electrodes show remarkably higher energy and power performance compared to conventional supercapacitors. Furthermore, considering the simplicity and scalability of roll-to-roll (R2R) electrode patterning processes, the proposed method would enable cheaper and larger-scale synthesis and patterning of graphene–graphitic carbon electrodes for various energy applications in the future

High-Energy and Long-Lasting Organic Electrode for a Rechargeable Aqueous Battery

Redox-active organic materials (ROMs) hold great promise as potential electrode materials for eco-friendly, cost-effective, and sustainable batteries; however, the poor cycle stability arising from the chronic dissolution issue of the ROMs in generic battery systems has impeded their practical employment. Herein, we present that a rational selection of electrolytes considering the solubility tendency can unlock the hidden full redox capability of the DMPZ electrode (i.e., 5,10-dihydro-5,10-dimethylphenazine) with unprecedentedly high reversibility. It is demonstrated that a multiredox activity of DMPZ/DMPZ+/DMPZ2+, which has been previously regarded to degrade with repeated cycles, in the newly designed electrolyte can be utilized with surprisingly robust cycle stability over 1000 cycles at 1C. This work signifies that tailoring the electrode–electrolyte compatibility can possibly unleash the hidden potential of many common ROMs, catalyzing the rediscovery of organic electrodes with long-lasting and high energy density

Tuning the Carbon Crystallinity for Highly Stable Li–O₂ Batteries

The Li–O₂ battery is capable of delivering the highest energy density among currently known battery chemistries and is thus regarded as one of the most promising candidates for emerging high-energy-density applications such as electric vehicles. Although much progress has been made in the past decade in understanding the reaction chemistry of this battery system, many issues must be resolved regarding the active components, including the air electrode and electrolyte, to overcome the presently insufficient cycle life. In this work, we demonstrate that the degradation kinetics of both the air electrode and electrolyte during cycles can be significantly retarded through control of the crystallinity of the carbon electrode, the most frequently used air electrode in current Li–O₂ batteries. Using ¹³C-based air electrodes with various degrees of graphitic crystallinity and in situ differential electrochemical mass spectroscopy analysis, it is demonstrated that, as the crystallinity increases in the carbon, the CO₂ evolution from the cell is significantly reduced, which leads to a 3-fold enhancement in the cyclic stability of the cell