Multi-functional integrated design of a copper foam-based cathode for high-performance lithium-oxygen batteries.

Lithium-oxygen batteries (LOBs) with extraordinarily high energy density are some of the most captivating energy storage devices. Designing an efficient catalyst system that can minimize the energy barriers and address the oxidant intermediate and side-product issues is the major challenge regarding LOBs. Herein, we have developed a new type of integrated cathode of Cu foam-supported hierarchical nanowires decorated with highly catalytic Au nanoparticles which achieves a good combination of a gas diffusion electrode and a catalyst electrode, contributing to the synchronous multiphase transport of ions, oxygen, and electrons as well as improving the cathode reaction kinetics effectively. Benefiting from such a unique hierarchical architecture, the integrated cathode delivered superior electrochemical performance, including a high discharge capacity of up to 11.5 mA h cm-2 and a small overpotential of 0.49 V at 0.1 mA cm-2, a favorable energy efficiency of 84.3% and exceptional cycling stability with nearly 1200 h at 0.1 mA cm-2 under a fixed capacity of 0.25 mA h cm-2. Furthermore, density functional theory (DFT) calculations further reveal the intrinsic direct catalytic ability to form/decompose Li2O2 during the ORR/OER process. As a consequence, this work provides an insightful investigation on the structural engineering of catalysts and holds great potential for advanced integrated cathode design for LOBs.

In Situ Monitored (N, O)-Doping of Flexible Vertical Graphene Films with High-Flux Plasma Enhanced Chemical Vapor Deposition for Remarkable Metal-Free Redox Catalysis Essential to Alkaline Zinc-Air Batteries.

Rechargeable zinc-air batteries (ZABs) have attracted great interests for emerging energy applications. Nevertheless, one of the major bottlenecks lies in the fabrication of bifunctional catalysts with high electrochemical activity, high stability, low cost, and free of precious and rare metals. Herein, a high-performance metal-free bifunctional catalyst is synthesized in a single step by regulating radicals within the recently invented high-flux plasma enhanced chemical vapor deposition (HPECVD) system equipped with in situ plasma diagnostics. Thus-derived (N, O)-doped vertical few-layer graphene film (VGNO) is of high areal population with perfect vertical orientation, tunable catalytic states, and configurations, thus enabling significantly enhanced electrochemical kinetic processes of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with reference to milestone achievements to date. Application of such VGNO to aqueous ZABs (A-ZABs) and flexible solid-state ZABs (S-ZABs) exhibited high discharge power density and excellent cycling stability, which remarkably outperformed ZABs using benchmarked precious-metal based catalysts. The current work provides a solid basis toward developing low-cost, resource-sustainable, and eco-friendly ZABs without using any metals for outstanding OER and ORR catalysis.

Theoretical formulation of Li3a+bNaXb (X = halogen) as a potential artificial solid electrolyte interphase (ASEI) to protect the Li anode.

A major problem against the realization of high energy density and safe solid Li-ion batteries lies in detrimental reactions at the interface between the lithium anode and the solid electrolytes. This makes it necessary to develop an artificial solid electrolyte interphase (ASEI) as an effective protective coating to the lithium anode, which is the "Holy Grail" to enable high energy density batteries owing to its extremely high capacity. Here in this work, we carried out high-throughput first-principles modelling in the framework of materials genome engineering to identify potential ASEIs based on lithium nitric halides Li3a+bNaXb (X: halogen F, Cl, Br, I). On the basis of comprehensive assessments covering material stability, ionic conductivity, elastic modulus, and electrochemical compatibility with Li and potential SSEs, we have identified lithium nitric halides such as Li6NCl3 as superb ASEI candidates in line with their adequate ionic conductivity and fairly wide electrochemical window from 0 to 2 V (vs. Li/Li+). This makes them compatible with the lithium anode and various well-recognized thiophosphate SSEs such as LGPS, Li6PS5Cl, and Li3PS4, which have typical reduction potentials around 1.71 V. Besides, the large elastic modulus (e.g. 61.12 GPa for Li6NCl3) could be highly effective against the formation of lithium dendrites.