Gas induced formation of inactive Li in rechargeable lithium metal batteries.

The formation of inactive lithium by side reactions with liquid electrolyte contributes to cell failure of lithium metal batteries. To inhibit the formation and growth of inactive lithium, further understanding of the formation mechanisms and composition of inactive lithium are needed. Here we study the impact of gas producing reactions on the formation of inactive lithium using ethylene carbonate as a case study.

Insights of the Electrochemical Reversibility of P2-Type Sodium Manganese Oxide Cathodes via Modulation of Transition Metal Vacancies.

Among cathode materials for sodium-ion batteries, Mn-based layered oxides have attracted enormous attention owing to their high capacity, cost-effectiveness, and fast transport channels. However, their practical application is hindered by the unsatisfied structural stability and the deficient understanding of electrochemical reaction mechanisms. Among these issues, the research of transition metal (TM) vacancy remains highly active due to their modulation roles on the anionic redox reactions, but their effects on structural and electrochemical stability remain obscure.

Visualizing the growth process of sodium microstructures in sodium batteries by in-situ Na MRI and NMR spectroscopy.

The growth of sodium dendrites and the associated solid electrolyte interface (SEI) layer is a critical and fundamental issue influencing the safety and cycling lifespan of sodium batteries. In this work, we use in-situ Na magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) techniques, along with an innovative analytical approach, to provide space-resolved and quantitative insights into the formation and evolution of sodium metal microstructures (SMSs; that is, dendritic and mossy Na metal) during the deposition and stripping processes. Our results reveal that the growing SMSs give rise to a linear increase in the overpotential until a transition voltage of 0.

The stability of P2-layered sodium transition metal oxides in ambient atmospheres.

Air-stability is one of the most important considerations for the practical application of electrode materials in energy-harvesting/storage devices, ranging from solar cells to rechargeable batteries. The promising P2-layered sodium transition metal oxides (P2-NaTmO) often suffer from structural/chemical transformations when contacted with moist air. However, these elaborate transitions and the evaluation rules towards air-stable P2-NaTmO have not yet been clearly elucidated.

High-Efficiency Lithium Metal Anode Enabled by a Concentrated/Fluorinated Ester Electrolyte.

Lithium (Li) metal anode (LMA) has received growing attention due to its highest theoretical capacity (3860 mA h g) and lowest redox potential (-3.04 V versus standard hydrogen electrode). However, practical application of LMA is obstructed by the detrimental side reactions between Li metal and organic electrolytes, especially when cycled in traditional carbonate ester electrolytes.