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Emerging Era of Electrolyte Solvation Structure and Interfacial Model in Batteries

Prospects of Electrode Materials and Electrolytes for Practical Potassium-Based Batteries

Sanitary tissue is utilized as the precursor to construct a hard carbon microbelt paper (HCMB), which can be employed as a high-initial-coulombic-efficiency and low-discharge-platform K + -storage anode for 4.5 V hybrid capacitors. 

Tissue-derived carbon microbelt paper: a high-initial-coulombic-efficiency and low-discharge-platform K<sup>+</sup>-storage anode for 4.5 V hybrid capacitors

Graphite is one of the most attractive anode materials due to its low cost, environmental friendliness, and high energy density for potassium ion batteries (PIBs). However, the severe capacity fade...

Regulating Solvent Molecule Coordination with KPF6 for Superstable Graphite Potassium Anodes.

High-voltage lithium-ion batteries (LIBs) enabled by high-voltage electrolytes can effectively boost energy density and power density, which are critical requirements to achieve long travel distances, fast-charging, and reliable safety performance for electric vehicles. However, operating these batteries beyond the typical conditions of LIBs (4.3 V vs Li/Li+ ) leads to severe electrolyte decomposition, while interfacial side reactions remain elusive. These critical issues have become a bottleneck for developing electrolytes for applications in extreme conditions. Herein, an additive-free electrolyte is presented that affords high stability at high voltage (4.5 V vs Li/Li+ ), lithium-dendrite-free features upon fast-charging operations (e.g., 162 mAh g-1 at 3 C), and superior long-term battery performance at low temperature. More importantly, a new solvation structure-related interfacial model is presented, incorporating molecular-scale interactions between the lithium-ion, anion, and solvents at the electrolyte-electrode interfaces to help interpret battery performance. This report is a pioneering study that explores the dynamic mutual-interaction interfacial behaviors on the lithium layered oxide cathode and graphite anode simultaneously in the battery. This interfacial model enables new insights into electrode performances that differ from the known solid electrolyte interphase approach to be revealed, and sets new guidelines for the design of versatile electrolytes for metal-ion batteries.

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Interfacial Model Deciphering High-Voltage Electrolytes for High Energy Density, High Safety, and Fast-Charging Lithium-Ion Batteries

Alloying anodes exhibit very high capacity when used in potassium-ion batteries, but their severe capacity fading hinders their practical applications. The failure mechanism has traditionally been attributed to the large volumetric change and/or their fragile solid electrolyte interphase. Herein, it is reported that an antimony (Sb) alloying anode, even in bulk form, can be stabilized readily by electrolyte engineering. The Sb anode delivers an extremely high capacity of 628 and 305 mAh g-1 at current densities of 100 and 3000 mA g-1 , respectively, and remains stable for more than 200 cycles. Interestingly, there is no need to do nanostructural engineering and/or carbon modification to achieve this excellent performance. It is shown that the change in K+ solvation structure, which is tuned by electrolyte composition (i.e., anion, solvent, and concentration), is the main reason for achieving this excellent performance. Moreover, an interfacial model based on the K+ -solvent-anion complex behavior is presented. The electronegativity of the K+ -solvent-anion complex, which can be tuned by changing the solvent type and anion species, is used to predict and control electrode stability. The results shed new light on the failure mechanism of alloying anodes, and provide a new guideline for electrolyte design that stabilizes metal-ion batteries using alloying anodes.

Hraoran Cheng

Papers

Electrolyte-Mediated Stabilization of High-Capacity Micro-Sized Antimony Anodes for Potassium-Ion Batteries.