Research progress on preparation and purification of fluorine-containing chemicals in lithium-ion batteries

With the development of digital products,electric vehicles and energy storage technology,electronic chemicals play an increasingly prominent role in the field of new energy such as lithium-ion batteries.Electronic chemicals have attracted extensive attention in various fields.Characteristics of high-end electronic chemicals are high purity and low impurity content,which requires a very strict separation and purification process.At present,crystallization is a key technology for their separation and purification of electronic chemicals.In this work,the representative fluorine-containing compounds in cathode and anode materials,separator and electrolyte of lithium-ion batteries are introduced.The latest technologies for the preparation and purification of four kinds of fluorine-containing battery chemicals by crystallization technology are reviewed.In addition,the research prospects and suggestions are put forward for the separation of fluorine-containing battery chemicals.

Functional Optical Fiber Sensors Detecting Imperceptible Physical/Chemical Changes for Smart Batteries

The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal state.The battery should“sense its internal physical/chemical conditions”,which puts strict requirements on embedded sensing parts.This paper summarizes the application of advanced optical fiber sensors in lithium-ion batteries and energy storage technologies that may be mass deployed,focuses on the insights of advanced optical fiber sensors into the processes of one-dimensional nano-micro-level battery material structural phase transition,electrolyte degradation,electrode-electrolyte interface dynamics to three-dimensional macro-safety evolution.The paper contributes to understanding how to use optical fiber sensors to achieve“real”and“embedded”monitoring.Through the inherent advantages of the advanced optical fiber sensor,it helps clarify the battery internal state and reaction mechanism,aiding in the establishment of more detailed models.These advancements can promote the development of smart batteries,with significant importance lying in essentially promoting the improvement of system consistency.Furthermore,with the help of smart batteries in the future,the importance of consistency can be weakened or even eliminated.The application of advanced optical fiber sensors helps comprehensively improve the battery quality,reliability,and life.

Effective exposure of nitrogen heteroatoms in 3D porous graphene framework for oxygen reduction reaction and lithium–sulfur batteries

The introduction of nitrogen heteroatoms into carbon materials is a facile and efficient strategy to regulate their reactivities and facilitate their potential applications in energy conversion and storage. However,most of nitrogen heteroatoms are doped into the bulk phase of carbon without site selectivity, which significantly reduces the contacts of feedstocks with the active dopants in a conductive scaffold. Herein we proposed the chemical vapor deposition of a nitrogen-doped graphene skin on the 3D porous graphene framework and donated the carbon/carbon composite as surface N-doped grapheme（SNG）. In contrast with routine N-doped graphene framework（NGF） with bulk distribution of N heteroatoms, the SNG renders a high surface N content of 1.81 at%, enhanced electrical conductivity of 31 S cm^（-1）, a large surface area of 1531 m^2 g^（-1）, a low defect density with a low I_D/I_G ratio of 1.55 calculated from Raman spectrum, and a high oxidation peak of 532.7 ℃ in oxygen atmosphere. The selective distribution of N heteroatoms on the surface of SNG affords the effective exposure of active sites at the interfaces of the electrode/electrolyte, so that more N heteroatoms are able to contact with oxygen feedstocks in oxygen reduction reaction or serve as polysulfide anchoring sites to retard the shuttle of polysulfides in a lithium–sulfur battery. This work opens a fresh viewpoint on the manipulation of active site distribution in a conductive scaffolds for multi-electron redox reaction based energy conversion and storage.

Zn-air batteries for electric vehicles

The increasingly serious environmental challenges have gradually aroused people's interest in electric vehicles.Over the last decade,governments and automakers have collaborated on the manufacturing of electric vehicles with high performance.Cutting-edge battery technologies are pivotal for the performance of electric vehicles.Zn-air batteries are considered as potential power batteries for electric vehicles due to their high capacity.Zn-air battery researches can be classified into three categories:primary batteries,mechanically rechargeable batteries,and chemically rechargeable batteries.The majority of current studies aim at developing and improving chemically rechargeable and mechanically rechargeable Zn-air batteries.Researchers have tried to use catalytic materials design and device design for Zn-air batteries to make it possible for their applications in electric vehicles.This review will highlight the state-of-the-art in primary batteries,mechanically rechargeable batteries,and chemically rechargeable batteries,revealing the prospects of Zn-air batteries for electric vehicles.

Chloromethyl pivalate based electrolyte for non-aqueous lithium oxygen batteries

A novel electrolyte with chloromethyl pivalate （CP） used as solvent was first reported for non-aqueous lithium-oxygen （Li-O2） batteries. Since there are no α-H atoms in the structure of CP, the CP based electrolyte in both superoxide radical solution and real LifO2 battery environment showed good chemical stability against superoxide radicals, which was confirmed by ^1H NMR and ^13C NMR measurements. Without a catalyst in the cathode of Li-O2 batteries, the batteries showed high specific capacity and cycling stability.