A perspective on energy chemistry of low-temperature lithium metal batteries

Dendrite growth of lithium(Li)metal anode severely hinders its practical application,while the situation becomes more serious at low temperatures due to the sluggish kinetics of Liion diffusion.This perspective is intended to clearly understand the energy chemistry of lowtemperature Li metal batteries(LMBs).The lowtemperature chemistries between LMBs and traditional Liion batteries are firstly compared to figure out the features of the lowtemperature LMBs.Li deposition behaviors at low temperatures are then discussed concerning the variation in Liion diffusion behaviors and solid electrolyte interphase(SEI)features.Subsequently,the strategies to enhance the diffusion kinetics of Li ions and suppress dendrite growth including designing electrolytes and electrode/electrolyte interfaces are analyzed.Finally,conclusions and outlooks are drawn to shed lights on the future design of highperformance lowtemperature LMBs.

Effect of the anionic composition of sulfolane based electrolytes on the performances of lithium-sulfur batteries

In lithium-sulfur batteries,cell design,specifically electrolyte design,has a key impact on the battery performance.The effect of lithium salt anion donor number(DN)(DN[PF_(6)]^(-)=2.5,DN[N(SO_(2)CF_(3))_(2)]^(-)=5.4,DN[ClO_(4)]^(-)=8.4,DN[SO_(3)CF_(3)]^(-)=16.9,and DN[NO_(3)]^(-)=21.1)on the patterns of lithium-sulfur batteries and lithium metal electrode performances with sulfola ne-based electrolytes is investigated.An increase in DN of lithium salt anions leads to an increase in the depth and rate of electrochemical reduction of sulfur and long-chain lithium polysulfides and to a decrease in those for medium-and short-chain lithium polysulfides.DN of lithium salt anions has weak effect on the discharge capacity of lithium-sulfur batteries and the Coulomb efficiency during cycling,with the exception of LiSO_(3)CF_(3)and LiNO_(3).An increase in DN of lithium salt anions leads to an increase in the cycling duration of lithium metal anodes and to a decrease in the presence of lithium polysulfides.In sulfolane solutions of LiNO_(3)and LiSO_(3)CF_(3),lithium polysulfides do not affect the cycling duration of lithium metal anodes.

The dynamic evolution of aggregated lithium dendrites in lithium metal batteries

Lithium(Li)metal anodes promise an ultrahigh theoretical energy density and low redox potential,thus being the critical energy material for next-generation batteries.Unfortunately,the formation of Li dendrites in Li metal anodes remarkably hinders the practical applications of Li metal anodes.Herein,the dynamic evolution of discrete Li dendrites and aggregated Li dendrites with increasing current densities is visualized by in-situ optical microscopy in conjunction with ex-situ scanning electron microscopy.As revealed by the phase field simulations,the formation of aggregated Li dendrites under high current density is attributed to the locally concentrated electric field rather than the depletion of Li ions.More specifically,the locally concentrated electric field stems from the spatial inhomogeneity on the Li metal surface and will be further enhanced with increasing current densities.Adjusting the above two factors with the help of the constructed phase field model is able to regulate the electrodeposited morphology from aggregated Li dendrites to discrete Li dendrites,and ultimately columnar Li morphology.The methodology and mechanistic understanding established herein give a significant step toward the practical applications of Li metal anodes.

A review of solid-state lithium metal batteries through in-situ solidification

High-energy-density lithium metal batteries are the next-generation battery systems of choice,and replacing the flammable liquid electrolyte with a polymer solid-state electrolyte is a prominent conduct towards realizing the goal of high-safety and high-specific-energy devices.Unfortunately,the inherent intractable problems of poor solid-solid contacts between the electrode/electrolyte and the growth of Li dendrites hinder their practical applications.The in-situ solidification has demonstrated a variety of advantages in the application of polymer electrolytes and artificial interphase,including the design of integrated polymer electrolytes and asymmetric polymer electrolytes to enhance the compatibility of solid–solid contact and compatibility between various electrolytes,and the construction of artificial interphase between the Li anode and cathode to suppress the formation of Li dendrites and to enhance the high-voltage stability of polymer electrolytes.This review firstly elaborates the history of in-situ solidification for solid-state batteries,and then focuses on the synthetic methods of solidified electrolytes.Furthermore,the recent progress of in-situ solidification technology from both the design of polymer electrolytes and the construction of artificial interphase is summarized,and the importance of in-situ solidification technology in enhancing safety is emphasized.Finally,prospects,emerging challenges,and practical applications of in-situ solidification are envisioned.

Synthesis and Physico-chemical Properties of (Co)polymers of 2-[(2E)-1-methyl-2-buten-1-yl]aniline and Aniline

A new soluble polymer on 2-[(2 E)-1-methyl-2-buten-1-yl]aniline and its copolymers with aniline basis have been synthesized in various molar ratios. For all samples, the electrical conductivity, morphology, solubility, electrochemical properties, as well as spectral and molecular mass characteristics have been studied, and a comparative analysis with polyaniline has been carried out. The substituent introduced into the aniline aromatic ring significantly improves the solubility in typical organic solvents of a high molecular weight product. The morphology of the test compounds depends on the co-monomer ratio. As the content of the substituted aniline in the initial mixture increases, the morphology of the polymer changes from the inherent polyaniline fibrous microstructure to the globular one with irregular substituted polyaniline shapes and sizes. Electrochemical study of the samples revealed that the higher the oxidation potential, the wider the band gap(ranging from 2.00 to 2.15). The electrical conductivity decreases in proportion to the increase in the substituted aniline concentration of the initial co-monomer mixture and amounts to 12.5–35.7 × 10~6 nSm.