Microstructural Insights into Performance Loss of High-Voltage Spinel Cathodes for Lithium-ion Batteries.

Spinel-structured LiNi Mn O (LNMO), with low-cost earth-abundant constituents, is a promising high-voltage cathode material for lithium-ion batteries. Even though extensive electrochemical investigations have been conducted on these materials, few studies have explored correlations between their loss in performance and associated changes in microstructure. Here, down to the atomic scale, the structural evolution of these materials is investigated upon the progressive cycling of lithium-ion cells.

Fluctuation cepstral scanning transmission electron microscopy of mixed-phase amorphous materials.

Four-dimensional scanning transmission electron microscopy (4D-STEM) is a versatile analytical tool for characterizing materials structural properties. However, extending such analysis to disordered materials is challenging, especially in technologically important samples with mixed ordered and disordered phases. Here, we present a new 4D-STEM method, called fluctuation cepstral STEM (FC-STEM), based on the fluctuation analysis of cepstral transform of diffraction patterns.

Physicochemical Heterogeneity in Silicon Anodes from Cycled Lithium-Ion Cells.

The severe capacity fade of lithium-ion cells with silicon-dominant anodes has hindered their widescale commercialization. In this work, we link cell capacity fade to the heterogeneous physicochemical evolution of silicon anodes during battery cycling. Through a multilength scale characterization approach, we demonstrate that silicon particles near the anode surface react differently from those near the copper current collector.

Dual-Salt Electrolytes to Effectively Reduce Impedance Rise of High-Nickel Lithium-Ion Batteries.

Simply mixing several lithium salts in one electrolyte to obtain blended salt electrolytes has been demonstrated as a promising strategy to formulate advanced electrolytes for lithium metal batteries (LMBs) and lithium-ion batteries (LIBs). In this study, we report the use of dual-salt electrolytes containing lithium hexafluorophosphate (LiPF) and lithium difluorophosphate (LiDFP) in ethylene carbonate/ethyl methyl carbonate (EC/EMC) mixture and tested them in layered high-nickel LIB cells. LiNiCoO was synthesized through a coprecipitation method and was used as a representative high-nickel cathode for the U.

X-ray spatial profiling reveals uneven compression of electrode assemblies and steep lateral gradients in lithium-ion coin cells.

Coin cells are used extensively as test devices in battery research for evaluation of new materials and optimization of cycling protocols. In this study, in situ X-ray diffraction profilometry is used to characterize spatial distribution of the active materials, lithiation, and phase distribution in electrodes of NCM523/graphite coin cells. The X-ray data indicate uneven areal compression of the electrode assembly in such cells, which we trace to a specific design feature that leads to elastic deformation of a metal spacer.

In Situ Lithiated Reference Electrode: Four Electrode Design for In-operando Impedance Spectroscopy.

Extending operating voltage of Li-ion batteries results in higher energy output from these devices. High voltages, however, may trigger or accelerate multiple processes responsible for long-term performance decay. Given the complexity of physical processes occurring inside the cell, it is often challenging to achieve a full understanding of the root causes of this performance degradation.

In Situ Measurement of the Plane-Strain Modulus of the Solid Electrolyte Interphase on Lithium-Metal Anodes in Ionic Liquid Electrolytes.

We present an experimental approach for in situ measurement of elastic modulus of the solid electrolyte interphase (SEI), which is formed from reactions between a lithium thin-film [on a polydimethylsiloxane (PDMS) substrate] and a room-temperature ionic liquid (RTIL) electrolyte. The SEI forms under a state of compressive stress, which causes buckling of the sample surface. In situ atomic force microscopy is used to measure the dominant wavelength of the wrinkled surface topography.

Spontaneous aggregation of lithium ion coordination polymers in fluorinated electrolytes for high-voltage batteries.

Fluorinated carbonates are pursued as liquid electrolyte solvents for high-voltage Li-ion batteries. Here we report aggregation of [Li(+)(FEC)3]n polymer species in fluoroethylene carbonate containing electrolytes and scrutinize the causes for this behavior.

Correlating cation ordering and voltage fade in a lithium-manganese-rich lithium-ion battery cathode oxide: a joint magnetic susceptibility and TEM study.

Structure-electrochemical property correlation is presented for lithium-manganese-rich layered-layered nickel manganese cobalt oxide (LMR-NMC) having composition Li1.2Co0.1Mn0.