Cathode Performance as a Function of Inactive Material and Void Fractions

Abstract

Li[Ni1/3Co1/3Mn1/3]normalO2 -based laminates of approximately the same loading and of varying levels of poly(vinylidene fluoride) (PVDF) binder and acetylene black (ratio held constant) were fabricated and calendered to different porosities, with the objective to investigate performance on a volume basis. The electronic conductivity of the laminates depends strongly on the inactive material content but not significantly on porosity. Electrochemical impedance spectroscopy studies found that charge-transfer resistance with calendering varied greatly with inactive material content. When the electrode contains low levels of inactive material (2% PVDF and 1.6% carbon), calendering significantly reduced the bulk resistance of the electrode. With high levels of inactive material (8% PVDF and 6.4% carbon), charge-transfer resistance increased with increased calendering. Above a certain level, depending on the overall composition, the inactive material reduces ionic transport to the active material surface. For a plug-in hybrid electric vehicle required to go 40 miles at an average rate of 20 miles/h with a 38 kW 10 s power-pulse capability, the cell chemistry studied is energy-limited. Therefore, based on the results of this study, the cathode should be compressed to 10% porosity with a minimal amount of inactive material.

Development of In Situ Cross-Sectional Raman Imaging of LiCoO₂ Cathode for Li-ion Battery

“…In order to satisfy these demands, it is crucial to optimize the structure of the electrode as well as exploring new materials because the kinetics of the electrode reaction depends on the structure of the composite electrode. [2][3][4][5] The main process in the electrode reaction of LIBs is an intercalation/deintercalation of Li + into/from host materials. In case of LiCoO 2 cathode and carbon anode, for instance, the electrode reaction is represented as follows:…”

Unveiling the Roles of Binder in the Mechanical Integrity of Electrodes for Lithium-Ion Batteries

“…In recent years, new binder development includes (1) seeking new electronically conductive binders with high elasticity in order to accommodate the large volume change of AMs during insertion and extraction of lithium-ions, 7,[10][11][12][13][14][15][16][17] (2) replacing the costly, environmentally unfriendly, and volatile organic solvent used in the manufacturing of electrode, [18][19][20] and (3) increasing the adhesion strength between the binder and other components of electrode (AMs and conductive materials in general). 5,[21][22][23][24][25][26] However, the development of binders is hindered by the lack of standard tests of binder adhesion properties and a fundamental understanding of adhesion mechanism.…”

Effect of LiCoO2Cathode Density and Thickness on Electrochemical Performance of Lithium-Ion Batteries

“…The latter has sometimes been considered as more important factors by many manufacturers. Unfortunately, there are limited research works on electrode design parameters such as density and thickness, [8][9][10][11][12][13][14][15] and moreover they are not various and wide enough to understand many parameters in a variety of points of view.…”

“…As for cathode active materials, Zheng et al [11][12][13] controlled the cathode porosity from 50% to 0% while maintaining the electrode loading level, which meant that the thickness would be thinner with decreasing porosity, and found some relationship between porosity and electrochemical performance. Recently, Chen et al 14) and Cho et al 15) tried to correlate experimental electrochemical data with simulated results under different porosity and thickness conditions, respectively.…”