A Facile and Very Effective Method to Enhance the Mechanical Strength and the Cyclability of Si‐Based Electrodes for Li‐Ion Batteries

Abstract

It is well known that the mechanical properties of lithium‐ion battery electrodes impact their electrochemical performance. This is especially critical for Si‐based negative electrodes, which suffer from large volume changes of the active mass upon cycling. Here, this study presents a postprocessing treatment (called maturation) that improves the mechanical and electrochemical stabilities of silicon‐based anodes made with an acidic aqueous binder. It consists of storing the electrode in a humid atmosphere for a few days before drying and cell assembly. This results in a beneficial in situ reactive modification of the interfaces within the electrode. First, the binder tends to concentrate at the silicon interparticle contacts. As a result, the cohesion of the composite film is strengthened. Second, the corrosion of the copper current collector, inducing the formation of copper carboxylate bonds, improves the adhesion of the composite film. The great improvement of the mechanical stability of the matured electrode is confirmed by in‐operando optical microscopy showing the absence of film delamination. The result is a significant electrochemical performance gain, up to a factor 10, compared to a not‐matured electrode. This maturation procedure can be applied to other types of electrodes for improving their electrochemical performance and also their handling during cell manufacturing.

Optimizing Micrometer-Sized Sn Powder Composite Electrodes for Sodium-Ion Batteries

“…6 into consideration, we tried introducing the porosity into micro-Sn composite layer and thinner binder coating on micro-Sn particles by adjusting the drying temperature after slurry coating and by adding different conductive carbon powders having different particle sizes. 22 According to previous reports, the binder distribution and electrode porosity are affected by varying drying temperatures, 23 and suitable choice of conductive carbon is effective for controlling porosity and inducing formation of conductive network in the composite layer. 24 First, the effect of drying temperature after the slurry consisting of micro-Sn powder:3-µm graphite:PANa = 8:1:1 pasted onto a current collector was examined with reference to 80°C used as a standard one.…”

Conjugation with carbon nanotubes improves the performance of mesoporous silicon as Li-ion battery anode

“…The well-known drawbacks with silicon itself are the huge volumetric changes upon the lithiation and delithiation processes, and the subsequent loss of electrical contact during the delithiation phase as the material collapses 6 . New binders, binder architectures and electrolyte additives are being studied to mitigate this obstacle [7][8][9] . The current approaches to overcome the issue with silicon are typically based on different nanomaterials like nanoparticles, nanowires and thin films [10][11][12] .…”

Effect of carboxymethyl cellulose on the flow behavior of lithium-ion battery anode slurries and the electrical as well as mechanical properties of corresponding dry layers

“…The volume fluctuations can induce a local delamination of the electrode layer from the current collector and cracking within the layer. Hence, considerable research work dealt with the determination of adhesive strength between electrode layer and substrate [17,[33][34][35][36][37][38][39][40][41][42][43][44][45][46]. However, the cohesive strength in the electrode layer has not received much attention yet.…”

“…Nevertheless, it remains elusive whether such local force measurements are representative for the cohesive strength of the electrode layer. Finally, indentation and tensile tests have been carried out to determine the mechanical properties of electrode layers [37,[50][51][52]. These studies provided some understanding about how wet processing of the slurry affects porosity and mechanical properties of the dry layer.…”