Insights on microstructural evolution and capacity fade on diatom SiO <inf>2</inf> anodes for lithium-ion batteries

Abstract

is a promising material for developing high-capacity anodes for lithium-ion batteries (LIBs). However, microstructural changes of anodes at the particle and electrode level upon prolonged cycling remains unclear. In this work, the causes leading to capacity fade on anodes were investigated and simple strategies to attenuate anode degradation were explored. Nanostructured from diatomaceous earth was integrated into anodes containing different quantities of conductive carbon in the form of either a conductive additive or a nanometric coating layer. Galvanostatic cycling was conducted for 200 cycles and distinctive trends on capacity fade were identified. A thorough analysis of the anodes at selected cycle numbers was performed using a toolset of characterization techniques, including electrochemical impedance spectroscopy, FIB-SEM cross-sectional analysis and TEM inspections. Significant fragmentation of particles surface and formation of filigree structures upon cycling are reported for the first time. Morphological changes are accompanied by an increase in impedance and a loss of electroactive surface area. Carbon-coating is found to restrict particle fracture and to increase capacity retention to 66%, compared to 47% for uncoated samples after 200 cycles. Results provide valuable insights to improve cycling stability of anodes for next-generation LIBs.