Improving the Performance\nof Silicon-Based Negative\nElectrodes in All-Solid-State Batteries by In Situ Coating with Lithium\nPolyacrylate Polymers

In all-solid-state batteries (ASSBs), silicon-based negative\nelectrodes\nhave the advantages of high theoretical specific capacity, low lithiation\npotential, and lower susceptibility to lithium dendrites. However,\ntheir significant volume variation presents persistent interfacial\nchallenges. A promising solution lies in finding a material that combines\nionic-electronic conductivity, stable physicochemical properties,\nand adhesive characteristics. Poly(acrylic acid) (PAA) is widely used\nin liquid-state batteries due to its superior properties compared\nto polyvinylidene fluoride (PVDF). In this study, silicon particles\nwere coated with varying concentrations of PAA and LiPAA using an\nin situ liquid-phase coating method to form electrode sheets. The\nexperimental and analytical results revealed significant trends in\nthe impact of different additive concentrations on the electrochemical\nperformance, with 1.0 wt % LiPAA showing notable improvements in Coulombic\nefficiency, rate capability, and long-term cycling stability. The\nassembled all-solid-state batteries exhibited a high initial discharge\ncapacity of 3200 mAh/g, with a capacity retention of 81.9% after 300\ncycles at 0.3 C, and a stable discharge capacity of 1300 mAh/g at\na 2 C rate. A rapid and efficient in situ liquid-phase coating method\nfor LiPAA was developed and confirmed through FTIR, XRD, and TEM characterization.\nSEM and XPS analyses demonstrated that LiPAA encapsulation effectively\nalleviates interfacial issues. This study demonstrated for the first\ntime that an appropriate amount of LiPAA coating on silicon particles\ncan mitigate the interfacial challenges caused by the volume expansion\nof silicon-based negative electrodes. These findings improve electrochemical\nperformance and promote the application of silicon-based negative\nelectrodes in all-solid-state batteries.