Lithiated Hybrid Polymer/Inorganic PAA/MnO2 Protection Layer for High-Performance Tin Oxide Alloy Anode

Tin oxide (SnO2) has been regarded as a promising anode candidate compared to commercial graphite in lithium-ion batteries. However, it usually suffers from high irreversibility of the conversion reaction and huge volume variation, leading to low initial Coulombic efficiency and rapid capacity fading. Engineering a reliable protection layer and subsequent prelithiation is essential to address these issues. In this work, a hybrid poly(acrylic acid) (PAA) and manganese oxide (MnO2) composite layer has been conformally coated on SnO2 nanoparticles (NPs). Here, PAA not only works as a catalyst to make the MnO2 coating conformal but also ensures the hybrid protection layer flexible enough to tolerate volume variation of the SnO2 particles. The obtained core-shell SnO2@PAA/MnO2 NPs were then converted into alloy composite via thermal lithiation. Due to the robust lithiated PAA/MnO2 (Li-PAA/MnO2) protection layer, most side reactions and undesirable solid electrolyte interphases are suppressed, ensuring lower polarization and faster reaction kinetics for lithium storage. With fully expanded LixSn NPs confined in the Li-PAA/MnO2 matrix, the composite exhibits stable cycling performance with high Coulombic efficiency. It delivers a high delithiation capacity of 683 mAh g-1 at 1 C (0.005-1 V), and similar to 80% capacity retention is achieved after 500 cycles. Moreover, the composite exhibits stable full cell cycling paired with a LiFePO4 cathode, indicating its great application potential.

Automated summary

A composite layer of poly(acrylic acid) and manganese oxide was coated on SnO2 nanoparticles to address volume variation issues, improving the performance and cycling life of lithium-ion batteries. The protection layer and prelithiation technology effectively suppressed side reactions and solid electrolyte interphases, resulting in stable cycling performance and high Coulombic efficiency.