Polymer-derived C-Sn/SnO₂@rGO heterostructures with dual assistance of gallic acid for high-performance lithium-ion batteries

Sn-based materials are promising anodes for lithium-ion batteries (LIBs) due to their high theoretical capacity and safe operating potential, yet their practical application is hampered by severe volume expansion and poor cycling stability. Herein, we propose a facile strategy for the preparation of C-Sn/SnO₂@rGO heterostructures through the well-controlled pyrolysis of Sn-gallic acid (GAS), a metal-phenolic coordination polymers anchored on the reduced graphene oxide (rGO). The GA ligands play a vital role in forming GAS and partially reducing GO simultaneously, ensuring the atomically uniform dispersion of Sn atoms within the robust carbon matrices. During Li⁺ storage, the nano-scaled Sn/SnO₂ cluster mitigates volume variation under spatial confinement of GA-derived carbon and the π-π constraints of rGO. Moreover, the abundant hetero-interfaces among Sn, SnO₂, and rGO modulate the intrinsic electronic structure of Sn/SnO₂, enhancing Li-ion diffusion kinetics and thereby significantly boosting the rate performance. The C-Sn/SnO₂@rGO delivers an excellent rate capability of 488 mAh g⁻¹ at 5 A g⁻¹ and maintains 78.6 % capacity after 500 cycles at 1 A g⁻¹, offering advisable insights into the design of advanced Sn-based anode materials for LIBs.