Self-Relaxant Superelastic Matrix Derived from C₆₀ Incorporated Sn Nanoparticles for Ultra-High-Performance Li-Ion Batteries

Homogeneously dispersed Sn nanoparticles approximately ≤10 nm in a polymerized C₆₀ (PC₆₀) matrix, employed as the anode of a Li-ion battery, are prepared using plasma-assisted thermal evaporation coupled by chemical vapor deposition. The self-relaxant superelastic characteristics of the PC₆₀ possess the ability to absorb the stress-strain generated by the Sn nanoparticles and can thus alleviate the problem of their extreme volume changes. Meanwhile, well-dispersed dot-like Sn nanoparticles, which are surrounded by a thin SnO₂ layer, have suitable interparticle spacing and multilayer structures for alleviating the aggregation of Sn nanoparticles during repeated cycles. The Ohmic characteristic and the built-in electric field formed in the interparticle junction play important roles in enhancing the diffusion and transport rate of Li ions. SPC-50, a Sn-PC₆₀ anode consisting of 50 wt % Sn and 50 wt % PC₆₀, as confirmed by energy-dispersive X-ray spectroscopy analysis, exhibited the highest electrochemical performance. The resulting SPC-50 anode, in a half-cell configuration, exhibited an excellent capacity retention of 97.18%, even after 5000 cycles at a current density of 1000 mA g^-1 with a discharge capacity of 834.25 mAh g^-1. In addition, the rate-capability performance of this SPC-50 half-cell exhibited a discharge capacity of 544.33 mAh g^-1 at a high current density of 10,000 mA g^-1, even after the current density was increased 100-fold. Moreover, a very high discharge capacity of 1040.09 mAh g^-1 was achieved with a capacity retention of 98.67% after 50 cycles at a current density of 100 mA g^-1. Futhermore, a SPC-50 full-cell containing the LiCoO₂ cathode exhibited a discharge capacity of 801.04 mAh g^-1 and an areal capacity of 1.57 mAh cm^-2 with a capacity retention of 95.27% after 350 cycles at a current density of 1000 mA g^-1.