Synergistic effects of dielectric polarization and ball-milling-induced structural evolution in graphite/TiO2 composite anodes for high-performance lithium-ion batteries

초록

Despite being the commercial standard anode for lithium-ion batteries (LIBs), graphite remains limited by sluggish fast-charging kinetics and gradual degradation during prolonged cycling. Here, artificial graphite was integrated with rutile TiO2 particles of different sizes (30, 100, and 200 nm) via a high-energy ball-milling process, and the effects of TiO2 size on structural evolution, dielectric polarization behavior, and electrochemical performance were systematically investigated. Among the three composites, G@R100 exhibited an optimal combination of structural refinement and polarization characteristics, showing the smallest in-plane crystallite size (La), the highest saturation polarization (Ps = 0.32 mu C cm(-2)), and enhanced Li+ transport kinetics. Notably, the reduction in stacking height (Lc) was relatively insensitive to TiO2 size. By contrast, the in-plane crystallite refinement and the polarization response both showed a clear optimum at 100 nm, indicating a coupled effect of ball-milling-induced structural evolution and particle-size-dependent polarization on Li+ transport. As a result, G@R100 delivered a reversible capacity of 235.29 mAh g(-1) at 10C and retained 87.24% of its capacity after 200 cycles. These findings demonstrate that particle-size-controlled incorporation of polarization-responsive TiO2, together with ball-milling-induced structural tuning, provides an effective strategy for improving both rate capability and long-term durability in graphite-based composite anodes.

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