Unlocking Rapid Charging and Extended Lifetimes for Li-Ion Batteries Using Freestanding Quantum Conversion-Type...

Batteries capable of quick charging as fast as fossil fuel vehicles are becoming a vital issue in the electric vehicle market. However, conversion-type materials promising as a next-generation anode have many problems to satisfy fast charging and long-term cycles due to their low conductivity and large irreversibility despite a high theoretical capacity. Here, we report effective strategies for a SnO₂-based anode to enable rapid-charging, long-cycle, and high reversible capacity. The quantum size of SnO₂ nanoparticles uniformly embedded within a 3D conductive carbon matrix as a prerequisite for high reversible capacity increases the interdiffusion layer and facilitates a highly reversible conversion reaction between Li₂O/Sn and SnO₂. In particular, the Sn-C chemical bond achieves ion-site control and direct electron transfer, enabling boost charging. Further, the robust and porous structure of the binder-free three-dimensional electrode buffers the massive volume expansion during Li insertion/desertion and allows for multidimensional rapid-ion diffusion. As a result, our quantum SnO₂ anode delivers a high reversible capacity of about 753 mAh g^-1 with a 468% capacity increase after 4000 cycles at 10 C. It also presents a gradually increasing capacity up to 548 mAh g^-1 even at 20 C and superior cyclability over 20 000 cycles in capacity stabilization. This study will contribute to designing aerofilm-based conversion-type electrodes for fast charging devices.