The energy density and cycle life of sodium-ion batteries are still too low for practical applications. Recently, Tin phosphide (Sn4P3) has emerged as a promising anode candidate for Na-ion batteries owing to its high theoretical capacity (1133mAhg-1). Most importantly, the synergistic Na storage reactions provide a self-healing mechanism, greatly improving the cycle life as an anode for an SIB compared to those electrode materials prepared from Sn and P elements. However, Sn4P3 still suffers from large volumetric change during sodiation/desodiation, which is a practical obstacle for its commercialization. Rational design and developing new materials are required to solve these issues. In this work, we report an easy, time- and energy-efficient method for the fabrication of novel hybrid materials with highly integrated nano-architectures for the development of SIB anode materials with high energy density and stable cycling performance. In these novel hybrids, transition metal phosphide (Sn3P4) nanoparticles with an average size of 20 nm are encaged by a porous carbon shell instead of simply being immobilized on the surface of a carbon materials. These nanoparticle/carbon shell structures are naturally connected with a highly porous phosphorous doped graphitic carbon matrix (PGc). The large atomic radius of phosphorus results in a wrinkled morphology in the PGc. This unique structure not only provides ideal porosity and conductivity for fast and efficient electron and Na ion transport, but also flexibility to accommodate to the large volume change of Sn4P3 during charging/discharging, therefore alleviating cell deformation. The Sn4P3@PGc hybrid was tested as an anode for SIB. A superior capacity of 515 mAh/g after 750 cycles at a charge and discharge current of 0.2 C. A capacity of ~390 mAh/g was maintained even after 1150 cycles at a charge/discharge current of 1 C, indicating the robustness of the electrode for long-term use.

Novel one step microwave assisted fabrication of Sn4P3 @ phosphorous doped carbon as a superior anode material for sodium ion batteries

256th National Meeting (2018)

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