Xiaolin Li¹, Haiping Jia¹, Jiguang Zhang¹, David Reed¹, Vincent L Sprenkle¹; ¹Pacific Northwest National Laboratory

To improve energy density and cycling stability of Li-/Na-ion batteries, several nanostructured materials including porous Si and yolk-shell structured Sb@C have been designed as high-performance anodes. For Li-ion batteries, mesoporous Si sponge have controlled porosity and pore size, which limit the particle volume expansion at full lithiation to ~30% and prevent bulk particle pulverization. The anodes deliver a specific capacity of ~750 mAh/g and >80% capacity retention over 1,000 cycles. The electrodes (~1.5 mAh/cm2) demonstrated ~92% retention over 300 cycles. The composite electrodes of porous Si and graphite (~3 mAh/cm2) with a specific capacity of ~650 mAh/g demonstrate ~82% retention over 450 cycles. For Na-ion batteries, The Sb@C yolk-shell structure can accommodate the Sb swelling upon sodiation and improve the structural/electrical integrity against pulverization. It delivers a high specific capacity of ~554 mAh/g, good rate capability (315 mhA/g at 10C rate) and long cyclability (92% capacity retention over 200 cycles).