Direct synthesis of 3D hierarchically porous carbon/Sn composites <i>via in situ</i> generated NaCl crystals as templates for potassium-ion batteries anode

3D hierarchically porous carbon/Sn composites is synthesized by <italic>in situ</italic> NaCl template method, which can effectively avoid the direct exposure of elemental Sn to the electrolyte, efficiently alleviate the volume expansion and exhibits good potassiation/depotassiation capacity.