Silicon is electrochemically alloyed and de-alloyed with Li at potentials close to Li + /Li and is widely recognized as the most promising candidate for the anode of LIBs with a high energy density (250-300 Wh kg −1 ) in the next generation. The most serious issue of Si anode is poor capacity retention owing to large volume changes during charging and discharging. We developed Si LeafPowder ® with a nano-flake structure to overcome the poor capacity retention. However Si anodes still have some problems such as large irreversible capacity, ceaseless electrolyte decomposition, swelling of the electrode, etc. for use in high-energy density LIBs in the next generation. In this article, these problems and the challenges to mitigate them are overviewed based on our resent data obtained by Si nano-flakes (Si LeafPowder ® ).