The electrode/electrolyte interface in lithium-based batteries, including lithium and lithium-ion batteries, plays a key role in battery chemistry. The atomic structure and phase distribution of the solid-electrolyte-interphase (SEI) can be elucidated through the use of ultra-low dosage, aberration-corrected cryo-transmission electron microscopy (cryo-TEM). In modern lithium-ion batteries (LIBs), electrolyte additives are routinely employed to optimize the SEI for achieving desired performances. Lithium metal battery has a higher energy-density than LIBs, but lithium metal anode suffers from the problems such as lithium dendrite growth, interface instability and large volume expansion during cycling. We have proposed a variety of strategies to address these challenges, including optimizing the electrolyte composition, enhancing the solid electrolyte interface, constructing three-dimensional collector structures, fabricating self-organized core-shell liquid metal/lithium composite anodes, and manufacturing three-dimensional lithium composites that exhibit minimal apparent volume expansion.