Abstract: When hypervelocity space debris or micrometeoroids strike lithium-ion battery packs exposed to the outer space environment, the cell casing may be penetrated, inducing internal short circuits and subsequently triggering thermal runaway or even fire. To investigate the damage mechanisms of lithium-ion cells under hypervelocity impacts, structural analyses of the cells were performed. Ground-based nail penetration tests on commercial lithium-ion batteries, impact tests on nickel-hydrogen battery cells conducted by NASA Lewis Research Center, and hypervelocity impact tests on lithium-ion batteries aboard the International Space Station were reviewed. A preliminary ground-based test scheme for hypervelocity impacts on lithium-ion cells was also proposed. Based on the operational characteristics of GEO spacecraft, the impact risk from space debris and micrometeoroids to lithium-ion cells was assessed, and corresponding protection measures were suggested. This work provides a technical reference for the debris-impact protection design of lithium-ion battery packs on spacecraft.