To　boost　the　use　of　electronic　devices　and　driving　mileage　of　electric　vehicles,　it　is　urgent　to　develop　lithium-ion　batteries　(LIBs)　with　higher　energy　density　and　longer　life.　High-voltage　and　high-capacity　cathode　materials,　such　as　LiCoO2,　LiNi0.5Mn1.5O4,　Ni-rich　layered　oxides,　and　lithium-rich　layered　oxides,　are　critically　important　for　LIBs　to　obtain　high　energy　density.　Among　various　forms　of　these　materials,　＇single-crystal＇cathodes　(SCCs)　have　shown　many　advantages　over　other　forms　for　industrial　applications,　including　good　crystallinity,　high　mechanical　strength,　high　reaction　homogeneity,　small　specific　surface　area,　excellent　structural　stability,　and　high　thermal　stability,　which　can　noticeably　improve　the　cycling　performance　and　safety　of　SCC-based　batteries.　Therefore,　SCCs　have　received　wide　attention　from　academic　to　industrial　communities　and　have　been　applied　to　the　liquid-based　and　solid-state　batteries　in　recent　years.　In　this　paper,　the　advantages,　progress,　and　challenges　of　SCCs　for　high-voltage　cathode　materials　are　reviewed.　Moreover,　we　summarize　the　efforts　for　improving　the　electrochemical　performance　of　SCCs,　intending　to　provide　insights　into　the　development　of　high-performance　cathodes　for　practical　LIBs.　©　2021　American　Chemical　Society.　All　rights　reserved.