Ionic　liquids,　defined　here　as　room-temperature　molten　salts,　composed　mainly　of　organic　cations　and　(in)organic　anions　ions　that　may　undergo　almost　unlimited　structural　variations　with　melting　points　below　100　degrees　C.　They　offer　a　unique　series　of　physical　and　chemical　properties　that　make　them　extreme　important　candidates　for　several　energy　applications,　especially　for　clean　and　sustainable　energy　storage　and　conversion　materials　and　devices.　Ionic　liquids　exhibit　high　thermal　and　electrochemical　stability　coupled　with　low　volatility,　create　the　possibility　of　designing　appropriate　electrolytes　for　different　type　batteries　and　supercapacitors.　Herein,　varieties　of　ionic　liquids　applications　are　reviewed　on　their　utilization　as　electrolytes　for　Li-ion　batteries,　Na-ion　batteries,　Li-O-2(air)　batteries,　Li-Sulfur　(Li-S)　batteries,　supercapacitors　and　as　precursors　to　prepare　and　modify　the　electrode　materials,　meanwhile,　some　important　research　results　in　recent　years　are　specially　introduced,　and　the　perspective　on　novel　application　of　ionic　liquids　is　also　discussed.　(C)　2019　Published　by　Elsevier　Ltd　on　behalf　of　The　editorial　office　of　Journal　of　Materials　Science　&　Technology.