Li-S　batteries　are　regarded　as　one　of　the　most　promising　energy-storage　devices　due　to　their　high　theoretical　energy　density,　five　times　higher　than　that　of　lithium-ion　batteries　(2600　vs.　similar　to　500　W　h　kg(-1)).　However,　the　polysulfide　shuttle　effect　is　the　primary　challenge　for　future　applications　of　Li-S　batteries.　Herein,　a　novel　barrier　layer　material,　nonstoichiometric　W18O49　nanowires,　is　reported　to　alleviate　the　undesirable　shuttle　effect,　thereby　largely　boosting　the　specific　capacity　and　cyclability　of　Li-S　batteries.　Without　particular　cathode　design,　the　introduction　of　W18O49　nanowires　enables　the　commercially　available　micro-sized　sulfur　cathode　with　70%　sulfur　loading　to　deliver　a　respectable　initial　discharge　capacity　of　1142　mA　h　g(-1)　and　retain　a　specific　capacity　of　about　809　mA　h　g(-1)　after　50　cycles,　even　at　a　current　density　of　0.5　A　g(-1).　To　the　best　of　our　knowledge,　such　a　capacity　fading　for　Li-S　batteries　based　on　high　loading　of　commercial　micro-sized　sulfur　has　been　rarely　reported.