Sodium/potassium-ion　batteries　(SIBs/PIBs)　with　high　electrochemical　performance　are　promising　but　there　still　remain　daunting　challenges　to　explore　an　anode　material　with　appealing　cycling　stability　and　rate　capability.　In　addition,　the　utilization　of　waste　biomass　arouses　tremendous　researches　in　energy　storage　applications.　Herein,　we　elaborately　coupling　ultrathin　few-layered　WSe2　nanosheets　with　N,　P-doped　biochar　by　utilizing　waste　chlorella　as　adsorbent　and　reactor.　It　displays　a　prominent　long-term　cycling　property　(265　mAh　g−1　at　1　A　g−1　up　to　1500　cycles)　in　SIBs,　which　is　the　best　long-cycle　performance　ever　reported　for　WSe2.　Paired　with　Na3V2(PO4)3　cathode,　full　SIBs　also　exhibit　superior　capacity　of　210　mAh　g−1　at　0.5　A　g−1　for　120　cycles.　Notably,　we　also　report　WSe2-based　anode　material　in　PIBs,　which　delivers　a　high　capacity　of　333　mAh　g−1　at　0.1　A　g−1　for　100　cycles　and　superior　cycling　lifespan　(155　mAh　g−1　at　1　A　g−1　up　to　5300　cycles)　as　well　as　excellent　rate　properties.　Additionally,　the　mechanism　of　the　repeated　process　of　sodiation/desodiation　is　revealed,　by　the　deep　characterization,　such　as　ex-situ　XRD/Raman,　galvanostatic　intermittent　titration　technique　and　CV　measurements.　©　2020　Elsevier　Inc.