Cobalt　sulfides　have　been　popularly　used　in　energy　storage　because　of　their　high　theoretical　capacity　and　abundant　redox　reactions.　However,　poor　reaction　kinetics,　rapid　capacity　decay,　and　severe　polarization　owing　to　volume　changes　during　electrochemical　reaction　are　still　huge　challenges　for　cobalt　sulfides　in　practical　applications.　Herein,　cobalt　sulfide　yolk–shell　spheres　were　synthesized　by　phosphorus　doping　(P-CoS)　to　stabilize　the　structure　of　cobalt　sulfides　and　improve　their　electronic/ion　conductivity.　Kinetic　tests　and　density　functional　theory　calculations　confirm　that　the　introduction　of　phosphorus　into　cobalt　sulfides　greatly　reduces　the　diffusion　barrier　of　Li+　in　the　intrinsic　structure,　thereby　improving　the　reaction　kinetics　of　electrode　materials　during　the　Li+　insertion/extraction　process.　In　consequence,　the　P-CoS　electrode　delivers　a　high　lithium　storage　capacity　(781　mAh　g−1　after　100　cycles　at　0.2　A　g−1),　excellent　rate　capability　(489　mAh　g−1　at　10　A　g−1),　and　outstanding　cycling　stability　(no　significant　capacity　decay　over　4000　cycles　at　5　A　g−1).　Especially　for　sodium-ion　battery　application,　the　P-CoS　electrode　expresses　a　striking　capacity　of　approximately　260　mAh　g−1　at　2　A　g−1　after　900　cycles.　©　2020　Wiley-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim