Three　types　of　new-structured　phosphorized　tin　microspheres　(Sn–P),　phosphorized　tin　microsphere-carbon　(Sn–P–C),　and　phosphorized　tin　nanoparticles　embedded　in　interconnected　porous　carbon　microspheres　(Sn–P@PCMs)　were　prepared　through　a　carbothermal　reduction-assisted　phosphorization　strategy.　The　characterization　of　the　formation　mechanism　and　microstructure　of　Sn–P,　Sn–P–C,　and　Sn–P@PCMs　composites　demonstrated　that　the　controllable　evaporation　of　coordinated　phosphorus　in　the　thermally　unstable　tin　phosphide　intermediate　by　accurate　thermal　treatment　contributed　to　the　formation　of　a　ca.　3　wt　%　P-doped　metallic　tin　structure　featuring　a　nonstoichiometric　SnxPy　(y/x　=　0.2)　core,　a　Sn-rich　phosphorized　metallic　(y/x　=　0.05)　shell,　and　an　increased　phosphorus　concentration　from　the　outer　surface　to　the　inner　core.　The　as-prepared　phosphorized　tin-based　composites　were　applied　as　counter　electrode　materials　for　dye-sensitized　solar　cells　(DSSCs),　in　which　the　Sn–P–C　counter　electrode　exhibited　the　lowest　charge　transfer　resistance　of　3.47　Ω　and　the　assembled　DSSCs　delivered　an　optimum　power　conversion　efficiency　of　8.59%,　superior　to　those　of　Pt-based　cells　(6.78　Ω　and　7.46%,　respectively).　The　unique　bifunctional　structure　of　the　SnxPy　conductive　core　coupled　with　the　phosphorized　metallic　Snδ+　(0　–1　at　0.1C　after　400　cycles　and　435　mAh　g–1　at　5C　after　30　cycles.　The　superior　Li-ion　storage,　cyclability,　and　rate　performance　of　Sn–P@PCMs　could　be　attributed　to　the　incorporation　of　Sn–P　nanoparticles　into　interconnected　porous　carbon　microspheres　that　effectively　buffered　the　large　volumetric　change　and　enhanced　the　electronic–ionic　conductivity　during　the　lithiation　and　delithiation　process.　©　2022　American　Chemical　Society