Bismuth　telluride-based　thermoelectric　generators　(TEG)　were　widely　used　in　waste　heat　recovery,　but　the　failure　problem　at　the　electrode　interface　was　serious,　which　was　related　to　the　severe　diffusion　between　Sn　and　Bi2Te3.　However,　the　diffusion　behavior　and　process　have　not　been　reasonably　evaluated　and　mechanism　analyzed,　which　was　not　conducive　to　the　design　and　improvement　of　TEGs.　In　this　work,　hot-end　electrode　aging　was　performed　at　150　°C,　and　the　diffusion,　intermetallic　compounds　(IMC),　as　well　as　crack　induction　between　Bi2Te3　and　Sn-based　solder　were　systematically　investigated.　It　was　found　that　the　interdiffusion　of　Sn　and　Te　atoms　led　to　the　formation　of　Bi2Te　with　HCP　structure　and　SnTe　with　FCC　structure　at　the　interface.　Bi2Te　was　a　Bi-rich　layer　formed　after　the　migration　of　Te　atoms　away　from　Bi2Te3,　and　SnTe　had　a　double-layer　structure　respectively　attributing　to　the　diffusion　of　Sn　and　Te　atoms.　Diffusion-induced　cracks　tended　to　occur　at　Bi2Te/SnTe　interfaces　and　SnTe/Sn　interfaces.　The　former　was　related　to　the　diffusion-induced　phase　transformation　at　the　diffusion　front　of　Sn　atoms,　while　the　latter　generated　from　the　initiation　and　expansion　of　Kirkendall　voids.　In　addition,　the　brittleness　of　the　Bi-rich　phase　aggravated　the　crack　propagation.　The　shear　test　results　of　the　electrodes　confirmed　that　these　cracks　were　the　weakness　of　TEG　electrodes.　It　was　recommended　to　introduce　a　barrier　layer　at　the　interface　to　provide　protection,　and　the　fabrication　of　direct　soldering　was　not　suggested.　©　2023　Elsevier　Inc.