The　mechanical　properties　of　the　electrodes　are　dynamic　change　during　the　cycle,　which　will　affect　the　wave　propagation　characteristics　in　the　lithium-ion　battery.　It　is　feasible　for　the　non-destructive　characterization　of　lithium-ion　batteries　based　on　the　relationship　between　the　wave　characteristic　and　the　state　of　charge　(SOC).　In　this　research,　an　ultrasonic　bulk　wave　detection　technique　for　detecting　the　SOC　of　multi-area　lithium-ion　batteries　using　arrayed　flexible　sensors　is　proposed.　Firstly,　the　simulation　model　of　type　1-3　piezoelectric　composites　was　established　based　on　the　finite　element　simulation　software　COMSOL,　and　the　effects　of　different　structural　parameters,　such　as　piezoelectric　phase　volume　fraction,　composite　thickness,　and　piezoelectric　column　aspect　ratio,　on　their　properties　were　analyzed.　Based　on　the　simulation　optimization　results,　a　5×5　1-3　piezoelectric　composite　sensor　was　designed　and　prepared.　The　ultrasonic　bulk　wave　detection　system　for　lithium-ion　batteries　was　built　with　the　optimized　arrayed　sensor,　and　the　connection　between　SOC　and　wave　propagation　properties　was　experimentally　investigated,　and　the　inhomogeneity　of　the　SOC　of　lithium-ion　batteries　was　visualized　and　analyzed.　Furthermore,　the　ultrasonic　flexible　sensing　detection　approach　has　also　been　shown　to　be　a　sensitive　means　of　determining　the　SOC　of　multi-area　lithium-ion　batteries.　©　2024　IEEE.