Are you needing some incredibly thin batteries for the purpose of backup or power you mobile application (be it a IoT or microchip). If yes in this case you can just take a look at the EFL700A39. This miniature lithium battery which is just 220um thick (like the processor of an old pc).
Stunning also the fact that possess a fast recharge qualities and a cycle capacity of 4000 discharges. More info in the pdf. The product is now obsolete.
Links
https://www.st.com/en/power-management/efl700a39.html