Searching "***Li battery shelf life"*** yields:
Lithium-ion batteries degrade, with an estimated shelf life of 2-3 years, regardless of whether they are in use.
New Li batteries are typically charged to ~50%.
Any battery will self discharge over time.
LI batteries between 0.5-3% per month.
Maintaining them at ~50% will increase the shelf life.
They don't like to be discharged or fully charged.