I noticed, by reading the article, that Nickel 63 decays to Copper 63 which is stable.
"Betavolt further states the battery is environmentally friendly. “After the decay period, the nickel 63 isotopes become a stable isotope of copper, which is non-radioactive and does not pose any threat or pollution to the environment,” the company explains. “Therefore, unlike existing chemical batteries, nuclear batteries do not require expensive recycling processes.” "
I noticed, by reading the article, that Nickel 63 decays to Copper 63 which is stable.
"Betavolt further states the battery is environmentally friendly. “After the decay period, the nickel 63 isotopes become a stable isotope of copper, which is non-radioactive and does not pose any threat or pollution to the environment,” the company explains. “Therefore, unlike existing chemical batteries, nuclear batteries do not require expensive recycling processes.” "
https://en.wikipedia.org/wiki/Isotopes_of_nickel
Key word ‘after decay period’, which means after it’s lost all or most of its radioactivity… still a lot of time.