You seem to not understand some of the physics here...so let me give you a tour of why this is stupid. Not a little stupid, very stupid.
First off, this is not novel or new. There are horror stories of old soviet era equipment breaking down with thermal nuclear batteries. It's RTG...and it's great if you want a constant source of power and heat as long as your power draw is minimal and you can choose a blend of radioactive isotopes that you can wrap in sufficiently dense material to absorb the daughter particles from the radioactive decay inside the unit. This is how it's "safe..." but there are some pretty gnarly stories of what these safe long life batteries do in the wild.
Wikipedia on RTG
Summary and youtube video link on Soviet shenanigans
Now let me explain the technical side here...you have capacity, size, or duration. It's a triangle. The isotope blend that gives you more output requires either a larger size, or a shorter duration. This is how things like light houses were powered for years...by a reactor the size of a car that ran a lightbulb. If you want a lifetime pacemaker battery you need to either have a very small output, or a much larger battery. The article you linked to doesn't actually disagree with this...they just indicate Elon Musk levels of BS selling snake oil science.
Let me also suggest that this is not safe...it's a matter of relative danger. If you want to understand check out videos on youtube by Plainly Difficult... The gist of this is that radioactive stuff is very safe until anything vents...and the second you lose shielding you get lots of dead people.
I'm also going to call shenanigans on a lot of stupidity here...that people often miss. A nuclear battery cannot ramp up, it's always going down. I'm sure a lot of people have had an electronic device that absolutely chewed through battery capacity, because it's potential. That is the potential difference between the two poles can be pulled out quickly or slowly....but nuclear batteries do not. Imagine if your cell phone was stuck in the 90s...when they had a brick of battery and managed a few hours of life...which is because they ran full tilt at all times. Bleh. This is also why we don't have magic tech like thorium powered cars (another nuclear decay battery), which is because nobody in their right mind would have a car that has to output energy constantly whether at 100 Mph or at 0...meaning that you would basically require your nuclear battery to either output enormous heat when idle.
-Edit-
Maybe a slightly less mewling repeat article that is Chinese propaganda would be in order:
Tom's Hardware article
It's actually showing diamond sheets converting the decay of Nickel into Copper via stacked sheets. Holy crap, that's using a conductive crystal lattice with introduced beta decay to generate your power. That would theoretically be great....but then you're looking at something that isn't commercially viable. Why not? Well that's different tech that hasn't been made feasible in almost a decade. Proof, maybe this 2016 article:
2016 Magic carbon battery tech...
So...without proof what I'm seeing is a lattice that would generate energy in two ways. Thermal variation generates piezo effects and some beta decay might generate some power...that you need the carbon lattice to convert and would slowly be turned to an unstable isotope that itself would decay into Nitrogen over time.
So...yeah. I went down the rabbit hole, and what I see is not a new beta decay model. What I see is people assuming that despite the last 7 years not providing that as viable and the power output being much closer to an RTG than the theoretical beta decay...which based on a much older article would last thousands of years instead of 20.
The "we can withstand any temperature, and tolerate output variation" is also a dead give-away in my book. Radioactive decay cannot be currently modelled...so being able to generate variable output is often made possible by using the generating thermocouple as a storage medium of sorts. That's great for an RTG...but a true beta decay based battery has no buffer. If you get 100 decays in 60 seconds, then 1000 in the next 60 seconds, then you have nothing to do but deliver unclean power. In a thermocouple you meter that by the energy produced being a function of the delta between hot and cold...so variation in thermocouple end temperatures offers the variability. Beta decay...doesn't have that feature....unless they mean dozens of layers will always average out to a known range...but it's not like that's a practical way to meter conversion.
-
Edit end-
Let me top this off with one final note. This is a dumb proposition by a start-up that will die in less than a year...if they make it that long. Hopefully people can finally understand it...but I'll explain this simply. I don't power my blender with a V10 engine, my phone doesn't have a bio-reactor, and my electronics that matter are powered by a stable chemical reaction. None of this is because "I don't want a brighter future." All of it is because of the same logic that sees me not spreading napalm on my lawn to both shorten and dispose of grass clippings. You don't use the wrong tool for the job, and RTG is not the right tech for ultra small batteries.
Let me also introduce you to a simple calculation. e=mC^2. Note that a nuclear battery, which is not 100% converting mass into energy, has to derive that from somewhere. Imagine that 5 Watts, which is 5 Joules per second, over 50 years. 50 years * 31,536,000 seconds/year * 10 Joules/second * 1/0.1 (assuming a 10% conversion of mass from mother particle to daughter particles during decay) * 1/0.5 (assuming a 50% efficiency in converting the energy into usable electrical energy based on a very generous interpretation of RTG) and suddenly that small battery being capable of every powering a modern phone for 50 years requires that you stick a laptop battery level weight to the thing...and if I do that I'm already capable of not needing to recharge my phone but once a month even with the propensity for the phone to vary wildly in energy consumption to provide the best performance and battery life depending on the situation. In three words, "I call shenanigans."
_________________________
As a reference;
1) Hyperloop is not Elon Musk's idea...it was dreamt up and tried ages ago. Heck, Jules Verne referred to a vacuum train.
2) Hyperloop as of the date of this post is officially dead...so Musk has proven "it is really simple" isn't really true.
3) Speaking of dead, and poor taste in words, how's that automatic driving going? Hmmm.... That bad. Oooh. That is...discouraging.
4) The US knew where to stick RTG. Both the US and Soviets used these generators in long term space missions. This is why today we are still getting data from probes.
5) Seriously...RTG is insanely freaking dangerous. The second the outer shell decays at all you go from "no radiation" to liquified internal organs. I support nuclear power, and these things scare the crap out of me such that proposing I stick one in a pacemaker inside of me is a stupid risk. Why in hades do you think that this is safe because somebody told you so...when even a small amount of research proves they lied about the origin of the idea, the author did a terrible job highlighting the obvious trade-off between output-size-lifetime, and the available stories on RTG are the stuff of pure nightmare fuel? People fear spent reactor water, that can be distributed into the ocean at levels which don't exceed background, why in Hade wouldn't they fear a very literal item that if they failed like the cheap lithium batteries we have now would quite literally cause a national disaster requiring superfund dollars (if you're in the US) to clean?
While the technology is interesting, there is no way this will find it's way into consumer products in the near future.
,
.