“Hazelnut chocolate” Design Improves Solid-State Batteries

The world is flooded with stories about lithium battery fires (more frequently in consumer gadgets than in electric vehicles), putting a premium on battery safety research.

One of the most promising research fields is in solid state batteries, but they’re still subject to one of the biggest fire risks, however – the formation of dendrite structures on the anode surface, which can cause shorts.

Harvard researchers reckon they’ve stolen a march in the research race, announcing a lithium metal battery that features charging “in a matter of minutes”, a cycle life of at least 6,000 charges, and a way to manage the formation of dendrites.

The researchers from the university’s John A Paulson School of Engineering and Applied Sciences were led by associate professor Xin Li, who, in 2021, offered a multilayer design as a way to prevent dendrite formation.

In his latest research, Harvard’s media release explained, Li and his team use micron-sized silicon particles in the anode to stop dendrites forming.

“When lithium ions move from the cathode to the anode during charging, the lithiation reaction is constricted at the shallow surface and the ions attach to the surface of the silicon particle but don’t penetrate further,” the university explained.


“This is markedly different from the chemistry of liquid lithium ion batteries in which the lithium ions penetrate through deep lithiation reaction and ultimately destroy silicon particles in the anode.”

In the solid-state battery, ions on the surface of the silicon undergo lithiation, forming a lithium metal plate around the silicon core. As Xi said:

“In our design, lithium metal gets wrapped around the silicon particle, like a hard chocolate shell around a hazelnut core in a chocolate truffle.”

This creates a homogeneous surface across which the current density is evenly distributed, which prevents the growth of dendrites.

The even surface allows plating and stripping to happen quickly, which the research team claims allows ten-minute charging.

Their prototype, the size of a postage stamp, retained 80% of its capacity after 6,000 cycles.

Li and three Harvard alumni have co-founded a company called Adden Energy to license the technology, and the company says it’s scaled the battery up to a pouch battery the size of a smartphone.

“Lithium metal anode batteries are considered the holy grail of batteries because they have ten times the capacity of commercial graphite anodes and could drastically increase the driving distance of electric vehicles,” Li said.

Their research is published here, in Nature Materials.

About Richard Chirgwin

Joining the SolarQuotes blog team in 2019, Richard is a journalist with more than 30 years of experience covering a wide range of technology topics, including electronics, telecommunications, computing, science and solar. When not writing for us, he runs a solar-powered off-grid eco-resort in NSW’s blue mountains. Read Richard's full bio.


  1. The spread of these early development batteries in increasing numbers of appliances is turning us into guinea pigs for the technology, suffering random fires in all the toys we are increasingly taking in to close contact in our homes to recharge like the popular scooters, bikes, cars etc. This, if it hasn’t already will push up the already ridiculously high house and contents insurance especially as these fires are not easily extinguished.
    As a real fan and follower of technology I hope the holy grail of batteries is discovered soon.

  2. Max Scholefield says

    This is completely amazing, I knew once the phase-out of fossil fuels became a reality, the absolute necessity to create better battery storage would see speedy and massive improvement in batteries. How long do you think it could take to actually apply this technology to production?

  3. This was in my feed this morning, and so was this:

    These two are very exciting for the near future of everything solar, off-grid, EV etc.

    If they are not too good to be true that is…
    I would be interested to see an article with your take on that new solar technology!

    • I am not trying to put a damper on this, however the 1,000 may not be real – it is compared to the same thickness as pure “barium titanate”. What is the overall efficiency compared to “standard solar panels?” – anyones guess (unless I missed it somewhere…

      • Yeah, the 1,000 I think is just cherry picking by a website that makes money with ‘good news’.

        The original Science Advances article mentions that number in context, and buried within. But I can’t make much sense of that article, I lack the knowledge and skill.

    • Ian Thompson says

      Sounds like BS to me…

      Currently, the best panels are approaching 25% efficiency. That is, they convert nearly 25% of the light falling on them, to electricity.
      So, if new designs become 100% (probably not feasible for various reasons), then the upper limit becomes only 4x that of the very best current panels.

      • Thanks for replying.

        That Brighterside website looks very much like a clickbait site, but their source is the journal Science Advances, where they try hard to present it in a very much non-clickbait style:


        I don’t know enough about it to call BS (‘breaking science’), which is why I am eager to hear solar blog’s opinion.
        Of course, there have been heaps of promising concepts that could not be made commercially viable or only worked in a lab etc.

    • Ian Thompson says

      Well Lauren – first time I’ve heard the term ‘BS’ referred to as ‘breaking science’…!

      My point was that if a panel is being illuminated with a solar intensity of 1kW/square metre, it CANNOT generate an electrical power output exceeding 1kW/square metre of panel area. Fundamental physics/thermodynamics. No free lunches. So about 4x is the fundamental limit.

      But I note the article states the experimental panels were illuminated with laser light. This may be the source of the confusion. I have read of experimental (tiny) panels that can generate a much greater output than 1 kW/square metre of panel size. They can do this when illuminated with light many, many times more intense that sunlight e.g., concentrated sunlight. This can be done with magnifying lenses, mirrors, etc. Of course, these panels require the use of relatively massive heatsinks to prevent them from melting, very large lens, etc. And, of course would require very elaborate and precise tracking mechanisms to keep the units accurately focussed on the Sun if used for Solar PV.
      You wouldn’t want these perched on you roof!

  4. When these batteries are on the market get back to us please.

    I’m getting rather tired of these constant stories of incredible cheap, easy to manufacture, fast charging, high power density, ultra safe new tech batteries.
    One of the worst offenders for such stories is Toyota, who have had solid state batteries “just around the corner” for way more than six years now.
    It’s all FUD, just dangling a carrot and fake news and trying to get people to hold off to buy their tech, (in other words BS).

    There is typically a HUGE long lead time even for a very successful battery design technology, and of course numerous others that never ever get within cooee of living up to expectations and/or making it into production.

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