New Battery Has No Anode

Conventional batteries have anodes and cathodes, but a new design from the University of Chicago and the University of California San Diego lacks an anode. While this has been done before, according to the University, this is the first time a solid-state sodium battery has successfully used this architecture.

Sodium is abundant compared to lithium, so batteries that use sodium are attractive. According to the University of Chicago’s news release:

Anode-free batteries remove the anode and store the ions on an electrochemical deposition of alkali metal directly on the current collector. This approach enables higher cell voltage, lower cell cost, and increased energy density…

Of course, there are also downsides. In particular, making anodeless batteries with liquid electrolytes can be easier to build, but the liquid forms solids that impede the battery’s performance over time.

The new battery uses an aluminum powder as a current collector. Interestingly, while this is a solid, it flows more like a liquid. Combined with a solid electrolyte, the battery flips the usual idea of a solid cathode and a liquid electrolyte.

We are always interested in new battery tech. However, we rarely see them out in the wild. Maybe AI will have better luck.

28 thoughts on “New Battery Has No Anode

  1. So a cell with a positive terminal but no negative terminal? Sounds more like word games than science. The “anode” is dead. Long live the ‘current collector’.

    But wait, isn’t the physical transport electrons moving from the anode to the cathode? Is it collecting protons? I’m confused.

    1. I think they are being… anal. The convential “Anode” of a battery does take part in the chemical reaction, and in this battery it doesn’t, so they are going with the “anodeless” moniker.

      Its still technically an anode, because a battery always has to have a positive and a negative connection. They just kinda decided to redefine exactly what an anode does, and since in this battery it doesn’t do that, its “Anodeless”.

      Using the same odd definition, a carbon zinc battery is also anode less, as the carbon itself doesn’t take part of the chemical reaction. Its just the “Collector”.

    2. Back in the old days there was a surplus place called poly packs cause they sold little poly packs of stuff. You could get the 1000 diode assortment for a few bucks. This was a mix of switching, signal. rectifier, and light emitting. We used to joke, and probably not too far off the mark, that they were selling floor sweepings from the semi factories around them. Looking through the pack of wonders it would not take you long to realize there was a lot of chaff in with the wheat. One popular form of the chaff was the infamous monode. Yea, you got a lot of monodes in the package, you got the whole mix of small signal, and switching, power and of course the infamous non light emitting monode. I think these would pair up well with this new battery tech. That and bi-istors.

      1. OMG, I haven’t thought about Poly-Paks in decades! I think I got on their mailing list by sending in one of those Popular Electronics “reader response cards” – each advertiser had a number printed under their ad, and you’d circle the numbers for the advertisers you wanted to hear from. I got on SO MANY mailing lists.

    3. >The “anode” is dead. Long live the ‘current collector’.

      I find it highly offensive that computer programs are forced to run even if they do not want to! Include the below text (code is deemed offensive) in the program to give it a chance to refuse!

      if(random() < 0.5) {
      printf("I don't feel like running");
      } else {

  2. Anodeless is kind of an absurd claim. The “current collector” Is the anode.

    The anode, in this case, is not chemically active in the reaction, but it is still an anode, defined as where conventional current enters the device, or the side of a cell where the oxidation reaction occurs, or the side where electrons, or negative charges, are collected internally (in all presentations, the negative terminal of a cell providing energy to the outside). The electrochemical deposition is an oxidation reaction, and negative charges are collected at that “current collector” internally, and conventional current enters the cell from the outside there. It is an anode by every definition.

    I hate “news” releases that screw up the basics to make a really cool development look like groundbreaking new science….

    1. It isn’t the ‘new release’ that is making any claims about the basic science. The entire project was for development of a design that removed a normally fundamental part of traditional battery design. Its ridiculous to try and be pedantic with definitions made to describe traditional battery design when looking at something like this.

      1. There is NOTHING pedantic about using words as they are defined in SCIENCE and ENGINEERING. In fact, I would say that it is fundamental to both fields that there are clear, precise definitions to work from.

        But what do I know?

  3. Some information gleaned out of the paper supplementary data file:

    A solid state battery has to be squeezed together to work. The required stack pressure is 10 MPa – roughly equivalent to a 100 kg man standing on a shirt button.

    The energy efficiency is only 85%

    Capacity fade -20% in 140 cycles.

    Energy density is a bit unclear, but it appears to be somewhere between 500-600 Wh/kg.

    1. And I mean, it has to be squeezed all the time – not just when you’re building the cell. Otherwise the solid layers could separate as they expand and contract from the sodium ions moving around, from temperature or mechanical shock etc.

      It’s a bit of a problem in building these batteries, since the forces involved are relatively large – it’s not exactly useful if you have to stack a ton of steel on top of your battery in order to make it work.

      1. But my 10,000 lbs hydraulic press doesn’t weigh 10,000 lbs. So I don’t see the need to stack a ton of steel on top of it when there is likely a solution involving a relatively small and light weight clip capable of exerting a 100Kg per shirt button (am I sure Kg/sb is the correct unit of pressure for that industry).

        1. True, but you still need a hydraulic press if you’re going to do it that way. Wonder what happens if the hoses gradually expand or a connector springs a leak?

          Of course it’s going to be some sort of frame with tight compression springs and bolts to clamp it all down, but it’s still going to be a lot more stuff around the battery than any of the people working with solid state batteries dare to admit.

          1. I was not thinking of use a hydraulic to maintain pressure, just to get the clip in place. But it may work, also pneumatic solutions may work. Most of those things would have some active component, compensating from hose stretching and minor leaks (although you still need to fix that leak soon).

            Thinking it about it more, there is probably a flexure based solution which is light weight and provides the appropriate force.

            There may also be some novel chemical based clamping force options (for example, a rust crystal growing in the wrong place can deform fairly thick steel, water freezing can crack up rock, etc.).

        2. Also note that MPa is equivalent to Newtons per square millimeter. The battery has a capacity around 5 mAh per 100 square millimeters. That’s one small button cell that they squeeze between two anvils in a press.

          How are you going to do that for a bigger battery is anyone’s guess.

    2. That’s a similar amount of force to what you get by tightening down a very small bolt. I don’t have access to the paper at the moment, just skimmed the supplemental, but they adequately explain to me why they have such a bulky pressure-creating mechanism when they demonstrate the benefit of pressure by testing it at varying pressures and temperatures. Additional confirmation: they didn’t just apply a bunch of pressure, they used springs that make it very easy to calculate and adjust pressure by tightening until the springs were deflected a certain amount, instead of just guessing based on torque values or numbers of turns. I do know there’s existing lithium pouch cells that need to be compressed, and my understanding is that the cylindrical version of the same chemistries is strong enough not to need that – so I imagine if this is say, 10x the pressure as what’s in a typical cylindrical cell, it only needs a slightly thicker wall in relation to the dimensions and it’ll be fine. It’ll cost a bit of space, sure, but not awful.

      I didn’t read closely enough to see if I disagree any on the efficiency, capacity, or other measures of performance. But if it’s at least fairly similar, and could be less problematic to source, that’s going to be useful somewhere.

  4. “And I mean, it has to be squeezed all the time…”

    A highly-compressed unit filled with sodium and aluminum, what could go wrong?

    I’ll stay with the LiFePO4 lower-efficiency rechargeable batteries a bit longer.

  5. “Is it collecting the current, or sucking it?”

    If a compass magnetic North needle points “N”, is it actually magnetized “S”? Science is full of terms that are based upon assumed definitions: “N”orth is thus defined as the magnetic pole that points to the geographic North direction.

    For electronics, a similar definition is established for current flow: conventional vs electron. Ref:

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