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…
As a result of the European Union’s push for greater repairability of consumer devices like smartphones, Apple sees itself forced to make the batteries in the iPhone user-replaceable by 2027. Reportedly, this has led Apple to look at using electroadhesion rather than conventional adhesives which require either heat, isopropyl alcohol, violence, or all of the above to release. Although details are scarce, it seems that the general idea would be that the battery is wrapped in metal, which, together with the inside of the metal case, would allow for the creation of a cationic/anionic pair capable of permanent adhesion with the application of a low-voltage DC current.
This is not an entirely wild idea. Tesa has already commercialized it in the electrical debonding form of its Debonding on Demand product. This uses a tape that’s applied to one side of the (metal) surfaces, with a 5 bar pressure being applied for 5 seconds. Afterwards, the two parts can be released again without residue as shown in the above image. This involves applying a 12V DC voltage for 60 seconds, with the two parts afterward removable without force.
Regulations surrounding disposable batteries have accelerated a quiet race to replace coin cells, which on the whole are not readily rechargeable. TDK produces solid-state batteries and has announced a new material that claims an energy density of about 100 times that of their conventional batteries.
Energy density measures how much energy a system contains relative to its volume. The new battery has 1000 Wh/L. For comparison, old nickel-cadmium cells had about 150 Wh/L. A typical lithium-ion battery usually turns in about 200 – 250 Wh/L.
There aren’t many technical details, but a few things caught our interest. For one, it uses an oxide-based solid electrolyte and lithium alloy anodes. However, what really caught our eye was that it is “intended for use in wearables… that come in direct contact with the human body.” We don’t know if that means the material is safe for your skin or if it depends on being next to your body to operate.
While the energy density is high, keep in mind that the batteries of this type are usually tiny, so the total actual power available is probably not very high. Tiny batteries are definitely a thing. We are always hearing about breakthroughs, but we always wonder if and when we’ll see actual products.
For those willing to put some elbow grease into it, there is an almost unlimited supply of 18650 lithium ion batteries around for cheap (or free) just waiting to be put into a battery pack of some sort. Old laptop and power tool batteries are prime sources, as these often fail because of one bad cell while the others are still perfectly usable. [limpkin] built a few of these battery packs and now that he’s built a few, he’s back with a new project that allows him to use four custom packs simultaneously.
The problem with using different battery packs in parallel is that unless the batteries are charged to similar voltages, they could generate a very high and potentially dangerous amount of current when connected in parallel. This circuit board, powered by a small ATtiny microcontroller, has four XT60 connectors for batteries and a fifth for output. It then watches for current draw from each of the batteries and, using a set of solid-state relays, makes sure that no dangerous over-current conditions occur if the batteries are connected with mismatched voltages. The code for the microcontroller is available on this GitHub page as well.
An array of batteries with a balancing system like this has a number of uses, from ebikes to off-grid power solutions, and of course if you build your own packs you’ll also want to build a cell balancer of some sort as well. Batteries go outside the realm of theory and into that of chemistry, so we’ll also provide a general warning about working in potentially dangerous situations without specialized knowledge, but you can see how [limpkin] built his original packs here if you want to take a look at one person’s strategy for repurposing old cells.
Cheap uninterruptable power supply (UPS) boards that take Li-ion cells of some description seem to have cropped up everywhere the past years. Finding use in applications such as keeping single-board computers ticking along in the case of a power failure, they would seem to be a panacea. Unfortunately most of these boards come with a series of fatal flaws, such as those that [MisterHW] found in an LX-2BUPS board obtained from AliExpress. Worst of all was the deep discharge of the Li-ion cells to below 2 V, which took some ingenuity and hard work to fix this and other problems.
The patched up XR2981 boost IC with MCP809 reset IC installed. (Credit: [MisterHW])This particular board is rated for 5V at 3A, featuring the all too common TP4056 as charging IC and the XYSemi XR2981 boost converter. Since there is no off-switch or other protections on the board, the XR2981 will happily keep operating until around 2.6V, at a rather astoundingly high idle power consumption. Because of this the fixes mostly concentrated on optimizing the XR2981, by using better resistor values (R7, R8, R9), as well as adding a 3.15V MCP809 reset IC, to reduce idle power usage of the boost converter and disable it below a safe cell voltage.
The final coup de grâce was the eviction of the red LED (D6) and replacing it with the blue LED from D2, to stop the former from draining the cell as well. With these changes in place, no-load power usage dropped from nearly 900 µA to just over 200 µA, while preventing deep discharge. Although this board now has a second life, it does raise the question of what the point of these cheap UPS boards is if you have to spend money and time on reworking them before they’re somewhat acceptable. What is your go-to solution for these boards?
Today’s hack is an unexpected but appreciated contribution from members of the iFixit crew, published by [Shahram Mokhtari]. This is an ROG Ally Asus-produced handheld gaming console mod that has you upgrade the battery to an aftermarket battery from an Asus laptop to double your battery life (40 Wh to 88 Wh).
There are two main things you need to do: replace the back cover with a 3D printed version that accommodates the new battery, and move the battery wires into the shell of an old connector. No soldering or crimping needed — just take the wires out of the old connector, one by one, and put them into a new connector. Once that is done and you reassemble your handheld, everything just works; the battery is recognized by the OS, can be charged, runs the handheld wonderfully all the same, and the only downside is that your ROG Ally becomes a bit thicker.
We’re still in the early days of modern EV infrastructure, so minor issues can lead to a full high voltage pack replacement given the lack of high voltage-trained mechanics. [Ed’s Garage] was able to source a Spark EV battery pack that had succumbed to a single bad cell and takes us along for the disassembly of the faulty module.
The Spark EV was the predecessor to the more well-known Chevy Bolt, so its nearly ten year old systems might not reflect the state-of-the-art in EV batteries, but they are certainly more modern than the battery in your great-grandmother’s Baker Electric. The Li-ion polymer pouch cells are sandwiched together with cooling and shock absorbing panels to keep the cells healthy and happy, at least in theory.
In a previous video, [Ed’s Garage] takes apart the full pack and shows how the last 2P16S module has assumed a darker color on its yellow plastic, seeming to indicate that it wasn’t receiving sufficient cooling during its life in the car. It would seem that the cooling plates inside the module weren’t quite up to the task. These cells are destined for other projects, but it doesn’t seem like this particular type of battery module would be too difficult to reassemble and put back in a car as long as you could get the right torque settings for the compression bolts.
If you’re looking for other EV teardowns, might we suggest this Tesla Model S pack or one from a passively-cooled Nissan Leaf?
![The patched up XR2981 boost IC with MCP809 reset IC installed. (Credit: [MisterHW])](https://hackaday.com/wp-content/uploads/2024/05/upload_34f9a5c70d7738a67185359c3110505b.jpg)
