Stable-state batteries are the long run. They’re extra highly effective, compact, protected, and sustainable than Lithium-ion options, however true all-solid state batteries can’t be mass-produced cost-effectively. That’s why Kuxiu has gone semi-solid state for what it calls the “world’s most secure” energy financial institution, whereas calling dibs on it being a world first.
Kuxiu’s $79.99 S2 Qi2 5000mAh MagSafe Stable-State Energy Financial institution helps Qi2 for 15W wi-fi charging. And with a 5,000mAh (19Wh) capability, it holds sufficient power to simply cost the newest iPhone 16 fashions — with batteries starting from 3,561mAh to 4,685mAh — from zero to full a minimum of as soon as. And regardless of utilizing the truncated “stable state” within the S2 title and product web page, the corporate confirmed to me that it’s constructed round a semi-solid state battery and that distinction issues.
I’ve been carrying the Kuxiu S2 for the previous few weeks. Whereas I didn’t hammer, pierce, or tear the battery aside or expose it to fireplace like Kuxiu did, I can a minimum of affirm that it in any other case works as anticipated.
“Stable state” ambiguity
It’s not simply you, the battery business itself can’t appear to agree on what qualifies as a solid-state battery. There’s all-solid state, semi-solid state, and quasi-solid state, to call just some of the extra standard phrases. All-solid state is the place the hype is and it’s the liquid-free battery of the long run. However getting there at scale will possible require a couple of go-between steps.
Stable-state batteries use a stable electrolyte — the element liable for transferring electrically charged particles between the 2 terminals — however differ when it comes to the quantity of liquid current. If the quantity of the liquid electrolyte is between 5 and 10 % of the burden of the energetic a part of the battery then it’s usually categorized as semi-solid state. Lower than 5 % and it’s quasi-solid state. 0 %, you guessed it: all-solid state. The battery contained in the Kuxiu S2 incorporates a solid-liquid combined electrolyte that varieties a gel-like consistency that’s seen within the video above. It due to this fact suits the definition of semi-solid state, in response to the corporate.
So why is “Battery Kind: Li Polymer Battery” listed within the effective print on the label stamped onto Kuxiu’s S2 energy financial institution? LiPo batteries have been round in energy banks for years, and endure from comparatively quick lifespans and low power densities — precisely the alternative of what Kuxiu claims for the brand new S2. Seems that the stable electrolyte inside solid-state batteries will be created from numerous supplies like ceramics and sure, polymers. So Kuxiu’s declare is probably going true, the S2 is a Li Polymer battery that’s additionally a solid-state battery, or semi-solid state to be exact. Subsequently, it might very effectively be the world’s first energy financial institution to make use of a solid-state battery as the corporate says.
For comparability, the Lithium-ion battery discovered within the energy financial institution you possible have laying round at dwelling incorporates over 25wt % liquid, making it extra susceptible to leakage, thermal runaway, and fireplace than the S2. Kuxiu’s energy financial institution doesn’t profit from each benefit of going stable state — like ever increased power densities and higher security achieved with all-solid state batteries — but it surely’s a step in the fitting route. Notably, Kuxiu can mass produce the S2 in the present day utilizing many present manufacturing processes to assist hold prices down.
Corporations like Anker will inform you {that a} typical 5,000mAh energy financial institution often begins to degrade after 300–500 charging cycles. At that time, it’ll solely maintain about 60 to 80 % of the unique capability. Kuxiu tells me that the S2 is nice for 1,000 charging cycles earlier than capability drops to 80 %. So, whereas it prices about 60 % greater than a comparable liquid-based energy financial institution from firms like Anker or EcoFlow, it ought to simply final twice as lengthy earlier than you see any noticeable degradation.
Kuxiu claims an improved 360Wh/kg power density in comparison with 300Wh/kg for liquid cells. The S2 is actually compact and light-weight at 10.4 x 6.7 x 1.0cm / 145g, which makes it extra transportable than EcoFlow’s direct competitor which measures 10.8 x 7.0 x 1.44cm / 180g. However EcoFlow’s 5,000mAh energy financial institution additionally features a kickstand and 30W of extra highly effective bidirectional wired charging. Anker, nevertheless, edges out the S2 in measurement and weight with its 5K energy financial institution measuring 10.2 x 7.0 x 0.9cm / 120g. However that possible says extra in regards to the supplies used to embellish and shield the batteries than their respective power densities.
As a MagSafe-compatible Qi2 energy financial institution, the Kuxiu S2 routinely begins charging as quickly as its 16 N52 magnets seize maintain of my iPhone 15 Professional. These magnets are robust and preserve the bond at the same time as I slip the combo right into a unfastened pocket or bag. Nonetheless, they’re not proof against a well-placed bump that might ship the battery to the ground. That might spell bother for the aluminum S2 sandwiched between two sheets of Corning Gorilla Glass, every protected by an “explosion-proof movie.” After three weeks of careless dealing with, my S2 overview unit has a small however noticeable nick on the shell, however in any other case seems to be new.
Sadly, the underside of the battery extends past my iPhone 15 Professional to upset the symmetry I’d possible get pleasure from when paired with certainly one of Apple’s bigger Qi2-compatible iPhones. At the very least the cameras aren’t obscured. I might additionally do with out all of the specs listed on the skin of the unit. The ability financial institution does work with or with out a MagSafe-compatible case on my iPhone, however the case does trigger the S2 to warmth up barely (making it much less environment friendly) to assist overcome the hole.
The USB-C port on the underside of the S2 options passthrough, so you’ll be able to cost the facility financial institution and a magnetically hooked up iPhone or AirPods on the identical time. Charging the S2 solo from my MacBook’s wall charger took the facility financial institution from zero to full in a relatively gradual 90 minutes.
The ability financial institution can even cost non-Qi2 units due to its bidirectional USB-C port. That’s helpful to juice up units like over-the-ear headphones and Android telephones at as much as 20W. The S2 additionally proved able to topping up my beefy 14-inch MacBook Professional, albeit very, very slowly.
A double-tap on the button alongside the underside edge places the facility financial institution right into a low-current mode. That manner, the S2 can cost small units like sensible rings and wi-fi earbuds whereas bypassing automated shutoff mechanisms designed for extra power-hungry units. Sensible, however not distinctive to the S2.
I do want that Kuxiu put a kickstand on the S2 like so a lot of its rivals. At the very least it’s obtainable in each black and titanium colours to raised match your telephone.
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Deceptive battery advertising apart, I’m very impressed by the Kuxiu S2 Qi2 5000mAh MagSafe “Stable-State” Energy Financial institution when it comes to what it’s and what it guarantees. Sure, it’s dearer than equally specced energy banks utilizing conventional liquid electrolytes, however the S2’s semi-solid state battery ought to show to be safer and cheaper than rivals over its for much longer lifetime.
Photographs by Thomas Ricker / The Verge
