Stable-state batteries are the long run. They’re extra highly effective, compact, secure, and sustainable than Lithium-ion alternate 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 Solid-State Power Bank helps Qi2 for 15W wi-fi charging. And with a 5,000mAh (19Wh) capability, it holds sufficient vitality to simply cost the most recent iPhone 16 fashions — with batteries starting from 3,561mAh to 4,685mAh — from zero to full not less than as soon as. And regardless of utilizing the truncated “strong 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 fireside like Kuxiu did, I can not less than verify that it in any other case works as anticipated.
“Stable state” ambiguity
It’s not simply you, the battery trade 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 only a few of the extra widespread 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 probably require a number of go-between steps.
Stable-state batteries use a strong electrolyte — the part answerable for transferring electrically charged particles between the 2 terminals — however differ by way of the quantity of liquid current. If the quantity of the liquid electrolyte is between 5 and 10 % of the burden of the lively 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 blended electrolyte that kinds a gel-like consistency that’s seen within the video above. It subsequently matches the definition of semi-solid state, based on the corporate.
So why is “Battery Kind: Li Polymer Battery” listed within the fantastic 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 brief lifespans and low vitality densities — precisely the alternative of what Kuxiu claims for the brand new S2. Seems that the strong electrolyte inside solid-state batteries might be produced 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. Due to this fact, it could very properly 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 probably have laying round at residence incorporates over 25wt % liquid, making it extra susceptible to leakage, thermal runaway, and hearth than the S2. However Kuxiu’s energy financial institution doesn’t profit from each benefit of going strong state — like ever larger vitality densities and larger security achieved with all-solid state batteries — however it’s a step in the proper path. Notably, Kuxiu can mass produce the S2 at this time utilizing many current manufacturing processes to assist hold prices down.
Corporations like Anker will tell you {that a} typical 5,000mAh energy financial institution normally 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 sweet 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.
The vitality density is one other benefit of the semi-solid state battery contained in the S2. Kuxiu claims 360Wh/kg in comparison with 300Wh/kg for liquid cells. The S2 is definitely compact and light-weight at 10.4 x 6.7 x 1.0cm / 145g, which makes it extra moveable than EcoFlow’s direct competitor which measures 10.8 x 7.0 x 1.44cm / 180g. However EcoFlow’s 5,000mAh power bank additionally features a kickstand and 30W of bidirectional wired charging. Anker, nevertheless, edges out the S2 in dimension and weight with its 5K power bank measuring 10.2 x 7.0 x 0.9cm / 120g. However that probably says extra in regards to the supplies used to brighten and defend the batteries than their respective vitality 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 sturdy and keep the bond whilst I slip the combo right into a unfastened pocket or bag. Nonetheless, they’re not proof against a well-placed bump that would ship the battery to the ground. That would spell hassle 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 evaluation unit has a small however noticeable nick on the shell, however in any other case seems new.
Sadly, the underside of the battery extends past my iPhone 15 Professional to upset the symmetry I’d probably take pleasure in when paired with considered one of Apple’s bigger Qi2-compatible iPhones. Not less than 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 and not using 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 possibly can cost the ability financial institution and a magnetically connected iPhone or AirPods on the identical time. Charging the S2 solo from my MacBook’s wall charger took the ability financial institution from zero to full in a moderately gradual 90 minutes.
The ability financial institution can even cost non-Qi2 gadgets because of its bidirectional USB-C port. That’s helpful to juice up gadgets 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 ability financial institution right into a low-current mode. That method, the S2 can cost small gadgets like good rings and wi-fi earbuds whereas bypassing automated shutoff mechanisms designed for extra power-hungry gadgets. 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. Not less than it’s accessible in each black and titanium colours to higher match your cellphone.
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Deceptive battery advertising and marketing apart, I’m very impressed by the Kuxiu S2 Qi2 5000mAh MagSafe “Stable-State” Energy Financial institution by way of what it’s and what it guarantees. Sure, it’s costlier 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.
Pictures by Thomas Ricker / The Verge