Strong-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 Strong-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 most recent 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 “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 fireplace like Kuxiu did, I can a minimum of verify that it in any other case works as anticipated.
“Strong 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 just some of the extra common 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 doubtless require a number of go-between steps.
Strong-state batteries use a strong electrolyte — the element accountable 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 load of the energetic a part of the battery then it’s usually categorised 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 due to this fact suits the definition of semi-solid state, based on the corporate.
So why is “Battery Kind: Li Polymer Battery” listed within the tremendous print on the label stamped onto Kuxiu’s S2 energy financial institution? LiPo batteries have been round in energy banks for years, and undergo from comparatively quick lifespans and low power densities — precisely the alternative of what Kuxiu claims for the brand new S2. Seems that the strong electrolyte inside solid-state batteries may be comprised of 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 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 doubtless have laying round at house incorporates over 25wt % liquid, making it extra liable 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 greater power densities and higher security achieved with all-solid state batteries — nevertheless it’s a step in the correct course. Notably, Kuxiu can mass produce the S2 at present utilizing many current manufacturing processes to assist maintain prices down.
Firms like Anker will let you know {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 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.
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 doubtless says extra in regards to the supplies used to brighten 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 whilst I slip the combo right into a free pocket or bag. Nonetheless, they’re not proof against a well-placed bump that might 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 appears new.
Sadly, the underside of the battery extends past my iPhone 15 Professional to upset the symmetry I’d doubtless get pleasure from when paired with one among Apple’s bigger Qi2-compatible iPhones. At the least the cameras aren’t obscured. I might additionally do with out all of the specs listed on the skin of the unit. The facility 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’ll be able to 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 somewhat sluggish 90 minutes.
The facility 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 sensible rings and wi-fi earbuds whereas bypassing automated shutoff mechanisms designed for extra power-hungry gadgets. Good, however not distinctive to the S2.
I do want that Kuxiu put a kickstand on the S2 like so lots of its rivals. At the least it’s accessible in each black and titanium colours to higher match your telephone.
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Deceptive battery advertising and marketing apart, I’m very impressed by the Kuxiu S2 Qi2 5000mAh MagSafe “Strong-State” Energy Financial institution when it comes to 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.
Photographs by Thomas Ricker / The Verge
