How semi-solid-state batteries are about to change power banks forever

Lithium-ion batteries have been the cornerstone of virtually all modern gadgets and the battery packs used to charge them up. They’ve been pretty good on the whole, enabling reasonably fast charging and good-sized portable capacities for our power banks and gadgets. However, there’s a new technology on the block that promises to take the best of traditional batteries and make them safer and faster: semi-solid-state batteries.

Take Singapore-based BMX’s new SolidSafe magnetic power bank lineup, for instance, which is built on a semi-solid-state battery. It promises 5,000mAh and 10,000mAh capacities and Qi2 magnetic wireless charging in a compact form factor measuring just 6.8mm thin. Best of all, the range starts at just $59, proving that new technology doesn’t have to cost a small fortune.

Power banks are an ideal proving ground for semi-solid-state batteries, allowing manufacturers to introduce and refine new battery technologies quickly before we see them in our phones, laptops, and other gadgets. If you’re wondering what a semi-solid-state battery even is and how it differs from the battery technology your power bank and gadgets already use, you’ve found the right article.

Conventional lithium-ion batteries use a liquid electrolyte that allows lithium ions to move between the cathode and anode during charging and discharging. Modern versions incorporate silicon-carbon (Si/C) into the anode, increasing energy density and helping manufacturers fit larger capacities into the same physical space, such as phones that now pack 7,000 mAh in the same space as older 5,000 mAh cells. But this core idea has remained mostly unchanged for well over a decade.

At the other end of the spectrum is solid-state battery technology. This is an entirely different approach to battery design that eliminates the liquid electrolyte and uses lithium metal or a similar material in the anode (hence, a solid-state battery).  Solid-state batteries can charge faster, are potentially much safer/far less flammable, and offer extremely high energy density. However, engineers are still working through challenges, including interface resistance, durability, manufacturing yield, and cost.

Enter semi-solid-state, which sits between the classic and cutting-edge designs. The key difference is that the electrolyte is neither fully liquid nor fully solid; instead, it uses a polymer or gel-based electrolyte, sometimes with a small amount of liquid added to improve conductivity. Semi-solid-state batteries typically retain many of the same cathode materials as modern lithium-ion batteries, such as Nickel Manganese Cobalt and Nickel Cobalt Aluminum.

The bottom line is that semi-solid-state aims to address the problems of legacy Li-ion batteries by leveraging solid-state ideas but making them more practical. However, not all semi-solid-state batteries are created equal, and the exact perks depend on how much liquid electrolyte remains in the design and the chemistry used by each manufacturer.

Now that we understand the technological differences, let’s get into what this actually means for the gadgets that you and I want to buy.

Let’s start with the pros and cons of traditional Li-ion battery packs. They’re moderately energy-dense (150–250 Wh per kg), allowing good-sized 10,000 mAh packs that aren’t too large or heavy. They can also fast charge at 1-3 times the cell’s C rate, which isn’t bad, but pushing higher is riskier from a heat perspective. However, Li-Ion battery packs have a mixed safety history and are a fire hazard if punctured. Airlines are increasingly unhappy about the risk, for example.

Semi-solid-state addresses many of these issues. The gel is far less of a safety risk, for a start. While not as “dry” as solid-state, the gels are less susceptible to thermal runaway, though the risk is not completely eliminated. But the major benefit for consumers is that the gel is also more power-dense, with some companies touting 300 Wh/kg or higher at the top end.

That’s a big potential benefit for consumers, meaning substantially higher energy per weight than standard Li-ion battery packs. Alternatively, brands can make their products slimmer, lighter, and more portable without sacrificing capacity. Meanwhile, semi-solid-state batteries retain comparable or better fast-charging capabilities (greater than 2C). Some semi-solid-state designs also promise improved cycle lives before capacity reduces, though real-world longevity will depend on the specific chemistry and implementation. Still, that’s a nice e-waste win.

But perhaps the most important point is that semi-solid-state batteries are a much more economically realistic prospect than the long-touted but yet-to-be-realized solid-state breakthrough. These new batteries can be manufactured on repurposed manufacturing lines and with existing materials, rather than solid-state’s entirely new tooling setup.

In fact, they’re already here and are comparable to the existing prices of traditional high-end battery packs. The Statik State Power Bank, BMX SolidSafe Power Banks, and Momax 1-Power S.Pass are just a few of the first-wave products already announced, priced between $50 and $100 depending on capacity.

While undoubtedly premium at the moment, semi-solid-state battery packs (and gadgets) potentially offer longer battery life, thinner devices, and longer-lasting products without costing substantially more. That’s undoubtedly a game-changer to keep an eye on.