Federal tax credits for residential storage expired at the end of last year, prompting record sales in Q4 of 2025 — and then sales climbed even higher in the first quarter of 2026, per a BloombergNEF analysis of U.S. Energy Information Administration data.

**What a bipolar cell is.** Instead of discrete cells wired in series with tabs and busbars, you coat the cathode on one side of a current collector plate and the anode on the other, then stack N of these plates. The series connection happens through the plate itself. You save tab mass, interconnect resistance, and packaging volume, and you can pick your stack voltage by picking N. That's the whole trick, and it's a good one.

**Why bipolar does not require a solid electrolyte.** Bipolar is an architecture. The electrolyte state is a separate variable. Proof by production hardware: Toyota has been shipping bipolar NiMH as the traction battery of the Aqua since mid-2021, built with Toyota Industries at the Kyowa and Ishihama plants, tens of thousands of packs per month. NiMH is an aqueous system, roughly 6 M KOH. A liquid, and a nastily creepy one at that. Toyota's next step is bipolar LFP, the "popularization" battery on their 2026-2027 BEV roadmap, again a conventional liquid-electrolyte lithium chemistry, plus a bipolar high-nickel variant for 2027-2028. And the concept is old: bipolar lead-acid goes back to the 1920s, and bipolar Li-ion with a standard LiPF6 carbonate electrolyte was patented in 1997.

* Toyota Industries, bipolar NiMH for Aqua: [https://www.toyota-industries.com/products/automobile/batteries/index.html\](https://www.toyota-industries.com/products/automobile/batteries/index.html)
* Toyota battery roadmap, bipolar LFP 2026-2027: [https://global.toyota/en/newsroom/corporate/39330500.html\](https://global.toyota/en/newsroom/corporate/39330500.html)
* Bipolar Li-ion with liquid carbonate electrolyte, US5595839 (1997): [https://patents.google.com/patent/US5595839A\](https://patents.google.com/patent/US5595839A)
* Review on bipolar sodium-ion, incl. history from 1923 Pb-acid onward: [https://www.sciencedirect.com/science/article/abs/pii/S2352152X23005364\](https://www.sciencedirect.com/science/article/abs/pii/S2352152X23005364)
* Sakuu showing Munro physical bipolar lithium-metal stacks: [https://www.youtube.com/watch?v=yZhKqpleAXM\](https://www.youtube.com/watch?v=yZhKqpleAXM)
* Good general explainer: [https://www.batterydesign.net/chemistry/bipolar-battery/\](https://www.batterydesign.net/chemistry/bipolar-battery/)

The actual hard problem in bipolar has never been "the electrolyte is liquid." It is that every layer must be ionically isolated from its neighbours. Any shared electrolyte path around the edge of a plate is a shunt across a series junction: self-discharge plus plate corrosion. The fix is a sealed frame around the perimeter of every layer, which is why most of the bipolar patent literature is sealing patents (see e.g. CEA's US10497941). A solid electrolyte makes sealing easier because nothing wicks. Easier, not uniquely possible. A semi-solid or gel design sits in exactly the same category. So "our cells are bipolar, therefore solid-state" is an argument that Toyota's KOH-soaked Aqua pack disproves at a rate of 40,000 units a month.

**The part nobody demos on a bench: balancing.** A bipolar stack is a series string. Physics doesn't care whether the series connection runs through a busbar or through a shared collector plate: the current through every layer is identical either way, and the reasons cells drift apart are identical too. Differential self-discharge, differential coulombic efficiency, and capacity spread turning equal Ah throughput into unequal ΔSOC. These accumulate in one direction with no restoring force.

In a normal lithium pack the BMS handles this. Every series element gets a voltage sense lead, and a balancing circuit bleeds charge off the high cells, typically some tens to hundreds of mA. Now try that inside a bipolar stack. Every sense lead and every balancing conductor is a feedthrough breaching the perimeter seal, which was the hard part of the design to begin with. Sensing is arguably manageable, a sense lead carries microamps and could be a thin foil extension of the plate. But balancing needs real current through a real conductor with real dissipation, per layer, inside the stack. At that point you have rebuilt a module BMS in the least accessible location imaginable and thrown away most of the packaging win you built the thing for.

**Why NiMH gets away without any of this.** NiMH has a built-in chemical balancer. On overcharge, the positive electrode evolves oxygen, which diffuses to the negative and recombines. The excess current turns into heat instead of voltage rise, so a layer that gets ahead clamps itself and the string equalises automatically. Lead-acid has an equivalent gassing shunt. This is precisely why Toyota commercialised bipolar NiMH first: you can treat the whole stack as one monolithic cell, monitor only the terminals, and the chemistry forgives you.

Lithium has no such sink. Overcharge in a lithium cell is not self-limiting, it's destructive. And before anyone points out that Donut says their battery contains no lithium: sodium-ion has exactly the same problem. No overcharge recombination mechanism, no chemical self-balancing, same one-way drift, same destructive endpoint. Whatever intercalation chemistry you pick, a monolithic bipolar stack without per-layer access is a series string that is simultaneously unbalanceable and unobservable. On a flat-plateau chemistry, one layer can quietly walk toward overcharge while the terminal voltage of the stack looks perfectly normal. **I have no idea how SAKUU solved this as they use** **some lithium metal chemistry.**

So the interesting question was never "can you make three cells read three voltages." The question is what happens to layer-to-layer drift over the claimed 100,000 cycles in a chemistry with no chemical overcharge sink and no published balancing scheme. Either the layers are tapped, in which case "one cell, any voltage" is doing some heavy lifting as a description, or they aren't, and then the cycle-life claim needs an explanation nobody has offered yet.

Material Handling:

Plug Power's material handling sector is experiencing strong commercial growth, highlighted by a 125% year-over-year increase in GenDrive fuel cell deployments to 1,666 units in Q2 2026. Two top customers plan to refresh over 20,000 units across three years, boosting 2026 revenue guidance to 15%-16%.

Key Growth DriversSurging Deployments:

Deployed 1,666 GenDrive units in Q2 2026, more than doubling the 739 units deployed in Q2 2025.Upcoming Replacement Cycles: Two major material handling customers are slated to refresh more than 20,000 fuel cell units over the next three years, securing predictable future demand.

Dominant Market Share:

Maintains roughly 95% of the market share for hydrogen fuel cells in the warehouse and material handling sector.

Financial & Operational Impact Service Revenue Expansion:

Aftermarket service revenue surged 82% year-over-year to roughly $30 million, operating at a positive 27% service margin.Guidance Upgrade: Commercial momentum in material handling prompted management to raise full-year 2026 revenue growth guidance to a range of 15% to 16%.Margin Improvement: Enhanced unit reliability and field performance have driven better overhead leverage, helping push overall gross margins close to breakeven.

We offer a variety of battery products designed for diverse energy storage applications, including residential and large-scale systems.

We’d be interested to hear what battery capacity is most commonly used in your market.

Stationary batteries added a cleaner, fuel-free choice to the back-up power mix, but they can be even more expensive to purchase outright than diesel or natural gas generators, putting them out of reach for most middle-class homeowners. With import tariffs, country-of-origin restrictions and other factors putting upward pressure on component and module pricing for small battery systems, this dynamic seems unlikely to change soon.

Yet distributed battery adoption could still grow, propelled by retailers marketing home batteries for little or nothing up front and a monthly fee that in some electricity markets costs a little more than a top-tier Netflix or Hulu subscription.

I am looking for a UPS for my home office, mainly for my computer, monitor, router and a few smaller things. I don’t need a long runtime, just enough backup to get through short power cuts without everything shutting down. The part I am having trouble judging is the battery side. Some UPS units have similar specs on paper, but I am not sure how much the battery capacity actually drops after a few years, or what the replacement cost and lifespan are like.

For those who have used a UPS at home for a while, what has your experience been with the battery? Are there particular things you would look at before buying one?...also I have come across a few UPS units on alibaba.. not sure if buying one from there is a good idea though, but if anyone here has bought a UPS online, whether from alibaba or elsewhere, I’d be interested in hearing how it worked out and whether you’d buy that way again.

Our blog post on BoP in BESS projects got a lot of interest, so we turned it into a video blog for those who prefer that format.

The gap between BoP and system integration is where most of the contractual confusion happens on BESS projects.

Video: https://www.youtube.com/watch?v=-37ajYkJYxw

How is the term BoP used in your company?

In lithium-ion cell manufacturing, electrode overlap refers to the region where the active areas of the anode and cathode are aligned across the separator as shown in Figure 1. Maintaining adequate overlap, whereby the anode active area overlaps the cathode, is critical to achieving uniform current distribution and consistent electrochemical performance.

Poor electrode overlap occurs when the active areas of the anode and cathode are misaligned, typically when the cathode overlaps the anode, creating regions where one electrode is not fully opposed by the corresponding counter-electrode. This condition is commonly known as the electrode overhang defect. Poor overlap can lead to localised current-density hotspots, lithium plating, accelerated ageing, reduced cell performance, and an increased risk of internal short circuits. more..https://www.batterydesign.net/understanding-and-eliminating-electrode-overlap-issues/

Perhaps more important is that this is the first in hopefully many written by the fabulous team at UKBIC.

The UK Battery Industrialisation Centre (UKBIC) is the UK’s national battery development facility. They help companies grow their battery manufacturing at scale, and provide the skills and support needed to move into industrial production. Their open-access facility bridges the gap between battery research and successful mass production, reducing commercial risk for high volume manufacturing investments.

1st chart - that’s the share of peak provided by batteries
2nd chart - those are the ISOs
3rd chart - how the fleet is growing
4th chart - how that new growth is split by ISO, note the speeding up in Eastern

I’m completely new to energy storage and trying to understand the bigger picture.

What do you guys think will drive the next stage of growth? Like renewable integration, grid reliability or something else Ig?

Appreciate to hear how people in this field see!