CALB u shaped battery. Courtesy of CALB via CNEvPost

CALB Introduces U-Shaped Battery Technology

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CALB is a Chinese battery manufacturer that wants to compete with the much larger and well known CATL. It has a long way to go. CATL has about a third of the global battery market. CALB has only a 3.7% market share, but thinks it has a tiger by the tail with its latest battery technology — the U-shaped battery.

If you look at the photos from CALB, it’s hard to understand what all the hoopla is about. Its battery cells look like any other battery cells you have ever seen. But according to, until now, round cells for electric cars had their positive and negative poles at opposite ends of the cell housing. For those who are technology challenged, the “U shape” part of the description describes the path electrons follow within the battery, not the shape of the exterior housing.

With the “U-structure,” CALB installs both the plus and the minus pole at one end of the housing. The positive pole is in the middle and slightly elevated, where it normally is, but the negative pole is on the outside. For integration into a battery module or pack, this means the round cell is treated more like a prismatic cell with both poles on one end of the housing.

While CALB has not released any details about the structure inside its new cells with the “U-structure,” it does say that they feature new chemistries and that electrical current “flow paths” have been reduced by 70%. That in turn has the effect of reducing the internal resistance of the cell by 50%, according to the company.

A lower internal resistance also means the cell heats up less — an important factor in fast charging, for example. CALB states that the new round cell can be charged at up to 6C, and CNEvPost says that means it can be fully recharged in just ten minutes.

The 6C charging rate is presumed to apply to the NMC variant of the “U-structure” cell, which has an energy density of 300 Wh/kg. There will also be LFP and LMFP versions of the new battery cells from CALB and those will have an energy density of 200 Wh/kg.

CALB Battery
Image courtesy of CALB via CNEvPost

While the 300 Wh/kg and the 6C charging rate should be interesting for high end vehicles, the “U-structure” is said to offer another advantage, one which will be important in making electric cars that cost less. CALB vice president Xie Qiu told the China EV 100 Forum last month that compared to tabless round cells such as Tesla’s 4680 cells, the production line for the new cells requires about 70% fewer welding machines in the production line for this battery. Fewer machines should mean less expensive batteries.

“We have made a disruptive innovation to the structure of the cylindrical battery by introducing the U type structure,” Xie Qiu is quoted as saying. While the tabless structure solves some of the current path problems, treating the cell shell as a conductive component results in a relatively long path for current flow, he said. The newly developed “U-structure” is supposed to do this much better. However, it is not known when CALB plans to go into series production with this new type of cell.

Xie added that treating the shell of a battery cell as a conductive component results in a relatively long path for the current to flow through. Most battery shells are made of steel, which is not a particularly good conductor of electricity. He also indicated the new cells from CALB are about 3% more space efficient.

Tabless, 4680, & Qilin Batteries

The pace of research and development in batteries is torrid these days, as the transition to electric transportation gains momentum. Tesla started things off by introducing large format 4680 battery cells — 46 mm in diameter by 80 mm long — which it claims are more energy-dense than the 2170 cells it has been using for years. Tesla has also introduced so-called “tabless” batteries that also can charge and discharge faster. As my colleague Alex Voigt said back in 2020, tabless batteries promote the rapid flow of electrons, which reduces charging times and creates less heat as well.

CATL, of course, is not standing idly by during all this innovation frenzy. It has just started production of its so-called Qilin battery, which the company says has 13% more energy density than the Tesla 4680 battery and can power an EV for up to 1000 kilometers. CATL claims an energy density for the Qilin battery of 255 Wh/kg and says that is higher than what Tesla is getting from its 4680 batteries. Tesla would probably disagree with that if Tesla actually spoke to the press.

According to CnEVPost, in the cell-to-pack arrangement used for the new Qilin batteries, CATL has quadrupled the heat transfer area by placing the liquid cooling element — which is typically found at the bottom of the battery cells — between the cells instead. This allows for faster charging times, better thermal control of cell temperatures, and faster warmup of the battery cells in cold weather for better performance.

The new design supports a fast hot start in 5 minutes and charging to 80% in 10 minutes, CATL says. In extreme conditions, the cells can be cooled down rapidly, effectively blocking abnormal heat transfer between cells and reducing the chance of thermal runaway events (fires, to us non-technical types).

If the CALB announcement is to be believed, its U-shaped cells have a significantly higher energy density than CATL can manage. Not surprisingly, CATL is suing CALB , claiming the smaller company is guilty of poaching battery engineers and using its proprietary knowledge to gain a competitive advantage.

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The Takeaway

Whatever you knew about the latest in battery technology this morning will probably be obsolete by this evening. There is a lot of money and prestige on the line these days for any company that can build a battery that has a higher energy density and/or lower manufacturing costs. The ultimate winners will be the consumers, who get to drive less expensive electric cars that can go farther and suffer less performance degradation when ambient temperatures dip below freezing.

Politically, Chinese companies control much of the battery manufacturing space, and that’s a problem for the rest of the world, particularly America and Europe, which slept through the first two decades of the new century thinking that outsourcing and globalization were the greatest things since sliced bread and ice cream.

The pace of innovation will only increase as governments pour more money into incentives. The batteries that will power new electric vehicles in 2030 have not even been invented yet. Although the pace of change is dizzying, the rewards of living on a greener planet will make all the disruptions along the way worthwhile.

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Steve Hanley

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new."

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