The Evolution of Lithium-Ion Cells
The lithium-ion cell and battery world has changed significantly over the last 10 years. From the evolution of Electric Vehicles (EVs) to advancements in the construction industry, many companies see lithium-ion cells as major players in the future of electrification. To understand the current and future state of lithium-ion cells, it is helpful to look at the history of lithium usage.
The history of lithium-ion cell types
The progression of lithium-ion cell types can be grouped into three main iterations.
- Cylindrical: Twenty-five years ago, the 18650 cylindrical cell size powered cell phones, camcorders, and laptops
- Prismatic with Metal Can: Rectangular or square shape cell types took over from their cylindrical predecessors for portable applications. Grouped by thickness, width, and length – Example: 103450 cells would be a 10mm x 34mm x 50mm size and a 53450 would be a 5mm x 34mm x 50mm)
- Pouch/polymer: These cells almost entirely replaced the metal-can prismatic types in cell phones, tablets and laptops. The size of these cell types is mostly governed by the size of their application.
One of the only consistencies within the cell industry is the predictable cadence of new technology forcing the old into obsolescence. This pattern forces the industries reliant on cell selection to keep careful watch over a mercurial supply chain. Camcorders are an electronic fossil by today’s standards, but the 18650 cell size is still in circulation. This is in large part due to the demands of the market. In recent years, the EV industry has exerted significant influence over the production of lithium-ion cells. As of 2021, EV giant Tesla, Inc. became the largest single user of lithium-ion cells in the world, as well as one of the largest co-producers. Automotive companies are somewhat constrained by the nature of their product to only use the highest capacity, most space-efficient cells in their vehicles. In a 18650 cell size, this is approximately 3.5Ah. One of Tesla’s standard range vehicles uses approximately six thousand 18650 cell equivalents.
The effect of market demands
How does a high consumption rate by one manufacturer affect other cell types? In some cases, market demands can force cell types into rarity or extinction. Unquestionably, the 18650 cell size received a huge lift as a direct result of Tesla’s decision to use the cell type and other EV makers following suit. While the 18650 is still in production, its days may be numbered. In 2017, Panasonic (Tesla’s US battery partner since 2012) introduced the enhanced 2170 lithium-ion cells for the Model 3, which went into production in the summer of the same year. The 2170 cell pack is more energy-dense and can accept higher charge rates than 18650 cells. From a manufacturing perspective, if the 2170 cell demand surpasses that of the 18650 cells, then the latter could be forced into obsolescence. A manufacturing line that can make 18650 cells, can make 21700 cells with a minimal investment in tooling. Consequently, when a cell supplier announces that they have won a contract to supply an automobile manufacturer with lithium cells or batteries, it essentially means that their production and support will likely be more focused on higher capacity, bigger and newer cell types (5Ah 21700s).
Keeping with the theme of constant change, Panasonic announced a new cell type in 2021, the 9Ah, 4680 cell size. It is too early to tell how dramatically this new cell size will influence the current market. Unlike the relatively easy switch from a 18650 to a 2170 production line, the 4680 will likely require new, dedicated production lines. Other factors, such as focused engineering time and raw material consumption, are still unknown for the 4680, but will undoubtedly affect the production of other cell types.
We may have some time to wait before another new and improved cell size announcement, but that time will come. Cell development and selection is characterized by a unique double vision, with one view focused on the present market and the other always looking toward the future.