Choosing the Right Battery Chemistry Isn’t Just About the Chemistry
Cell chemistry is critical in determining a battery pack’s performance, characteristics, and safety profile. It’s also an important decision an engineering team would make when integrating a lithium battery solution into their products.
However, choosing the right chemistry isn’t always as cut-and-dry as a purely engineering exercise. Factors other than metrics and measurements may influence the battery characteristics you’ve got to work with. Meanwhile, selecting battery chemistry may look more like the Buddhist’s teaching of the Middle Way than a hardcore scientific evaluation.
Let’s delve into the nuances.
Understanding battery characteristics
Many factors go into deciding exactly which flavor of battery chemistry is best for your application. Some seem clear-cut, many are confusing, and several are conflicting and mutually exclusive. These include energy density, discharge rate, cycle life, longevity, power density, shelf life, safety, form factor, cost, and more.
Additionally, consider variables like depth of discharge, charging rate, temperature, etc., which strongly affect a battery pack's useful life.
All options are fair game for non-margin-sensitive, geopolitically insensitive, and low unit count products. You can make the tradeoffs primarily based on technical merits. But life is rarely this simple.
Now, let’s look at the not-so-obvious factors affecting the decision-making processes and may inevitably impact the battery characteristics you have to work with.
Example: Lithium Iron Phosphate (LFP or LiFePO4) batteries in EV cars
Cobalt (a component in most non-iron-based EV batteries) has been under the spotlight thanks to the mining process’s negative environmental impact. Are you or your customers ok with being associated with the image of a 14-year-old on one flip-flop, somewhere in the middle of nowhere in the Democratic Republic of Congo (DRC), digging out cobalt from a 50’ deep hole with nothing more than a plastic bucket and an empty stomach?
Additionally, the geopolitical instability in the DRC region may create supply chain issues, causing challenges in your manufacturing process down the road.
However, switching chemistry could mean trading instability in Africa for uncertainties in China, which dominates the global LFP battery market and may use this position as a bargaining chip.
Even though FLP batteries can’t charge in freezing temperatures and have a lower energy density (which translates into limited range), it’s the battery chemistry of choice for Chinese EV manufacturers because of political and business factors.
Tesla incorporated LFP batteries in its Model 3 cars in China 4 years ago and has started using LFP cells in Western markets for its shorter-range models. The decision-making went beyond technical merits to consider geopolitical, supply chain, economic, and business factors.
In these scenarios, product teams probably had their battery chemistry pre-determined and had to do their best to design the product around the battery characteristics.
(On the other hand, for a piece of mining gear that operates in relatively constant non-freezing temperature but requires a higher level of intrinsic thermal stability, LFP is the obvious choice for the chemistry’s technical merits, regardless of other factors.)
How to choose the right battery chemistry
Different lithium battery chemistries cater to specific applications and performance requirements. For example, Lithium Cobalt Oxide (LiCoO2 or LCO) provides high energy density and long cycle life but has a limited lifespan in high-discharge applications. Meanwhile, Lithium Iron Phosphate (LiFePO4) offers excellent thermal stability but has lower energy density.
Selecting the right battery chemistry is essentially an exercise of balancing tradeoffs. Battery engineering teams must develop a deep understanding of cell behaviors and the know-how to manage most battery chemistry’s temperamental character — especially to ensure user safety.
Chemistries that store more energy tend to be more volatile (i.e., less safe). You can have high capacity, safety, and cheap. But you can’t have all three maxed out simultaneously. It comes down to making informed decisions and balancing tradeoffs on safety, reliability, cost, longevity, performance, and other factors — walking the Middle Way most of the time.
The Samsungs, Teslas, and Apples of the world have fine-tuned the balance to make the batteries in their products good, cheap, and safe enough by adjusting battery chemistries to balance cost, energy density, and safety to hit the sweet spot.
Making the best choice requires balancing various factors, and you must build the foundation by aligning business and technical requirements and decisions.
But what if you must move forward without knowing all the parameters and requirements?
Cell behaviors in traditional battery packs are fixed once you’ve designed the solution. There’s no going back. On the other hand, software-defined batteries (SDBs) make it easy to adjust battery characteristics on the fly and hit the sweet spot in a broad range of operating conditions.
For example, you may mix and match cells to introduce different characteristics into a battery pack to address various use cases or rearrange cells from being connected in series to parallel with a few clicks to change voltage and current on the fly.
When you can’t nail down the operating conditions or requirements upfront and/or require more safety margins for your battery pack, SDBs offer the flexibility and agility to create a product with more versatility — giving you room for continuous improvement and new features.
Don’t get stuck in analysis paralysis. We can help you make meaningful progress in selecting your battery solution and designing an integration strategy in a day in our new Battery Strategy Workshop. Learn more to see how we can help you build electrified products cost-effectively with cutting-edge insights and deep industry knowledge.
