Safety Considerations for Battery Storage Options

Safety is a critical design feature in lithium batteries, and for good reason. As we've all observed, the chemistry and energy density that make lithium-ion batteries so effective also render them flammable. When these batteries malfunction, they can create hazardous and dramatic incidents.

Not all lithium chemistries are the same. In fact, the majority of American consumers—aside from electronics enthusiasts—are familiar with only a limited selection of lithium solutions. The most common types are based on formulations of cobalt oxide, manganese oxide, and nickel oxide.

Let’s take a moment to reflect on the evolution of lithium-ion batteries. This technology is relatively new, having emerged in the last 25 years. During this time, lithium technologies have gained popularity for their effectiveness in powering smaller electronics like laptops and cell phones. However, as many news stories have highlighted, lithium-ion batteries have also developed a reputation for catching fire. Until recently, this concern was one of the main reasons lithium was seldom used in large battery banks.

Enter lithium iron phosphate (LiFePO4). This newer lithium solution is inherently non-combustible, albeit with a slightly lower energy density. LiFePO4 batteries not only offer enhanced safety but also provide several advantages over other lithium chemistries, particularly for high-power applications like renewable energy.

Before we explore the safety features of lithium iron phosphate, let’s review how lithium battery malfunctions occur.

Lithium-ion batteries can explode when their full charge is released instantaneously or when the liquid chemicals mix with foreign contaminants and ignite. This typically happens in three scenarios: physical damage, overcharging, or electrolyte breakdown.

For instance, if the internal separator or charging circuitry is damaged or malfunctions, safety barriers are compromised. This can lead to the electrolytes merging, triggering an explosive chemical reaction that ruptures the battery casing, combines the chemical slurry with oxygen, and ignites all components.

While there are other ways lithium batteries can explode or catch fire, thermal runaway scenarios like these are the most common. However, it's important to note that such incidents are relatively rare, especially given that lithium-ion batteries power the majority of rechargeable products on the market. Large-scale recalls or safety scares are uncommon.

While lithium iron phosphate (LiFePO4) batteries are not entirely new, they are gaining traction in global commercial markets. Here’s a quick overview of what makes LiFePO4 batteries safer than other lithium solutions.

LiFePO4 batteries are renowned for their strong safety profile, attributed to their highly stable chemistry. Phosphate-based batteries feature a superior chemical and mechanical structure that prevents overheating to unsafe levels, enhancing safety compared to lithium-ion batteries with other cathode materials.

The charged and uncharged states of LiFePO4 are physically similar and robust, allowing ions to remain stable during oxygen flux associated with charge cycles or potential malfunctions. The iron phosphate-oxide bond is stronger than the cobalt-oxide bond. Therefore, when overcharged or physically damaged, the phosphate-oxide bond maintains its structural integrity, whereas other lithium chemistries tend to break down, releasing excessive heat and potentially triggering thermal runaway.

LiFePO4 cells are incombustible, an essential feature in case of mishandling during charging or discharging. They can also endure harsh conditions, including extreme temperatures and rough terrain. When faced with hazardous events such as collisions or short-circuiting, they won’t explode or catch fire, significantly reducing the risk of harm. If you anticipate using a lithium battery in hazardous or unstable environments, LiFePO4 is likely your best option.

Most LiFePO4 batteries come equipped with a Battery Management System (BMS) that includes additional safety features such as over-current, over-voltage, under-voltage, and over-temperature protection. The cells are often housed in explosion-proof stainless steel casings.

Additionally, LiFePO4 batteries are non-toxic, non-contaminating, and free of rare earth metals, making them an environmentally friendly choice. In contrast, lead-acid and nickel oxide lithium batteries pose significant environmental risks, particularly lead-acid batteries, which can degrade over time and leak harmful substances.

Compared to lead-acid and other lithium batteries, lithium iron phosphate batteries offer substantial advantages, including improved charge and discharge efficiency, longer lifespan, and the ability to deep cycle while maintaining performance. Although LiFePO4 batteries may come with a higher initial price, their lower lifetime costs, minimal maintenance, and infrequent replacements make them a worthwhile investment and a safer long-term solution.