Lithium-ion refers to a variety of lithium-based battery chemistries. Each chemistry material has its strong and weak points, which means certain types of chemistries are better-suited for particular applications. There continues to be new lithium-based chemistries being developed, but it is still too early to tell which one will become commercially viable.

Li-ion batteries typically come in one of three formats: pouch, cylindrical, and prismatic. Pouch types tend to be used in small portable devices, such as smart phones and tablet PCs, or in devices where low weight is important, such as hobbyist remote control vehicles. Cylindrical forms lend themselves to powering medium-sized portable devices, such as power tools.

 Prismatic are generally the largest, and are typically used in electric vehicles. Prismatic types are also favored in applications that were previously powered by lead-acid NI-CD Rechargeable batteries, such as backup or off-grid telecommunication systems. Prismatic types usually have hard corrugated sides, which creates air gaps between adjacent cells.

If Polymer Lithium-ion battery has an application for residential RE storage, the best candidate is the large-format prismatic lithium iron phosphate battery. But how do they compare with lead-acid technologies?

Comparing weight versus available energy storage, a Lifepo4 is about one-third the weight of a lead-acid battery. This is a great advantage for mobile applications, such as boats/RVs. But for stationary RE applications, weight are usually considerations only during battery change-out.

At about half the volume of a lead acid battery with equivalent energy storage, Lifepo4 batteries take up far less space. This may be an advantage for mobile applications, but for stationary RE applications, size or volume is typically not a deciding factor.

The storage capacity of lead acid batteries drops by 50% at -4°F, compared to 8% with Lifepo4 batteries. Keeping lead-acid batteries warm so that they maintain reasonable capacity in cold climates can be challenging, giving Lifepo4 batteries an advantage. However, Lifepo4 batteries generally should be charged at a slower rate when cold, usually no more than a C/10 at ambient temperatures below 32°F.