Battery Chemistry Guide

Chemistry	Maximum discharge rate	Energy density	Cell voltage range	Voltage curve	Self-discharge rate (%/month)	Shelf life	Temperature range
Zinc	1C	very low	0.9-1.5-1.5V	Sloped	0.1~2%	2 years	0~45C, -10~25C
Alkaline	1~4C	medium	0.8-1.5-1.6V	Sloped	<1%	5 years	-18~55C, -40~50C
Lithium-Iron	1~2C	very high	0.9-1.5-1.8V	Flat	<1%	10 years	-40~60C, -40~60C
NiCd	15~20C	very low	0.9-1.2-1.3V	Flat	10%	5 years	-20~65C, 10~30C, 0~50C
NiMH	1~10C	medium	0.9-1.2-1.3V	Flat	15~30%	5 years	0~50C, -20~30C, 0~50C
LSD NiMH	1~10C	low	0.9-1.2-1.3V	Flat	1~2%	5 years	0~50C, -20~30C, 0~50C
Lithium (3V)	1~2C	very high	2.0-3.0-3.0V	Flat	<1%	5-8 years	-30~75C, -55~75C
Li-Ion (ICR)	1~3C	high	2.8-3.6-4.2V	Flat	8%	3 years	-20~60C, -20~50C, 0~45C
Li-Ion (IMR)	5~15C	medium	2.8-3.6-4.2V	Flat	8%	3 years	-20~60C, -20~50C, 0~45C
Li-Ion (INR)	5~15C	high	2.8-3.6-4.2V	Flat	8%	3 years	-20~60C, -20~50C, 0~45C
Li-Poly	10~100C	very high	3.0-3.6-4.2V	Flat	5%	3 years	-20~60C, -20~25C, 0~45C
Silver Oxide	<0.1C	high	1.2-1.55-1.6V	Flat	<0.1%	5 years	-10~55C, -10~55C
Zinc Air	<0.1C	extremely high	0.9-1.45-1.65V	Flat	0.1~2%	2 years	-10~55C, 10~25C
Lead Acid	2~10C	very low	1.75-2.1-2.4V	Flat	3~20%	6 months	-40~60C, -40~50C, -20~50C

Terminology

Energy

If a battery were a reservoir, the mass of water multiplied by the average height the water needs to drop to reach the outflow would be its total energy. We call the mass of the water its capacity and measure it in amp-hours, the average height of the water is called the nominal voltage measured in volts, and the energy of a battery calculated by multiplying the two is measured in watt-hours.

Power

If we continue the reservoir analogy, the rate of water flowing through the dam is the current measured in amps, and the pressure on the water forcing it out is its voltage. Multiplying the voltage and amperage gives us the wattage or rate at which energy is being drained from the reservoir.

Primary/Secondary Cell

A primary cell cannot be recharged. A secondary cell can be recharged. The two terms are used interchangeably.

Cell vs. Battery

A cell is a combination of electrodes and electrolyte which generates an electric charge. A battery is a collection of one or more cells working together.

Table Columns

Chemistry

All common cells have two electrodes and an electrolyte, the specific combination of materials used to make these components is called a chemistry. A cell's chemistry largely determines its properties, while most variations within them caused by additives, purification, and improved design.

Rechargeable

Checked boxes indicate that batteries made with this chemistry are rechargeable.

Maximum Discharge Rate

Battery manufacturers often list discharge rates as C ratings, which multiply the battery's rated capacity. If a battery with a 3000mAh capacity has a 2C rating, you can discharge it at 6A, or twice its rated capacity. Discharging above the rated value or for an extended period can lead to reduced battery life or cell failure.

Energy Density

This measures how much energy can be stored in a battery at a particular size. Incremental improvements in cell design change the exact values every year, but we can be fairly sure that alkaline and zinc, ICR and IMR, and other chemistries with large gaps in energy density will continue to hold their place. Use this as a starting point to

Cell Voltage Range

This value is given in the format minimum-nominal-maximum. A cell can be considered dead at the minimum voltage, typically provides the nominal voltage while being discharged, and is fully charged at the maximum voltage. Please note that battery voltages can vary widely depending on the discharge rate and other factors.

Voltage Curve

Cells do not maintain the same voltage throughout their discharge cycles, they go from the maximum voltage when fully charged to the minimum voltage when fully drained. Alkaline cells will continually drop in voltage on a steady downward slope from the maximum to the minimum while silver oxide ones typically keep a flat voltage near their nominal rating for years before abruptly dropping out within a few hours.

Self-Discharge Rate

All batteries slowly lose their charge over time through internal chemical reactions. This effect is minuscule in most primary cell chemistries but can be quite large in rechargeable ones, particularly when they are fully charged. Usually, this just means that you'll have to recharge the battery if it sits on a shelf for over a month before use.

Shelf Life

Many factors affect how long a battery will last, but cells stored for this long without maintenance at room temperature should still perform well.

Temperature Range

Temperature ranges are given in the format "discharge, storage, charge". A battery should be supply power in the discharge temperature range, degrade slowly in the storage range, and maintain capacity in the charge temperature range if charged. Use outside of this range affects batteries differently depending on the chemistry used.

Battery Types

Standard Batteries

Primary Cells

These are your standard AAA, AA, C, D, 9V, and lantern batteries found in every grocery store. Best used to provide a very low to moderate amount of power for devices with occasional use, a good primary cell (non-rechargeable) battery offers lower cost, longer shelf life, and easier maintenance than rechargeable alternatives with similar capacity. The vast majority of standard batteries are made using these chemistries:

Zinc Carbon and Zinc Chloride (often labeled "general purpose" and "heavy duty" respectively)
Alkaline
Lithium iron disulfide (LiFeS₂ or "voltage compatible lithium", often labeled "lithium")

Zinc

"General purpose" zinc-carbon and "heavy duty" zinc-chloride cells are the cheapest class of batteries on the market. They store less energy than other primary cell chemistries, cannot power medium drain devices for more than a few minutes, and often leak, but cost significantly less. If price is your main concern and the battery is only running a low power device (e.g. clock, remote control, calculator) with occasional use then these are a good option, otherwise avoid it.

Alkaline

Alkaline cells have medium energy density, can provide moderate power with minimal energy loss, and occasionally leak. A middle of the road battery, alkaline can be used in everything from clocks to cordless phones with no issues. They cannot handle high drain however, they heat up and deliver much less energy than their rating. Get them if you want the best bang for the buck and a general purpose battery.

Li-FeS₂

Lithium cells have very high energy density, can provide high power, and rarely leak. Able to run well in any device, these are true general purpose batteries without the high drain caveat of alkaline. Their superiority is tempered by low to moderate drain devices where alkaline is cheaper, and in high drain devices it's usually better to invest in rechargeable batteries. We recommend them in very low drain products with hard to reach battery compartments, where the longer life of the cell offsets the cost.

Secondary Cells

Primary batteries are better in low drain devices, but if you have a product which eats alkaline and lithium alike, rechargeable secondary cells are a better option. Their lower voltage may cause issues in some devices, but they can still be used nearly everywhere primary cells are. Common chemistries include:

Nickel-Cadmium
Nickel-Metal Hydride
Low Self Discharge Nickel-Metal Hydride (often labeled "precharged")

NiCd

Nickel-Cadmium is the premier rechargeable battery chemistry of the 1980s. NiCd cells have comparable energy density to zinc, can provide extremely high power if necessary. Self-discharge is moderate, so they may need to be recharged before use after a few months. Don't overcharge them or they will suffer from voltage depression (premature drop in voltage) which will drastically reduce the usable charge. Unlike every other common rechargeable chemistry, NiCd cells can be stored fully discharged with no ill effect, and memory effect is rare, so they should work normally until the end of their cycle lives. Due to advancements in other rechargeable chemistries, we recommend them for extremely high power applications only.

NiMH

Nickel-Metal Hydride batteries have significantly higher energy density comparable to alkaline batteries, can provide high power comparable to lithium, but suffer from very high self-discharge, making recharging desirable after a few weeks. If you want to run a camera or similar device that drains batteries very quickly, these are a good option.

LSD NiMH

Low Self Discharge NiMH batteries are the best replacement for primary cells we have. Their performance approaches standard NiMH while reducing the self-discharge to a very low level. If you want to switch to rechargeable, these are your best option.

High-Performance Batteries

Small high-powered devices like bright flashlights, e-cigarettes, laptops, cameras, RC aircraft, and phones need small, lightweight, high energy and power batteries to power them. Store cells away from flammable objects in a non-conductive container, in the worst failure case they can vent with flame as the case ruptures from excessive pressure. Common chemistries include:

Lithium manganese dioxide (3V, LiMnO₂ or "lithium")
Lithium cobalt oxide (LiCoO₂ or ICR or LCO)
Lithium manganese oxide (LiMn₂O₄ or IMR or LMO)
Lithium nickel manganese cobalt oxide (LiNiMnCoO₂ or INR on NMC or "hybrid")
Lithium-ion polymer (LiPo or Li-poly)

Lithium Primary

LiMnO₂

Generally if a device needs a lot of power and cannot fit a large bank of alkaline cells, they will use some of these. They can be found in many sizes and are have similar performance to lithium-iron, with the same high energy density and power output, but 3V instead of 1.5V.

Lithium-Ion

ICR

This is the main chemistry used in laptop battery packs, high power flashlights, and building battery backup power systems. They have high capacity and can be run in high drain devices, but are very sensitive to overcharge and over-discharge and overheat in extremely high discharge scenarios. Cells labeled "protected" have a circuit attached to monitor the voltage and current and disconnect the contacts if it gets out of the safe range. Unprotected cells are also available but those are only recommended for battery packs with full battery management systems handling the protection. If your device draws extremely high power, use IMR or INR cells instead, but the higher capacity is great if you can settle for 'just' high power draw.

IMR

IMR cells have lower capacity than ICR, but can run extremely high drain devices without issue. Due to the safer chemistry, IMR cells are typically unprotected. These are the cells of choice in the e-cigarette community, they allow for all but the most excessive power demands to be met and keep cool while doing so.

INR

These "hybrid" cells maintain the power draw capabilities of IMR while storing significantly more energy like ICR. While they may not support IMR's highest power draw or hold ICR's greatest energy capacity many find these cells have an ideal balance of the two.

Lithium-Polymer

Lithium Polymer cells are used where high energy and power is needed but Li-Ion would be too heavy. They have the advantage of light weight, a slim form factor, and can support the highest power draw of any commercial cell. This makes them popular in phones, small laptops, and RC planes. This chemistry does not tolerate use outside of its specifications, and should be stored carefully.

Small Batteries

Silver Oxide

These batteries are used in watches, hearing aids, and aerospace due to their high energy density and long shelf life. While they cannot sustain even low continuous power, the high drain variant can be pulsed to run alarms and lights from time to time.

Zinc Air

These batteries have the highest energy density of any cell, but need access to air to work. This keeps them from being used in watches, but they are very popular in hearing aids because of the longer period between replacements.

Lead Acid

Lead acid is one of the oldest battery chemistries, and has proved itself as one of the most reliable rechargeable cell types. Self-discharge combined with issues when cells lose charge make periodic recharging (and sometimes other maintenance, refer to the manufacturer's instructions) necessary to maintain a long life. Despite the maintenance requirement, and other chemistries being much lighter and smaller for the same performance, lead-acid cells maintain an advantage with an excellent price for the amount of power they provide.