Engineer working on NIMH cells

Lithium-ion (Li-ion) rechargeable (secondary) cells are often seen to be advantageous over Nickel Metal Hydride (NiMH), also a rechargeable cell type. Steatite works with both, but what do the different chemistries offer in reality? We’ve taken a look into the pros and cons of both in this insight, Nickel Metal Hydride vs Lithium-ion Cells.

Nickel Metal Hydride cells

NiMH cells have been developed from Nickel-cadmium (NiCd) cells, which provided rechargeable options for electrical devices for over 100 years (Waldemar Jungner introduced them in Europe in 1899 and Thomas Edison patented a version in the US in 1902). While this chemistry was robust and reliable, manufacturers in the 1990s started producing NiMH cells which had a lower environmental impact and up to 40% higher energy density. 

Modern NiMH cells offer lower production and development costs and a safe, stable chemistry. They are widely used in consumer goods, with most of the largest manufacturers offering AA and AAA sizes. In industry, NiMH cells are often used for lower power consumption applications, small scale backup power and where standard size single use cells are commonly used, in applications such as torches and remote control units.

Additionally industrial battery sizes are available to manufacture larger packs with more capacity include 18650, D, F and other sizes. A large number of hybrid powered vehicles use NiMH as the energy store, notably Toyota in their Prius model. 

Lithium-ion battery

This is currently the most requested rechargeable chemistry and has been available for almost thirty years. These cells offer the most energy dense solution of the currently available chemistries, measured both by mass (watts per kilogram) and volume (watts per cubic metre). 

Li-ion packs come in assorted shapes and sizes. Primarily there are three formats, cylindrical cells, prismatic cells and pouch cells. Pouch cells are typically used for applications that need the battery in a particular shape, or where the highest energy density (energy within a given volume) is sought. Examples include smart watches, tablet computers and some battery powered electric vehicles.

A drawback of pouch cells is they are prone to swelling, particularly as they age, which leads to rapid loss of capacity and, ultimately, failure. In larger applications they are frequently contained in strong structures to keep them compressed to avoid this swelling which helps in maintaining their life. Cylindrical cells are the most produced format securing the chemical and electrical components in a steel can.

These cells offer a similar energy density to pouch cells, and are also used in a diverse range of applications including laptops, power tools, robotics and electric vehicles. Prismatic cells are the least common type but are still widely used and are also formed in a metal case but of a broadly rectangular shape. They were most commonly found in mobile phones in the 90s when the battery was replaceable and are now often used in medical devices and other consumer/industrial applications.

Summary of pros and cons of NiMH and Li-Ion cells 



Lithium Ion – Li-ion

• Lightweight cells ideal for portable devices.

• Higher cell voltage requires fewer cells for the same power.

• Able to withstand a wider range of environmental temperatures than NiMH. 

• Low self-discharge (around 1% per month).

• Lower environmental impact.

• Wide selection of chemistries available for different applications, particularly suited to long-life uses. 

• More expensive to develop and manufacture.

• Requires electronics inside to ensure battery safe operation.

• More reactive chemistry so requires additional care in storage, transport and use.

• Tight restrictions on storage and shipping add time and cost to final delivery.

Nickel Metal Hydride - NiMH

• Lower development and production costs (less than 50%of the cost of producing Li-ion cells).

• Fewer active materials therefore more stable and less likely to rapidly disassemble.

• Can be fully discharged between charge cycles 
No requirement for transportation testing so cheaper to transport.

• Can be shipped by air without needing to meet regulations so quicker to transport.

• Long shelf-life; the latest generation of NiMH has self-discharge characteristics as low as 20% over 12 months.

• Self-discharge (around 1% per day) but some cell brands can reduce this.

• Heavier chemistry.

• Voltage output will drop in extreme temperatures.

• More heat generated during charging so not suited to certain applications.

• Tolerates fewer charging cycles.

Knowing what battery will work best depends on numerous factors and you’ll need to consider every aspect of the requirements in order to make an informed and accurate decision. There is no overall better or worse option – only the best option for your application. 

Steatite offers a range of battery packs which can be customised where required; you can see more by browsing this website. We’ve been providing reliable power to sectors across military, oceanographic, oil and gas, transport, industry and robotics for over 50 years and our service extends far beyond the sales process.

We provide battery support throughout the lifecycle of our products from initial design, through the custom build and testing process to distribution and transportation, and finally environmental disposal of depleted packs. 

Contact our team of battery specialists to see what the best option will be for your power needs.