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Brainstorm: Batteries

Thu, 03/11/2010 - 4:34am
Edited by Jason Lomberg, Technical Editor

What is the next breakthrough in battery technology?

T Russell - UltralifeThomas J. Russell, Ultralife Corporation, www.ulbi.com

The industry is aggressively working towards higher volumetric lithium ion cell capacities. In concert with this effort for these higher capacity cells, battery designers are working to ensure that those cells are utilized more efficiently through the use of smart technologies and other electronic control. These two improvements in the fundamental components a battery have allowed for very large arrays of cells with very high capacity to be considered.

As the number of cells increases from tens of cells to thousands of cells, no longer will reliance on the manufactures’ cell to cell repeatability be sufficient to balance the batteries. Circuitry to actively balance the cells within a battery will be incorporated to more completely utilize the increased capacity of each cell. This monitoring and control of the battery will be required both during charge and discharge of the battery. With these improvements in the cells and batteries, it will be possible to power applications not previously considered, with increasingly large format battery configurations.


  

Sol JacobsSol Jacobs., Tadiran Batteries, www.tadiranbat.com

Major breakthroughs in technology rarely occur in a vacuum. They occur in response to the unfulfilled needs of design engineers. A case in point involves the growing needs of machine-to-machine (m2m) devices to become increasingly feature-rich and power-hungry while simultaneously becoming much smaller in size. Battery manufacturers must respond to these contradictory requirements with batteries that are increasingly capable of delivering high capacity and high energy density without sacrificing long-term reliability. Since every battery chemistry has a theoretical limit, more exotic chemistries are bound to emerge. Likewise, the operating lives of batteries will have to match those of the remote devices they power. Today Tadiran manufactures batteries that have been designed into wireless products with operating lives of 30 years. The limiting factor is now the life of the device itself and not so much the battery that powers it. Many people look to energy harvesting for an answer, and maybe one day it will be proven, small and cost effective. But in the future devices might have to last 50 to 100 years while cast in cement walls and we believe that there will be batteries around to power them into the twenty second century. 

Chris Turner-NexergyChris Turner, Director of Battery Technology, Nexergy, www.nexergy.com

The next breakthrough in battery technology may not be something that would typically qualify as a breakthrough at all.  What the market is seeing is considerable effort to improve certain characteristics of lithium ion (Li-ion) based technology.  The characteristics being targeted for improvement depend on the intended markets or applications. Recent developments for Li-ion have focused on improving the following: safety (non-flammable electrolytes), robustness (particularly high/low temp performance), cycle/calendar life (Iron and Manganese phosphates, Li-titanate), energy density (Silicon or Tin based anodes, Lithium-air), discharge/charge rate capability (phosphates, titanate), and reducing the cost (all).   While everyone strives to have a battery that would set the benchmark in all of these characteristics, typically to be the best at one increases the likelihood of not setting the benchmark in others.

Each characteristic tends to rise as 'top priority' for a particular application therefore the 'breakthroughs' in the future likely will be around setting the new benchmark for a specific metric for a particular application.  Silicon or Tin anodes for example will help the conventional Li-ion cells achieve energy densities not previously seen and allow the notebook PC makers for example to finally have 18650 cells approaching 3.5Ah.  Perhaps, one of the renewable energy storage solutions may be lithium titanate Li-ion cells that can meet that markets demands for fast charge and discharges while delivering thousands of cycles and years of use.  We will see cells designed to work at extreme low temperatures and high temperatures. Perhaps most importantly, and a benefit to all, should be the introduction this year of Li-ion cells with non-flammable electrolyte.

Jeff VanZwolJeffrey VanZwol, Micro Power Electronics, www.micro-power.com

Looking back over the last few years, we had the introduction and commercialization of Lithium Iron Phosphate battery technology. Advantages of Iron Phosphate includes peak currents of 100 Amps per 26650 cell, while a traditional Cobalt Oxide cell supports 10 Amps per 26650 cell. With only a few suppliers offering Iron Phosphate cells, we have witnessed the power tool industry migrate for Nickel based battery packs (NiCad, NiMH) to Iron Phosphate packs.

Looking forward, we now have numerous cell manufacturers offering several variations of Iron Phosphate. The supply side of this market has commoditized, with multiple sources for every common cell configuration. As the cost per watt/hour decreases, we see Iron Phosphate packs starting to erode the Lead Acid battery market. A typical Lead Acid configuration using Iron Phosphate cells is lighter and smaller. Lead Acid still has a lower cost per watt/hour and better low temperature performance. But over the last few years, we have seen the pricing of Iron Phosphate packs drop from 8X to 4X the cost of equivalent Lead Acid batteries. When size and weight are strong design criteria for a battery, Iron Phosphate is becoming a more economical solution for these applications. 

 

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