August 15, 2015
Batteries are becoming ever more important for the global goal of sustainability and nickel is playing its part.
While the first nickel battery (nickel-iron battery patented by the Edison Laboratory in 1901) has been around for over a century, the last three decades have seen extraordinary changes in the nature and composition of cells that, when connected in parallel or series or both, give us batteries. Also, the uses to which those batteries are being put are constantly expanding. And while not as obvious as when the common chemistries were nickel cadmium (NiCd) and nickel metal hydride (NiMH), nickel remains prominent in innovative lithium ion batteries for stationary, portable and motive energy.
They are also becoming more complex. Now cells and batteries are designed to maximise the desired parameters: specific voltages, voltage stability, specific energy and specific power (amount of available energy by volume or mass), speed of recharging, heat generation or any trade-offs between these and other parameters. Manufacturers now design to the performance of today’s diverse availability of batteries or discuss with battery manufacturers their needs. And manufacturers have more and more options for meeting diverse specifications. It’s a dynamic scene.
This, in turn, means that it is impossible to predict what comes next. A safe bet, however, is that nickel in combination with other metals and minerals will only increase in importance as the shift from carbon-based energy continues.
Energy goes to the wall
To call the Tesla Powerwall® a game-changer understates the impact it is going to have on how electricity is generated, distributed and stored. The Powerwall challenges current models and responds in a cost-efficient way to the increasing complexity of electrical grids and the growing role of environmentally-driven (wind, solar, etc.) sources. And nickel is essential to this revolution.
At this early stage technical details are scarce. It is known that the Tesla stationary storage battery for residential use weighs 100kg (see Specifications) and will use far fewer cells per unit than in the Tesla Model S. The number of Powerwall units, however, could number in the millions.
More important: industrial and grid applications
The attention and imagination of the public is centred on the residential applications. These are literally “close to home” and are designed with that in mind with choices of colour for the mounted battery systems. Potentially much more disruptive to the energy industry, however, are the scaled-up versions referred to as “power packs” that will compete with other energy storage systems to provide the traditional capacities of peak shaving (storing off-peak energy), load shifting and voltage firming (voltage leveling).
According to Tesla Energy, utility-scale systems will group individual 100kWh batteries for capacities ranging from 500kWh to 10MWH and greater. They are to be capable of two to four hours of continuous net discharge power to compensate for grid power in case of outages. This will be delivered by the same nickel-containing batteries of the Tesla automobiles and at a price estimated at about US$250/kW hour of capacity, a reduction of at least 50% from alternative technologies.
It is still very early days. Performance and economics have yet to be severely tested but it is clear that the whole model of electrical power distribution, storage and use is being disrupted to the benefit of end-users (everyone) and the environment.
Today’s nickel-dependent battery chemistries
Nickel Zinc (NiZn): A rechargeable version of the nickel oxyhydride battery. High self-discharge rate but higher energy-to-mass and power-to-mass ratios because they are 75% lighter than equivalent lead acid batteries. They have a fast rate of charging and are price competitive with NiCd batteries.
Nickel Cadmium (NiCd): Once a dominant battery type for portable tools, it has evolved technologically and still has significant end-uses in stationary emergency power situations such as railway signalling, emergency lighting and grid levelling (voltage maintenance) as well as emergency short-term grid power supply.
Nickel Metal Hydride (NiMH): It was an exciting emerging technology 30 years ago. It is now a mature technology that still fills many roles. It was and remains the dominant battery chemistry for electric vehicles as it powers all the Toyota® Prius models.
Lithium Nickel Manganese Cobalt Oxide (NMC): A chemistry that can be tuned to deliver either high specific energy or high specific power, but not both. It is typically one-third nickel, one-third manganese and one-third cobalt but there are many variations to deliver different performance characteristics. It is the current power source of choice for electric tools, e-bikes and electric power trains. But not the Tesla…
Lithium Nickel Cobalt Aluminum Oxide (NCA): This variation was the choice for Tesla vehicles. It shares similarity with NMC by offering high specific energy, good specific power and a long life span. The addition of aluminum brings greater stability to the chemistry.