Fig.1 Laboratory SPA model. Mass 100 g, energy 1.2 W-hr. Maximum power 250 W.
Energy storage devices comparison.
Mass and cost of energy accumulators for a hybrid car.
At present there are two application areas proposed:
The accumulator also can be used in other fields, where there is a necessity to give back the accumulated power over a relatively short time of 1 to 100 sec.
Accumulator of super power (SPA) is an alkaline accumulator with water electrolyte.
The positive electrode is an oxide-nickel type electrode as in Ni-Cd and Ni-metal-hydride accumulators. However a special construction and technology of obtaining the positive electrodes provide the very high charge and discharge current densities up to 1,5 – 2 A/cm2 and a high specific power of the accumulator.
The negative electrode is a fundamentally new type and doesn’t have any analog. It consists of a substrate – nickel foil 25 – 40 mkm thick and a layer of active material with a very high specific area 100-120 m2/g with nanopores of 1 – 3 nm. The basic material of the active mass of the negative electrode is nickel in composition with oxygen, hydrogen and doping elements.
Thus the new accumulator should be named nickel - nickel oxide or nickel-nickel accumulator.
Specific capacity of the active mass is 100 A×hr/kg for the negative electrode and 270 A×hr/kg for the positive electrode. Both positive and negative electrodes are obtained by means of electrochemical synthesis of active layers on the nickel substrate. That is why the active layers have a good mechanical and electrical contact, which is necessary for the operation in high power modes.
The basic specifications of the SPA models with the above electrodes:
Specific energy – 12-18 A×hr/kg
Specific power – 2-5 kW/kg
Cost for mass production – 10-20 $/kg
Cyclic lifetime at 10 sec discharge and 100 sec charge – 12-20 thousand.
SPA is an accumulator of a fundamentally new type. At present on market there are no accumulators having high specific power, high specific energy and moderate price at the same time. Competitive energy accumulators for SPA are conventional accumulators and electrochemical capacitors (super capacitors). Table 1 shows the comparison of SPA characteristics with those of competitive energy accumulators.
Additional SPA advantages are simplicity of utilization of wasted SPA due to homogeneity of the electrode material and ecological safety.
It is seen that SPA has significantly higher specific power in comparison with all known types of batteries, but has lower specific energy. Compared to super capacitors SPA has an advantage of much higher specific energy.
Therefore SPA has an advantage at the discharge time from 1 to 100 sec. With shorter discharge duration SPA doesn’t have enough time to give away its energy and so looses to super capacitors. With discharge periods longer than 100sec, many types of batteries e.g. lead or Metal-hydride ones, turn out more preferable technically and economically.
To illustrate SPA advantages over competitive devices here we shall come up with the results of tech-cost effectiveness calculations for an energy accumulator for a hybrid car.
Let’s assume that for the car (10 sec) speed-up it would require 50 kW power. So the energy necessary for the speed-up will a mounts to 0.14 kW×hr. Three consecutive starts with no extra charge of the accumulator will consume 0.14×3=0.42 kW×hr.
Table 2 shows estimations of mass and cost of an accumulator needed for such a vehicle. SPA advantages are obvious.
A technology of fabricating positive and negative electrode has been developed and tested. The principles of construction of the batteries have been studied. Laboratory SPA models (see fig.1) have been made and tested.
Positive and negative electrodes as well as accumulators and any other energy storage device using at least one of the above electrodes have been patented (Patent Russia N2170468 priority date 10.04.2000)
There is an international patent application lodged PCT/RU 01/00147, WO 01/78172A2 covering 50 countries. At present patenting is in process in USA and Germany, i.d. transferring PCT in to the national phase. Patent-holders (owners) are four Russian citizens: Mirzoyev R.A., Stiroff M.I., Stepanova N.I., Mayoroff A.I.
To lead project to the full realization it is necessary:
To carry out this task technical and economical cooperation is desirable with a company having experience in developing and manufacturing hermetic alkaline accumulators. The following options of economic interaction are possible:
Mass production cost for the accumulator is 10-20$/kg.
It is determined mainly by the cost nickel - the basic material for the substrate and active mass of positive and negative electrodes. Cost of the other construction elements of SPA (electrolyte, separator, body, current leads, sealing spots) is not high, since the water electrolyte is cheap.