Energy crisis of the notebook computer

Notebook computer user go out business trip, never forget the intersection of rechargeable battery and sufficient cable in the the computers, then remove CD-ROM driver and install the second battery here, takes the third batteries in the brief case finally. A lot of user needs work in the long flight continuously, moreover, function of high energy consumption that they still hope to use such as wireless network. Quicker, stronger demand of notebook computer can cause the huge power gap between the the intersection of sum and required system that offer in battery.

Though the notebook computer is profitting from Moore law constantly, the battery is not so lucky. Future of computer must depend on, already has long for one year, the electrochemical technology making little progress. This to say the intersection of computer and characteristic of battery raise, put before 5 year in the computer that produce battery of today, the battery life-span is still more than sufficient in 8 hours. The problem is, the notebook computer needs larger power.

Have already become and chosen one of the notebook computer 3 most important indexes in battery life-span. The production firm pursues more high characteristic, more quick wireless connections, the system should be thinner, this has further compressed the space of the battery. The Centrino moving chip of Intel really reduces the power consumption, brings operation time up to 5 hours from 2~3 hours, but this still can't meet the wishes of user's work of 8 hours. Work, need 100wh at least 8 hour ' Watt-hour) Power, and the preferably battery technology (lithium battery) at present Output under powered 60wh ( See Fig. 1) .

Recently, the suppliers realize the knot of the question and solicit progressively. Over these years, the technical research and development fund of battery claims to be enough relatively. Not only that, government department and individual enterprise put the research and development fund which engages in quantity into fuel cell, and it is extremely deficient to pour into the basic design work fund of the battery. It is expected to be practical after applying to 7, 8 years because of fuel cell. The bias of the investment orientation has caused the situation of the power gap at present finally.

Fully excavate the potentiality of the battery

Came out from the lithium battery at the beginning of the 1990s last century, the production firm had already carried on the great improvement to its characteristic. Over the past 5 years, the lithium battery has already replaced NiCd and NiMH technology in moving the computer apparatus. The lithium battery has energy density of higher unit volume; The memory effect that NiCd battery will shorten the life-span does not exist; And consider from the environment, cadmium is that one kind is harmful to metal, will pollute the environment, the lithium battery wants much more safely than NiCd battery.

The capacity that the chemical cell of the nickel base has already reached it is terminal, but lithium battery always has little harvest. In recent years, its capacity has increased progressively with 10% speed of every year. And 10%~20% with every year of cost are reduced. On the other hand, though the lithium battery has not reached its theory limit yet, but the industry thinks unanimously, very anticipated result is not enough to remedy the gap of the power yet. The new round of upsurge that this conclusion has stimulated the battery and studied.

Electrovaya Company adopts lithium ionic polymer technology, using gel electrolyte. Though has not realized the Er early commitment, this technological cost is higher than the lithium battery, energy density also has breakthrough progress. But it really has a overhanging advantage, the polymer-based battery can be processed into the tabular appearance of suitable small-scale equipment installation, and company's limit of lithium battery shows cylindrically and designs. Company, Pionie of Japan, show one the intersection of battery and sample, the intersection of energy density and at present reachable 600 wh/l. its already, most lithium batteries are among 200wh 250wh/1. Except polymer, other suppliers are launching the design based on a kind of material of Li-S and lithium phosphorus too.

Even traditional alkaline battery want to return to the historical stage. The cycles of charging and discharging of the zinc-based alkaline battery are only about 10 times. Some companies substitute the alkaline battery traditional electrolyte with the polymer-based prescription, the number of times that it is periodic to charge and discharge in order to increase, has obtained several hundred periodic gratifying achievements, energy density reachable 600wh/1. It is expected that produced the notebook computer and used the battery in 2006.

Various portable battery alternativeses are shown in Table 1.

The fuel cell shoulders heavy responsiblities

For a long time, most suppliers will hope to place on fuel cell. Government department and individual enterprise spent the research of investing fuel cell of a huge sum of money, there are designs that more than 60 companies are engaged in power electronics. The fuel cell forms the chemical reaction with oxyhydrogen compound or oxygen compound of methanol. The most popular design is the direct methanol fuel cell, use methanol or admixture fuel of methanol / water. The fuel cell is expected to offer extremely high energy density. It changes working way of the fuel pot to guarantee it is nearly infinite power. Can produce the electricity of 1Wh as little as the fuel of 1CC. Enough operating handset is 2 hours. However, this technology faces a great deal of challenges. It is that a fuel cell is very complicated at first, need an engine to become piles; Miniature pump, sensor and relevant electronic circuit; Ventilating device; And fuel pot ( Refer to fig. mouth) . Compress the volume of the battery to the notebook computer workable magnitude, and can sell at reasonable price, work reliably, it is a main obstacle on the project.

Secondly, fuel cell unefficient, nearly have 70% empty heat of energy transformation, only 10% are turned into the power of battery, the notebook computer designer has a difficult problem has happened, they must face the thermal challenge. The system should set up the ventilating device to list carbon dioxide and steam of drib. The response rate of the fuel cell is relatively slow, can't respond to the increased suddenly power to require fast. So, design in early days, such as IP3 RFIC sensor prototype machine of Intermec Technologies Company, its fuel cell uses with lithium battery. IP3 fuel cell be charged to the battery continuously while being RFID producing device direct power supply. 55CC alkene material pot can work for 30 hours continuously, and the traditional battery is only 10 hours. Also suppliers are carrying on the super and capacitive test, this is a kind of solid-state device, offer the transient supplement power for peak load.

Toshiba is the investor of alkene material battery maximum. It has already shown one " Change the cabin " The prototype machine designed, " change the cabin " Attached to computer as a external component. Certainly, will not also have practical products before relevant standards are issued formally. Design needing to get the public extensive admittance with standard fuel mixture and fuel pot, the regulations of its safety and operation method also need the approval of the related departments. Especially on the plane, want through a regulation, allows to carry flammable methanol pot on the civil aircraft, it is not an easy thing.

Relevant experts point out, during some time in the past, material battery producer had already taken a gratifying great step with alkene, battery volume decrease 50%, it is tested that the energy density of the unit has exceeded the lithium battery. It is estimated that there is early fuel cell supply of drib this year and next year, rise to thousands of products slowly by 2007, and year when the fuel cell will be vigorous in 2010.

(east China)

Table 1, portable battery alternatives

Variety

Advantage

Shortcoming

NiCd

Can offer at cheap price heavy-dutily, charge and discharge fast

Energy density is low; There are memory effects, will shorten the people's life-span of the battery if it is improper to maintain, Cd battery pollutes the environment, will be probably eliminated.

NiMH

High discharge rate; The output power ratio under the equal volume is NiCd big; There is no memory effect.

Cycle is 300~500 times to charge and discharge, NiCd is 1, 500 times by contrast.

Lithium ion

It is light to combine with, energy density is high; There is no memory effect; Charge and discharge for cycle the same as NiMH.

More expensive; The chemical reaction is unstable, need special security service and rigorous production control.

Ionic polymer of lithium

The characteristic is the same as lithium ion, but can press and cast the extremely light and thin appearance

More expensive than the traditional lithium ion

Can reuse the alkaline battery

Not the discharge rate is low when using; It is only 0.3% every month, the lithium ion is 10% by contrast, NiMH is 30%.

The cycle of charging and discharging is limited to for 50 times, the lithium-base battery is 300~500 times by contrast.

Direct methanol alkene material battery

Operation time is long, can lengthen operation time while giving replenish fuel of device.

Still in sample state, there are no mature products before 2010, unefficient, produce empty heat; The reaction rate is slow, unable to meet the needs of peak load.

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