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                                                                    EXHIBIT 10.4

                                  ASSIGNMENT

                  WHEREAS, I, STEVEN C. AMENDOLA, a citizen of the United States
of America, whose post office address is 22 Lambert Johnson Drive, Ocean, New
Jersey 07712, have made the inventions identified in the attached Schedule A;

                  WHEREAS, the inventions identified in the attached Schedule A
were the subject of a License Agreement dated July 31, 1997, which has now been
terminated; and

                  WHEREAS, MILLENNIUM CELL INC., a corporation organized and
existing under the laws of the State of Delaware, and having an office for the
transaction of business at 1 Industrial Way West, Eatontown, New Jersey 07724,
is desirous of acquiring the entire right, title and interest in and to the
inventions identified in Schedule A and in and to the applications for Letters
Patent therefor, and any Letters Patent which may be obtained therefor,
including any reissued or re-examined patents and each and every foreign
counterpart of said inventions, all as set forth in Schedule A;

                  NOW, THEREFORE, TO ALL WHOM IT MAY CONCERN, BE IT KNOWN, that
I, STEVEN C. AMENDOLA, for the consideration recited in the attached AGREEMENT,
hereby acknowledge at or before the ensealing and delivery of these presents,
and the receipt of which is hereby acknowledged, have sold, assigned,
transferred and conveyed and by these presents do sell, assign, transfer and
convey, unto said MILLENNIUM CELL INC., its successors and assigns the entire
right, title and interest in and to the inventions identified in Schedule A,
including all rights, past, present and future, to enforce any and all patents
issuing thereon, and any and all improvements thereon, and in and to said
applications and any divisions, continuations or continuations-in-part thereof,
and in and to any Letters Patent of the United
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States of America which may be issued on any of said applications, and any
reissues and/or re-examinations thereof, and in and to any and all applications
for Letters Patent filed in foreign countries for said inventions or
improvements including all priority rights, and any and all Letters Patent which
may be granted in foreign countries therefor, and further including any future
invention(s) relating to the subject matter of the inventions assigned herein,
TO HAVE AND TO HOLD THE SAME to the full end of the term or terms for which any
and all said Letters Patent may be granted;

                  AND I, STEVEN C. AMENDOLA, do hereby authorize and request the
Commissioner of Patents and Trademarks to issue Letters Patent of the United
States of America to said MILLENNIUM CELL INC., as the assignee of the entire
right, title and interest in and to the same, for the sole use and benefit of
said MILLENNIUM CELL INC., its successors and assigns;

                  AND I, STEVEN C. AMENDOLA, do hereby covenant and agree to and
with said MILLENNIUM CELL INC., its successors and assigns, that I have the full
power to make this assignment, and that the rights assigned are not encumbered
by any grant, license or right heretofore given, and that I, my executors or
administrators, shall and will do all lawful acts and things and make, execute
and deliver without further compensation, any and all other instruments in
writing, further applications, papers, affidavits, powers of attorney,
assignments, and other documents which, in the opinion of counsel for said
MILLENNIUM CELL INC., its successors and assigns, may be required or necessary
more effectively to secure to and vest in said MILLENNIUM CELL INC., its
successors and assigns, the entire right, title and interest in and to said
inventions and improvements, applications, Letters Patent, rights, titles,
benefits, privileges, and advantages hereby sold, assigned, transferred and
conveyed, including the

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perfection of the right of first refusal granted to MILLENNIUM CELL INC. in the
License Agreement, and that I will sign any applications for reissue or
re-examination which may be desired by the owner of the patents assigned hereby.

                  IN WITNESS WHEREOF, I, STEVEN C. AMENDOLA, have hereunto set
my hand and seal on the date below written.

DATED:____________________                 /s/ STEVEN C. AMENDOLA
                                           ______________________
                                               STEVEN C. AMENDOLA

STATE OF          )
                  ) ss.:
COUNTY OF         )

         BE IT KNOWN, that on this ___ day of ____________, 2000, before me
personally came STEVEN C. AMENDOLA, to me known and known to me to be the person
mentioned in and who executed the foregoing assignment, and he acknowledged to
me that he executed the same as his free act and deed for the use and purposes
therein mentioned.

                                           _____________________________________
                                           Notary Public

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                                   SCHEDULE A

United States Patent No. 5,948,558
for HIGH ENERGY DENSITY BORIDE BATTERIES
(Appln. Ser. No. 08/829,497)

Australian Appln. Ser. No. 64462/98

Canadian Appln. Ser. No. 2297167

United Kingdom Appln. Ser. No. 9922864.5

Israeli Appln. Ser. No. 132091

Japanese Appln. Ser. No. 10-541641

South Korean Appln. Ser. No. 98-7008826

Mexican Appln. Ser. No. 99 8865

Singapore Appln. Ser. No. 9904715-1

WIPO Appln. Ser. No. US98/04185

WIPO Appln. Ser. No. US99/22303

United States Appln. Ser. No. 09/162,428
for HIGH ENERGY DENSITY BORIDE BATTERIES
(CIP  of Appln. Ser. No. 08/829,497)

United States Appln. Ser. No. 09/479,362
for SYSTEM FOR HYDROGEN GENERATION

United States Appln. Ser. No. 09/552,017
for ELECTROCHEMICAL CELL AND ASSEMBLY FOR SAME
(Baker Botts File No. A32147)

United States Appln. Ser. No. 09/559,024
for ENGINE CYCLE AND FUELS FOR SAME
(Baker Botts File No. A32672)

Proposed United States Appln.
for MEMBRANE ELECTRODE ASSEMBLY FOR USE
IN BOROHYDRIDE ELECTROCHEMICAL CELLS<PAGE>   1
                                                                    EXHIBIT 10.5

                                    AGREEMENT

This agreement dated May 16, 2000 between Stephen S. Tang (Executive) and
Millennium Cell Inc. (Company). The following are the terms of this agreement.

1.       Title - The Executive shall be the President and Chief Executive
         Officer of the Company, reporting directly to the Board of Directors.

2.       Base Salary - Base salary shall be at $225,000, (payable on a
         semi-monthly basis) per annum, increasing to $250,000 upon the earlier
         of the Company's IPO or January 1, 2001. - (Salary can be increased,
         but not decreased).

3.       Bonus - The Executive will be eligible for a target bonus of 50% of
         base salary. For the remainder of 2000 and 2001, a bonus of 50% of base
         salary would be guaranteed as follows:

         -        1/2 of the bonus guaranteed - no conditions.

         -        The remaining 50% of 2000 and 2001 bonus, shall be guaranteed
                  upon the earlier of the Company's IPO or January 1, 2001.

         -        All Bonuses shall be paid within 90 days of the end of the
                  calendar year.

4.       Signing Bonus - The Executive will receive a signing bonus of One
         hundred and thirty-five thousand ($135,000). 1/2 of the bonus shall be
         paid upon joining the Company. The remaining portion shall be paid upon
         the earlier of the Company's IPO or January 1, 2001.

5.       Equity/Stock Options - Upon joining Millennium, the Executive shall
         receive stock options on a total of 3.75% of the Company's equity;
         based on 27,000,000 common shares outstanding, this 3.75% equity grant
         is equivalent to 1,012,500 Options at a strike price in the range of
         $2.82 - $2.90 per share. The Options will have a term of a minimum of 5
         years and a maximum of 10 years. The exact term shall be determined by
         the Company and shall apply to all other Executives as well.

         Additionally, the new Board will be implementing a Stock Option Plan
         granting up to an additional 8% Equity and the Company anticipates that
         the Executive would be a major participant in that program.

         The Vesting Schedule of the initial 3.75% Equity Grant (1,012,500 Stock
         Options) is based on the Agreement anniversary date in accordance with
         the following schedule:

         Year 1 - 1/3  (33.33%)
         Year 2 - 1/3  (33.33%)
         Year 3 - 1/3  (33.33%)

6.       Termination - If the Executive is terminated by the Company other than
         for "Cause" (Cause is defined as fraud, embezzlement, or conviction of
         a crime involving moral turpitude) or the Executive resigns/terminates
         from employment for "Good Reason" (Good Reason is defined as
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         no longer being the President and Chief Executive Officer of the
         Company that reports directly to the Board of Directors or the
         Executive is not elected to the Board of Directors), then the following
         will occur:

         a 1) With respect to 3.5% Equity - 945,000 Stock Options, the
         Executive's Options shall vest as if he were employed throughout the
         entire year of the year of termination. For example, if the Executive
         is terminated on July 15, 2001 (assume agreement date June 1, 2000),
         then the Executive would be deemed as if he were employed through May
         31, 2002 and would vest in 2/3 of his Stock Options (June 1, 2000
         through May 31, 2001 = one year - June 1, 2001 through May 31, 2002 =
         two years). Notwithstanding the above, the Executive shall always vest
         a minimum of 50% of his Stock Options. For example, if the Executive
         resigns for "Good Reason" on August 15, 2000 (assume agreement date of
         June 1, 2000), then the Executive would still vest in 50% of his Stock
         Options and not 1/3.

         a 2) With respect to .25% Equity - 67,500 Options, the Executive's
         Options will vest in accordance with the terms of the Company's Stock
         Option Plan.

         b)       The executive will have 12 months from the termination of his
                  employment to exercise his Stock Options.

         c)       There shall be severance of one times the then base salary
                  plus one year bonus (bonus at the greater of 50% of then base
                  salary or the actual bonus paid for the full year preceding
                  the year of termination. The severance shall be paid in 4
                  quarterly/equal increments with no duty to mitigate; nor shall
                  this be a right of set-off.

         In the event of a "Change in Control", (40% or more in the change of
         stock ownership in the company or the sale of substantially all of the
         company's assets), all stock options and other equity will vest
         immediately and the Executive shall be entitled to the severance
         contained in paragraph 6(c) and the 12 month time period of 6(b) as if
         the Executive had been terminated other than for "Cause". However, the
         Executive shall not be entitled to severance under paragraph 6(c) if
         the Executive is the CEO of the acquiring company or is elected to the
         acquiring company's Board of Directors.

7.       Tax Gross-Up - The Executive shall be grossed-up for any excise taxes
         under Section 280(g) - Parachute Payments or any successor provision.
         The intent of this gross-up is to put the Executive in the same after
         tax position as if the excise tax was not imposed. The Company's
         accounting firm shall compute the Excise Tax. If the Company's
         accountant's determination of the Excise Taxes turns out to be
         inconsistent with the IRS, then the Executive shall notify the Company
         on the IRS's position. The Company shall defend its position and
         increase the gross-up amount to the extent the IRS prevails in its
         position; plus reimburse the Executive for any interest and penalties
         associated with the accountants computations.

8.       Board of Directors - The Executive shall serve on the Board of the
         Company and shall be entitled to indemnification from lawsuits and have
         coverage under a D&O Insurance Policy on the same terms as other
         Directors when such policy is obtained.
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9.       Death or Disability - All the Executive's Stock Options shall vest
         immediately in the event of death or disability and the Executive or
         his personal representative shall have 12 months from termination of
         employment to exercise his Stock Options. Disability shall be
         determined by an independent physician selected jointly by the Company
         and the Executive's personal representative, to determine that by
         reason of mental or physical illness the Executive would be able to
         resume his duties in the foreseeable future.

10.      Stock Option Plan - In the event there are any terms contained in the
         Company's Stock Option Plan (to be created) that may be more favorable
         to the Executive than those contained in this Agreement, then the
         Executive shall be entitled to those more favorable terms contained in
         the Plan. The terms of the Plan shall only apply where they are more
         favorable than those under this agreement.

11.      Non-Compete/Non-Solicitation - During employment and for a period of 12
         months following termination of employment, the Executive is not
         permitted to engage directly or indirectly in any business that
         generates hydrogen for the use in conventional engines, fuel cells, or
         batteries; nor shall the Executive for the same period, directly or
         indirectly endeavor to entice away any employees of the Company.

Agreed and Accepted:            Company /s/ G. CHRIS ANDERSEN
                                       -----------------------------------------
                                            G. CHRIS ANDERSEN

                                       /s/  STEPHEN S. TANG
                                       -----------------------------------------
                                            STEPHEN S. TANG

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