POWER OF ATTORNEY

        With respect to holdings of and transactions in securities issued by
Aeva Technologies, Inc. (the "Company"), the undersigned hereby constitutes and
appoints Segolene Scarborough with full power of substitution and
resubstitution, to act as the undersigned's true and lawful attorney-in-fact to
execute for and on behalf of the undersigned, in the undersigned's individual
capacity and in the undersigned's capacity as an authorized representative of
any legal entity, any statements, reports or filings with respect to the
undersigned necessary or advisable in connection with any disclosure requirement
promulgated under the federal or state securities laws of the United States or
any other applicable regulatory body, including, without limitation, compliance
with the Securities Exchange Act of 1934, as amended, and the rules and
regulations promulgated thereunder (including, without limitation, any filings
on Schedule 13D, Schedule 13G, Form 3, Form 4 and Form 5 and any forms or
statements required to be submitted in connection with any electronic filing),
and any and all amendments to such statements, reports and filings, and any
disclosure requirement promulgated under the securities laws or any similar laws
or regulations of any jurisdiction whether inside or outside of the United
States, and all amendments to such statements, reports and filings, and to file
the same, with all exhibits thereto, and all other documents in connection
therewith, with the United States Securities and Exchange Commission or any
other applicable regulatory body, said attorney-in-fact having full power and
authority to do and perform in the name of and on behalf of any of the
undersigned every act necessary to be done in the premises as fully and as
effectually as the undersigned might or could do in person; and the undersigned
hereby ratifies and confirms all that said attorney-in-fact shall do or cause to
be done by virtue hereof.


        The undersigned acknowledges that the foregoing attorney-in-fact, in
serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply
with the Securities Exchange Act of 1934, as amended, or other applicable
securities laws.


        IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 18th day of March, 2021.


                                        Peter Hebert


                                        Signature: /s/ Peter Hebert
                                                  -------------------------
                                        Print Name:  Peter Hebert