Maxell, Ltd. v. Amperex Technology Limited

N OTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
MAXELL, LTD.,
Appellant
v.
AMPEREX TECHNOLOGY LIMITED,
Appellee
______________________
2023-2256, 2023-2258
______________________
Appeals from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in Nos. IPR2021-
01440, IPR2021-01443.
-------------------------------------------------
MAXELL, LTD.,
Appellant
v.
AMPEREX TECHNOLOGY LIMITED,
Appellee
______________________
2023-2257
______________________
Case: 23-2256 Document: 39 Page: 1 Filed: 01/23/2025

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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 2
Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. IPR2021-
01441.
______________________
Decided: January 23, 2025
______________________
ERIK SHALLMAN, Vinson & Elkins LLP, Austin, TX, ar-
gued for appellant. Also represented by CORBIN CESSNA,
J EFFREY T A-HWA HAN, HILARY L. P RESTON; ERIC J OSEPH
K LEIN, P AIGE HOLLAND WRIGHT , Dallas, TX.
BRADY COX , Alston & Bird LLP, Dallas, TX, argued for
appellee. Also represented by K IRK T. BRADLEY ,
CHRISTOPHER T IMOTHY L AWN D OUGLAS , N ICHOLAS
CHRISTOPHER M ARAIS , Charlotte, NC.
______________________
Before L OURIE, REYNA , and CHEN, Circuit Judges.
L OURIE, Circuit Judge.
Maxell, Ltd. appeals from three decisions of the U.S.
Patent Trial and Appeal Board (“the Board”) holding
claims 1–5 of U.S. Patent 8,691,446 (“the ’446 patent”),
claims 1–5 of U.S. Patent 9,350,019 (“the ’019 patent”), and
claims 1–11 of U.S. Patent 9,077,035 (“the ’035 patent”) un-
patentable as obvious.1 Amperex Tech. Ltd. v. Maxell, Ltd.,
No. IPR2021-01440 (P.T.A.B. Mar. 28, 2023) (“’1440 Deci-
sion”), Appeal No. 23-2256, J.A. 1–42; Amperex Tech. Ltd.
1 Appeal No. 23-2256 (relating to the ’446 patent)
and Appeal No. 23-2258 (relating to the ’019 patent) were
consolidated for briefing. Appeal No. 23-2257 (relating to
the ’035 patent) was briefed separately. Because the issues
across the appeals largely overlap, we address all three to-
gether.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 3
v. Maxell, Ltd., No. IPR2021-01443 (P.T.A.B. Mar. 28,
2023), Appeal No. 23-2256, J.A. 43–85; Amperex Tech. Ltd.
v. Maxell, Ltd., No. IPR2021-01441 (P.T.A.B. Mar. 28,
2023) (“’1441 Decision”), Appeal No. 23-2257, J.A. 1–44.2
For the following reasons, we affirm.
BACKGROUND
Maxell owns the ’446 patent, the ’019 patent, and the
’035 patent, which are each generally directed to recharge-
able lithium-ion batteries. The patents seek to address
problems associated with basic lithium cobalt oxide
(LiCoO 2) electrode materials, such as structural decay, re-
liability, and gas generation, by incorporating cathode ma-
terials that contain at least two lithium-containing
transition metal oxides having different average particle
sizes. See, e.g., ’446 patent, Abstract. For example, claim
1 of the ’446 patent recites:
1. A nonaqueous secondary battery comprising: a
positive electrode having a positive electrode mix-
ture layer, a negative electrode, and a nonaqueous
electrolyte,
wherein the positive electrode contains, as
an active material, at least two lithium-
containing transition metal oxides having
different average particle sizes,
wherein said at least two lithium-contain-
ing transition metal oxides having differ-
ent average particle sizes have different
compositions of elements between them,
2 For simplicity, we cite the ’1440 Decision on issues
pertaining to both the ’446 and ’019 patents and the ’1441
Decision on issues pertaining to the ’035 patent.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 4
said lithium-containing transition metal
oxide having the smallest average particle
size is a lithium-containing transition
metal oxide represented by the formula (1):
Li x M1y M2zM3v O 2 (1)
wherein M1 represents at least one transi-
tion metal element selected from Co, Ni
and Mn, M2 represents Mg and at least one
metal element selected from the group con-
sisting of Ti, Zr, Ge, Nb, Al and Sn, M3 rep-
resents an element other than Li, M1 and
M2, and x, y, z and v are numbers satisfying
the equations respectively: 0.97≤x<1.02,
0.8≤y<1.02, 0.002≤z≤0.05, and 0≤v≤0.05,
the positive electrode mixture layer has a
density of at least 3.5 g/cm 3, and
the nonaqueous electrolyte contains a com-
pound having at least two nitrile groups in
the molecule.
Id. col. 28 ll. 35–60.
All three patents recite the limitation that the “lith-
ium-containing transition metal oxide having the smallest
average particle size is a lithium-containing transition
metal oxide represented by the formula (1):
Li x M1y M2zM3v O 2.” See, e.g., id. col. 28 ll. 44–48. Relevant
to these appeals is the identity of M2 in that formula. Each
of the ’446 and ’035 patents claims that M2 “represents Mg
and at least one metal element selected from the group con-
sisting of Ti, Zr, Ge, Nb, Al and Sn.” Id. col. 28 ll. 50–52;
’035 patent, col. 29 ll. 33–35. Similarly, the ’019 patent
claims that M2 “represents Mg, or Mg and at least one
metal element selected from the group consisting of Ti, Zr,
Ge, Nb, Al and Sn.” ’019 patent, col. 28 ll. 54–56. Accord-
ingly, all three patents recite that M2 can be represented
by Mg and Al.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 5
In addition to the cathode material, the patents seek to
enhance thermal stability of the battery through the use of
additives in the nonaqueous electrolyte. Each of the ’446
and ’019 patents claims that the electrolyte “contains a
compound having at least two nitrile groups in the mole-
cule.” ’446 patent, col. 28 ll. 59–60; ’019 patent, col. 28 ll.
65–67. The ’035 patent claims that the electrolyte “con-
tains a fluorine-containing organic solvent.” ’035 patent,
col. 29 ll. 53–54.
Amperex Technology Limited (“Amperex”) petitioned
for, and the Board instituted, inter partes review (“IPR”) of
all claims of the ’446, ’035, and ’019 patents. Amperex ar-
gued, inter alia, that claims 1–5 of the ’446 patent and
claims 1–5 of the ’019 patent are invalid because, at the
time of the invention, they would have been obvious over
U.S. Patent Application Publication 2006/0257745
(“Choi”)3 in combination with U.S. Patent Application
2005/0208371 (“Kim”), and that claims 1–11 of the ’035 pa-
tent are invalid because, at the time of the invention, they
would have been obvious over Choi in combination with
U.S. Patent Application 2004/0197667 (“Noh”).
Choi, which relates to “lithium batteries having high
voltage stability, thermal stability and high rate discharge
characteristics,” discloses a cathode material for a lithium
battery that includes large and small diameter materials.
Choi, Abstract, ¶ 2. The small diameter material can have
the formula Li x Co 1-y-zNi y MzO 2-αXα, where M “is selected
from the group consisting of Al, Ni, Mn, Cr, Fe, Mg, Sr, V,
rare earth elements and mixtures thereof.” Choi,
¶¶ 31–32. Choi further discloses that the battery includes
3 In each of the ’446 and ’019 patent IPR, Amperex
cited Chinese Patent Application Publication 1822414, the
Chinese counterpart to Choi. For simplicity, we cite to the
U.S. publication of Choi.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 6
an electrolytic solution that can comprise benzonitrile and
acetonitrile, i.e., mononitrile solvents. Id. ¶ 61.
Kim relates to improving thermal stability of cathode
materials, such as lithium-containing transition metal ox-
ide, through “a protection layer formed by a complex be-
tween the surface of a cathode active material and an
aliphatic nitrile compound.” Kim, Abstract, ¶ 8. The ali-
phatic nitrile compound can be succinonitrile, i.e., a dini-
trile compound. Id. ¶ 32.
Noh relates to improving the discharge and thermal
stability of lithium batteries using an electrolyte of “lith-
ium salts, an organic solvent with a high boiling point, and
a carbonate-based additive compound having substituents
selected from the group consisting of a halogen, a cyano
(CN), and a nitro (NO 2).” Noh, Abstract. The carbonate-
based additive compound can include, for example, a fluor-
inated aromatic hydrocarbon, such as fluorobenzene and
fluorotoluene. Id. ¶ 49.
The Board determined that Amperex had established
that a person of ordinary skill in the art “would have been
motivated by a desire for increased thermal stability and
improved discharged characteristics” to combine Choi with
each of Kim and Noh to arrive at the claimed inventions of
the challenged patents. ’1440 Decision, J.A. 10; ’1441 De-
cision, J.A. 11. Specifically, the Board found that Amperex
had presented undisputed testimony that improving ther-
mal stability is critical to battery safety, and that even
Maxell agreed that each of Choi, Kim, and Noh is directed
to improving the thermal stability and discharge charac-
teristics of lithium batteries. ’1440 Decision, J.A. 11; ’1441
Decision, J.A. 12. The Board further noted the parties’
agreement that the references teach different ways of
achieving those goals. While Choi teaches improving ther-
mal stability through a composite cathode material having
large and small diameter particles, each of Kim and Noh
teaches improving thermal stability through electrolytic
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 7
additives. ’1440 Decision, J.A. 11–12; ’1441 Decision, J.A.
12–13. The Board found that, given that Kim and Noh
taught cathode materials similar to those of Choi, and that
Choi taught electrolyte materials similar to those of Kim
and Noh, a person of ordinary skill in the art would have
been motivated to combine the improved electrolytes of
Kim and Noh with the improved cathode materials of Choi,
and done so with a reasonable expectation of success. ’1440
Decision, J.A. 12–22; ’1441 Decision, J.A. 13–24.
Having found that Amperex satisfied its burden of es-
tablishing a motivation to combine the references, the
Board turned to its obviousness analysis. The only dispute
between the parties relevant here was whether a person of
ordinary skill in the art would have selected Mg and Al
from Choi in the claimed amount to arrive at the claimed
inventions. See ’1440 Decision, J.A. 22; ’1441 Decision, J.A.
25. The Board found that undisputed evidence, including
unrebutted expert testimony, which was corroborated with
various secondary references, established that a person of
ordinary skill in the art would have been motivated to in-
corporate Mg and Al into a cathode to impart conductivity
and structural enhancements, respectively. ’1440 Deci-
sion, J.A. 24–29; ’1441 Decision, J.A. 27–32. In light of that
unrebutted evidence, the Board rejected Maxell’s argu-
ments that Mg and Al are just one of 600 possible pairs of
elements that could have been selected from Choi such that
Amperex must have improperly relied on hindsight to ar-
rive at that combination. ’1440 Decision, J.A. 27–28; ’1441
Decision, J.A. 30–31.
The Board further found that Amperex had established
by preponderant evidence that Choi teaches a molar
amount of M2, i.e., 0≤z≤0.5, that encompasses the claimed
range, i.e., 0.002≤z≤0.05, therefore establishing a prima fa-
cie case of obviousness for that limitation. ’1440 Decision,
J.A. 29–30; ’1441 Decision, J.A. 32–33. Moreover, the
Board found that undisputed evidence established that the
molar amount of M2 would have been understood to be a
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 8
result-effective variable that a person of ordinary skill in
the art would have been motivated and capable of optimiz-
ing through routine experimentation. ’1440 Decision,
J.A. 30–35 (citing expert testimony and supporting second-
ary references); ’1441 Decision, J.A. 33–38 (same).
Finding that a preponderance of evidence established
that a person of ordinary skill in the art would have arrived
at a cathode material that falls within the scope of the
claims, the Board held that Amperex had met its burden in
showing that the claims would have been obvious over the
asserted prior art. Accordingly, the Board held all claims
unpatentable under 35 U.S.C. § 103.
Maxell timely appealed. We have jurisdiction under
28 U.S.C. § 1295(a)(4)(A).
D ISCUSSION
Maxell raises two arguments on appeal. First, it ar-
gues that the Board’s motivation-to-combine analyses were
not supported by substantial evidence because, inter alia,
a generic goal to improve thermal stability of a battery is
not enough to induce one of ordinary skill to combine Choi
with each of Kim and Noh when the references undisput-
edly teach different ways of achieving that goal. Second, it
argues that, even if there had been a motivation to combine
the references, the Board’s obviousness analyses were not
supported by substantial evidence because selecting Mg
and Al in the claimed amounts from Choi to arrive at the
claimed invention would have been akin to selecting the
“proverbial needle in the haystack.” See Appeal No.
23-2256, Oral Arg. at 3:53–4:12, available at https://
oralarguments.cafc.uscourts.gov/default.aspx?fl=23-2256_
01072025.mp3. We disagree and address each argument
in turn.
I
Substantial evidence supports the Board’s findings
that a person of ordinary skill in the art would have been
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 9
motivated to combine Choi with each of Kim and Noh to
arrive at a lithium battery having improved thermal sta-
bility and discharge characteristics. In reaching that de-
termination, the Board relied on the express teachings of
the references and the undisputed testimony of Amperex’s
expert witness, as well as the corroboration of that testi-
mony by various supporting references. See, e.g., ’1440 De-
cision, J.A. 10–22.
Maxell’s primary argument on this issue is that “a gen-
eral expectation of further improvement is not a sufficient
basis for a motivation to combine.” Reply Br. 5.4 Specifi-
cally, it is Maxell’s position that a person of ordinary skill
in the art would not have been motivated to combine Choi
with Kim and Noh “because Choi already sufficiently ad-
dresses the problems that Kim [and Noh] seek[] to solve:
thermal stability and discharge characteristics.” Maxell
Br. 34. This argument is unpersuasive. While we gener-
ally agree that, without more, the mere motivation to
“build something better” may not always be enough to com-
bine various references, that is not the case here. See id.
at 37 (citing ActiveVideo Networks, Inc. v. Verizon
Commc’ns, Inc., 694 F.3d 1312, 1328 (Fed. Cir. 2012)).
In contrast with ActiveVideo, where there was no rela-
tion of the alleged motivation “to any specific combination
of prior art elements,” 694 F.3d at 1328, the Board thor-
oughly explained, relying on expert testimony, how Am-
perex had established that a person of ordinary skill in the
art would have combined the specific cathode material of
Choi, which was designed to improve thermal stability of
the battery, with the specific electrolyte of Kim and Noh,
which too were designed to improve thermal stability. See
’1440 Decision, J.A. 11–20. The Board therefore did not
4 Unless otherwise indicated, references to the brief-
ing are to those filed in connection with Appeal No.
23-2256.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 10
rely on the mere fact that the references were each gener-
ally directed to improving thermal stability.
Moreover, Maxell’s argument that the fact that the ref-
erences use different means to solve the same problem
would have disincentivized combination misses the mark.
Under the circumstances of this case, it is the very fact that
the references teach different means that would have led a
person of ordinary skill in the art to combine them. As Am-
perex’s expert explained:
A person of ordinary skill [would] seek out a cath-
ode that would provide as much [thermal stability]
as possible . . . . But a person of ordinary skill
would also have understood that the electrolyte is
an important part of the battery, and that inclusion
of a proper electrolyte to impart properties of the
battery that would enhance . . . thermal resistance
to temperature excursions would [be desired]. So
[the person of ordinary skill in the art] would have
sought out Choi and Kim [and Noh] as a combina-
tion to achieve the desired battery with the desired
characteristics.
’1440 Decision, J.A. 19. In other words, the fact that the
references teach discrete means to achieve the same goal
in batteries that are otherwise very similar is entirely con-
sistent with a motivation to combine because each of the
cathode material of Choi and electrolyte of Kim or Noh, in-
dependently, would have been expected to increase ther-
mal stability.
Accordingly, we conclude that the Board’s motivation-
to-combine findings were supported by substantial evi-
dence.
II
Maxell next argues that, even if a person of ordinary
skill in the art would have combined Choi with each of Kim
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 11
and Noh, the Board did not support its obviousness deter-
mination with substantial evidence. Again, we disagree.
Maxell’s argument is essentially that Choi discloses
numerous options for the M2 component of its cathode ma-
terial such that arriving at the selection of Mg and Al,
which falls within the scope of the challenged claims, would
be akin to finding a needle in a haystack. This argument,
however, ignores the fact that Maxell does not specifically
claim that needle, i.e., a cathode material wherein M2 is Mg
and Al. Rather, the challenged claims recite a haystack of
their own, in which Mg and Al are just one possible combi-
nation. See, e.g., ’446 patent, col. 28 ll. 50–52. Maxell’s
arguments therefore lack persuasion insofar as this case
does not involve the patentability of a claim to a species
where the prior art discloses only a genus encompassing
that species. Cf. In re Baird, 16 F.3d 380, 382 (Fed. Cir.
1994) (“The fact that a claimed compound may be encom-
passed by a disclosed generic formula does not by itself ren-
der that compound obvious.”).
We conclude that substantial evidence otherwise sup-
ports the Board’s obviousness determination. The Board
relied on ample evidence to explain why a person of ordi-
nary skill in the art would have been specifically motivated
to select Mg and Al from Choi. In particular, the Board
relied not only on expert testimony, but explained how that
testimony itself was supported by the disclosures of addi-
tional literary references, such as Tukamoto5 (teaching
that Mg doping of a lithium cobalt oxide cathode can sig-
nificantly increase conductivity), Madhavi6 (teaching that
5 H. Tukamoto & A.R. West, Electronic Conductivity
of LiCoO 2 and Its Enhancement by Magnesium Doping, 144
J. ELECTROCHEM . SOC’ Y 3164 (1997), J.A. 2913–18.
6 S. Madhavi et al., Cathodic properties of (Al, Mg)
co-doped LiNi0.7Co 0.3O 2, 152 SOLID STATE I ONICS 199
(2002), J.A. 2926–32.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 12
Mg and Al doping of a lithium cobalt oxide cathode im-
proves thermal stability), and Sato7 (claiming a lithium co-
balt oxide cathode material comprising at least one of Mg
and Al). Those disclosures, pre-dating the priority date of
the challenged claims and teaching the specific selection of
Al and Mg—a selection that Maxell does not dispute falls
within the scope of the challenged claims—constitutes sub-
stantial evidence supporting the Board’s determination
that it would have been obvious to arrive at the claimed
cathode materials.
Maxell further challenges the Board’s treatment of the
claimed amount of the M2 component, arguing that Choi’s
range, i.e., 0≤z≤0.5, is so broad, encompassing a very large
number of distinct compositions, such that it cannot render
obvious the claimed range of 0.002≤z≤0.05. We disagree.
Choi’s range entirely encompasses the claimed range. “[A]
prior art reference that discloses a range encompassing a
somewhat narrower claimed range is sufficient to establish
a prima facie case of obviousness.” In re Peterson, 315 F.3d
1325, 1330 (Fed. Cir. 2003). And here, Maxell provides no
argument as to why the claimed range is critical or other-
wise meaningfully different from that of Choi. Cf. Genen-
tech, Inc. v. Hospira, Inc., 946 F.3d 1333, 1341 (Fed. Cir.
2020) (noting that one way to rebut obviousness of an over-
lapping range is to show “that there is something special or
critical about the claimed range.” (citation omitted)). In-
stead, Maxell argues that, for the claimed range to overlap
with the prior art, a person of ordinary skill in the art
would first have to particularly select Al and Mg from the
materials disclosed in Choi, and only then select a molar
concentration within the claimed range, falling on the
lower end of Choi’s range. But because we have already
concluded that substantial evidence supports a motivation
to particularly select Mg and Al from Choi, we are unmoved
7 U.S. Patent Application Publication 2005/0266315.
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MAXELL, LTD. v. AMPEREX TECHNOLOGY LIMITED 13
by Maxell’s argument on this issue. And, in any event, the
Board found, based on testimony and documentary
sources, that the lower end of Choi’s range had particularly
desirable features. ’1440 Decision, J.A. 30–34.
CONCLUSIONS
We have considered Maxell’s remaining arguments
and find them unpersuasive. For the foregoing reasons,
the Board’s decisions holding claims 1–5 of the ’446 patent,
claims 1–5 of the ’019 patent, and claims 1–11 of the ’035
patent invalid as obvious are affirmed.
AFFIRMED
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