Appeal 2007-1524
Application 09/770,725
1 electrode, and a non-aqueous electrolytic solution containing LiPF6.
2 (Kurose, 8:42-67.) Kurose teaches (2:14-18):
3 Use of an active material in a state with a lot of absorbed
4 moisture in battery causes problems such as decrease in a
5 charge/discharge capacity of the battery, increase in internal
6 resistance, and deterioration of the preservation property.
7
8 Thus, Kurose (like Watanabe) explicitly states that moisture in a positive
9 electrode that is compositionally and structurally similar to that described in
10 Takami causes problems in lithium batteries.
11 Compared to the subject matter of appealed claim 1, Takami does not
12 disclose “a cumulative concentration of water (H2O) released from both of
13 the said positive electrode and said negative electrode in relation to the
14 weight of said electrode unit, exclusive of current collectors, is suppressed to
15 5,000 ppm or lower in case of heating both electrodes at 25 to 200°C and to
16 1,500 ppm or lower in case of heating said electrodes at 200 to 300°C.”
17 Nevertheless, we agree with the Examiner’s conclusion that the claimed
18 subject matter as a whole would have been obvious to a person of ordinary
19 skill in the art over the prior art.
20 We start with the negative electrode. Takami discloses that water in
21 the electrolyte solvent is one of the main impurities that causes “the
22 formation of an insulating film on the surface of a graphitized substance,
23 thereby increasing the surface resistance of the electrodes.” (Takami, 10:27-
24 30.) This may, in turn, “give a bad influence to the battery, thereby not only
25 deteriorating the cycle life or capacity thereof, but also increasing the-self-
26 discharge during a high temperature (60° C. or more) storage of the battery.”
27 (Takami, 10:31-35.) For these reasons, Takami discloses that it would be
28 desirable to eliminate water as an impurity from the electrolyte containing a
13
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