Appeal 2007-1524
Application 09/770,725
1 non-aqueous solvent as much as possible, such that the content of water does
2 not exceed 50 ppm. (Takami, 10:38-39.)
3 These teachings in Takami would have led a person having ordinary
4 skill in the art to reasonably draw an inference that the presence of water in
5 the carbonaceous material of the negative electrode should also be avoided.
6 Furthermore, Watanabe teaches that the moisture content of a negative
7 electrode that may contain calcined carbonaceous material (in addition to
8 lithium-containing silicon oxide) in a similar battery should be below 50
9 ppm “from the point of cycle property.” (Watanabe, 7:37-40, 14:37-51.)
10 Under these circumstances, we conclude that one of ordinary skill in the art
11 would have been led to reduce the amount of moisture in Takami’s negative
12 electrode to the greatest extent possible, such as 50 ppm or lower, in order to
13 avoid the known problems associated with moisture, as disclosed in both
14 Takami and Watanabe.
15 With respect to the positive electrode, we have found that Kurose
16 teaches that a positive electrode including nickel-containing lithium oxide,
17 which may further contain Mn, absorbs moisture, causing problems such as
18 a decrease in charge/discharge capacity, an increase in internal resistance,
19 and deterioration of preservation property. In a similar fashion, Watanabe
20 also cautions against the presence of moisture for a lithium-titanium oxide
21 based positive electrode that may additionally contain Mn and Ni. Based on
22 the reasonable expectation that the problems caused by moisture as
23 described in Kurose and Watanabe would also occur in other electrodes of
24 similar composition, we conclude that one of ordinary skill in the art would
25 have found it obvious to reduce the amount of water in Takami’s positive
14
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