Appeal 2007-1118
Application 10/237,089
It is the Si that is active, SiO2 being inactive electrochemically
(Specification 4:11-16).
Umeno also describes an anode active material for a lithium
secondary battery (Umeno, col. 1, ll. 11-12). Umeno’s anode is said to have
a large capacity, high safety, and excellent charging and discharging cycle
property (Umeno, col. 1, ll. 12-14). Umeno recognized a problem with the
volume of the anode expanding several-fold as lithium alloyed with the
active material (e.g., silicon) within the anode, the expansion resulting in
powderizing which destroys the anode (Umeno, col. 2, ll. 12-39). Umeno
solves the problem of electrode powderization and destruction by covering
the lithium alloy-forming core particles with an expansion inhibiting layer of
carbon (Umeno, col. 2, ll. 48-68). The coating further suppresses oxidation
during charging and discharging of the battery (Umeno, col. 6, ll. 22-24) as
well as improves the conductivity of the particulate core and allows the
lithium to be supplied uniformly to the core from the whole outer surface of
the carbon layer thus improving charging and discharging speeds (Umeno,
col. 6, ll. 26-33). As the material for the core particles, Umeno suggests
selecting “metal and semimetal … capable of forming a lithium alloy” and
discloses a preference for titanium, iron, boron, and silicon with a particular
preference for silicon (Umeno, col. 4, ll. 38-44). Umeno does not expressly
state that SiOx can be used as a particulate core material, although Umeno
notes that silicon oxide is present in silicon as an allowable impurity, it
being inactive electrochemically (Umeno, col. 4, ll. 45-49).
The Fukuoka I Declaration provides data for lithium ion secondary
battery cells constructed and tested as in Appellants’ Example 2 of the
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