DETAILED ACTION
Introductory Notes
Any paragraph citation of the instant is in reference to the U.S. published patent application.
Claim Rejections - 35 USC § 103
The text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 1 and 3-18 are rejected under 35 U.S.C. 103 as being unpatentable over FUJIWARA (JP 2004095306 A, listed on an IDS, machine translation used for citations) in view of TOSHIRO (JP 2013030355 A, machine translation used for citations) in view of BISWAL (US 20130045420 A1).
Regarding claims 1, 3-4, 10 and 15-16, FUJIWARA discloses an active material for negative electrode (Abstract) comprising:
silicon-based particles (“Si-containing particles” [0026]).
FUJIWARA does not expressly teach the Si-containing particles are porous.
BISWAL is directed to porous silicon particles for a lithium-ion battery such as that of modified FUJIWARA. BISWAL discloses “the methods of the present disclosure can allow users to control the thickness, pore diameter and porosity of the pores” [0075] as well as “the porous silicon films of the present disclosure may also be split into small porous silicon particles” [0064].
BISWAL teaches particles meeting the above characteristics as having “may have at least 3 times the capacity of the currently used anode materials for more than 550 cycles” [0077]. BISWAL further teaches the problems associated with the use of silicon, namely “volume expansion can result in severe cracking of the silicon, thereby leading to electrode failure. In fact, it is believed that lithiation-induced stress and structural destruction of silicon in batteries are the main cause for capacity loss during charge/discharge” [0024], and the teachings of BISWAL are aimed at addressing these problems.
Before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to utilize the porous silicon particles of BISWAL as the Si-containing particles of FUJIWARA to increase capacity.
Therefore, modified FUJIWARA discloses porous silicon-based particles (as taught by BISWAL).
FUJIWARA further discloses carbon particles, wherein the carbon particles comprise fine carbon particles and coarse carbon particles respectively having different average particle diameters (“first graphite particles” and “second graphite particles” [0009]),
wherein an average particle diameter (D50) of the fine carbon particles is in a range of 1 µm to 5 µm (“second graphite particles having a 50% particle size D50 of 2 to 10 μm” [0056] as well as example 5 in Table 1 with a second graphite particles D50 of 4 µm),
wherein an average particle diameter (D50) of the coarse carbon particles is in a range of 10 µm to 30 µm (“first graphite particles having a 50% particle size D50 of 5 to 20 μm” [0056] as well as example 5 in Table with a first graphite particles D50 of 10 µm),
wherein the shape of the fine carbon particles is spherical, point-like, scaly, or a mixture thereof (graphite reading on spherical, scaly and/or mixture thereof and it matches the graphite used in instant example 1 [0079]).
FUJIWARA discloses a 2:1 ratio of first to second, or coarse to fine, graphite particles in paragraph [0063]. FUJIWARA does not expressly teach the coarse carbon particles are included in an amount of 70 wt% to 99 wt% based on the total weight of all of the fine carbon particles and coarse carbon particles.
TOSHIRO is directed to negative electrode of a lithium-ion secondary battery like FUJIWARA. TOSHIRO discloses second graphitic carbon material B has a particle size smaller than the first graphitic carbon material A (Abstract), again like FUJIWARA. TOSHIRO discloses “the active material B is more preferably 20% to 30% by weight of the active material A” [0036] as well as example 2 with “active material A and negative electrode active material B in a mixing ratio of 80/20” [0050] thereby reading on the ranges of claims 1, 3, and 4)
TOSHIRO teaches when the weight ratio of active material B (fine) is above the minimum “the voids can be filled” [0036] and when the weight ratio of active material B (fine) is below the maximum “it can suppress a decrease in capacity” [0036].
Before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to balance the weights of coarse and fine particles in FUJIWARA to the 80:20 ratio of TOSHIRO in order to fill voids and retain capacity.
Therefore, modified FUJIWARA discloses the coarse carbon particles are included in an amount of 70 wt% to 99 wt% based on the total weight of all of the fine carbon particles and coarse carbon particles, as well as associated limitations of dependent claims (as taught by TOSHIRO).
Regarding claims 5 and 18, modified FUJIWARA discloses all the claim limitations as set forth above and BISWAL further discloses an average particle diameter (D50) of the porous silicon-based particles is in a range of 1 μm to 12 μm (“porous silicon particles with diameters that range from about 1 μm to about 50 μm” [0005]).
Overlapping ranges are prima facie obvious (see MPEP 2144.05, I). Before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to select the overlapping portion of the claimed diameter range in order to arrive at favorable capacity characteristics over multiple charge/discharge cycles.
Regarding claim 6, modified FUJIWARA discloses all the claim limitations as set forth above and BISWAL further discloses an average pore diameter of the porous silicon-based particles is in a range of 30 nm to 500 nm (“porous silicon particles of the present disclosure may have pores with diameters of less than about 2 nm (i.e., micropores), between 2 nm and 50 nm (i.e., mesopores), more than about 50 nm (macropores), or combinations of such pore diameters” [0067] and a range of “1 nanometer to about 5 micrometers” [0067]; BISWAL also discloses Fig. 8C which “shows weak absorption at low pressures, corresponding to few micropores, and a steep adsorption curve at higher pressures, suggesting the presence of macropores” [0105]).
Regarding claim 7, modified FUJIWARA discloses all the claim limitations as set forth above and BISWAL further discloses a specific surface area (Brunauer-Emmett-Teller (BET)-SSA) of the porous silicon-based particles is in a range of 5 m2/g to 50 m2/g (in comparing the macroporous silicon micro-particulates of BISWAL’s invention and commercial silicon nanoparticles BISWAL states “BET surface area for macroporous silicon micro-particulates was 46.84 m2/g, whereas for silicon nanoparticles is 34.86 m2/g” [0123] as such notably both the macroporous silicon micro-particulates and the commercial silicon nanoparticles have surface areas falling within the claimed range).
Regarding claim 8, modified FUJIWARA discloses all the claim limitations as set forth above and BISWAL further discloses the porous silicon-based particles comprise porous SiOx (where 0<x<2) (“by adjusting the current density or HF concentration … When the supply of the fluoride ion is insufficient, it starts forming a silicon dioxide rather than SiF62- … leads to isotropic etching at the tip of the pores, thereby resulting in a layer of silicon that is more porous … ” [0084], emphasis added; notably similar to the instant use of HF as outlined in [0059]).
Regarding claim 9, modified FUJIWARA discloses all the claim limitations as set forth above and BISWAL further discloses the porous silicon-based particles are porous silicon (Si) particles (“porous silicon particles” Abstract).
Regarding claim 11, modified FUJIWARA discloses all the claim limitations as set forth above and FUJIWARA further discloses a shape of the coarse carbon particles is irregular, scaly, planar, fibrous, spherical, or a mixed shape thereof (graphite reading on irregular, scaly, planar, spherical and/or a mixed shape thereof and it matches the graphite used in instant example 1 [0079]).
Regarding claim 12, modified FUJIWARA discloses all the claim limitations as set forth above and FUJIWARA further discloses the porous silicon-based particles and the carbon particles are mixed together or composited by mechanical milling (“mixing” [0063]).
Regarding claims 13 and 14, modified FUJIWARA discloses all the claim limitations as set forth above and FUJIWARA further discloses a negative electrode comprising the active material ([0063]) and a lithium secondary battery ([0067]).
Regarding claim 17, modified FUJIWARA discloses all the claim limitations as set forth above and FUJIWARA further discloses the fine carbon particles are disposed between the porous silicon-based particles and the coarse carbon particles (via mixing there are numerous instances of fine carbon particles between silicon-based particles and coarse carbon particles throughout the mixture).
Claim 2 is rejected under 35 U.S.C. 103 as being unpatentable over FUJIWARA in view of TOSHIRO in view of BISWAL in view of KONISHI (US 20130164618 A1).
Regarding claim 2, modified FUJIWARA does not expressly teach a mixing ratio of the porous silicon-based particles to the carbon particles is in a range of 1:1 to 1:20 as a weight ratio.
KONISHI is directed to negative electrode active material, like modified FUJIWARA. KONISHI also similarly discloses the use of two carbon materials of differing sizes (first active material with D50 15 μm to 20 μm [0031] and second active material with D50 10 μm or less [0019]) as well a third active material which contains silicon [0020], like FUJIWARA.
KONISHI discloses the “third active material is 1 wt % to 10 wt % of the total weight of the negative electrode active material” [0022] as well as example 1 [0092] with a 10:90 ratio of silicon containing material to total carbon materials. Regarding the amount of silicon containing material, KONISHI teaches being above a minimum “to adequately ensure the effect of increasing the capacity” [0050] and being below a maximum “to successfully avoid the problem due to the volume change” [0050].
Before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art to utilize the ratio of silicon containing material to total carbon materials of KONISHI in the mixture of FUJIWARA to increase the capacity while avoiding problems due to volume change.
Therefore, modified FUJIWARA discloses a mixing ratio of the porous silicon-based particles to the carbon particles is in a range of 1:1 to 1:20 as a weight ratio (as taught by KONISHI).
Response to Arguments
Applicant's arguments with respect to the claims have been considered and are persuasive. Notably this action is non-final.
Conclusion
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/T.L.M./Examiner, Art Unit 1721
/ALLISON BOURKE/Supervisory Patent Examiner, Art Unit 1721
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