US 11,749,840 B2
Non-aqueous electrolyte secondary battery and charging method
Atsuhiko Minagawa, Shinagawa-ku (JP); and Hideyuki Sugiyama, Shinagawa-ku (JP)
Assigned to ELIIY POWER CO., LTD., Tokyo (JP)
Appl. No. 16/487,307
Filed by ELIIY POWER CO., LTD., Tokyo (JP)
PCT Filed Feb. 22, 2018, PCT No. PCT/JP2018/006544
§ 371(c)(1), (2) Date Apr. 24, 2020,
PCT Pub. No. WO2018/155582, PCT Pub. Date Aug. 30, 2018.
Claims priority of application No. 2017-034137 (JP), filed on Feb. 24, 2017.
Prior Publication US 2020/0176757 A1, Jun. 4, 2020
Int. Cl. H01M 10/0568 (2010.01); H01M 10/0525 (2010.01); H01M 4/133 (2010.01); H01M 4/58 (2010.01); H01M 10/0569 (2010.01); H01M 4/02 (2006.01)
CPC H01M 10/0568 (2013.01) [H01M 4/133 (2013.01); H01M 4/5825 (2013.01); H01M 10/0525 (2013.01); H01M 10/0569 (2013.01); H01M 2004/021 (2013.01); H01M 2004/027 (2013.01); H01M 2004/028 (2013.01)] 2 Claims
 
1. A non-aqueous electrolyte secondary battery comprising: a positive electrode in which lithium iron phosphate is used as a positive electrode active material; a negative electrode in which amorphous-based carbon is used as a negative electrode active material; a separator sandwiched between the positive electrode and the negative electrode; a non-aqueous electrolyte; and a casing which houses the positive electrode, the negative electrode, the separator, and the non-aqueous electrolyte, wherein
the non-aqueous electrolyte contains a lithium salt and a carbonate compound,
the lithium salt includes at least one selected from the group consisting of LiCF3SO3, LiAsF6, LiClO4, LiBF4, LiPF6, LiBOB, LiN (CF3SO2)2, and LiN(C2F5SO2),
the positive electrode, the negative electrode, and the non-aqueous electrolyte are configured to satisfy an inequality: (Rn/(Rp+Rn))≤0.54, where Rp is a positive electrode internal resistance attributed to both the positive electrode and a positive electrode reaction during charging of the secondary battery, Rn is a negative electrode internal resistance attributed to both the negative electrode and a negative electrode reaction during charging of the secondary battery, and (Rp+Rn) is an inter-terminal internal resistance of the secondary battery during charging of the secondary battery, Rn/(Rp+Rn)) being measured by using the secondary battery in which a metallic lithium electrode is provided as a reference electrode in such a manner that in a state where a state of charge (SOC) is the same, a terminal voltage, a potential of the negative electrode of the secondary battery containing the reference electrode is measured during 10 seconds of charging at 0.2 ItA, 0.5 ItA, and 1 ItA, from the measured terminal voltages, the internal resistance value (Rp+Rn) of the secondary battery is calculated, from the measured potentials (V vs. Li+/Li) of the negative electrode, the negative electrode internal resistance value Rn is calculated, and from these values, (Rn/(Rp+Rn)) is calculated,
the positive electrode, the negative electrode, and the non-aqueous electrolyte are formed so that an open-circuit potential of the negative electrode is higher than or equal to 0.1 V (vs. Li/Li+) and lower than or equal to 1.5 V (vs. Li/Li+) in a state where the SOC of the secondary battery is 0% to 100%,
the negative electrode is formed so that a utilization capacity of the negative electrode active material is greater than 0 mAh/g and smaller than or equal to 190 mAh/g,
the positive electrode comprises a positive electrode current collector in a sheet shape, and a positive electrode active material layer provided on the positive electrode current collector, and
the negative electrode comprises a negative electrode current collector in a sheet shape, and a negative electrode active material layer provided on the negative electrode current collector, wherein the negative electrode active material layer is a porous layer and has a porosity greater than 47% and lower than or equal to 53%.