Toyota Jidosha Kabushiki Kaisha

Kenta Ishii

Masahiro Morita

Koji Abe

Koji Takahata

Masaki Kato

Kei Shimamoto

Ryosuke Ohsawa

Atsushi Watarai

Yusuke Onoda

Makoto Babazono

Shusaku Goto

Ryo Hanasaki

Risa Sato

According to the present disclosure, there is provided a technique making it possible to improve suitably the performance of a nonaqueous electrolyte secondary cell in which a SEI film is formed on the surface of a negative electrode active material. The nonaqueous electrolyte secondary cell disclosed herein includes a positive electrode, a negative electrode, and a nonaqueous electrolytic solution, wherein a negative electrode SEI filmincluding at least a LiBOB skeleton and a fluorosulfonic acid skeleton is formed on the surface of a negative electrode active material, and a positive electrode SEI filmincluding at least a phosphoric acid skeleton is formed on the surface of a positive electrode active material. Where the component amount of the LiBOB skeleton in the negative electrode SEI filmis denoted by I, the component amount of the fluorosulfonic acid skeleton in the negative electrode SEI filmis denoted by I, and the component amount of the phosphoric acid skeleton in the positive electrode SEI filmis denoted by I, a formula of 4&#x2264;I/I&#x2264;10 and a formula of 5 &#x3bc;mol/m&#x2264;I&#x2264;15 &#x3bc;mol/mare satisfied.

Nonaqueous electrolyte secondary cell and method for manufacturing nonaqueous electrolyte secondary cell

According to the present invention, there is provided a technique making it possible to improve suitably the performance of a nonaqueous electrolyte secondary cell in which a SEI film is formed on the surface of a negative electrode active material. The nonaqueous electrolyte secondary cell disclosed herein includes a positive electrode, a negative electrode, and a nonaqueous electrolytic solution, wherein a negative electrode SEI filmincluding at least a LiBOB skeleton and a fluorosulfonic acid skeleton is formed on the surface of a negative electrode active material, and a positive electrode SEI filmincluding at least a phosphoric acid skeleton is formed on the surface of a positive electrode active material. Where the component amount of the LiBOB skeleton in the negative electrode SEI filmis denoted by I, the component amount of the fluorosulfonic acid skeleton in the negative electrode SEI filmis denoted by I, and the component amount of the phosphoric acid skeleton in the positive electrode SEI filmis denoted by I, a formula (1) represented by 4&#x2264;I/I&#x2264;10 and a formula (2) represented by 5 &#x3bc;mol/m&#x2264;I&#x2264;15 &#x3bc;mol/mare satisfied. Furthermore, the BET specific surface area of the negative electrode active material is 3.5 m/g or more and 5.0 m/g or less, and the component amount Iof the LiBOB skeleton is 4.3 &#x3bc;mol/mor more.

Nonaqueous electrolyte secondary cell

In the nonaqueous electrolyte secondary cell disclosed herein, a negative electrode SEI filmincluding a LiBOB skeleton and a fluorosulfonic acid skeleton is formed, and a positive electrode SEI filmincluding a phosphoric acid skeleton is formed. Where the component amount of the LiBOB skeleton is denoted fey I, the component amount of the fluorosulfonic acid skeleton is demoted by I, and the component amount of the phosphoric acid skeleton is denoted by I, a formula of 4&#x2264;I/I&#x2264;10 and a formula of 5 &#x3bc;mol/m&#x2264;I&#x2264;15 &#x3bc;mol/mare satisfied. Furthermore, the total amount of lithium phosphate relative to a BET specific surface area of the negative electrode active material, is 0.6 mol/mto 1.0 mol/m, and the component amount Iof the fluorosulfonic acid skeleton is 0.6 &#x3bc;mol/mto 1.0 &#x3bc;mol/m.

The present teaching provides a non-aqueous electrolyte secondary battery provided with a non-aqueous electrolyte solution having a composition able to achieve high battery performance even in an extremely low temperature region (for example, &#x2212;30&#xb0; C. or lower). The non-aqueous electrolyte solution disclosed herein contains, as non-aqueous solvents, ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and ethyl propionate (EP), and when the total volume of the non-aqueous solvents is 100 vol. %, the content of EC is 20 to 30 vol. %, the content of PC is 5 to 10 vol. %, the content of EP is 5 to 10 vol. %, and the content of DMC+EMC is 50 to 70 vol. %.

Non-aqueous electrolyte secondary battery

The present invention provides a nonaqueous secondary battery having a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The nonaqueous electrolyte solution contains a nonaqueous solvent and a supporting salt. The nonaqueous solvent contains N,N-dimethylformamide. The concentration of the supporting salt is 1 mol/L to 2 mol/L. At least one of the positive electrode and the negative electrode is provided with a collector, and an electrode mixture layer that is fixed to the collector and contains an active material and a binder. The binder contains a network polymer compound with a structure resulting from urethane-bonding of four-branch prepolymers having a polyethylene glycol backbone.

Nonaqueous secondary battery

In a nonaqueous secondary battery including a pressure-operated current interrupt device, a ratio (Vt/Cr) of a sum Vt (cm) of an effective pore volume Vp of the positive electrode active material layer, an effective pore volume Vn of the negative electrode active material layer, and a pore volume Vs of the separator to a volume Cr (cm) of a remaining space in the battery case is 0.92 to 1.05. The volume Cr of the remaining space in the battery case is calculated by subtracting a volume Ce of the electrode body, a volume Cna of the nonaqueous electrolytic solution, and a volume Cc of auxiliary components from a volume Ct of the battery case. The remaining space volume Cr (cm) is 14.8 vol % or higher of the volume Ct (cm) of the battery case.

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Seto, Japan

Kenta Ishii