An electrochemical cell comprises an anode, a cathode and an electrolyte composition, wherein the anode comprises as anode active material a combination of at least a carbon material and a silicon material; and the electrolyte composition comprises a solvent, from 0.5 wt. % to 70 wt. %, based on the total weight of the electrolyte, of a fluorinated acyclic carboxylic acid ester compound, from 0.5 wt. % 10 wt. %, based on the total weight of the electrolyte, of a fluorinated cyclic carbonate compound; and an electrolyte salt.

An electrode plate includes a current collector and an active material layer provided on the current collector. The active material layer includes a first composite particle including a first active material particle and a first binder particle and a second composite particle including a second active material particle and a second binder particle. In a thickness direction of the active material layer, the first composite particle is closer to the current collector than the second composite particle. A quantity of the first active material particle contained in the first composite particle is greater than a quantity of the second active material particle contained in the second composite particle. Components of both the first binder particle and the second binder particle include polypropylene.

An electrode plate includes a current collector and an active material layer provided on the current collector. The active material layer includes a first composite particle including a first active material particle and a first binder particle and a second composite particle including a second active material particle and a second binder particle. In a thickness direction of the active material layer, the first composite particle is closer to the current collector than the second composite particle. A quantity of the first active material particle contained in the first composite particle is greater than a quantity of the second active material particle contained in the second composite particle. Components of both the first binder particle and the second binder particle include polypropylene.

According to one embodiment of the present invention, a secondary battery that can be used at a wide range of temperatures and is less likely to be influenced by an environmental temperature is provided. Furthermore, a secondary battery with high safety is provided. An electrolyte obtained by mixing an acyclic ester having high temperature characteristics with a fluorinated carbonic ester at 5 vol. % or higher, preferably 20 vol. % or higher, is used for the purpose of reducing interface resistance between an electrode and an electrolyte, whereby a secondary battery capable of operating at a wide range of temperatures, specifically, at temperatures higher than or equal to −40° C. and lower than or equal to 150° C., preferably higher than or equal to −40° C. and lower than or equal to 85° C. can be achieved.

According to one embodiment of the present invention, a secondary battery that can be used at a wide range of temperatures and is less likely to be influenced by an environmental temperature is provided. Furthermore, a secondary battery with high safety is provided. An electrolyte obtained by mixing an acyclic ester having high temperature characteristics with a fluorinated carbonic ester at 5 vol. % or higher, preferably 20 vol. % or higher, is used for the purpose of reducing interface resistance between an electrode and an electrolyte, whereby a secondary battery capable of operating at a wide range of temperatures, specifically, at temperatures higher than or equal to −40° C. and lower than or equal to 150° C., preferably higher than or equal to −40° C. and lower than or equal to 85° C. can be achieved.

A non-aqueous electrolyte secondary battery according to an aspect of the present disclosure is provided with a negative electrode having: a negative electrode collector: a first negative electrode mixture layer provided on the surface of the negative electrode collector; and a second negative electrode mixture layer provided on the surface of the first negative electrode mixture layer. Each of the first negative electrode mixture layer and the second negative electrode mixture layer contains graphite particles. The ratio (S2/S1) of the inter-particle porosity (S2) of the graphite particles in the second negative electrode mixture layer to the inter-particle porosity (S1) of the graphite particles in the first negative electrode mixture layer is 1.1-2.0. The ratio (D2/D1) of the filling density (D2) of the second negative electrode mixture layer to the filling density (D1) of the first negative electrode mixture layer is 0.9-1.1.

A non-aqueous electrolyte secondary battery according to an aspect of the present disclosure is provided with a negative electrode having: a negative electrode collector: a first negative electrode mixture layer provided on the surface of the negative electrode collector; and a second negative electrode mixture layer provided on the surface of the first negative electrode mixture layer. Each of the first negative electrode mixture layer and the second negative electrode mixture layer contains graphite particles. The ratio (S2/S1) of the inter-particle porosity (S2) of the graphite particles in the second negative electrode mixture layer to the inter-particle porosity (S1) of the graphite particles in the first negative electrode mixture layer is 1.1-2.0. The ratio (D2/D1) of the filling density (D2) of the second negative electrode mixture layer to the filling density (D1) of the first negative electrode mixture layer is 0.9-1.1.

A nonaqueous electrolyte secondary battery that is an aspect of the present disclosure comprises a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer contains graphite particles A and graphite particles B as negative electrode active materials. The graphite particles A have an internal void ratio of 5% or less. The graphite particles B have an internal void ratio of 8-20%. When the negative electrode active material layer is divided in half in the thickness direction, the region of the half to the side of the outer surface contains more graphite particles A than the region of the half to the side of the negative electrode current collector.

A nonaqueous electrolyte secondary battery that is an aspect of the present disclosure comprises a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer contains graphite particles A and graphite particles B as negative electrode active materials. The graphite particles A have an internal void ratio of 5% or less. The graphite particles B have an internal void ratio of 8-20%. When the negative electrode active material layer is divided in half in the thickness direction, the region of the half to the side of the outer surface contains more graphite particles A than the region of the half to the side of the negative electrode current collector.

The non-aqueous electrolyte secondary cell according to an embodiment of the present disclosure has a positive electrode, a negative electrode, and a non-aqueous electrolytic solution. The negative electrode has a negative electrode collector and a negative electrode active material layer provided on the negative electrode collector. The negative electrode active material layer contains graphite particles A and graphite particles B as negative electrode active materials. The graphite particles A have an internal void rate of 5% or below. The graphite particles B have an internal void rate of 8 to 20%. When the negative electrode active material layer is halved in the thickness direction, a region on the half closer to the outer surface contains more graphite particles A than a region on the half closer to the negative electrode collector.