Battery and energy system

An energy system, comprising:

• an electric energy generation apparatus for generating electric energy;
• a secondary battery capable of being charged with the electric energy generated by said electric energy generation apparatus and capable of discharging the charged electric energy;
• and
• a line for electrically connecting said electric energy generation apparatus and said secondary battery to each other,
• said secondary battery including
• a positive electrode,
• a negative electrode mainly composed of sodium, and
• an electrolyte provided between said positive electrode and said negative electrode,
• said electrolyte being molten salt containing anions expressed with chemical formula (I) below and cations of metal,
• R1 and R2 in said chemical formula (I) independently representing fluorine atom or fluoroalkyl group, and
• said cations of metal containing at least one of at least one type of cations of alkali metal and at least one type of cations of alkaline-earth metal.

A battery, comprising:

• a positive electrode containing a metal or a metal compound expressed with chemical formula (II) below,
• NaxM1yM2zM3w (II)
• in said chemical formula (II),
• M1 representing any one type of Fe, Ti, Cr, and Mn,
• M2 representing any one of PO4 and S,
• M3 representing any one of F and O,
• a composition ratio x of Na being a real number satisfying relation of 0≦x≦2,
• a composition ratio y of M1 being a real number satisfying relation of 0≦y≦1,
• a composition ratio z of M2 being a real number satisfying relation of 0≦z≦2,
• a composition ratio w of M3 being a real number satisfying relation of 0≦w≦3, and
• relation of x+y>0 and relation of z+w>0 being satisfied;
• a negative electrode mainly composed of sodium;
• and
• an electrolyte provided between said positive electrode and said negative electrode,
• said electrolyte being molten salt containing anions expressed with chemical formula (I) below and cations of metal,
• in said chemical formula (I), R1 and R2 both representing fluorine atom, or R1 representing fluorine atom and R2 representing fluoroalkyl group, and
• said cations of metal containing at least one of at least one type of cations of alkali metal and at least one type of cations of alkaline-earth metal.

An energy system, comprising:

• an electric energy generation apparatus for generating electric energy;
• a secondary battery capable of being charged with the electric energy generated by said electric energy generation apparatus and capable of discharging the charged electric energy;
• and
• a line for electrically connecting said electric energy generation apparatus and said secondary battery to each other,
• said secondary battery including
• a positive electrode,
• a negative electrode mainly composed of sodium, and
• an electrolyte provided between said positive electrode and said negative electrode,
• said electrolyte being molten salt containing anions expressed with chemical formula (I) below and cations of metal,
• in said chemical formula (I), R1 and R2 both representing fluorine atom, or R1 representing fluorine atom and R2 representing fluoroalkyl group, and
• said cations of metal containing at least one of at least one type of cations of alkali metal and at least one type of cations of alkaline-earth metal.