Secondary battery
AssigneeAsahi Kasei Kogyo Kabushiki Kaisha
InventorsAkira Yoshino, Yumiko Takizawa, Akira Koyama, Katsuhiko Inoue, Masataka Yamashita, Yasufumi Minato, Isao Kuribayashi
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Abstract
A secondary battery is comprising an organic electrolytic solution contained in a casing and, disposed therein, a positive electrode comprised of a lithium-containing composite metal oxide as a cathode active material and a negative electrode comprised of a carbonaceous material as an anode active material, wherein the positive and negative electrodes are separated through a separator disposed therebetween and wherein the organic electrolytic solution has a water content of from 5 ppm to 450 ppm.
Claims17
A secondary battery comprising:
- a casing,
- an organic electrolytic solution contained in said casing, said solution having a water content of from 5 to 450 ppm,
- a positive electrode comprising a lithium-containing composite metal oxide as a cathode active material,
- a negative electrode comprising a carbonaceous material as an anode active material,
- a separator disposed between said positive and negative electrodes, and
- a PTC element which has an operative temperature of from 80.degree. C. to 140.degree. C. and has a sensitive temperature coefficient of from -10 to -130,
- said operative temperature being defined as a temperature at which a resistance value of the PTC element becomes 1000-fold the resistance value measured at room temperature when the PTC element is heated without flowing current,
- said sensitive temperature coefficient being defined as a gradient of a straight line obtained by plotting temperatures, at which, when currents of various values are individually flowed through the PTC element, resistance values of the PTC element individually become 1000-fold the corresponding resistance values measured at room temperature, against the currents in coordinates of current (abscissa) and temperature (ordinate),
- said positive and negative electrodes and separator being disposed in said organic electrolytic solution,
- wherein at least one of said positive and negative electrodes is in the form of a coating composition formed on a metallic current collector, said coating composition comprising an active material corresponding to said respective electrode and a binder, said metallic current collector being formed of a metallic foil having a surface roughness of from 0.1 to 0.9 .mu.m.
A method for preventing gas generation and rapid temperature elevation at overcharge of a secondary battery, thereby ensuring safety of the secondary battery, which comprises:
- providing a PTC element such that said PTC element has an operative temperature of from 80.degree. C. to 140.degree. C. and a sensitive temperature coefficient of from -10 to -130,
- said operative temperature being defined as a temperature at which a resistance value of the PTC element becomes 1000-fold the resistance value measured at room temperature when the PTC element is heated without flowing current,
- said sensitive temperature coefficient being defined as a gradient of a straight line obtained by plotting temperatures, at which, when currents of various values are individually flowed through the PTC element, resistance values of the PTC element individually become 1000-fold the corresponding resistance values measured at room temperature, against the currents in coordinates of current (abscissa) and temperature (ordinate), and
- operably connecting said PTC element to a secondary battery, said secondary battery comprising:
- a casing,
- an organic electrolytic solution contained in said casing, said solution having a water content of from 5 to 450 ppm,
- a positive electrode comprising a lithium-containing composite metal oxide as a cathode active material,
- a negative electrode comprising a carbonaceous material as an anode active material, and
- a separator disposed between said positive and negative electrodes,
- said positive and negative electrodes and separator being disposed in said organic electrolytic solution,
- wherein at least one of said positive and negative electrodes is in the form of a coating composition formed on a metallic current collector, said coating composition comprising an active material corresponding to said respective electrode and a binder, said metallic current collector being formed of a metallic foil having a surface roughness of from 0.1 to 0.9 .mu.m.
Dependencies are inferred from the claim text.