Electrochemical cell, method of producing electrochemical cell, battery pack, and car

A method of producing an electrochemical cell comprising:

• forming a positive electrode material layer on a surface of a positive electrode current collector using a nonaqueous slurry to produce a positive electrode, and the nonaqueous slurry containing an oxide-based solid electrolyte, positive electrode active material particles absorbing and releasing lithium ions at a potential of 3 V (vs. Li/Li+) or more and an oxide-based solid electrolyte layer provided on surfaces of the positive electrode active material particles;
• forming a negative electrode material layer on a surface of a negative electrode current collector using a slurry to produce a negative electrode, and the slurry containing a negative electrode active material and a sulfide-based solid electrolyte;
• and
• disposing the positive electrode and the negative electrode with interposing a sulfide-based solid electrolyte layer between the positive electrode material layer and the negative electrode material layer, and with providing a carbon layer on the positive or negative electrode material layer, or the positive or negative electrode current collector, and integrating a resulting laminate by thermocompression bonding.