Electric storage device and electric storage apparatus

A lithium ion secondary battery cell comprising:

• a container:
• an electrode assembly contained in the container, the electrode assembly comprising:
• a positive electrode comprising a positive electrode substrate and a positive electrode active material layer formed on the positive electrode substrate, the positive electrode active material layer containing a positive electrode active material comprising a lithium composite oxide,
• a negative electrode comprising a negative electrode substrate and a negative electrode active material layer formed on the negative electrode substrate, the negative electrode active material containing a negative electrode active material, and
• a separator interposed between the positive electrode and the negative electrode;
• and
• an electrolyte contained in the container, the electrolyte comprising a lithium salt,
• wherein the separator is configured such that a stress that is caused at a specific compressed depth in the separator, which corresponds to 5% of the thickness of the negative electrode active material, is 0.5 MPa or more and 14 MPa or less;
• the negative electrode active material contains hard carbon;
• and
• a ratio of a volume of the electrolyte with respect to a void volume of the lithium ion secondary battery cell is 120% or more and 180% or less.