LITHIUM ION SECONDARY BATTERY AND METHOD FOR MANUFACTURING THE SAME
There is provided a lithium ion secondary battery comprising a positive electrode containing, as a positive electrode active material, a lithium nickel composite oxide having a layered rock salt structure, a negative electrode containing a negative electrode active material capable of occluding and releasing lithium ions, an electrolyte, and an outer package, wherein the lithium nickel composite oxide is represented by the composition formula LiNi x M 1-x O 2 (x represents a numerical value of 0.75 to 1, and M represents at least one metal element occupying nickel sites other than Ni), and has a crystal phase having, in a full charge state, an interplanar spacing d(003) larger than an interplanar spacing d(003) in a complete discharge state.
1 . A lithium ion secondary battery, comprising: a positive electrode comprising, as a positive electrode active material, a lithium nickel composite oxide having a layered rock salt structure; a negative electrode comprising a negative electrode active material capable of occluding and releasing lithium ions; an electrolyte; and an outer package,
wherein the lithium nickel composite oxide is represented by the composition formula LiNi x M 1-x O 2 where x represents a numerical value of 0.75 to 1, and M represents at least one metal element occupying nickel sites other than Ni; and
the lithium nickel composite oxide has a crystal phase having, in a full charge state, an interplanar spacing d(003) larger than an interplanar spacing d(003) in a complete discharge state.
2 . The lithium ion secondary battery according to claim 1 , wherein the crystal phase has a ratio of the interplanar spacing d(003) in the full charge state to the interplanar spacing d(003) in the complete discharge state of 1.001 or higher.
3 . The lithium ion secondary battery according to claim 1 , wherein x in the composition formula is 0.75 to 0.9.
4 . The lithium ion secondary battery according to claim 1 , wherein M comprises at least one selected from the group consisting of Co, Mn and Al.
5 . The lithium ion secondary battery according to claim 1 , wherein M comprises at least Co and Mn.
6 . The lithium ion secondary battery according to claim 1 , wherein the battery has an upper limit voltage in a range of 3.7 to 4.25 V (vs. Li/Li + ).
7 . A method for manufacturing a lithium ion secondary battery comprising: a positive electrode comprising, as a positive electrode active material, a lithium nickel composite oxide having a layered rock salt structure; a negative electrode comprising a negative electrode active material capable of occluding and releasing lithium ions; an electrolyte; and an outer package, the method comprising:
forming the positive electrode;
forming the negative electrode;
accommodating the positive electrode, the negative electrode and the electrolyte in the outer package,
wherein the lithium nickel composite oxide is represented by the composition formula LiNi x M 1-x O 2 where x represents a numerical value of 0.75 to 1, and M represents at least one metal element occupying nickel sites other than Ni; and
interplanar spacings d(003) of the lithium nickel composite oxide in charge voltages in a range including a lower limit voltage and an upper limit voltage are measured by X-ray analysis, and the upper limit voltage is set in a range in the charge voltages where a crystal phase having an interplanar spacing d(003) larger than an interplanar spacing d(003) in a complete discharge state is present.
8 . The manufacturing method according to claim 7 , wherein the crystal phase has a ratio of the interplanar spacing d(003) in the full charge state to the interplanar spacing d(003) in the complete discharge state of 1.001 or higher.
9 . The manufacturing method according to claim 7 , wherein x in the composition formula is 0.75 to 0.9.
10 . The manufacturing method according to claim 7 , wherein M comprises at least one selected from the group consisting of Co, Mn and Al.
11 . The manufacturing method according to claim 7 , wherein the upper limit voltage is in the range of 3.7 to 4.25 V (vs. Li/Li + ).