Patent ID: 8586222

Claim:
A lithium-ion cell comprising a positive electrode with a lithium-reaction active positive electrode material and a negative electrode with a lithium-reaction active negative electrode material, and an array of discrete reference electrodes carried on a common electrically insulating ceramic substrate for independently determining the state of charge of each of the positive electrode material and negative electrode material; the positive electrode, the negative electrode and the array of reference electrodes carried on the common electrically insulating ceramic substrate being in electrochemical contact with a common electrolyte; the reference electrode array comprising: a first group of at least two duplicate reference electrodes, each of the duplicate reference electrodes comprising a first composition of reference electrode material; and at least one additional group of at least two duplicate reference electrodes, each additional group of duplicate reference electrodes comprising a composition of reference electrode material that is different from the first composition of reference electrode material and from the composition of reference material of each additional group of duplicate reference electrodes; where all such groups of duplicate reference electrodes are grouped on the common electrically insulating ceramic substrate for effectively equivalent determination of an electrochemical potential of the positive electrode material and the negative electrode material and each reference electrode is separately connectable with at least one of the positive electrode material and the negative electrode material.