A micro-hybrid battery system includes a lithium ion battery module configured to be coupled to an electrical load. The lithium ion battery module includes a housing. The lithium ion battery module also includes a first lithium ion battery cell disposed in the housing and having a first active material chemistry including a first cathode active material and a first anode active material. The lithium ion battery module also includes a second lithium ion battery cell electrically connected to the first lithium ion battery cell and disposed in the housing. The second lithium ion battery cell has a second active material chemistry including a second cathode active material and a second anode active material. The first and second active material chemistries are different such that the first and second lithium ion battery cells have different open circuit voltages.