Conversion-reaction-based anode materials for lithium ion batteries (LIBs) such as transition metal oxides have been considered as high-capacity alternatives to graphite. In the conversion reactions, interestingly, microparticles have been known to be superior to nanoparticles in terms of capacity retention along repeated cycles. In this work, a cross-linked two-component binder system of poly(acrylic acid) and carboxymethyl cellulose (PAA/CMC) was used for nanoparticular Co3O4. The binder was characterized by high modulus and strong bonding to the surface oxide of Co3O4. Even without carbon coating, the composite electrodes of nanoparticular Co3O4 in the presence of PAA/CMC showed significantly enhanced cycle retention with improved reversibility of the conversion reaction.