As　cathode　materials,　LiFePO4　particles　have　been　investigated　after　a　supercritical　carbon　dioxide　(scCO(2))　treatment.　We　first　produced　LiFePO4　through　a　hydrothermal　method.　Then,　scCO(2)　was　introduced　to　change　the　morphology　of　the　particles.　Three　effects　have　been　found　after　the　scCO(2)　treatment;　the　breakup　of　the　aggregated　LiFePO4　platelets　into　separate　plates,　the　purification　of　LiFePO4,　and　the　formation　of　porous　LiFePO4.　Electrochemical　measurements　showed　that　the　performance　of　LiFePO4　greatly　improved　after　the　scCO(2)　treatment.　Finally,　a　theoretical　model　was　used　to　explain　the　mechanism　of　the　morphology　change.