Synthesis And Modification Of XLiF-(Ni_1/6Co_1/6Mn_4/6)₃O₄?1?x?2.5? Composite As A Novel Cathode Material

The increasing actual demand of the market requires the improvement of the energy density for the battery system,as a result,the conversion reaction attracts much attention from the researchers,which has become one of the key research directions in the field of electrochemistry.Different from other electrode reactions,the conversion reaction breaks through the restriction of the active material's structural phase change in the reaction process.As long as the phase transition of the reaction system can be reversible,the multi-electron transfer of the active material component can be maximize utilized to obtain multiple capacity….1.We used different high-energy ball milling methods to explore the synthesis of LiF-(Ni_1/6Co_1/6Mn_4/6)₃O₄ composite cathode materials and study their electrochemical properties.The results show that LiF-(Ni_1/6Co_1/6Mn_4/6)₃O₄ composite cathode material can be synthesized by high-energy ball milling with WC grinding beads under argon atmosphere for 24 hours and the specific discharge capacity of the cathode is 114.2 mAh g^-1at 0.05 C(1C=250 mAh g^-1)from 2 V to 4.8 V at room temperature.LiF and(Ni_1/6Co_1/6Mn_4/6)₃O₄ were mixed in a ball mill jar and ball milled at 1000 rmp for 2,6,12,24,36,and 48 hours respectively at a molar ratio of1:1.5?ball ratio:12:1?.it indicates that the product begins to form an amorphous solid solution structure with 12 hours-ball milling and the complex is completely formed after 24 hours.The resultant cathode demonstrates the highest discharge capacity of 157.3 mAh g^-11 when the time of ball milling is 24 hour.Additionally,the cathode materials of LiF and(Ni_1/6Co_1/6Mn_4/6)₃O₄ in different molar ratios?x=1,1.3,1.5,1.7,2,2.5?were synthesized by ball milling for 24 hours,and the highest discharge capacity was acquired when the molar ratio was 1.5:1?x=1.5?.Moreover,the charge-discharge performance of the composite cathode at different cut-off voltage from 4.0 V to 5.3V are tested,the results display that the discharge specific capacity increases with enhanced charge-discharge cut-off voltage.When the cut-off voltage is 5.0 V,the discharge specific capacity reaches 198.6 mAh g^-1.However,after the cut-off voltage is more than 5.1 V,the discharge curve fluctuations are obvious and the specific capacity deteriorates sharply.2.In order to investigate the discharge specific capacity of the 1.5LiF-(Ni_1/6Co_1/6Mn_4/6)₃O₄ composite cathode material at the low voltage end,we expanded the cut-off voltage from 2 V to 1.5 V,and the discharge specific capacity was increased from 157.3 mAh g^-1to 199.6 mAh g^-1.In addition,20wt%graphene was involved with 1.5LiF-(Ni_1/6Co_1/6Mn_4/6)₃O₄composite cathode material by 2 hours high energy ball milling to synthesize 1.5LiF-(Ni_1/6Co_1/6Mn_4/6)₃O₄/Graphene composite.