Study On Optimization Of Lithium Ion Battery Electrolyte For Titanium Oxide Anode Materials

The electrolyte,cathode and anode materials constitute a lithium-ion battery.The electrolyte plays a key role in ion transmission.Therefore,the type of electrolyte also determines the electrochemical performance and safety performance of lithium-ion batteries,especially at low temperatures.Titanium dioxide?TiO₂?has good structural stability,cycle stability and high safety,and is one of the candidate materials for the next generation of lithium-ion battery anodes.In this paper,by designing the composition of the electrolyte,an optimized conventional liquid electrolyte and gel electrolyte were prepared and applied to TiO₂ and Li₄Ti₅O₁₂ anode,respectively.Thereby improving the electrochemical performance of lithium ion batteries.Different characterization techniques,electrochemical analysis,simulation and calculation were used to optimize the electrolyte of lithium ion batteries with titanium oxide as the anode material.The main research contents are as follows:C-doped TiO₂?B?/graphene nanocomposite was prepared by hydrothermal method and heat treatment,and used as anode for lithium ion batteries.EMC,EC,PC were selected as the organic solvents of the electrolyte,LiBF₄ was used as the electrolyte salt.Adjust the ratio of EMC and EC in the electrolyte,prepare 6 kinds of electrolytes with different EMC/EC ratios,and study the electrochemical performance of different electrolytes at-20?.The electrochemical results and simulation calculations show that:EMC:EC:PC at 7:2:1 in the electrolyte,the TiO₂?B?/graphene anode using this electrolyte shows more excellent low temperature performance at-20°C.When the current density is 0.1 A/g,the discharge specific capacity is 240 mAh/g,which also has excellent rate performance and cycle performance.When the current density is 5 A/g,the discharge specific capacity can reach 105 mAh/g.After 500 cycles at a current density of 2A/g,the discharge specific capacity can still reach 153 mAh/g.Even at-30°C,the TiO₂?B?/graphene anode with the best electrolyte ratio showed very excellent electrochemical performance.Based on polyvinylidene fluoride?PVDF?,PVDF-based gel electrolyte membrane was prepared by electrospinning.Gel electrolyte membranes GP,GP-B,GP-B-CTN3,GP-B-CTN4 and GP-B-CTN5 were prepared by introducing BN and TiO₂ heat-treated at different temperatures.Through a series of characterization tests,showed that the introduction of BN nanosheets improves the mechanical properties of PVDF-based gel electrolytes,and the introduction of inorganic filler TiO₂ improves the ionic conductivity and electrolyte absorption rate of PVDF-based gel electrolyte membranes.Inorganic filler CTN-4 with anatase phase TiO₂?A?and bronze phase TiO₂?B?dual crystal phase has the best lifting effect.Electrochemical results show that commercial Li₄Ti₅O₁₂ anode using GP-B-CTN4 gel electrolytes exhibit reversible discharge capacities of approximately 180and 81 mAh/g at current densities of 0.1 and 5 A/g,respectively.Reversible discharge capacity of 81 mAh/g was retained after 5500 cycles at a current density of 2 A/g.GP-B-CTN4 gel electrolyte also has excellent electrochemical performance and cycle stability.