4C快充锂离子电池的石墨负极和电解液设计OA

Fast-charging capability in lithium-ion batteries(LIBs)is essential for the large-scale commercial success of electric vehicles,and the development of 4 C fast-charging technology is therefore critical.To address the sluggish kinetics of lithium-ion intercalation into graphite—the primary bottleneck for fast charging—this study evaluates soft carbon coating on graphite and the use of ethyl acetate(EA)as an electrolyte solvent.A three-factor,two-level full factorial experiment was conducted to investigate the coating method(solid-phase,liquid-phase),coating amount(1.0%,1.5%),and EA content in the electrolyte(10%,70%).Their effects on internal resistance,storage performance,and cycling performance in LIBs were systematically examined.Increasing graphite disorder through coating and adding EA to enhance electrolyte conductivity reduced internal resistance but deteriorated storage and cycling performance.For internal-resistance optimization,70%EA exhibited the strongest effect,while liquid-phase coating outperformed the 1.5%coating amount,achieving direct-current internal-resistance reductions of 21.12%,4.83%,and 2.53%.For storage performance deterioration,70%EA caused the largest decrease,slightly exceeding that of liquid-phase coating,with capacity-retention drops of 1.26%and 1.17%.The 1.5%coating amount impaired 7-day storage performance but showed no measurable deterioration at 28 days.Under 4 C fast-charging cycling,70%EA caused the most severe degradation,while liquid-phase coating and the 1.5%coating amount produced comparable decreases in 600-cycle capacity retention of 1.58%,0.35%,and 0.33%.For high-temperature cycling,70%EA again had the most detrimental effect,followed by 1.5%coating,inducing capacity-retention losses of 0.97%and 0.24%;liquid-phase coating showed no observable deterioration,demonstrating its advantage.These findings provide valuable guidance for material and system design in 4 C fast-charging LIBs.