External mechanical pressure can affect the cycle life of lithium-ion battery. In this paper, theevolution process of the mechanical pressure that a lithium-ion battery was subjected to duringapproximately 3000 cycles under the fixed constraint was studied through charge-discharge cyclingtests of a lithium-ion battery. The effect of external pressure on battery aging in the late cycle stagewas explored through SEM and incremental capacity analysis (ICA). In addition, three groups ofcomparative experiments, including a rigid constraint, an elastic silicone pad constraint and a springconstraint, were set up to explore the influence of different constraint schemes on battery cycle life.The experimental results showed that the mechanical pressure increased due to the aging of the batteryunder the fixed constraint, which could cause the anode material of the battery to crack. In thecomparative experiment, the capacity decrease rate of the spring compression constraint scheme was5.13% and 6.17% lower than those of the other two groups. The ohmic resistance increase rate was8.67% and 12.36% lower than those of the other two groups, and the coulombic efficiency of thespring constraint remained good in the late stage of the cycle. Therefore, the spring constraint schemecan maximize the positive effect of external pressure on lithium-ion batteries by maintaining arelatively stable external pressure. The results presented in this paper have a certain guidingsignificance for the design of the battery pack.
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