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Mechanical Failure Analysis of Graphite Anode Particles with PVDF Binders in Li-Ion Batteries
Iqbal, Noman,Lee, Seungjun The Electrochemical Society 2018 Journal of the Electrochemical Society Vol.165 No.9
<P>The mechanical failure of electrodes is one of the main mechanisms of degradation in Li-ion batteries. Many studies have been carried out on the fracture inside a single particle; however, studies on particles with binders are limited. In this study, we investigated stress development under the anisotropic lithium flux in a graphite particle partially attached to an ionically non-conductive polyvinylidene difluoride (PVDF) binder. The study reveals that the location of the maximum stress depends on the particle sizes and C-rates due to the anisotropic lithium intercalation and the mechanical failure can initiate with high probability either at the particle center or at the binder interface according to different sizes and C-rates. The simulations showed that small particles under low charging rates tend to produce high stress at the edge of the particle/binder interface, while large particles under high charging rates tend to generate high stress inside the particle. The possible fracture locations are determined by competition of the interface fracture due to expansion and at the inner fracture due to the gradients of lithium concentration. We also studied the effect of binder geometries on the level of stress and found that the stress concentration near the binder edges increases the possibility of the binder debonding as the binder size increases and the angle between the binder and particle decreases. The study will expand to crack propagation in the cluster of particles, eventually linking to the capacity fade issue due to mechanical failures. (C) 2018 The Electrochemical Society.</P>
( Nouman Memon ),( Faizan Iqbal ),( Syed Shahid Noor ),( Kazim Rahim Najjad ),( Muhammad Farhan Sozera ),( Arsalan Abro ),( Noman Khan ) 대한슬관절학회 2021 대한슬관절학회지 Vol.33 No.-
Background: Information regarding the use of hinged implants in non-oncological conditions is limited in our region due to a lack of adequate data collection and follow-up. The purpose of this study is to evaluate mid-term results and risk factors affecting the survivorship of third-generation rotating hinge knee (RHK) patients in nononcological conditions. Methods: We retrospectively reviewed 41 single, third-generation, rotating hinge prostheses in three complex primary knee procedures and 38 revision knee surgeries in between 2007 to 2014. Implant survival was assessed using the Kaplan-Meier method. Factors influencing implant survival were identified using the log-rank test. During the study period, clinical results along with complications were assessed. Clinical outcomes were assessed by using the Knee Society Score (KSS). Results: RHK arthroplasty was used in 41 patients. Out of 41 patients, a RHK was used in three patients with a complex primary deformed knee whereas in 38 patients, a RHK was used in revision arthroplasty surgery. The cumulative implant survival rate with re-revision due to any cause was found to be 87.8% (95% CI 69.2-90.1) at 5-7 years. Prosthetic joint infection, peri-prosthetic fracture and extensor mechanism complications were the commonest mode of failure. The P value was found to be significant when comparing KSS pre-operatively and post-operatively. Conclusion: The cumulative implant survival rate was found to be 87.8%. Prosthetic joint infection was the commonest mode of failure in patients who underwent third-generation RHK surgery for variable indications. Being a patient with a high Charlson comorbidity index is the main risk factor associated with failure of the rotating hinge implant.