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Performative prediction, as introduced by Perdomo et al, is a framework for studying social prediction in which the data distribution itself changes in response to the deployment of a model. Existing work in this field usually hinges on three assumptions that are easily violated in practice: that the performative risk is convex over the deployed model, that the mapping from the model to the data distribution is known to the model designer in advance, and the first-order information of the performative risk is available. In this paper, we initiate the study of performative prediction problems that do not require these assumptions. Specifically, we develop a reparameterization framework that reparametrizes the performative prediction objective as a function of the induced data distribution. We then develop a two-level zeroth-order optimization procedure, where the first level performs iterative optimization on the distribution parameter space, and the second level learns the model that induces a particular target distribution at each iteration. Under mild conditions, this reparameterization allows us to transform the non-convex objective into a convex one and achieve provable regret guarantees. In particular, we provide a regret bound that is sublinear in the total number of performative samples taken and is only polynomial in the dimension of the model parameter. 

Abstract Developing suitable cathodes of sodium‐ion batteries (SIBs) with robust electrochemical performance and industrial application potential is crucial for the commercialization of large‐scale stationary energy storage systems. Layered sodium transition metal oxides, Na_xTmO₂(Tm representing transition metal), possessing considerable specific capacity, high operational potential, facile synthesis, cost‐effectiveness, and environmentally friendly characteristics, stand out as viable cathode materials. Nevertheless, the prevailing challenge of air‐induced degradation in most Na_xTmO₂significantly increases costs associated with production, storage, and transportation, coupled with a rapid decay in reversible capacity. This inherent obstacle inevitably impedes the advancement and commercial viability of SIBs. To address this challenge, it is essential to decode the chemistry of degradation caused by air exposure and develop protective strategies accordingly. In this review, a comprehensive and in‐depth understanding of the fundamental mechanisms associated with air‐induced degradation is provided. Additionally, the current state‐of‐the‐art effective protective strategies are explored and discuss the corresponding sustainability and scalability features. This review concludes with an outlook on present and future research directions concerning air‐stable cathode materials, offering potential avenues for upcoming investigations in advancing alkali metal layered oxides. 

To address the alerting issue of energy demand, lithium-ion capacitors (LICs) have been widely studied as promising electrochemical energy storage devices, which can deliver higher energy density than supercapacitors (SCs), and have higher power density with longer cycling life than lithium-ion batteries (LIBs). In this work, the active material lithium nickel cobalt manganese oxide LiNi_0.5Co_0.2Mn_0.3O₂(NCM523) is grown on a cotton textile template and building a 3-dimensional (3D) integrity to improve capacitance and energy density of LICs by enhancing the interfacial ion-exchange process. With the 3D structure, the specific discharge capacitance is increased to 718.67 $F{g}^{-1}$at 0.1 $A{g}^{-1}$from that of non-textile NCM523 (265.97 $F{g}^{-1}$), and remains a high capacitance of 254.48 $F{g}^{-1}$at 10 $A{g}^{-1}$in the half-cell capacitors. In addition, the energy density can achieve up to 36.17 $Whk{g}^{-1}$at the power density of 1,200 $Wk{g}^{-1}$in the full-cell capacitor. The textile NCM can maintain an energy density of 28.26 $Whk{g}^{-1}$at the current density of 10 $A{g}^{-1}$and power density of 6,000 $Wk{g}^{-1}$. Our results present promising applications of electrodes with the 3D porous structure for high energy density LICs.