The global push toward decarbonization and electrification has led to a rapidly growing research effort to achieve ever-increasing device performance goals. These efforts have resulted in novel electrochemical energy storage devices (EESDs) with a variety of chemistries and materials, such as aerogels, which have significantly improved energy densities, power densities, and rate capabilities. To date, using thin-film electrode designs has been the state of the art, but with the need for increased performance, new and innovative approaches are being pursued.

One approach to meeting the continued demand to increase performance is to increase the fraction of active materials in the EESD (i.e., eliminating current collector and separator) by moving to thicker electrodes. Thick electrodes enable high-mass loading of active materials, which can effectively boost capacity and energy density. The increased mass loading of active materials also decreases the relative content of inactive components, such as substrates, current collectors, and separators, which helps to save cost, weight, and volume of the device. For devices with restricted footprint areas, such as on-chip power supplies, the application of thick electrodes can fully utilize the empty volume in these devices, which maximizes their energy storage capacity.

However, using a thick electrode will require finding novel methods to overcome ion-transport limitations. The distance and resistance of electron/ion transport through the electrode proportionally increases with electrode thickness, compared with conventional planar electrodes prepared by stacking dense layers of active materials on current collector films. The decreased efficiency of charge transfer and mass transfer because of inefficient electrical conduction, impeded ion diffusion, and reduced reaction site accessibility can cause inhomogeneous distributions of electric potential, ion concentration, and electrochemical reaction across the electrode. Thus, during charge/discharge, longer time, more electrons/ions, and a higher overpotential are required to fully utilize all active materials in the interior of electrodes, which can degrade the rate capability and undermine the increased energy density.

Here, we identify some critical breakthroughs and strategies that will aid in further improving the performance of EESDs by overcoming the transport limitations. These include promising additive manufacturing techniques, methods to integrate an energy-dense active material into the electrode, the development of 3D-printable inks and resins, and the use of design optimization to predict the optimal architecture of an electrode for a given objective and constraint.

全球对脱碳和电气化的推动导致了快速增长的研究工作，以实现不断提高的设备性能目标。这些努力产生了具有多种化学和材料（例如气凝胶）的新型电化学储能装置 (EESD) ，它们显着提高了能量密度、功率密度和倍率能力。迄今为止，使用薄膜电极设计一直是最先进的技术，但随着对性能提高的需求，人们正在寻求新的创新方法。

满足提高性能的持续需求的一种方法是通过转向更厚的电极来增加 EESD 中活性材料的比例（即消除集电器和隔板）。厚电极可实现活性材料的高质量负载，从而有效提高容量和能量密度。增加活性材料的质量负载也降低了非活性成分的相对含量，例如基板、集电器和隔膜，这有助于节省设备的成本、重量和体积。对于片上电源等占地面积有限的器件，厚电极的应用可以充分利用这些器件中的空体积，从而最大限度地提高其储能能力。

然而，使用厚电极将需要寻找新方法来克服离子传输限制。与通过在集电器薄膜上堆叠致密的活性材料层制备的传统平面电极相比，电子/离子传输通过电极的距离和电阻随电极厚度成比例增加。由于导电效率低下、离子扩散受阻和反应位点可及性降低导致电荷转移和质量转移效率降低，可能导致电极上的电势、离子浓度和电化学反应分布不均匀。因此，在充放电过程中，需要更长的时间、更多的电子/离子和更高的过电位才能充分利用电极内部的所有活性物质，

在这里，我们确定了一些关键的突破和策略，这些突破和策略将有助于通过克服传输限制进一步提高 EESD 的性能。其中包括有前途的增材制造技术、将能量密集型活性材料集成到电极中的方法、可 3D 打印油墨和树脂的开发，以及使用设计优化来预测给定目标和约束条件下电极的最佳结构.