The precise control of the ice crystal growth during a freezing process is of essential importance for achieving porous cryogels with desired architectures. The present work reports a systematic study on the achievement of multi‐structural cryogels from a binary dispersion containing 50 wt% 2,2,6,6‐tetramethylpiperidin‐1‐oxyl, radical‐mediated oxidized cellulose nanofibers (TOCNs), and 50 wt% graphene oxide (GO) via the unidirectional freeze‐drying (UDF) approach. It is found that the increase in the sol's pH imparts better dispersion of the two components through increased electrostatic repulsion, while also causing progressively weaker gel networks leading to micro‐lamella cryogels from the UDF process. At the pH of 5.2, an optimum between TOCN and GO self‐aggregation and dispersion is achieved, leading to the strongest TOCN‐GO interactions and their templating into the regular micro‐honeycomb structures. A two‐faceted mechanism for explaining the cryogel formation is proposed and it is shown that the interplay of the maximized TOCN‐GO interactions and the high affinity of the dispersoid complexes for the ice crystals are necessary for obtaining a micro‐honeycomb morphology along the freezing direction. Further, by linking the microstructure and rheology of the corresponding precursor sols, a diagram for predicting the microstructure of TOCN‐GO cryogels obtained through the UDF process is proposed.

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Development of lithium-ion batteries with composite solid polymer electrolytes (CPSEs) has attracted attention due to their higher energy density and improved safety compared to systems utilizing liquid electrolytes. While it is well known that the microstructure of CPSEs affects the ionic conductivity, thermal stability, and mechanical integrity/long-term stability, the bridge between the microscopic and macroscopic scales is still unclear. Herein, we present a systematic investigation of the distribution of TEMPO-oxidized cellulose nanofibrils (t-CNFs) in two different molecular weights of poly(ethylene oxide) (PEO) and its effect on Li+ ion mobility, bulk conductivity, and long-term stability. For the first time, we link local Li-ion mobility at the nanoscale level to the morphology of CPSEs defined by PEO spherulitic growth in the presence of t-CNF. In a low-MW PEO system, spherulites occupy a whole volume of the derived CPSE with t-CNF being incorporated in between lamellas, while their nuclei remain particle-free. In a high-MW PEO system, spherulites are scarce and their growth is arrested in a non-equilibrium cubic shape due to the strong t-CNF network surrounding them. Electrochemical strain microscopy and solid-state 7Li nuclear magnetic resonance spectroscopy confirm that t-CNF does not partake in Li+ ion transport regardless of its distribution within the polymer matrix. Free-standing CSPE films with low-MW PEO have higher conductivity but lack long-term stability due to the existence of uniformly distributed, particle-free, spherulite nuclei, which have very little resistance to Li dendrite growth. On the other hand, high-MW PEO has lower conductivity but demonstrates a highly stable Li cycling response for more than 1000 h at 0.2 mA/cm2 and 65 °C and more than 100 h at 85 °C. The study provides a direct link between the microscopic dynamic, Li-ion transport, bulk mechanical properties and long-term stability of the derived CPSE and, and as such, offers a pathway towards design of robust all-solid-state Li-metal batteries.

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