The phenomena of thermal runaway and accidental deformation due to external stresses in lithium batteries or film capacitors consti-tute their primary failure mechanisms.Therefore,monitoring and early warning of overh...The phenomena of thermal runaway and accidental deformation due to external stresses in lithium batteries or film capacitors consti-tute their primary failure mechanisms.Therefore,monitoring and early warning of overheating or localized strain are of great value for the safe use of lithium batteries or film capacitors;however,this function usually requires a system of multiple complex sensors.The realization of the above multiple hazards using a single sensor for monitoring and alarm functions has not been reported.Here,we exploit the thermally induced conductivity and modulus change during solid-liquid conversion of low melting point polyalloys to modulate the electronic relaxation polariza-tion and interfacial polarization in the composites for dielectric switching,and the reduction of alloy particle spacing during bending/compres-sive strain can be used to generate switchable tunneling effects for insulator-conductor transition.By synergizing dielectric switching and insula-tor-conductor transition,the final flexible thermoplastic polyurethane elastomer/low-melting-point polyalloy composite film achieves the func-tional integration of multi-level overheating warning and small deformation monitoring.展开更多
We revisit the classical problem of granular hopping conduction＇s σ∝exp[-（To/T）1/2] temperature dependence, where a denotes conductivity, T is temperature, and To is a sample-dependent constant. By using the hopp...We revisit the classical problem of granular hopping conduction＇s σ∝exp[-（To/T）1/2] temperature dependence, where a denotes conductivity, T is temperature, and To is a sample-dependent constant. By using the hopping conduction formulation in conjunction with the incorporation of the random potential that has been shown to exist in insulator-conductor composites, it is demonstrated that the widely observed temperature dependence of granular hopping conduction emerges very naturally through the immediate-neighbor critical-path argument. Here, immediate-neighbor pairs are defined to be those where a line connecting two grains does not cross or by-pass other grains, and the critical-path argument denotes the derivation of sample conductance based on the geometric percolation condition that is marked by the critical conduction path in a random granular composite. Simulations based on the exact electrical network evaluation of finite-sample conductance show that the configuration- averaged results agree well with those obtained using the immediate-neighbor critical-path method. Furthermore, the results obtained using both these methods show good agreement with experimental data on hopping conduction in a sputtered metal-insulator composite Agx（SnO2）1-x, where x denotes the metal volume fraction. The present approach offers a relatively straightforward and simple expla- nation for the temperature behavior that has been widely observed over diverse material systems, but which has remained a puzzle in spite of the various efforts made to explain this phenomenon.展开更多
基金financially supported by the National Natural Science Foundation of China (No.51503158)Key R&D Program of Hubei Province (No.2023BAB104)Open Project Program of High-Tech Organic Fibers Key Laboratory of Sichuan Province(No.PLN2024-08)
文摘The phenomena of thermal runaway and accidental deformation due to external stresses in lithium batteries or film capacitors consti-tute their primary failure mechanisms.Therefore,monitoring and early warning of overheating or localized strain are of great value for the safe use of lithium batteries or film capacitors;however,this function usually requires a system of multiple complex sensors.The realization of the above multiple hazards using a single sensor for monitoring and alarm functions has not been reported.Here,we exploit the thermally induced conductivity and modulus change during solid-liquid conversion of low melting point polyalloys to modulate the electronic relaxation polariza-tion and interfacial polarization in the composites for dielectric switching,and the reduction of alloy particle spacing during bending/compres-sive strain can be used to generate switchable tunneling effects for insulator-conductor transition.By synergizing dielectric switching and insula-tor-conductor transition,the final flexible thermoplastic polyurethane elastomer/low-melting-point polyalloy composite film achieves the func-tional integration of multi-level overheating warning and small deformation monitoring.
文摘We revisit the classical problem of granular hopping conduction＇s σ∝exp[-（To/T）1/2] temperature dependence, where a denotes conductivity, T is temperature, and To is a sample-dependent constant. By using the hopping conduction formulation in conjunction with the incorporation of the random potential that has been shown to exist in insulator-conductor composites, it is demonstrated that the widely observed temperature dependence of granular hopping conduction emerges very naturally through the immediate-neighbor critical-path argument. Here, immediate-neighbor pairs are defined to be those where a line connecting two grains does not cross or by-pass other grains, and the critical-path argument denotes the derivation of sample conductance based on the geometric percolation condition that is marked by the critical conduction path in a random granular composite. Simulations based on the exact electrical network evaluation of finite-sample conductance show that the configuration- averaged results agree well with those obtained using the immediate-neighbor critical-path method. Furthermore, the results obtained using both these methods show good agreement with experimental data on hopping conduction in a sputtered metal-insulator composite Agx（SnO2）1-x, where x denotes the metal volume fraction. The present approach offers a relatively straightforward and simple expla- nation for the temperature behavior that has been widely observed over diverse material systems, but which has remained a puzzle in spite of the various efforts made to explain this phenomenon.
