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The release of flammable gases during battery thermal runaway poses a risk of combustion and explosion, endangering personnel safety. The convective and diffusive properties of the gas make it challenging to accurately measure gas state, complicating the assessment of the battery pack exhaust design. In this paper, a thermal resistance network model is established, which is used to calculate the battery thermal runaway propagation. Gas accumulation after thermal runaway venting of a LiFeO4 module is studied using ANSYS Fluent under different venting schemes. The results show that the scheme of battery inversion and simultaneous exhaust from the side and bottom of the module is optimal. The methods and results presented can guide the design of LiFeO4 cell pack runners. [ABSTRACT FROM AUTHOR]

A newly designed dense SiO x@carbon nanotubes (CNTs) composite with a high conductivity of 3.5 S cm−1 and tap density of 1.13 g cm−3 was prepared, in which the CNTs were stripped by physical energy crushing and then coated on SiO x nanoparticles. The composite exhibits high capacities of 835 and 687 mAh g−1 at current densities of 100 and 200 mA g−1, which can be finely persevered over 100 cycles. Benefiting from this promising anode, two new full cells of SiO x@CNTs/LiMn2O4 and SiO x@CNTs/LiNi0.5Mn1.5O4 with high energy densities of 2273 and 2747 Wh kganode−1 (i. e. 413 and 500 Wh kgcathode−1), respectively, were successfully assembled and can cycle more than 400 cycles. Even with further cycling at the elevated temperature of 45 °C, the cells can still deliver relatively high capacities of 568 and 465 mAh ganode−1, respectively, over 100 cycles. Such desired high-energy lithium-ion batteries with working voltages over 4.0 V can be widely developed for diverse applications (e. g. in handheld devices, electric vehicles, and hybrid electric vehicles). The easy extension of the presented synthetic strategy and the configuration of high-energy battery system would be significant in materials synthesis and energy-storage devices. [ABSTRACT FROM AUTHOR]

High-voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathodes suffer from severe capacity degradation during long-term cycling due the manganese dissolution and their high operating voltage (∼4.95 V), which pose serious challenges at the surface or interface. Moreover, both traditional ion-doping and passivation layer coating are difficult to apply consistently to LNMO cathode because of their complicated procedures, especially in large-scale production. To address these issues, a strategy employing HNO 3 /H 2 O 2 leaching in synergy with a sintering process at a mid-temperature of 700 °C was used to achieve selective surface reconstruction. An optimal ratio of reactants was applied to balance the capacity and the cyclic stability of the LNMO cathode. The optimized valence composition of Mn on the material surface mitigates the occurrence of Jahn-Teller distortion, accompanied by a reasonable ratio of ordered and disordered phases and the concentration of oxygen vacancies after sintering, which improves the interface behavior between the electrode and electrolyte. This method delivers a high reversible capacity of 116.5 mAh g -1 after 200 cycles at 0.5 C (1 C = 147 mAh g -1 ) with a capacity retention of 91.30% and 110 mAh g -1 with a remarkably high capacity retention of 86.85% after 500 cycles at 2 C. This balanced approach, utilizing the protective effects of oxidation (O 2 2- ) and the erosive action of acid (H + ), is proposed to achieve regional surface reconstruction of advanced LNMO cathode. This opens up a strategy for improving oxide-based cathode materials with low cost and mass production capability, especially favoring high consistency.

Garnet Li 7 La 3 Zr 2 O 12 (LLZO) is a potential solid electrolyte for solid-state batteries (SSBs) because of its high ionic conductivity, electrochemical stability, and mechanical strength. However, large interface resistances arising from deserted cathodes and rigid garnet/electrode interfaces block its application. In order to deal with this issue, a gel polymer electrolyte (GPE) was introduced into the cathode and both sides of LLZO to achieve a solid-state battery. Especially, the provided GPE could be thermally polymerized and solidified in situ, which would integrate LLZO with both anode and cathode and dramatically simplify the battery manufacturing process. Since the interface from rigid LLZO is improved by the flexible GPE buffer, the inability of flexible GPE to inhibit lithium dendrites is compensated by the rigid LLZO in return. As a result, the interface resistances are reduced from 6880 to 473 Ω, the Li symmetric cell exhibits a flat galvanostatic charge/discharge for 400 h without lithium dendrites, and the solid-state Li|GPE@LLZO|LiCoO 2 battery exerts a capacity retention of 82.6% after 100 cycles at 0.5 C at room temperature. Such an interfacial engineering approach represents a promising strategy to address solid-solid interface issues and provides a new design for SSBs with high performance.

For high-voltage cycling of lithium-ion batteries, a gel polymer Li-ion conductor layer, P(VDF-HFP)/LiTFSI (PHL) with high electrochemical stability has been coated on the surfaces of as-formed LiCoO 2 (LCO) cathodes by a solution-casting technique at low temperature. An LCO cathode coated with around 3 μm thickness of the PHL ultrathin membrane, retains 88.4% of its original capacity (184.3 mA h g -1 ) after 200 cycles in the 3.0-4.6 V range with a standard carbonate electrolyte, while the non-coated one retains only 80.4% of its original capacity (171.5 mA h g -1 ). The reason for the better electrochemical behaviors and high-voltage cycling is related to the distinctive characteristics of the PHL coating layer that is compact, has highly-continuous surface coverage and penetrates the bulk of LCO, forming an integrated electrode. The PHL coating layer plays the role of an ion-conductive protection barrier to inhibit side reactions between the charged LCO surface and electrolyte, reduces the dissolution of cobalt ions and maintains the structural stability of LCO. Further, the PHL coated LCO cathode is well preserved, compared to the uncoated one which is severely cracked after 200 cycles at a charging cut-off voltage of 4.6 V., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)