The write operation asymmetry of many memory technologies causes different write failure rates at 0 → 1 and 1 → 0 bit-flipping's. Conventional error correction codes (ECCs) spend the same efforts on both bit-flipping directions, leading to very unbalanced write reliability enchantment over different bit-flipping distributions of codewords (i.e., the number of 0 → 1 or 1 → 0 bit-flipping's). In this work, we developed an analytic asymmetric write channel (AWC) model to analyze the asymmetric write errors in spin-transfer torque random access memory (
STT-RAM) designs. A new ECC design concept, namely, contentdependent ECC (CD-ECC), is proposed to achieve balanced error correction at both bit-flipping directions. Two CD-ECC schemes -typical-corner-ECC (TCE) and worst-corner-ECC (WCE), are designed for the codewords with different bit-flipping distributions. Our simulation results show that compared to the common ECC schemes utilized in embedded applications likeHamming code, CD-ECCs can improve the STT-RAM write reliability by 10 − 30× with low hardware overhead and very marginal impact on system performance.
Lithium-thionyl chloride batteries possess the highest specific energies of the batteries that are commercially available. These batteries also have high operating voltages, stable outputs, wide operating temperature ranges, and long storage lives and are of low cost. The main limitation of lithium-thionyl chloride batteries is their low discharge capacity at high discharge rates, which limits their commercial uses. In this study, a porous cathode carbon support was prepared by introducing ammonia bicarbonate as a pore-forming agent. The porous cathode carbon support that formed was systematically characterized by BET, SEM, and XRD. The support was then assembled into an ER18505M battery system, and the electrochemical performance of the battery was characterized. The effect of pore structure on the electrochemical performance was determined and enabled the preparation of a high capacity lithium-thionyl chloride battery with a high discharge rate.
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