STEM与日常科技·英语30篇（6）

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可充电电池为何随时间推移逐渐失容

Every time you charge and discharge a lithium-ion battery, microscopic changes occur inside its electrodes and electrolyte.
During charging, lithium ions move from cathode to anode, embedding themselves into graphite layers—a process called intercalation.
Repeated cycling causes some ions to get trapped or react with electrolyte, forming a solid-electrolyte interphase (SEI) layer.
While a thin SEI protects the anode, thickening over time blocks ion pathways and raises internal resistance.
Heat speeds up these side reactions, which is why storing batteries at 50% charge in cool places extends lifespan.
Cathode materials also degrade: nickel-rich types offer high energy density but suffer faster structural fatigue.
Manufacturers now use silicon blends in anodes to absorb more lithium—but swelling remains a key engineering challenge.
Smart chargers limit voltage peaks and avoid full 100% charges unless needed, reducing stress on aging cells.
Battery management systems track cycle count, voltage decay, and temperature history to estimate remaining health.
Understanding this wear helps engineers design longer-lasting batteries for phones, EVs, and grid storage alike.