Charli hangs up her pure-pop coat and dons the grim trench of robo-chic, infusing “Pop 2” with a newfound gruffness.

Her voice edging into autotune ghostliness, Charli XCX whispers, “Run through a city at midnight to feel like a star / I want it all, even if it’s fake.” The fake is key — few pop releases veer so heavily into the electronic and artificial. “Pop 2” distorts the “Boom Clap” singer’s vocals into a multilayered, brooding melange of sound — largely to her benefit. Charli’s last studio album, “Sucker,” was a headlong dive into pure aural sugar, but this toned-down mixtape builds on the minimalist stylings of “Number 1 Angel,” her first foray into avant-pop.

There’s a sullen, even perversely childish tone to the introductory tracks — fitting, as Charli twists her singing into dolphin-chirp-robot-screeching and declares herself “your femmebot” halfway through the 40-minute mixtape. “Pop 2” takes our pop soul ideal to its natural endpoint: chipmunk cries overlaid and buoyed by hollow vocal samples. Heck, contributing vocalist and songwriter Dorian Electra references “The Ghost in the Shell,” “Ex Machina,” and an assortment of other cyberpunk near-future media.

It’s weird and slightly disconcerting if you’ve grown accustomed to Charli XCX’s previous work, but “Pop 2” succeeds through its absolute devotion to this bizarro-land emptiness. The songs are damn catchy, too, though pieces like “Unlock It” overstay their ear-wormy welcome. They stop short of veering into total computerized mushiness, but still sound peculiarly like fodder for futuristic car commercials.

All but two songs feature other artists, boldly displaying names like MØ, Carly Rae Jepson, and Tove, a list sure to satisfy the alternative-pop aficionado. Their presence diversifies material which would otherwise pall.
The strangest, and strongest, piece on the mixtape is the disarmingly titled “Track 10,” an ethereal, wispy tune constructed on corkscrew autotune scraps and Charli’s haunting recitations of “I blame it on your love / I do,” a haphazard ode to disenchantment and disappointment. The erstwhile android transforms into an embarrassed ex-partner, mournfully admitting romantic guilt in an echo chamber comprised solely of her own vocals. A sweet harp interlude prevents “Track 10” from descending into utter desolation, but it’s a sobering swerve by the “Famous” singer.

Some pieces boast a choral backdrop, elevating Charli’s robotic loneliness into something of a lament. “Delicious” introduces a swelling Catholic-school choir and mumbled outro prayers, as if gently chiding the listener. These digressions from her future-robot schtick prove engaging and add dimension to “Pop 2”’s ethereal aspirations. After all, distort a human voice enough, beyond android anonymity, and it might just start to sound like an angel’s call — maybe.

Grade: B
Release Date: Dec. 15